TANYA'S

COMPREHENSIVE GUIDE TO

FELINE CHRONIC KIDNEY DISEASE

 

 

WHAT TO FEED, AND WHAT TO AVOID

 

ON THIS PAGE:


The Absolute Best Food for a CKD Cat...


Food Choices and Controversies


What to Look For in a Food


Therapeutic Kidney Diets


Non-Therapeutic Diets


Foods for Cats with Diabetes, Food Allergies or IBD, or Struvite Crystals


Homemade Foods


Feeding Frequency


Dry Foods Versus Canned Foods


Food Cautions (Including Onion, Garlic, Raw Food and Fish)


 

 

HOME


Site Overview


What You Need to Know First


Alphabetical Index


Glossary


Research Participation Opportunities


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WHAT IS CKD?


What Happens in CKD


Causes of CKD


How Bad is It?


Is There Any Hope?


Acute Kidney Injury


 

KEY ISSUES: PROLONGING LIFE


Phosphorus Control


Hypertension

(High Blood Pressure)


Proteinuria


Anaemia


Kidney Stones


 

KEY ISSUES:

HELPING YOUR CAT FEEL BETTER


Nausea, Vomiting, Appetite Loss and Excess Stomach Acid


Maintaining Hydration


Constipation


Potassium Imbalances


Metabolic Acidosis

 

SUPPORT


Coping with CKD


Tanya's Support Group


Success Stories


 

SYMPTOMS


Alphabetical List of Symptoms and Treatments


Fluid and Urinary  Imbalances (Dehydration, Overhydration and Urinary Issues)


Waste Product Regulation Imbalances (Vomiting, Appetite Loss, Excess Stomach Acid, Gastro-intestinal Problems, Mouth Ulcers Etc.)


Phosphorus and Calcium Imbalances


Miscellaneous Symptoms (Pain, Hiding Etc.)


 

DIAGNOSIS: WHAT DO ALL THE TEST RESULTS MEAN?


Blood Chemistry: Kidney Function, Potassium, Other Tests (ALT, Amylase, (Cholesterol, Etc.)


Calcium, Phosphorus, Parathyroid Hormone (PTH) and Secondary Hyperparathyroidism


Complete Blood Count (CBC): Red and White Blood Cells: Anaemia and Infection


Urinalysis (Urine Tests)


Other Tests: Ultrasound, Biopsy, X-rays etc.


Renomegaly (Enlarged Kidneys)


Which Tests to Have and Frequency of Testing


Factors that Affect Test Results


Normal Ranges


International and US Measuring Systems


 

TREATMENTS


Which Treatments are Essential


Fluid and Urinary Issues (Fluid Retention, Infections, Incontinence, Proteinuria)


Waste Product Regulation (Mouth Ulcers, GI Bleeding, Antioxidants, Adsorbents, Azodyl, Astro's CRF Oil)


Phosphorus, Calcium and Secondary Hyperparathyroidism (Calcitriol)


Miscellaneous Treatments: Stem Cell Transplants, ACE Inhibitors - Fortekor, Steroids, Kidney Transplants)


Antibiotics and Painkillers


Holistic Treatments (Including Slippery Elm Bark)


ESAs (Aranesp, Epogen etc.) for Severe Anaemia


General Health Issues in a CKD Cat: Fleas, Arthritis, Dementia, Vaccinations


Tips on Medicating Your Cat


Obtaining Supplies Cheaply in the UK, USA and Canada


Working with Your Vet and Recordkeeping


 

DIET & NUTRITION


Nutritional Requirements of CKD Cats


The B Vitamins (Including Methylcobalamin)


What to Feed (and What to Avoid)


Persuading Your Cat to Eat


Food Data Tables


USA Canned Food Data


USA Dry Food Data


USA Cat Food Manufacturers


UK Canned Food Data


UK Dry Food Data


UK Cat Food Manufacturers


2007 Food Recall USA


 

FLUID THERAPY


Intravenous Fluids


Subcutaneous Fluids


Tips on Giving Subcutaneous Fluids


How to Give Subcutaneous Fluids with a Giving Set


How to Give Subcutaneous Fluids with a Syringe


Subcutaneous Fluids - Winning Your Vet's Support


Dialysis


 

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Home > Diet and Nutrition > Which Foods to Feed, and Which to Avoid

 


Overview


  • Diet is a useful way of controlling CKD and helping your cat cope better with the disease. This page discusses which foods to feed. It contains information on therapeutic kidney diets, including what to do if your cat refuses to eat the diet which your vet recommends.

  • It also discusses other food options, i.e. non-therapeutic commercial cat foods and homemade foods, and what to feed if your cat has another health problem with particular dietary requirements.

  • There is also information on certain foods which are not suitable for cats.

  • Please also read the Nutritional Requirements page for more information on feline nutritional needs, such as the role of protein.


The Best Food for a CKD Cat...


 

...is a food that the cat will eat. I'm not trying to be flippant here. You can source the most expensive, organic, wholesome food on the planet, but if your cat would rather starve than eat it, it is of no use whatsoever.

 

It is not only I who thinks it is more important that a cat eats than that a cat eats certain foods. In Nutritional management of renal disease (2008) Presentation to the World Small Animal Veterinary Association World Congress Dr K Sturgess says "It is vital that the cat eats something, as body protein catabolism will have more serious adverse effect on CRD than almost any diet."

 

In 11 guidelines for conservatively treating chronic kidney disease (2007) Polzin D, Veterinary Medicine December 2007, Dr Polzin makes the shocking observation that "in many or most dogs and cats with chronic kidney disease, death or euthanasia results directly or indirectly from starvation."

 

Are you going to let your cat starve to death? I doubt it! So please read below about the best food choices and try to feed them, but if your cat refuses to eat them, alternatives are discussed too. Bottom line, your cat is going to eat!

 


Food Choices and Controversies


 

There is an amazing variety of opinions on what is the best food for healthy cats, and many of those opinions are strongly held. I sometimes get e-mails reproaching me for not advocating feeding x, y or z food. I've been told I'm condemning cats to death for not insisting my readers feed raw. Apparently even looking at a food containing by-products means I am heading for eternal damnation. I get referred to various websites, all of which I'm already familiar with, and none of which, whilst they may have some good points, convinces me that they have discovered the Holy Grail of feline nutrition.

 

It all reminds me of some kind of fundamentalist religion. My way good, your way bad. Please! We're talking cat food here, not the meaning of life. There are not that many studies into feline nutritional requirements, so many of the claims out there are simply personal opinion and prejudices. People love certain manufacturers. They hate others. Big names are suspect. Small firms are great. This despite the fact that both types of manufacturers may have their food manufactured in the exact same factory, by the exact same methods, using the exact same people and machinery and even in some cases the exact same ingredients, as came to light during the 2007 US food recall scandal.

 

Remember, if there were one perfect food for healthy cats out there, we'd all be feeding it, and all the manufacturers who didn't make it would go bankrupt. But there is no such food, so we must just do the best we can.

 

Like everybody else, I have my prejudices. But unlike many others out there, I'm not trying to sell you anything. I've just spent sixteen years researching CKD and I try to present everything as impartially as I can.

 

This website focuses on the nutritional needs of CKD cats. You may need to put your preferences for a "good food" aside and accept that quite often with a CKD cat, just getting any food into your cat is an encouraging start; getting him/her to eat a food appropriate for the CKD is an achievement; and feeding foods you think are "good" is a bonus.

 

I've had three CKD cats. I know the stress and guilt of the diagnosis - and no, you didn't cause the CKD by the foods you chose to feed to your cat. I also know the stress and worry of trying to get food into a CKD cat. I'm not going to give you a guilt trip on top of that. If manufacturer A is apparently loathed but makes a food my cat loves, that's good enough for me. My cat doesn't care. She doesn't do marketing and hype. She just eats. And when she eats, I feel very relieved, and very happy.

 

The savvy cat owner's guide: nutrition on the internet (2013) by the World Small Animal Veterinary Association Global Nutrition Committee gives tips on using nutritional resources online safely.

 


What to Look For in a Food


 

When it comes to food, here is what I recommend for CKD cats:

  1. Therapeutic kidney diets are proven to have benefits for CKD cats. I would definitely feed one of these foods if my cat would eat it, though in earlier stage CKD I would probably not feed the food exclusively, or would supplement it with additional nourishment (there is more on this below).

  2. The need for a reduced protein food is much debated, at least in the early stages of CKD (IRIS Stage 1 and early Stage 2). See Nutritional Requirements for more on the low protein debate. You do want to feed a food that is high quality protein (which in terms of CKD does not actually mean what you probably think it means).

  3. You should try to feed a food as low in phosphorus as possible. High phosphorus levels will make your cat feel bad and will make the CKD progress faster. Because this is so important, I've created tables of commercial foods in order of phosphorus content for the UK and US markets.

  4. Ideally feed a canned food, because this helps with problems such as dehydration. If your cat is a dry food junkie, you may be able to gradually switch him or her over to wet food. If you can't, don't sweat it. It's more important that your cat eats than that s/he eats a wet food. If your cat is prepared to eat a dry therapeutic kidney diet, I would feed that in preference to a canned non-therapeutic diet (though see point 1 in this list).

  5. I don't like complicated cat foods. I'm not a fan of all those foods containing yummy fruits and vegetables. They are marketed to appeal to you, but your obligate carnivore feline doesn't need them from a nutritional perspective. But if they are the only foods your cat likes, don't stress over it.

  6. I can't get too excited about "bad" ingredients. Who decides what is bad anyway? The Cat Food Police? There are certainly some ingredients I consider complete no-nos, such as onion and garlic, but that is for valid medical reasons (see below). Most of the other stuff, quite frankly, is a matter of personal choice. If I had a choice of feeding my cat a food she loved that contained by-products, for example, or letting her starve to death, the by-products would win every time.

  7. Feed a food your cat will eat! Even at the best of times, cats eat to live rather than live to eat. If you only provide a food your cat doesn't like, s/he will not eat it, especially if s/he is feeling poorly. Getting food into your cat is more important than letting him/her starve to death for your principles or because your cat is "only supposed to eat the therapeutic diet".

So remember your new mantra: my cat must eat!

 


Therapeutic Kidney Diets


 

Most vets will initially recommend that you feed a therapeutic kidney diet, and there are valid reasons for this. This section discusses the various therapeutic diets that are available, how they can help your cat, how to introduce these foods, and what to do if your cat won't eat them. It also explains why you should not feed therapeutic kidney foods exclusively to other family cats.

Composition of Therapeutic Kidney Diets


Everybody seems to know that these foods have reduced protein levels, and some people are aware that they also have reduced phosphorus levels. People therefore sometimes think that if they feed a commercial food that is relatively low in protein and/or phosphorus, they have replicated a therapeutic kidney diet.

