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TANYA'S
FELINE CHRONIC RENAL FAILURE INFORMATION CENTRE
FOOD COMPOSITION AND NUTRITIONAL REQUIREMENTS
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Introduction Diet can be a very useful way of controlling CRF and helping your cat to cope better with the disease. This section contains information on the nutritional requirements of CRF cats, and includes a discussion of the low protein debate. It also discusses other nutritional issues, such as whether to free feed. Please be sure to read the Which Foods to Feed and Persuading Your Cat To Eat pages too.
Whilst it is hard to be precise, a cat needs approximately 30-35 calories per day per pound of body weight, or possibly more if the cat is particularly active. As an example, a 9 lb cat would need 270-315 calories a day. Therefore, as you can see, feeding a teaspoonful of food a day is not going to be enough to maintain your cat's weight, let alone increase it if your cat is too thin.
Stanley Marks discusses feline dietary and calorie needs in Diagnostic and therapeutic approach to the anorectic cat (2001), World Small Animal Veterinary Association World Congress 2001. Metabolizable energy: a way to looks at caloric density by Dr Holly Nash explains how foods vary in terms of the number of calories which are actually available to a cat after digestion. "Pet foods with higher ME numbers provide your pet's body with more concentrated calories for more energy. With a higher ME, your pet's body will receive more energy from a smaller amount of food." This can be helpful for CRF cats who tend not to have much appetite. Petdiets can help you work out how much food your cat needs each day. Click on Pet Nutrition, then on Daily Energy Requirements, enter your cat's weight, then follow the instructions on the site.
Food Composition and Requirements
The usual guidelines for CRF cats are to feed a diet which has added potassium but which is low in protein, phosphorus and sodium. It is helpful to understand the reasoning behind these recommendations.
A healthy cat needs around 30% of its calorie intake to be protein, and since cats are obligate carnivores (which means that they need to eat meat in order to survive), virtually all of that must be animal protein. Protein contains essential amino acids which are necessary for maintaining muscle, but it also creates a large amount of waste, which is processed by the kidneys in the form of urea (BUN). Since urea/BUN levels tend to rise in a CRF cat because the kidneys are working less effectively, many vets recommend a diet low in protein so as to minimise the levels of urea/BUN which are produced. However, there is a lot of controversy about how useful low protein diets are for CRF cats, and when they should be introduced. Many vets recommend a low protein diet immediately; but this is not necessarily a good move. Cats need a relatively high amount of protein in their diets, compared to say, dogs or humans; and if protein is reduced too early, it can cause weight loss, raised liver enzymes, and may in some cases contribute to the development of anaemia. This is particularly true of those CRF cats who leak protein in their urine (proteinuria), leading to low protein levels in the blood. Having said that, the low protein prescription diets claim to have sufficient protein for cats at all stages of CRF. Low protein diets are also of concern for cats with metabolic acidosis, because studies of rats and humans with renal failure show that "acidosis may limit the ability of patients to adapt to dietary protein restrictions" (Nutrition and renal function in cats and dogs: acid-base, electrolytes and renal failure (1999) Polzin DJ, Osbourne CA, James K Supplement to Compendium on Continuing Education for the Practising Veterinarian 21 11(K)). It is not yet certain whether acidosis also affects cats in this way, but it seems reasonable to suspect that it does, given the cat's relatively high requirement for protein. Part of the controversy arises from the fact that the studies which advocate the feeding of lower protein diets to CRF patients were performed on humans and rats, and therefore may not be appropriate for cats, with their uniquely complex nutritional needs. Studies of cats are now being undertaken, but the situation is still unclear. In one recent 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 low protein, low phosphorus veterinary diet, while a further 21 cats did not eat the veterinary diet; some of the cats (presumably in both groups) were also given phosphorus binders. The cats fed the veterinary 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.
In one 1993 study in the USA, Effects of dietary protein and calorie restriction in clinically normal cats and in cats with surgically induced chronic renal failure Adams LG Polzin DJ Osborne CA & O'Brien TD American Journal of Veterinary Research 54 pp1653-1662, CRF cats were fed either high (38%) or low (20%) protein diets for one year. The cats fed a high protein diet had higher urea (BUN) levels (as might be expected) than the cats fed a low protein diet but they also had lower creatinine levels; and they also ate more and gained weight compared to the cats on the low protein diet. Some of the cats fed the high protein diet did develop transient hypokalaemia (low potassium), which might have been because the low protein diet contained more potassium. Please note that the CRF cats in this study did not have naturally occurring renal failure. In another more recent 12 month study at the University of Georgia in 1998 (Protein and calorie effects on progression of induced chronic renal failure in cats Finco DR, Brown SA, Brown CA, Crowell WA, Sunvold G & Cooper TL American Journal of Veterinary Research 59 pp575-582), the cats were divided into four groups: low protein, low calorie (A); low protein, high calorie (B); high protein, low calorie (C); and high calorie, high protein (D). No real differences were seen after a year, and there was no change in GFR in any group. In a November 1999 article (Effects of dietary protein intake on renal functions Supplement to Compendium on Continuing Education for the Practising Veterinarian 21) Dr Finco, who led the second trial, states "the negative results from the second study indicate that protein restriction in cats with renal disease remains to be proven as an effective maneuver for ameliorating progression of renal disease". A vet from Ohio State University stated with regard to the 1998 Finco study above: "recent findings in cats with induced renal insufficiency suggest that feeding diets restricted in protein may not be necessary for this species. Cats fed 9g of protein per kg of bodyweight per day had no more severe kidney lesions or lower GFR than did cats fed 5.2g of protein per kg of bodyweight per day". The University of Georgia (go to page 27) states that adequate calorie intake is essential - it recommends 3.73g of protein per kg bodyweight, which is what Hill's k/d contains, but mentions that some CRF cats lose weight on this amount and may need more.Thus it appears that feeding low protein is less critical than was once thought. However, since urea or BUN are influenced by diet, it does often help the cat feel better if you restrict protein intake as the CRF progresses. A recent study, 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, found that feeding a prescription diet (which of course is not only low protein) helped to keep BUN (urea) levels lower and appeared to help with preventing metabolic acidosis in cats with more advanced CRF. Certainly once urea is over 22 - 30 (BUN: 60 - 80), it is worth considering reducing protein intake if you can - The University of Georgia recommends protein restriction when BUN is over 75 (urea over 27) (page 28, VIII, C, 5). However, it can often be easier to switch a cat to a low protein diet when the cat is stable with lower numbers. Aim for 20-25% protein - never go below 20%. If you do reduce protein intake, it is important to ensure that your cat is still getting