 

Unfortunately this is not the case, because there is a lot more to therapeutic CKD diets than reduced protein and/or low phosphorus levels. Staged management of chronic kidney disease in dogs and cats (2009) Polzin D, Presentation to the World Small Animal Veterinary Association World Congress says "A common misconception is that renal diets are simply “low protein diets.” Renal diets encompass a variety of modifications beyond just a limitation of protein content, and, indeed, the principal beneficial effects of these diets may not accrue from their protein content. Thus, simply replacing a renal diet with a standard manufactured diet that is lower in protein content does not meet the guideline of feeding a renal diet. Since inappropriate diets can exacerbate clinical signs of uremia and/or promote progression of CKD, cats and dogs with CKD should be fed a renal diet."

 

So how do therapeutic kidney diets differ to non-therapeutic kidney diets? Diagnostic staging and management of dogs and cats with chronic kidney disease (2012) Ross SJ Presentation to the Australian Veterinary Association NSW Annual Regional Conference states "Compared to adult maintenance diets, diets formulated specifically for dogs and cats with chronic kidney disease typically have reduced protein, phosphorus, and sodium content; increased potassium, B-vitamin content and caloric density; a neutral effect on acid-base balance; and an increased omega-3/omega-6 polyunsaturated fatty acid (PUFA) ratio."

 

You can read about all of these dietary components and why they are important to CKD cats on the Nutritional Requirements page, but here is a brief overview:

 

Calorie Density


Therapeutic kidney diets have a relatively high calorie content. You can check the calorie content of some US foods here (canned) and here (dry). I am working on adding the calorie content to more foods in these tables and also to the UK tables.

 

Protein


It is true that these foods are relatively low in protein. Prolonging life and kidney function (2009) Chew DJ & DiBartola SP CVC in Kansas City Proceedings states that the protein in most of these diets is reduced by a third to a half. However, the key word there is "relatively": it does not mean these foods are too low in protein. On a dry matter analysis basis, most therapeutic kidney diets contain 28-35% protein, which is above the 26% minimum level of protein required by AAFCO for a food to be considered a complete adult food. As you can see from the food data tables, there are quite a lot of commercial non-therapeutic foods with a protein level as low as this, yet nobody refers to them as low protein foods.

 

What is important for CKD cats is that the protein is high quality protein. I hear from people quite regularly who say that they think many therapeutic kidney diets contain poor quality ingredients, so how can the protein within them be considered high quality? I explain more about high quality protein from a CKD perspective below.

 

Phosphorus


Therapeutic kidney diets are also relatively low in phosphorus. Prolonging life and kidney function (2009) Chew DJ & DiBartola SP CVC in Kansas City Proceedings states that the phosphorus level in these foods is reduced by 70 to 80%, but again, this does not mean levels are too low.

 

In contrast to the protein debate, nobody disputes the need to keep the phosphorus levels in foods fed to CKD cats as low as possible. Phosphorus is a mineral essential for good health which is contained in many foods. The body is very good at regulating its phosphorus levels by removing excess phosphorus via the kidneys. However, the kidneys of a CKD cat can no longer efficiently excrete excess phosphorus, so the vast majority of CKD cats will develop levels of phosphorus in their blood which are too high, which can make the cat feel ill and make the CKD progress faster. If you feed foods with a lower phosphorus content, this reduces the workload on the cat's damaged kidneys and reduces the risk of phosphorus levels in the cat's body rising too high.

 

Ideally, as mentioned by Dr Scott Brown in Management of feline chronic renal failure (1998) Waltham Focus 8(3), you want your cat to eat food with less than 0.5% phosphorus on dry matter analysis basis. In practice, most veterinary CKD foods have a phosphorus level of around 0.4%-0.7%, so many of them are above the AAFCO minimum for healthy adult cats of 0.5% on a dry matter analysis basis.

 

Essential Fatty Acids


These foods contain increased levels of essential fatty acids, which appear of increasing importance in the treatment of CKD.

 

Potassium


Therapeutic kidney diets have added potassium, usually in the form of potassium citrate because this can help with metabolic acidosis. According to Prolonging life and kidney function (2009) Chew DJ & DiBartola SP CVC in Kansas City Proceedings, dry CKD therapeutic foods have approximately twice as much potassium as standard dry cat foods.

 

Sodium


They are lower in sodium.

 

B Vitamins


They contain higher levels of B vitamins.

 

Fibre


They usually contain additional fibre.

 

The Benefits of Therapeutic Kidney Diets


I often hear from people who have little enthusiasm for choosing foods from major cat food manufacturers, or who may not have been feeding their cat a commercial diet of any kind, and they are often surprised to hear that if I had a CKD cat, I would try to persuade him or her to eat a therapeutic kidney diet. This is because therapeutic kidney diets are one of the few treatments with strong evidence that they are of benefit to CKD cats. Research indicates that therapeutic diets may:

  • slow the progression of kidney disease;

  • reduce the incidence of crises (which usually include vomiting and appetite loss and which in the worst case may manifest themselves as crashing); and

  • even extend life.

In one older study, Survival of cats with naturally occurring chronic renal failure: effect of dietary management (2000) Elliott J, Rawlings JM, Markwell PJ, Barber PJ Journal of Small Animal Practice 41 pp235-42, 29 cats were fed a reduced protein, low phosphorus therapeutic kidney diet, while a further 21 cats did not eat this diet. Some of the cats (presumably in both groups) were also given phosphorus binders. The cats fed the therapeutic kidney diet survived longer than the other cats, but it is not clear whether this was due to the reduction in phosphorus intake rather than the reduction in protein intake. The study concluded "Feeding a veterinary clinical diet (with intestinal phosphate binders where necessary) specifically formulated for feline renal failure was associated with a highly significant beneficial effect on survival of cats presenting with naturally occurring stable CKD. This is the first prospective dietary study involving naturally occurring feline CKD cases where survival from first diagnosis has been assessed."

 

A later study, Retrospective study of the survival of cats with acquired chronic renal insufficiency offered different commercial diets (2005) Plantinga EA, Everts H Kastelein AM & Beynen AC Veterinary Record 157(7) pp185-187, looked at CKD cats who had been fed therapeutic kidney diets (seven different foods were fed during the study). The cats fed a therapeutic kidney diet survived for more than twice as long as the cats given non-therapeutic diets (16 months versus 7 months). The diet fed to the cat who survived the longest (23 months) contained a relatively high level of essential fatty acids (the food in question was apparently Specific Kidney Support). In this non-randomised, non-double-blinded study, the cats could be fed a non-therapeutic diet for up to 25% of the time.

 

Clinical evaluation of dietary modification for treatment of spontaneous chronic kidney disease in cats (2006) Ross SJ, Osborne CA, Kirk CA, Lowry SR, Koehler LA, Polzin DJ Journal of the American Veterinary Medical Association 229(6) pp949-57 was a double-blinded randomised study which found that feeding a therapeutic kidney diet helped to keep BUN levels lower and appeared to help prevent metabolic acidosis in cats with more advanced CKD. The study concluded "The renal diet evaluated in this study was superior to an adult maintenance diet in minimizing uremic episodes and renal-related deaths in cats with spontaneous stage 2 or 3 CKD." By Stages 2 and 3, they are referring to cats with creatinine between 2.1 and 4.5 mg/dl or 185 and 400 µmol/L (which is not exactly the same range as the IRIS staging system). In this two year study, 22% (five) of the cats eating a standard commercial food died, but none died in the group eating a therapeutic kidney diet. The therapeutic food used (Hill's k/d) contained 28% protein and 0.5% phosphorus on a DMA basis, while the non-therapeutic food contained 46% protein and 0.9-1.0% phosphorus on a DMA basis. The cats were deemed to be eating the therapeutic kidney diet if 85% of their food intake came from this source. Despite the differences in the phosphorus levels in the foods, there was no difference in parathyroid hormone levels between the two groups of cats.

 

In The kidney patient: what's for dinner? (2010) A Presentation to the World Small Animal Veterinary Association World Congress, Dr T Francey states "The administration of a renal diet to dogs and cats with CKD stages 2 and 3 markedly prolonged their renal and overall survival, it decreased the rate of decline of renal function, and it delayed the onset of uremic crises. These findings, although they don't answer the central question of the mechanism of protection, clearly show the value and the benefit of early dietary intervention in animals with CKD. In summary, we now know that dogs and cats with CKD stages 2 and 3 benefit from receiving a renal diet, but we do not know: 1) whether earlier intervention would be more beneficial; 2) whether all renal diets are equal in efficacy; and 3) what in the renal diet is truly beneficial."

 

I know, I know, some of you are still muttering "but I hate the quality of these foods." It is entirely up to you whether you use therapeutic kidney diets, and it may actually be too early for your cat to start one (see below), but please do keep an open mind. Some members of Tanya's CKD Support Group have also been reluctant to use therapeutic kidney diets, but quite a few of them have changed their minds, for the simple reason that their cats feel better on these diets. They have also found that it saves them time and effort because they have been able to cut down on  giving supplements to their cats, such as phosphorus binders or essential fatty acids, because the food meets their cats' requirements without additional supplementation.

 

BalanceIT has a video about nutritional requirements in kidney disease.

Diet considerations in pets with kidney disease (2008) is a video presentation by Dr CL Langston.

Cornell University College of Veterinary Medicine has a short video with information on the composition of veterinary diets.

 

Therapeutic Kidney Diet Choices


Several manufacturers make therapeutic kidney diets, as follows:

US Therapeutic Kidney Diets


There are five brands available in the USA which in principle require a prescription. There are also a couple of foods intended for CKD cats which do not require a prescription. Most of the foods are available in both canned and dry versions. See Obtaining Supplies Cheaply for online suppliers in the USA at reduced prices, including suppliers who will allow you to purchase single cans so you can ensure your cat likes a food before buying a lot of it.

 

Prescription Required


  1. Royal Canin Veterinary Diet Feline Renal Support

  2. Hill's k/d

  3. Hill's g/d, which Hill's considers suitable for early stage CKD.

  4. Iams Veterinary Formula Renal Plus

  5. Purina NF Feline Formula

  6. CliniCare RF This is a complete liquid diet. There is more information about it on the Persuading Your Cat to Eat page.

No Prescription Required


  1. Hi-Tor Neo

  2. Dave's Pet Food Restricted Diet Protein-Phosphorus This food contains alfalfa, presumably because it is thought that alfalfa may support the kidneys. However, alfalfa contains a natural anticoagulant which may increase the risk of bleeding. The Veterinary Support Personnel Network states that alfalfa is toxic to cats. This food also contains parsley and dandelion, which are diuretics and thus not recommended for CKD cats. It is also not clear if this food has increased amounts of essential fatty acids, which are recommended for CKD cats.

  3. Forza10 Renal Active

Here are lists of the composition of the various diets available on a dry matter analysis basis (the calories are as fed):

 

US Canned Therapeutic Kidney Diets

%

Phosphorus

%

Protein

%

Sodium

%

Fat

%

Carbs

Calories

Per Oz

Data Obtained
Hill's Prescription Diet k/d with Chicken 0.40 28.90 0.30 27.00 35.40 33.27 15 Oct 15
Royal Canin Veterinary Diet Renal Support D 0.44 34.21 0.49 34.21 22.24 32.33 30 Oct 15
CliniCare RF Feline Liquid Diet 0.46 27.94 0.27 29.77 27.57 29.63 15 Oct 15
Royal Canin Veterinary Diet Renal Support E 0.46 33.59 0.25 29.59 27.32 29.48 30 Oct 15
Royal Canin Veterinary Diet Renal LP Modified (pâté) 0.47 32.75 0.30 41.83 27.53 35.33 24 Feb 15
Purina Pro Plan Veterinary Diets NF 0.49 34.69 0.21 25.25 tba tba 22 May 14
Hill's Prescription Diet k/d Vegetable & Tuna Stew 0.50 29.40 0.23 24.30 36.40 26.55 15 Oct 15
Hill's Prescription Diet k/d with Ocean Fish 0.50 29.70 0.23 26.70 34.20 34.00 15 Oct 15
Hill's Prescription Diet k/d Chicken & Vegetable Stew 0.50 29.70 0.24 26.80 35.90 26.90 15 Oct 15
Hill's Prescription Diet g/d Early Cardiac-Healthy Aging 0.50 34.30 0.32 19.50 38.60 30.00 15 Oct 15
Royal Canin Veterinary Diet Renal Support T 0.51 31.64 0.51 28.81 30.23 27.33 30 Oct 15
Iams Veterinary Formula Renal Plus 0.58 32.70 0.37 22.96 tba tba 16 May 14

Dave's Pet Food Restricted Diet Protein-Phosphorus Chicken Lickin' Good For Cats*

0.68 30.42 0.25 28.69 tba 31.91 04 Aug 15
Hi-Tor Neo (Premium Flavor) 0.72 36.54 0.43 43.18 tba tba 24 July 14

*Formula changed in 2016, figures may no longer be accurate

 

US Dry Therapeutic Kidney Diets

%

Phosphorus

%

Protein

%

Sodium

%

Fat

%

Carbs

Calories

Per Oz

Data Obtained
Purina Pro Plan Veterinary Diets NF 0.41 30.78 0.20 12.83 tba tba 22 May 14
Iams Veterinary Formula Renal Plus 0.42 32.01 0.39 25.48 tba tba 16 May 14
Royal Canin Veterinary Diet Renal Support S 0.44 25.78 0.44 22.60 41.36 49.75 30 Oct 15
Royal Canin Veterinary Diet Renal Support A 0.45 24.14 0.37 17.84 46.18 43.13 30 Oct 15
Royal Canin Veterinary Diet Renal Support F 0.46 27.13 0.41 17.73 43.41 46.63 30 Oct 15
Forza 10 Renal Active 0.54 tba tba tba tba tba 01 Nov 15
Hill's Prescription Diet k/d 0.60 28.80 0.22 22.10 42.60 118 15 Oct 15
Hill's Prescription Diet g/d Early Cardiac-Healthy Aging 0.60 33.30 0.30 19.10 41.00 111 15 Oct 15

 

If your cat does not like a particular therapeutic kidney food, many of the manufacturers will allow you to return the food for a full refund.

 

Nutritional management of renal disease - an evidence-based approach Nutritional management of renal disease - an evidence-based approach Dr SL Sanderson (2014) Today's Veterinary Practice 4(1) pp51-56 has a helpful table dated early 2014 with details of the composition of the various therapeutic kidney diets, so you can check which has the most essential fatty acids, for example. Don't forget, foods can change without warning.

Pet Food Direct allows you to check the ingredients of many cat foods, both therapeutic and non-therapeutic.

 

UK Therapeutic Kidney Diets


There are four brands available in the UK which in principle require a prescription. There are also a number of foods intended for CKD cats which do not require a prescription. Most of the foods are available in both canned and dry versions. See Obtaining Supplies Cheaply for online suppliers in the UK at reduced prices, most of whom do not require a prescription.

 

Prescription Required


  1. Royal Canin Veterinary Diet Feline Renal Support

  2. Hill's k/d

  3. Purina NF Feline Formula

  4. Eukanuba Renal Formula

No Prescription Required


Many of these foods are German brands. Most of them are available from various online suppliers, including Zooplus.

  1. Specific Kidney Support

  2. Animonda Integra Renal Protect - the kidney foods are labelled Nieren

  3. Affinity Advance Renal Formula

  4. Kattovit Niere/Renal

  5. Pro-Vet Renal

  6. Beaphar Renal Diet

  7. Happy Cat Kidney Diet This food contains some questionable ingredients in my opinion, including dandelion (a diuretic) and garlic. It also does not appear to have increased amounts of essential fatty acids, which are recommended for CKD cats.

UK Canned Therapeutic Kidney Diets

%

Phosphorus

%

Protein

%

Sodium

%

Fat

%

Carbs

Calories per Oz

Data Obtained
Royal Canin Veterinary Diet Renal with Chicken Chunks in Gravy Pouch 0.37 34.78 0.48 34.78 tba tba 15 Oct 15
Hill's Prescription Diet k/d Minced with Chicken 0.38 28.80 0.30 26.90 27.00 33.38 15 Oct 15
Royal Canin Veterinary Diet Renal with Beef Chunks in Gravy Pouch 0.40 34.00 0.50 33.00 tba tba 15 Oct 15
Royal Canin Veterinary Diet Renal with Tuna Chunks in Gravy Pouch 0.40 33.00 0.40 30.00 tba tba 15 Oct 15
Hill's Prescription Diet k/d Tender Chunks in Gravy with Beef Pouch 0.42 28.60 0.24 22.10 41.70 26.02 15 Oct 15
Hill's Prescription Diet k/d Tender Chunks in Gravy Chicken Pouch 0.43 29.20 0.25 22.00 41.20 27.34 15 Oct 15
Purina Veterinary Diets NF 0.43 34.78 0.61 26.09 tba tba 15 Oct 15
Royal Canin Veterinary Diet Renal Loaf 0.44 33.33 0.4 28.89 tba tba 15 Oct 15
Hill's Prescription Diet k/d Tender Chunks in Gravy with Salmon Pouch 0.45 29.40 0.24 23.20 40.00 28.99 15 Oct 15
Specific FKW 0.48 34.26 0.28 43.25 tba tba 15 Oct 15
Affinity Advance Veterinary Diets Renal Failure 0.67 31.67 0.17 30.00 tba tba 15 Oct 15
Animonda Integra Protect Renal Chicken 0.77 38.60 0.86 43.20 tba tba 15 Oct 15
Animonda Integra Protect Renal Pork 0.77 38.60 0.86 43.20 tba tba 15 Oct 15
Animonda Integra Protect Renal Beef 0.77 38.60 0.86 43.20 tba tba 15 Oct 15
Animonda Integra Protect Renal Turkey 0.77 38.60 0.86 43.20 tba tba 15 Oct 15
Kattovit Niere/Renal Lamb 0.78 34.78 0.35 43.48 tba tba 15 Oct 15
Kattovit Niere/Renal Chicken 0.78 34.78 0.35 43.48 tba tba 15 Oct 15
Kattovit Niere/Renal Fish 0.78 34.78 0.35 43.48 tba tba 15 Oct 15
Eukanuba Renal Formula for Cats 0.78 34.78 0.61 26.09 tba tba 15 Oct 15
Beaphar Kidney Diet with Chicken Breast 0.88 44.46 0.10 29.27 tba tba 15 Oct 15
Beaphar Kidney Diet with Pollock 0.88 44.46 0.10 29.27 tba tba 15 Oct 15
Beaphar Kidney Diet with Duck 0.88 44.46 0.10 29.27 tba tba 15 Oct 15
Beaphar Kidney Diet with Lamb 0.88 41.46 0.10 29.27 tba tba 15 Oct 15
Beaphar Kidney Diet with Taurine 0.88 41.46 0.10 29.27 tba tba 15 Oct 15

 

UK Dry Therapeutic Kidney Diets

%

Phosphorus

%

Protein

%

Sodium

%

Fat

%

Carbs

Calories per Oz   Data Obtained
Royal Canin Veterinary Diet Renal RF23 0.32 24.34 0.42 17.99 tba tba 15 Oct 15
Eukanuba Renal Formula 0.38 30.43 0.49 25.00 tba tba 15 Oct 15
Animonda Integra Protect 0.38 23.91 0.22 25.00 tba tba 17 Oct 15
Royal Canin Veterinary Diet Renal Select RSE 24 0.43 25.93 0.48 22.75 tba tba 15 Oct 15

Affinity Advance Renal Failure 

0.43 27.17 0.22  16.85 tba tba 15 Oct 15
Specific FKD 0.46 25.54 0.21 26.09 tba tba 15 Oct 15
Royal Canin Veterinary Diet Renal Special RSF26 0.47 27.51 0.42 17.99 tba tba 15 Oct 15
Hill's Prescription Diet k/d 0.47 29.20 0.28 23.00 41.10 118 15 Oct 15
Happy Cat Diet Nieren 0.49 25.99 0.22 21.66 tba tba 15 Oct 15

Virbac VetComplex Renal

0.49 29.35 tba 23.91 tba tba 16 Oct 15
Pro-Vet Renal 0.53 26.09 tba 21.74 tba tba 15 Oct 15

Purina Veterinary Diets NF

0.53 27.81 0.21 12.83 tba tba 15 Oct 15

Kattovit Niere/Renal

0.70 26.00 0.33 22.00 tba tba 15 Oct 15

 

Many people buy a variety of therapeutic kidney foods from a supplier such as zooplus, and then place a larger order once they know which food their cat prefers.

 

Royal Canin used to do a renal palatability pack containing a mix of dry and wet kidney foods so you can see which flavours your cat prefers. This may still be available from your vet.

 

Pets at Home sells individual tins of Eukanuba therapeutic kidney food. You can order online and either have it delivered to your home or collect your order from your local Pets at Home if you wish to save on postage costs.

 

If your cat does not like a particular therapeutic kidney food, many of the manufacturers will allow you to return the food for a full refund.

 

Zooplus allows you to check the composition of many cat foods, both therapeutic and non-therapeutic.

 

Nutritional management of renal disease - an evidence-based approach Nutritional management of renal disease - an evidence-based approach Dr SL Sanderson (2014) Today's Veterinary Practice 4(1) pp51-56 has a helpful table dated early 2014 with details of the composition of the various therapeutic kidney diets, so you can check which has the most essential fatty acids, for example. Don't forget, foods can change without warning, and foods available in Europe may differ from those in the table.

 

When to Start a Therapeutic Kidney Diet


Therapeutic kidney diets used to be routinely recommended for all CKD cats. However, in order to avoid weight loss and muscle wasting in cats with early stage CKD who might not benefit massively from early dietary changes, it is now usually not recommended to start them too soon. On the other hand, the longer you leave it, the lower your chances are of persuading your cat to accept a new food, and your cat would have less time to benefit from the therapeutic diet.

 

So when should you start such a diet? Prolonging life and kidney function (2009) Chew DJ & DiBartola SP CVC in Kansas City Proceedings states "Protein restriction should be considered when moderate to severe azotemia persists in the wellhydrated state. The clinician should strike a balance between reducing protein intake and the animal's willingness to eat... If possible, the animal should be acclimated to the new diet while its appetite is still reasonably good."

 

The International Renal Interest Society divides CKD into stages (see How Bad is It?) and suggests starting a veterinary diet in Stage 2, i.e. when the cat's creatinine is over 1.6 mg/dl or 140 µmol/L. However for cats with proteinuria, it states "feed a renal clinical diet" regardless of the stage the cat is in. It also says that introducing a therapeutic diet "may be accomplished more easily early in the course of CKD, before inappetance develops."

 

Another thing to consider when deciding when to introduce a therapeutic kidney diet is your cat's BUN (urea) level. BUN is influenced by protein intake, so it does often help the cat feel better if you restrict protein intake as the CKD progresses. Generally speaking, once BUN levels are over 60 mg/dl (urea over 21 µmol/L), you are more likely to see symptoms such as vomiting and nausea and a therapeutic diet may help with this. The study that most experts cite when recommending a therapeutic kidney diet is Clinical evaluation of dietary modification for treatment of spontaneous chronic kidney disease in cats (2006) Ross SJ, Osborne CA, Kirk CA, Lowry SR, Koehler LA, Polzin DJ Journal of the American Veterinary Medical Association 229(6) pp949-57. This study found that feeding a therapeutic kidney diet helped to keep BUN levels lower and appeared to help prevent metabolic acidosis in cats with more advanced CKD. The study concluded "The renal diet evaluated in this study [Hill's k/d] was superior to an adult maintenance diet in minimizing uremic episodes and renal-related deaths in cats with spontaneous stage 2 or 3 CKD." By Stages 2 and 3, they are referring to cats with creatinine between 2.1 and 4.5 mg/dl (165 - 400 µmol/L international).

 

So if your cat's creatinine is over 1.6 mg/dl or 140 µmol/L and your cat is eating and not in crisis (e.g. just returned home from a stay at the vet's), I would consider starting a therapeutic kidney diet. If your cat's creatinine is below this level but your cat is stable, I would introduce these foods, especially if your cat has proteinuria, so you know which of them most appeals to your cat, but I would not feed them exclusively (see below).

 

On the other hand, if your cat is underweight or has a very poor appetite, or is recovering from a crisis, I would wait a while - Cats Exclusive Veterinary Center states that it is better not to feed therapeutic kidney diets to thin cats or cats with poor appetites. You should always address possible causes of inappetance, such as excess stomach acid or anaemia, before trying to persuade your cat to eat a therapeutic kidney diet. 

 

I occasionally hear from people with a young CKD cat, maybe even a kitten. It may not be wise to feed a therapeutic kidney diet to a kitten, who is still growing and therefore needs a higher protein intake for growth and  a higher phosphorus intake for proper bone formation. Talk to your vet about this.

 

How to Introduce a Therapeutic Kidney Diet


It is better to get your cat used to a therapeutic kidney diet while his/her appetite is still relatively healthy, rather than trying to effect a switch at a time when your cat feels poorly. If your cat is not eating voluntarily, don't rush to introduce a therapeutic kidney diet. Feeding cats with different nutritional needs: a dilemma in the multicat household (2012) Dr M Scherk Presentation to the 73rd SCIVAC International Congress 2012 says on page 424 "Protein is a preferred flavour, so if a cat is already inappetant, restricting protein may result in inadequate intake of all nutrients, and the protein intake may fall below that required for normal function."

 

Instead, take steps to control any issues which may be causing your cat to feel sick or have no appetite (see Index of Symptoms and Treatments) before trying to introduce a therapeutic diet - the cat may associate feeling sick with the food and refuse to eat it at all; whereas if you had waited until the cat felt a little better, you might have been more successful. This is particularly important if your cat is diagnosed following a crisis and is still under the weather. In 11 guidelines for conservatively treating chronic kidney disease (2007) Polzin D, Veterinary Medicine December 2007, Dr Polzin says "Force-feeding new diets, exposing patients to new diets while hospitalized, or administering medications or other unpleasant events during and around feeding times should all be avoided. A renal diet should be introduced to patients gradually."

 

Diagnostic and Therapeutic Approach to the Anorectic Cat (2001), Stanley Marks, World Small Animal Veterinary Association World Congress 2001 says that it is also better for cats not to introduce any food too quickly because cats are creatures of habit when it comes to food, so introducing it suddenly may reduce your chances of success.

 

Some cats do actually like therapeutic kidney diets (ironically, they are often other family cats who are healthy and do not need them!). If you happen to have a cat who likes the therapeutic diet, it is still better not to try to switch your cat over in one fell swoop, because a sudden change of food may cause diarrhoea.

 

Instead, mix a little of the new food with your cat's favourite food to start with, and gradually increase the proportion of the new food, over a period of several days or even weeks. There is no need to rush the introduction of any new food, therapeutic or otherwise, go at your cat's pace. Diet considerations in pets with kidney disease (2008) is a video presentation by Dr CL Langston which says you can take as long as 4-6 weeks to introduce a therapeutic diet if necessary. Therapeutic kidney diets can be rather dry (even the canned food varieties), so it may also help to start with to put a little tuna water (the water in which tuna is packed) on the food to moisten it and make it taste a little better. You could also try warming the food. Some people have found puréeing the canned food makes it more attractive to their cats.

 

Your vet should advise you how much of a particular food your cat needs. You can also look at the manufacturer's website (there are links here to the various manufacturers) to see how much they recommend, and read here about calorie needs.

 

If you are lucky enough to have a CKD cat who will eat a therapeutic kidney diet, don't buy too much at first. It is a truth universally acknowledged that as soon as you buy 24 cans of a food, your cat will refuse to eat it.

 

You CAN change a cat's diet (2015) is a video with a tip by Dr D Chew on how to change a cat's diet which he states has never failed him yet.

Hill's has tips on changing your cat's diet.

 

Monitoring Cats on a Therapeutic Kidney Diet


Once you have begun a therapeutic kidney diet, you need to monitor your cat's weight and muscle status. I would weigh your cat at least once a week (you can find sources for suitable scales here) and also check his or her body condition score. The World Small Animal Veterinary Association has a Body Condition diagram showing how to gauge your cat's physical condition, as does Purina.

 

Prolonging life and kidney function (2009) Chew DJ & DiBartola SP CVC in Kansas City Proceedings states "Maintenance of stable body weight and serum albumin concentration suggests adequate intake of calories and protein whereas progressive declines in body weight and serum albumin concentration suggest malnutrition or progression of disease and are indications to increase the amount of protein fed."

 

If you notice any weight loss or if your cat seems less muscular, first make sure your cat is definitely eating the food, and eating enough of it - calories and total food intake also matter. If s/he is definitely eating the food, you could speak to your vet about topping up the therapeutic diet with additional high quality protein, such as egg whites. See Persuading Your Cat to Eat for ways to get additional nourishment into your cat.

 

If your cat continues to lose weight, speak to your vet about what to do. It may be that your cat would do better on another therapeutic kidney food, or may actually need another food, either instead of or in conjunction with the therapeutic kidney diet. Feeding cats with different nutritional needs: a dilemma in the multicat household (2012) Dr M Scherk Presentation to the 73rd SCIVAC International Congress 2012 says on page 425 "Just because someone has a specific illness does not automatically mean that the diet designed for that condition is the best diet for that individual. Every time we send home a therapeutic diet, we are performing a feeding trial with one subject in it (n=1). We have to get the cat back into the clinic and see how he/she is doing on that food. How is his weight? Increased? Decreased? How is his coat? Does he eat with enjoyment or vigour? What are his stools like (moist logs or dry pellets, cow patties or coloured water)? How energetic is he?...If his weight has decreased, is it because he isn't eating enough of the food we are giving him or is it because we aren't giving him enough of it? OR (and only once we have asked the previous questions can we consider this) is it because his illness has progressed or another illness has arisen." The article includes a very useful algorithm for what to consider if a CKD cat is losing weight.

 

Chronic kidney disease - feline (2010) Polzin DJ Nestlé Purina PetCare Handbook of Canine and Feline Clinical Nutrition pp84-89 has an algorithm on page 89 about when and how to feed a therapeutic kidney diet.

 

When a Cat Refuses a Therapeutic Kidney Diet


Despite your best efforts, you may fail to persuade your cat to eat these foods. It can be particularly scary if your vet returns your cat to you after a session on intravenous fluids and informs you that if you cannot persuade your cat to eat the therapeutic diet, you are effectively killing him or her. Well, I didn't succeed with Tanya and Thomas, so I'm a failure too. But I know more about it now, so here are some tips.

 

Firstly, don't try to introduce such a food when your cat is sick or not eating any food voluntarily - see above for more about this. When Thomas was seriously ill after initial diagnosis and returned home after four days on intravenous fluids (he also had anaemia, which can cause severe loss of appetite), we fed him whatever he would eat, and then tried to provide a more suitable diet once he was stable.

 

Assuming your cat is stable and is eating non-therapeutic food, take as long as you need - as long as 4-6 weeks if necessary.

 

Also try a different therapeutic food - some cats love one brand, but hate the others. You can find lists above of the various US therapeutic kidney diets and UK therapeutic kidney diets. Many vets can give or sell you one can of various varieties, so you can try to find one your cat likes. You can also find retailers who will sell individual cans here.

 

Another solution is to mix the therapeutic food with the lowest phosphorus food your cat will eat, or to add a topping of something tempting (see above and Persuading Your Cat to Eat).

 

If you absolutely cannot persuade your cat to eat any of these foods, please do not feel too despondent. Although the evidence for feeding a therapeutic kidney diet is strong, it is more important that a cat eats than that s/he eats nothing. Don't forget, cats with creatinine below 1.6 mg/dl or 140 µmol/L probably do not need a therapeutic kidney diet yet -    The Merck Veterinary Manual states "Animals in this stage [IRIS Stages 1 and 2] should be fed standard, commercially available maintenance diets, unless they are markedly proteinuric."

 

Even if your cat has more advanced CKD, starvation is far more life-threatening. Cats eat to live rather than live to eat, and if they do not like what is offered, they may simply refuse point blank to eat. This lack of food intake is particularly worrying with cats, because cats who do not eat may develop a condition called hepatic lipidosis (fatty liver disease) where the liver starts to function abnormally. Feline hepatic lipidosis: therapeutic considerations (2011) is a presentation by Dr PJ Armstrong to the 36th World Small Animal Veterinary Association World Congress which mentions that hepatic lipidosis can develop after only 2-7 days of not eating; and it can be life-threatening. Even if the cat does not develop hepatic lipidosis, not eating can be a risk. In Nutritional management of renal disease (2008) Presentation to the World Small Animal Veterinary Association World Congress Dr K Sturgess says "It is vital that the cat eats something, as body protein catabolism will have more serious adverse effect on CRD than almost any diet."

 

In The kidney patient: what's for dinner? (2010) A Presentation to the World Small Animal Veterinary Association World Congress, Dr T Francey states "By individual coaching most dogs and cats can be switched to renal diets and it is important to realize that this change should be made slowly over weeks to months if necessary. In advanced CKD, dietary changes are certainly more difficult and affected animals are less likely to accept diets to which they have not been used. Feeding these animals necessitates either a compromise with more palatable (and less optimal) diets or the use of assisted feeding strategies including feeding tubes."

 

So don't beat yourself up if, after trying your best to get your stable cat on a therapeutic kidney diet, over a period of several weeks if necessary, you simply cannot persuade him or her to eat these foods. You do have to consider your cat's quality of life: would you want to spend the rest of your life eating a food you detest? Feeding cats with different nutritional needs: a dilemma in the multicat household (2012) Dr M Scherk Presentation to the 73rd SCIVAC International Congress 2012 says on page 425 "for well-being, the patient should enjoy the diet offered, regardless of what illness he/she has. It is always more important that they eat, rather than what they eat."

 

Instead, aim for a compromise. You may be able to persuade your cat to eat a food that s/he enjoys that may replicate at least some of the benefits of these foods. Clinical evaluation of dietary modification for treatment of spontaneous chronic kidney disease in cats (2006) Ross SJ, Osborne CA, Kirk CA, Lowry SR, Koehler LA, Polzin DJ Journal of the American Veterinary Medical Association 229(6) pp949-57 is the study with the strongest evidence for therapeutic kidney diets, yet even that states "These findings emphasize the value of considering individual dietary components in the overall assessment of the benefits of dietary therapy. Individually or in combination, similar dietary modifications in the present  study may have minimized the number of uremic crises and mortality rate." See below for tips on choosing a non-therapeutic diet.

 

Therapeutic Kidney Diet Issues


If you purchase a US therapeutic kidney diet, you may note that the packaging says that you are not supposed to feed these diets for longer than six months, or that they are for supplementary or intermittent feeding only. This is because under AAFCO rules these diets are not a complete and balanced diet for a healthy adult cat - this is deliberate, otherwise they would not have their therapeutic qualities, such as low phosphorus levels. Pet Diets explains more about this (search for "supplemental or intermittent feeding" and the first response addresses this issue), and states that it is normally in order to feed these foods on an ongoing basis to CKD cats.

 

Most therapeutic kidney diets contain potassium in the form of potassium citrate. This is a potential concern if you are using an aluminium-based phosphorus binder, because products containing citrate may increase the absorption of aluminium. In practice, most people using therapeutic kidney diets will not also need to use a phosphorus binder; but if you need to use both, check Phosphorus Binders for possible solutions to this problem.

 

Feeding Therapeutic Kidney Diets to Healthy Cats


It seems that many vets suggest that it is acceptable to feed a therapeutic kidney diet to other family cats. I do not understand this. If the food is so potent that it is usually available by prescription only, how would it miraculously have no effect on other, healthy cats? The answer is that it will have an effect: non-CKD cats fed a therapeutic kidney diet for any length of time run the risk of malnutrition, particularly young cats and kittens, because of the reduced protein content of such foods. In a study into the use of a new phosphorus binder which was given to healthy cats, Efficacy and acceptability of the new oral phosphate binder Lenziaren in healthy cats fed a renal diet (2015) King JN, Delport PC, Luus HG, Erasmus HL, Barnes PM & Speranza C Journal of Veterinary Pharmacology and Therapeutics 38(3) pp278–289, a therapeutic kidney diet was also fed and the study states "the choice of baseline in the statistical analyses including group F (renal diet) was challenging due to the unexpected loss of body weight in the renal diet group, which was most pronounced in the acclimatization period."

 

Even for an older cat, it may not be wise to feed a lower protein diet if the cat is basically healthy. In Feeding the older cat to optimize health and longevity (2003) A Presentation to the Waltham Feline Medicine Symposium 2003, Dr LM Freeman states "some nutritionists actually recommend that older cats eat a higher protein level than younger cats. The jury is still out but for older cats without significant kidney disease, it is wise to avoid low protein diets unless there is a specific indication such as severe renal or hepatic disease."

 

I know it can be tricky feeding a multiple cat household. One possible solution is to use a feeder that only allows your CKD cat to eat the food within it - see below for links to such products. Alternatively, you may have to compromise by leaving out a therapeutic kidney food for all the cats when you are out of the house, but feeding the cats separately when you are home. But do always supplement a non-CKD cat with normal cat food. Not only is this better for their health, but it will also save you money - therapeutic diets are expensive.

 

Feeding cats with different nutritional needs: a dilemma in the multicat household (2012) Dr M Scherk Presentation to the 73rd SCIVAC International Congress 2012 pp421-430 is an excellent article about how to feed family cats with differing needs.

 

Meow Space sell systems that permit only one cat to eat a particular food.

Cat Cluez explains how to create a DIY version.

Sureflap is a pet feeder system that works if a cat is microchipped. You can also buy collars with RFID chips which act in a similar way.

 


Non-Therapeutic Diets: Commercial Foods or a Homemade Diet


 

If you are unable to persuade your cat to eat a therapeutic kidney diet, you will have to consider feeding other foods instead. Although therapeutic kidney diets are often the ideal (see above), keeping weight on and your cat eating regularly are more important. The main options are non-therapeutic commercial foods or a homemade diet.

 

Do not introduce any new food suddenly, follow the guidelines for introducing therapeutic diets.

 

Commercial Foods


Commercial Non-Therapeutic Food: Composition


When choosing a non-therapeutic diet, as far as possible you want to replicate the benefits of a therapeutic kidney diet. Unfortunately it is not known exactly what is in the therapeutic kidney diets that makes them so effective, and these foods themselves vary in their composition. You can read more about their main features above.

Low Phosphorus


Even if you do nothing else, aim to feed a food as low in phosphorus as you can. See the Phosphorus page for more information on why this is so important.

 

Ideally, as mentioned by Dr Scott Brown in Management of feline chronic renal failure (1998) Waltham Focus 8(3), you want your cat to eat food with less than 0.5% phosphorus on a dry matter analysis (DMA) basis. In practice, you are unlikely to find any complete adult cat foods in the USA with a phosphorus level lower than 0.5% because that is the minimum phosphorus level required by AAFCO.

 

Of course, you also need your cat to eat. Therefore you may have to have a less ambitious goal, at least to start with, of, say, feeding a food with less than  0.75% or less than 1% phosphorus. If your cat's phosphorus levels (as shown in blood tests) are not too high, you have a bit more room for manoeuvre. But the ultimate aim is to feed your cat a food containing as little phosphorus as possible  

 

Chronic kidney disease (CKD) in dogs and cats - staging and management strategies (2015) A Presentation to the Virginia Veterinary Medical Association 2015 Virginia Veterinary Conference, Dr D Chew has a very useful algorithm on how to control phosphorus levels via food and phosphorus binders.

 

If you think you have found a food which is low in phosphorus, please be sure that you are looking at it on a dry matter analysis (DMA) basis. The labels on cans usually do not provide information on a DMA basis, so that apparently low level of phosphorus is unfortunately unlikely to be accurate. For this reason I have created tables of many UK and US foods showing their phosphorus levels (see below).

 

High Quality Protein


During the breakdown of dietary protein in the digestive process, waste substances are created which are filtered out of the blood by the kidneys and excreted via urination. This is sometimes referred to as the removal of nitrogenous wastes. Unfortunately damaged kidneys find it harder to do this, which is why BUN (urea) levels rise in CKD.

 

Therefore the goal is to feed a protein with the correct balance of amino acids to provide the cat with the ability to maintain and repair bodily tissues but in a form which needs as little breaking down as possible. That is what we mean in this context by "high quality protein." Proteins of this nature are sometimes referred to as having a "high biologic value." The food with the highest biologic value is actually eggs.

 

Some people criticise the quality of the protein in therapeutic kidney diets. These foods may not have the type of protein that you would consider high quality for yourself (e.g. organic chicken breast) but the manufacturers do spend a lot of money trying to create foods that are relatively low in protein but which contain high quality protein from the CKD perspective, and studies do indicate that they tend to achieve this goal.

 

You can compare the phosphorus levels in commercial foods to those in therapeutic kidney diets quite easily because it is simply a matter of percentages; but it is harder to compare the protein levels in foods because you cannot easily measure biologic value. Therapeutic kidney diets have a protein content of around 28-35% on a DMA basis, so when choosing a commercial food, I would advise at least trying to find one with  protein around this level and with meat rather than grain proteins; but the fact remains that if you are feeding a non-therapeutic kidney diet, you are unlikely to be able to determine whether you are feeding high quality protein from a CKD perspective.

 

Other Components


To replicate higher levels of B vitamins and essential fatty acids, you can try adding supplements to your cat's food.

 

Not all CKD cats need additional potassium but if yours does, your vet can recommend a potassium supplement. Many people are not too concerned about sodium levels, but if for some reason you are, the food data tables (see below) do include sodium information.

 

Commercial Non-Veterinary Food: Ingredients and Quality


Many people who write to me do not like the idea of feeding a therapeutic kidney diet, and the most common reason for their reluctance is that they do not like the ingredients in these foods, often considering them to be poor quality compared to the foods they usually feed.

 

This is not the place for me to start a big debate about the best ingredients for cats, which could easily turn into a novel. But just as I mention above that you did not cause your cat's CKD because of the foods you chose to feed, it is equally true that whichever foods you did choose did not prevent your cat developing CKD. CKD is just not that simple.

 

The US Food and Drug Administration has some information on interpreting cat food labels which may help you to choose a good quality food.

So what's in a label really? is a slideshow by the Mark Morris Institute on how to read pet food labels. It addresses some of the issues below.

Pet food myth busters: Answering common questions owners ask about pet food (2015) LM Freeman NAVC/WVC Proceedings has a good overview of pet food issues.

Pet Education explains more about the guidelines of AAFPO (Association of American Feed Control Officials). Note that the amounts given here are minimums.

 

Premium, Natural and Human Grade Foods


As with any lucrative market, there is a lot of marketing and hype about quality cat foods. Let's take a brief look at some of those catchy marketing claims.

Premium Foods


People often assume that I feed so-called premium foods. However, I am not a fan of most premium foods: they often contain fruits and vegetables including cranberries, inappropriate for CKD cats, and in my opinion are unnecessarily complicated foods. Many of these foods seem to me to be designed to appeal to the humans buying them, not to the cat. The Association of American Feed Controls Officials has stated "Because cats and dogs do not select their own foods, and their human owners do, it is not rare at all that labeling and marketing information is designed to appeal to the latest trend in marketing human products."

 

Cats have very little need for fruits and vegetables - normally they would only eat the small amounts contained in a mouse's stomach, and even those would be pre-digested by the mouse - so I do not see the attraction of all those carrots, sweet potatoes and blueberries for my cats. Some of these foods, such as Wellness, are also acidified - many commercial foods are, unfortunately, but again this is not suitable for a CKD cat.

 

If you do decide to feed this type of food (and I know some cats do enjoy them), check the food data tables to find those with the lowest phosphorus levels. If you can't afford such foods, don't worry, because some relatively cheap foods are not as poor in quality as you might have been led to believe.

 

Natural Foods


Natural pet food: a review of natural diets and their impact on canine and feline physiology (2014) Buff PR, Carter RA, Bauer JE & Kersey JH Journal of Animal Science 92(9) pp3781-3791 says "The term "natural," when used to market commercial pet foods or pet food ingredients in the United States, has been defined by the Association of American Feed Control Officials and requires, at minimum, that the pet food be preserved with natural preservatives. However, pet owners may consider natural as something different than the regulatory definition."

 

The Association of American Feed Controls Officials (AAFCO) has also stated "in an effort to appeal to customers, marketers have increasingly used the term on pet food product labeling", and says "Natural is a liberal term that includes more ingredients than it excludes—most pet food ingredients are derived from “plant, animal or mined sources. A feed ingredient can be subject to a number of commonly-used processes during the manufacturing process and still be deemed natural."

 

Human Grade Foods


Some people tell me they have always fed human grade foods and are concerned that therapeutic kidney diets are not of this quality. The Veterinary Information Network quotes the chair of the Association of American Feed Control Officials’ Pet Food Committee as saying that human grade food "is essentially a made-up term used by marketing interests to describe and promote products in light of anthropomorphic responses people have to their pets.”

 

AAFCO says "There have been “human-grade” claims on some pet foods for a few years. This term has no definition in any animal feed regulations. Extremely few pet food products could be considered officially human edible or human-grade. A pet food that actually met these standards would be expensive. While pet owners can buy what they feel is best for their pet, they should understand the definitions and the odds."

 

Please also read the section above about high quality protein from a CKD perspective.

 

By-Products and Poor Quality Ingredients


Many people are reluctant to feed by-products, fearing they are not good quality ingredients. AAFCO defines meat by-products as "the non-rendered, clean parts, other than meat, derived from slaughtered mammals. It includes, but is not limited to, lungs, spleen, kidneys, brain, livers, blood, bone, partially de-fatted low temperature fatty tissue, and stomachs and intestines freed of their contents. It does not include hair, horns, teeth and hoofs. It shall be suitable for use in animal feed. If it bears a name descriptive of its kind, it must correspond thereto.”

 

As you can see, by-products include the parts of an animal which most of us humans would not choose to eat, but it mustn't be forgotten that when cats catch their own prey, they usually eat the lot. If I eat chicken, I prefer chicken breast, but my cats would happily eat giblets. So the presence of by-products in a cat food does not automatically put me off a food (for my cats; I live on chocolate).

 

I know some people dislike feeding food with grains, and try to avoid ingredients such as corn. One grain where I have fewer concerns is corn gluten meal. Corn gluten meal is actually the protein part of corn. As obligate carnivores, cats require a particular mix of amino acids, and corn gluten meal contains all of the ones that cats need (it may be a little low in lysine). Evaluation of meat meal, chicken meal, and corn gluten meal as dietary sources of protein in dry cat food (2005) Funaka M, Oka Y, Kobayashi S, Kaneko M & Yamamoto H, Namikawa K, Iriki T, Hatano Y & Abe M The Canadian Journal of Veterinary Research 69 pp299-304 found that corn gluten meal is almost as bioavailable as chicken meal. I would not choose a food that had corn gluten meal as its first ingredient but if it is further down the ingredient list, it would not be a concern to me.

 

Choosing a Food


So you have ploughed through this page, and your head is spinning and you're now thinking "please just tell me which food to feed!" I wish I could, but sadly it's not that simple - I don't know your cat, his or her particular needs or which foods are available where you live. But, assuming you really, truly cannot persuade your cat to eat a therapeutic kidney diet, here are some suggestions to get you started.

Food Data Tables


n order to make it easier for you to choose a food, I have compiled food data tables showing the phosphorus, protein, sodium and fat levels in many cat foods available in the UK and the USA, including the therapeutic kidney diets and some other therapeutic diets, so you can make comparisons of the components. Many of the UK foods are available in other parts of Europe, whilst most of the US foods are available in Canada.

 

It is not a case of looking at the tables and simply buying the food nearest the top of the table that is available to you locally. The tables simply list commercial cat foods in order of phosphorus content. I am not recommending any of these foods. The Food Data Tables page has more information about how to use the tables and links to them all.

 

How should you use the tables? The first thing to do is to check if the food you have been feeding your cat is on the tables and if so, how much phosphorus, protein etc. it contains. With any luck it will be a food near the top of the table, in which case you can speak to your vet about continuing to feed it.

 

If the food you are feeding is not on the table or is lower down with a higher phosphorus content (remember, you want a food with the phosphorus level as close to 0.5% as possible), you need to consider alternative foods. Many members of Tanya's CKD Support Group go to their local store and try to buy one can of various foods containing phosphorus below 0.75%. They choose foods based on their cat's preferences for texture, ingredients etc and also their own (grain-free etc). You can also contact manufacturers for samples - some will mail cans or vouchers to you. Then experiment to see which, if any, of these foods appeal to your cat and feed the lowest phosphorus food you can, maybe rotating two or more foods (i.e. feeding one food for a day, then another, or feeding one food in the mornings and another later in the day). Make sure you keep notes so you remember which foods may work, because your cat will probably go off whichever food you choose, at least for a while (you may be able to re-introduce such foods later after a break).

 

With canned foods, a lot of cats seem to like a pâté texture, in which case many of the Hill's foods (which are available in both the UK and the USA) are worth trying - a lot of Hill's foods are low in phosphorus and many CKD cats seem to like them.

 

Many senior foods are relatively low in phosphorus and protein, but they may also be lower in fat, which is not ideal for cats who are already on the thin side, or for older cats who tend to have poor fat digestibility.

 

Fancy Feast in the USA (the nearest UK equivalent is Purina Gourmet Gold) is often a big hit with cats but sadly it now has much higher phosphorus levels than it used to, so would not be my first choice, though it is worth keeping it in stock for times of crisis.

 

Foods which resemble human foods, such as Weruva or Applaws, often seem to be popular with CKD cats, and many of these are relatively low in phosphorus but they also tend to be relatively high in protein and relatively low in fat and calories too, so you should monitor your cat's weight closely.

 

Always ensure the food you are feeding is complete. Some of the Applaws foods, for example, are for supplementary feeding only.

 

Personally I would not feed fish-based foods exclusively. See below for more on this.

 

Treats


It can be hard for cats who are used to receiving treats to find that they are suddenly no longer given any. Some people like to use treats to reward their cats, for example after fluids.

 

If your cat normally eats canned food, you may find that a couple of pieces of dry therapeutic kidney food are considered a treat by your cat. Members of my support group have found Royal Canin Veterinary Diet Renal Select RSE 24 good for this because it is crunchy on the outside and soft on the inside. Hill's t/d (designed for dental care) is also popular, and contains only 0.8% phosphorus.

 

There are also one or two kidney-friendly treats available. If your cat really prefers another treat, since treats are only a small part of any diet, I personally would not worry about giving a couple each day.

 

Zooplus sells Beaphar kidney friendly treats.

 

See Persuading Your Cat to Eat for more information.

 


Foods for Cats with Other Conditions (Diabetes, Food Allergies or IBD)


 

Diabetes


For information on diet for cats with both diabetes and CKD, please see the Diabetes page.

 

Food Allergies or IBD (Inflammatory Bowel Disease)


Generally speaking, you need to control IBD over CKD, because it is academic what food you feed if your cat can't keep it down or in.

 

If your cat has IBD or food allergies and has been on a limited ingredient diet, you may be able to continue with this diet because some of these foods are relatively low in phosphorus. For example, Hill's z/d has only 0.64% phosphorus on a dry matter analysis basis in the canned version and 0.69% in the dry. Hill's d/d Duck and Pea canned food is 0.75%. Royal Canin HP Hypoallergenic dry food in the USA is apparently also low phosphorus, but the canned version is not.

 

Royal Canin has recently released a dry food called Feline multifunction renal support with hydrolyzed protein which is designed for cats with both CKD and food allergies.

 

BalanceIT has a video about the nutritional requirements of cats with food allergies.

 

Foods for Cats with Struvite Crystals (Feline Lower Urinary Tract Disease)


Although it is rare, your CKD cat may have struvite crystals. If this is the case, you may need to continue to feed an acidified food. However, many manufacturers now make foods that aim to balance the urine pH rather than to acidify it, so one of these foods may be a better choice for a CKD cat with struvite crystals. Discuss this with your vet.

 

If your cat has calcium oxalate crystals or stones, most therapeutic kidney diets are suitable for this problem, see Kidney Stones.

 


Homemade Foods          


 

Some people feed their cat a homemade diet, either raw or cooked. Since cats have very complex nutritional needs, this is not something which should be undertaken lightly; you need to do a lot of research in order to ensure that you are providing correct levels of essential nutrients. Pet Diets claims that "one survey found that 90% of the homemade diets prescribed by over 100 US veterinarians were not nutritionally adequate for adult dogs or cats". They also state that few recipes in books or on the internet have been properly tested to ensure they are nutritionally complete. Evaluation of recipes for home-prepared diets for dogs and cats with chronic kidney disease (2012) Larsen JA, Parks EM, Heinze CR & Fascetti AJ Journal of the American Veterinary Medical Association 240(5) pp532-8 found that many of the recipes analysed in the study would not meet nutritional needs. It is particularly important to get the ratio of phosphorus to calcium correct, and to ensure that you are providing enough taurine - taurine deficiency can cause blindness and heart failure. You also need to be particularly careful with raw diets since these may increase the risk of salmonella poisoning .

 

If you want to look into making a homemade diet, here are some sites with more information and recipes. Be careful about using a diet with a high amount of carbohydrate since cats have no nutritional requirement for large amounts of carbohydrate. It can also be difficult to work out the fatty acid ratio in a homemade food. Please check with your vet before using any of these diets. Be aware that CKD cats, who often have poor appetites, may not appreciate your culinary efforts.

 

Veterinary Recipes


Home Prepared Dog and Cat Diets (2010) Dr P Schenck has recipes from a vet. Scroll down to Cat Recipe Nutritional Breakdowns Renal, and click on http next to Cat Recipe Nutritional Breakdowns Renal. An excel file will download with five different recipes for CKD cats. Some people have expressed concern regarding baking soda and calcium carbonate being interchangeable in the recipes. Dr Schenck actually addresses this issue on her Amazon page. Please note the comment about working with your vet.

Pet Place offers another recipe from the Pocket Companion to Small Animal Clinical Nutrition, 4th Edition.

BalanceIT is a site run by veterinary nutritionists. It sells supplements which are designed to be used in the free recipes which the site generates based on your cat's particular nutritional needs,  including one for kidney disease, but it also offers free recipes based on supplements (such as fish oils) available from health food stores. The site provides a nutritional breakdown of the recipe you create on a metabolisable energy basis.

Petdiets - in the USA has veterinary nutritionists who  can design a personalised diet for your cat if required.

University of California at Davis in the USA can devise a diet to suit your cat if your vet contacts them and provides current bloodwork. The personalised diet cost around US$250 in 2015.

University of Penn College of Veterinary Medicine offers a similar service.

The American College of Veterinary Nutritionists can help you find a veterinary nutritionist in the USA.

 

Other Homemade Food Resources


USDA National Nutrient Database is a database where you can search for any food ingredient and get a nutritional breakdown, including phosphorus and protein levels.

Pet Place provides a recipe for Hill's homemade CKD food. This recipe was apparently originally provided by Hill's to vets to offer to people whose cats would not eat a commercial diet. Other versions of this recipe which I have seen also included two cups of rice.

Calcium/phosphorus calculator helps you to check the phosphorus:calcium ratio is correct in your homemade food.

Know What You Feed helps you create a homemade diet and check that it is balanced against AAFCO guidelines.

 


Other Dietary Issues


 

How Often to Feed Your Cat


The National Academies of Sciences, Engineering and Medicine report that "If given free access to food, cats will eat between 12 and 20 meals a day, evenly spread out over the 24-hour light-dark cycle. It goes against the nature of the cat to force it to eat only one meal a day."

 

Effects of feeding frequency on water intake in cats (2005) Kirschvink N, Lhoest E, Leemans J. Delvaux F, Istasse L, Gustin P, Diez M Journal of Veterinary Internal Medicine 19 p476 found that cats fed more frequently increased their fluid intake. Free feeding a CKD cat has an additional benefit, namely that feeding little and often may reduce the problem of excess stomach acid, a common problem in CKD cats.

 

Dry food tends to lend itself quite well to free feeding, but canned food may be a better choice for CKD cats. If you are out a lot and wish to free feed canned food, an automatic timed feeder is a good idea.

 

USA


Drs Foster and Smith in the USA sell a variety of feeders.

Mighty Pets sells an eight day automatic feeder for US$71.99.

Petco sells the PetSafe five meal feeder for US$52.99.

Amazon sells the Catmate for US$38.62.

Amazon sells the Petsafe five meal feeder for US$45.39.

Fancy Paws sells a two bowl 48 hour timed feeder for US$35.

 

UK


Pet Planet sells an automatic feeder in the UK for Ł29.99.

Zooplus sells a timed feeder for Ł24.90.

 

Dry Food versus Canned Food


As desert animals, healthy cats do not drink a lot, but instead they obtain moisture from their prey. A mouse, for example, is around 60% water. Canned cat foods contain even more moisture than this, between 75-85% in most cases, so a healthy cat who eats primarily canned food will not drink much at all.

 

Issues with Dry Food


Most dry cat foods only contain 8-10% moisture, so cats who eat dry food do tend to drink more than cats fed on wet food, but they simply cannot take in as much moisture overall as a cat fed on tinned food. The carnivore connection to nutrition in cats (2002) Zoran D Journal of the American Veterinary Medical Association 221 pp1559-67, states "cats eating commercial dry foods will consume approximately half the amount of water (in their diet and through drinking), compared with cats eating canned foods... In older cats that tend to produce urine with a lower concentration, an increase in water consumption becomes even more important to avoid dehydration and development of prerenal azotaemia."

 

This does not mean that dry foods cause CKD. Apparent total tract energy and macronutrient digestibility and fecal fermentative end-product concentrations of domestic cats fed extruded, raw beef-based, and cooked beef-based diets (2012) Kerr KR, Vester Boler BM, Morris CL, Liu KJ, Swanson KS Journal of Animal Science 90(2) pp515-22 found that there was no difference in urine concentration between cats fed the three types of diet used in the study (dry food, raw food and home-cooked food). In fact, the cats fed the raw and homemade diets had higher creatinine levels than the cats fed the dry food, though still within range (these were healthy cats).

 

However, whilst many healthy cats seem to manage fine with dry foods, it may be preferable to give a CKD cat a canned food if possible so as to reduce the possibility of dehydration. The cat food manufacturers produce their therapeutic kidney diets in both dry and canned versions, but I would try to feed your cat the canned version if possible. However, if my CKD cat would not eat canned CKD food but would eat the dry version, I would feed that.

 

Issues with Canned Food


One study, Epidemiologic study of relationships between consumption of commercial canned food and risk of hyperthyroidism in cats (2004) Edinboro CH, Scott-Moncrieff JC, Janovitz E, Thacker HL & Glickman LT Journal of the American Veterinary Medical Association 224 (6) pp 879-886, indicates that cats who eat canned food, particularly from pull-ring cans, appear to be at increased risk of developing hyperthyroidism. It is thought that this may be related to the lining used in these cans, bisphenol-A (BPA), a potential endocrine disrupter. It is therefore probably worth trying to feed your cat food from foil pouches or plastic trays rather than from cans. If you do use cans, be sure to store any leftover food in glass containers in the fridge rather than in the tins themselves. The University of Warwick has more information on this.

 

Effect of water content in a canned food in voluntary food intake and body weight in cats (2011) Wei A, Fascetti AJ, Villaverde C, Wong RK & Ramsey JJ American Journal of Veterinary Research 72(7) pp918-23 found that healthy cats fed a canned diet ate more than cats fed the same diet in freeze-dried form, but took in less energy and "had a significant decrease in body weight." This is perhaps because the amount of water in canned foods makes the cat feel full more quickly.

 

Another possible issue with canned food is that some cats find it harder to eat than dry food. Canned food does not allow cats to get their teeth into it as with a mouse. They often have to lap canned food up, almost as if it is liquid. Many cats do this with foods canned in gravy - my Persians (one of whom is not particularly flat-faced) always seem to simply lick the gravy and leave the chunks. Again, this may lead to a lower calorie intake overall. and in severe cases, the cat may go hungry. For this reason I usually feed pate-style canned food, and as my cats eat and spread the food all over the bowl, I put it back into little piles at intervals.

 

For a CKD cat, a possible compromise, especially with dry food junkies, is to feed them both dry and canned therapeutic kidney diets. Some people do this by feeding a dry therapeutic kidney diet while they are out at work all day, but they then feed the canned food when they are home.

 

Dry foods and risk of disease in cats (2008) Buffington CAB Canadian Veterinary Journal 49 p561-3 states that there is little evidence that dry food contributes to diabetes or ill health generally in cats.

 

AAFP-AAHA Feline Life Stage Guidelines (2010) state (page 48) "Both canned and dry food have been found to support health during all life stages. The panel examined published peer-reviewed evidence-based studies in healthy, client-owned cats for any significant health effect of: feeding canned versus dry food (including contribution to dental health); providing a variety of foods versus a consistent diet; feeding high protein, low carbohydrate versus lower calorie and high fiber diets; feeding raw diets; providing dietary supplements, or access to grass or plants.  Based on the available data, specific recommendations in favor of any of these practices cannot be made."

 

With CKD cats, obviously you wish to avoid dehydration as much as possible, but the most important thing is to keep them eating. If your cat is a dry food junkie, and is prepared to eat a dry therapeutic kidney food, I would feed it. You can always add water to the dry food to make it less dry, though if you do this, you should not leave the food down for too long because it will spoil. An alternative would be to switch to semi-moist renal food in pouches.

 


Food Cautions                                                                                                     


 

The following are not recommended for your CKD cat:

Onion and Garlic


You should never feed anything containing onions to any cat. Onions contain an alkaloid disulfide compound which can damage red blood cells and cause a cat to develop a serious form of anaemia called Heinz body anaemia. This can kill, and particularly susceptible cats may only need to eat a tiny amount of onion for this to happen, although symptoms may take several days to appear.

 

Since garlic is a member of the same family (allium), some people believe the same caution applies to garlic. Sixteen cases of allium poisoning in cats were dealt with by The Veterinary Poisons Information Service (VPIS) in the UK, which is part of the Medical Toxicology Unit at Guy's and St Thomas' Hospital in London. Follow up details were only available for four of these cats. One died, two recovered. As for the fourth, "anaemia and jaundice were ongoing problems at the time of follow up after a cat had eaten garlic cloves."

 

Pet Education has information on both onion and garlic.

The ASPCA has detailed information on onion and also mentions garlic.

Allium species poisoning in dogs and cats (2011) Salgado BS, Monteiro LN & Rocha NS Journal of Venomous Animals and Toxins including Tropical Diseases 17(1) pp4-11 found that all allium species can be toxic to cats and dogs but that cats are 2-3 more times susceptible to damage than other species. It states that poisoning can occur if a 10lb cat eats 10oz (250g) of onion and that it can still be dangerous even if the cat eats smaller amounts over several days.

How much onion or garlic is toxic to pets? (2012) Gwaltney-Brant S is an article by a veterinary toxicologist.

Allium species poisoning in dogs and cats (2005) Cope RB Veterinary Medicine 100 (8) pp562-566 mentions that onions, garlic, leeks and chives are potentially toxic to dogs and cats, and that problems may occur after consumption of a single large quantity or repeated consumption of small amounts, even of dietary supplements rather than garlic or onion themselves.

The National Research Council in the USA provides a summary of the findings from the Committee on Examining the Safety of Dietary Supplements for Horses, Dogs and Cats (2008) and states that the committee was unable to determine a presumed safe intake level of garlic for cats.

Pet Diets is a site owned by Dr Rebecca Remillard, a veterinary nutritionist, which states "the possibility of developing a Heinz body hemolytic anemia appears to be variable between pets, and it is not possible to predict which animals may or may not have such a reaction to onion or garlic." Search for garlic, and it is in the answer to the last question on page 3 (Is it OK to give my pet a garlic pill once a week?)

San Francisco Chronicle has an article by a vet which mentions both onion and garlic.

Heinz body anaemia in cats (2002) is a paper by J Tarigo-Martinie and P Krimer of the University of Georgia College of Veterinary Medicine.

Haematologic changes associated with the appearance of eccentrocytles after intragastric administration of garlic abstract to dogs (2000) Lee KW, Yamato O, Tajima M, Kuraoka M, Omae S & Maede Y American Journal of Veterinary Research 61(11) pp1446-50 found that HCT levels reduced in dogs fed garlic extract, and Heinz bodies were detected. The conclusion was that "foods containing garlic should not be fed to dogs." Cats are even more sensitive to Heinz body anaemia than dogs, so this advice applies even more so to cats.

 

Foods for Urinary Tract Health


People often assume that foods which state that they are designed to "support urinary tract health", or "magnesium-controlled", or words to that effect are intended for CKD cats, but this is not the case.

 

This type of food is acidified because it is designed to treat a different kind of problem called FLUTD (Feline Lower Urinary Tract Disease), where the cat's urine is too alkaline (sometimes referred to as struvite crystals). These foods are not intended for CKD cats at all, because CKD cats tend to have quite high acid levels anyway. Acidified foods may also have the effect of increasing the amounts of potassium lost in the urine, which is bad for most CKD cats.

 

You should also avoid foods that contain cranberries or additional Vitamin C for similar reasons.

 

If your cat has both CKD and struvite crystals, click here.

 

Raw Food


I sometimes hear from people who think a raw food diet will solve all their CKD cat's problems. I wish it were that simple! I'm not opposed to raw diets per se, I considered feeding one myself during the 2007 pet food recall scandal. But feeding raw is not a magic cure for CKD, and there are possible problems:

 

Firstly, it can be hard to create a proper balanced diet. It's not just a case of plonking a piece of raw chicken on a plate and thinking you've cracked it. You need the correct balance of nutrients, and it isn't easy. Please see homemade foods for more information.

 

Secondly, it can be hard to know the protein and phosphorus content of the food you are feeding.  The USDA National Nutrient Database may help with this - it is a database where you can search for any food ingredient and get a nutritional breakdown, including phosphorus and protein levels.

 

The main concern for CKD cats is the risk of infection, because CKD cats are immune compromised, so are more at risk of infection. Septicemic salmonellosis in two cats fed a raw-meat diet (2003) Stiver SL, Frazier KS, Mauel MJ &Styer EL Journal of the American Animal Hospital Association 39 pp538-542, found that raw foods may carry a greater risk of salmonella poisoning. Salmonella bacteriuria in a cat fed a salmonella-contaminated diet (2015) Fauth E, Freeman LM, Cornjeo L, Markovich JE, Janecko N & Weese JS Journal of the American Veterinary Association 247(5) pp525-530 reports on a cat fed a commercial diet that was not processed in the same way as most cat foods. It concludes "Such contamination is of particular concern with raw meat-based diets or diets that have not undergone standard industry cooking practices."

 

Survival of Salmonella Copenhagen in food bowls following contamination with experimentally inoculated raw meat: effects of time, cleaning and disinfection (2006) Scott Weese J & Rousseau J Canadian Veterinary Journal 47(9) pp887–889 found that salmonella could persist in bowls used to hold raw meat despite thorough cleaning. The study states that this was surprising, "particularly their survival following soaking in bleach and washing in a dishwasher at 85°C. Bleach is typically a highly effective disinfectant that would be expected to kill Salmonella spp. However, bleach is less effective in the presence of organic debris, so possibly the small amount of food residue in the bowl was enough to permit survival of the Salmonella sp. in some cases. This likely accounts for the finding that only scrubbing followed by soaking in bleach was effective at reducing the Salmonella sp. contamination. However, even this method of disinfection did not completely eliminate Salmonella bacteria in all bowls."

 

The incidence of salmonella in cats generally is very low, but immune-compromised CKD cats may be at greater risk. Salmonella is a very nasty disease which could push a CKD cat over the edge. At the very least it will probably take a CKD cat longer to recover from it than a healthy cat.

 

Salmonella is not the only risk: Raw meat diets spark concern (2005) is a report by the Journal of the American Veterinary Medical Association which found that 99% of raw meat samples intended for dogs were contaminated with a variety of bacteria. Some people believe that freezing the food before feeding kills pathogens but The New Zealand Food Safety Authority explains that this is not necessarily the case.

 

Current knowledge about the risks and benefits of raw meat-based diets for dogs and cats (2013) Freeman LM, Chandler ML, Hamper BA & Weeth LP Journal of the American Veterinary Medical Association 243(11) pp1549-1558 discusses the pros and cons of raw meat-based diets.

 

In Advising clients who feed raw diets to pets (2005) NAVC Clinician's Brief, Dr R Remillard, a veterinary nutritionist, says "No scientific evidence exists that a raw diet is superior to any dry or canned pet food. As a result, this practice is associated with health risks to pet and family with no demonstrable benefit."

 

The American Veterinary Medical Association advises against feeding raw. If you already feed a raw diet which your cat enjoys and with which you have had no problems, please do discuss whether to continue with your vet. If you have not previously fed raw, I would not recommend starting it because of the possible risks of infection and because it can be quite a change for an already sick cat. There are a few commercially available raw foods which are pasteurised.

 

Tufts University College of Veterinary Medicine discusses raw diets.

 

Fish, Particularly Tuna


Fish is not an ideal food for cats for a number of reasons:

 

Steatitis


If you feed a cat a fish diet exclusively, the cat can develop a condition called steatitis (yellow fat disease), which is caused by a Vitamin E deficiency resulting from the imbalanced diet. Firstly the cat becomes very nervous, and then becomes hypersensitive in all the nerve endings of its skin, so it is very painful for the cat to be touched.

 

The treatment is usually massive doses of vitamin E under a vet's supervision, and discontinuing any food containing vegetable oil or mineral oil because this will deplete the body's stores of vitamin E even more.

 

PetMD has an overview of steatitis.

Pet Place has some information about this condition (no need to register, just click on Close at the bottom of the pop-up).

Armed Forces Institute of Pathology discusses a case of steatitis in a cat (click on Case Study III) - this cat was put to sleep.

 

Lack of Taurine


Fish lacks taurine, an amino acid which cats need to obtain from their food. A lack of taurine in a cat's diet can cause heart and eye problems.

 

Poor Calcium:Phosphorus Ratio


Pro Vet states that "like meat, it is deficient in calcium with an inverse calcium:phosphorus ratio. Coley (or Saithe) a popular fish with cat owners in the UK and the fillet cut contains 15-20 mg calcium per 100g but over 200 mg phosphorus per 100g, a Ca:P ratio of 1:10. Cod and other white fish are similar."

 

Hyperthyroidism


One study, Evaluation of dietary and environmental risk factors for hyperthyroidism in cats (2000) Martin KM, Rossing MA, Ryland LM, DiGiacomo RF, Freitag WA Journal of the American Veterinary Medical Association 217(6) pp853-856, found that "cats that preferred fish or liver and giblets flavors of canned cat food had an increased risk" of developing hyperthyroidism. This may be because of the iodine content in the food.

 

Domoic Acid


Domoic acid is a neurotoxin found in shellfish which can cause permanent neurological damage sometimes referred to as amnesic shellfish poisoning. There are strict regulations on the levels of domoic acid permitted in shellfish for human consumption for this reason.

 

Domoic acid is excreted primarily via the kidneys, so researchers wanted to examine its effects on the kidneys. Characterization of renal toxicity in mice administered the marine toxin domoic acid (2014) Funk JA, Janech MG, Dillon JC, Bissler JJ, Siroky BJ & Bell PD Journal of the American Society of Nephrology 25(6) pp1187-97 found that domoic acid may damage kidneys at levels one hundred times lower than those which cause neurological problems. This research was performed in mice who were given domoic acid directly rather than in shellfish, and earlier studies indicate that this is more likely to cause problems. Further tests are necessary to understand the implications for humans and cats, but in the meantime, it might be wise to avoid feeding shellfish to your CKD cat.

 

Additional Risks for Tuna


 

Addictive Behaviour


Firstly, tuna can be a very addictive food for some cats, to the extent that they will refuse to eat anything else. Since tuna is not a balanced diet for cats, this can be a problem.

 

Neurologic Disturbances


Commercial cat foods formulated from tuna may be balanced, but The Merck Veterinary Manual states that "there are reports of commercial cat food causing severe neurologic disturbances in cats fed an exclusive tuna diet for 7-11 months."

 

Mercury Toxicity


The US Food & Drug Administration has guidelines on the amount of tuna that pregnant women can safely eat. However, the US Environmental Working Group, which worked on the studies with the FDA, believes that human-grade tuna has unusually high levels of the toxic metal methylmercury. They recommend that pregnant women should not eat tuna at all, and that children should eat tuna no more often than once a week. Human-grade tuna tends to consist of the white "meat", while animal-grade tuna tends to consist of the lower grade red "meat", so, at least in theory, animal-grade tuna could contain more pollutants.

 

A 2003 study in The Lancet indicates that eating tuna may not be a problem for pregnant women and children after all (Web MD has a report on this), but I think it might be wiser to err on the side of caution with a sick CKD cat.  A tuna fish diet influences cat behavior (1988) Houpt KA, Essick LA, Shaw EB, Alo DK, Gilmartin JE, Gutenmann WH, Littman CB, Lisk DJ Journal of Toxicolology & Environmental Health 24(2) pp161-72 found that "Cats fed the tuna had elevated tissue levels of mercury and selenium."

 

Thiamine (Vitamin B1) Deficiency


You might decide to feed human grade tuna instead, but that does not avoid another problem associated with tuna, namely vitamin B1 (thiamine) deficiency. Cats who eat tuna regularly can develop this problem - symptoms are often neurological and include the inability to hold up the head (ventroflexion), dilation of the pupils, loss of balance, seizures and death if left untreated. Pet Place has some information about this (no need to register, just click on Close at the bottom of the pop-up). Provet UK has information on this and on the dangers of feeding fish to cats generally.

 

As you can see, feeding fish regularly has some serious health implications for cats. A little fish occasionally is unlikely to be cause for concern, and feeding it for a few days during a time of crisis should not be a problem (in fact, if you're in the UK, I find feeding a bit of fish from the chippy - batter removed - can help with poor appetite in many cats), but I would not recommend feeding it for any length of time or too often, especially tuna.

 

Commercial Fish-Based Foods


Please also read the section immediately above about fish and tuna.

 

I tend to divide fish-based commercial foods into two camps:

  • the "old school type", which are often mixed with other ingredients (e.g. Chicken & Tuna) and which look like, well, catfood; and

  • the newer type foods which often contain fish only. These are often advertised as "natural ingredients" and "high quality" and tend to look like something that would be served to humans in a fancy restaurant.

These newer style foods are becoming increasingly popular with manufacturers, but in most cases they are actually manufactured in Thailand, which seems to be doing an amazing job marketing these foods. Brand names include Weruva, Soulistic, Best Feline Friend and Tiki Cat in the USA, and Schesir, Almo Nature and Cosma in Europe. Many manufacturers are introducing some of this style of food as part of their general range e.g. some of the Fancy Feast Elegant Medley foods.

 

Most commercial cat foods based on fish are usually complete because they do not only contain fish, and are formulated with additional ingredients such as taurine and Vitamin E to prevent steatitis and taurine deficiency. The Merck Veterinary Manual has more information on this (scroll down to thiamine). However, you do need to check the can closely because some commercial fish-based foods are not complete foods e.g. some Applaws foods in the UK.

 

Unfortunately, the newer type foods which only contain fish tend to be extremely low in both fat and calories, so you may find that your cat either needs to eat several cans a day (very expensive) or loses weight on such a food.

 

Personally speaking, I don't think I would choose to feed commercial fish-based foods exclusively. I also would not feed tuna-based ones longer-term exclusively - The Merck Veterinary Manual states that "there are reports of commercial cat food causing severe neurologic disturbances in cats fed an exclusive tuna diet for 7-11 months." However, most cats do seem to love the newer style fish-based foods in particular, so they may be helpful at times when your cat's appetite is poor - you can add a little to your cat's regular food to encourage him/her to eat.

 

One possible compromise is to add the water in which tuna is packed to your cat's veterinary or other diet in order to make it more palatable. See tuna water for more information.

 

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This page last updated: 08 May 2016

 

Links on this page last checked: 16 October 2015

 

   

*****

 

TREATING YOUR CAT WITHOUT VETERINARY ADVICE CAN BE EXTREMELY DANGEROUS.

 

I have tried very hard to ensure that the information provided in this website is accurate, but I am NOT a vet, just an ordinary person who has lived through CKD with three cats. This website is for educational purposes only, and is not intended to be used to diagnose or treat any cat. Before trying any of the treatments described herein, you MUST consult a qualified veterinarian and obtain professional advice on the correct regimen for your cat and his or her particular requirements; and you should only use any treatments described here with the full knowledge and approval of your vet. No responsibility can be accepted.

 

If your cat appears to be in pain or distress, do not waste time on the internet, contact your vet immediately.

 

*****

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If you wish to link to this site, please feel free to do so. Please make it clear that this is a link and not your own work. I would appreciate being informed of your link.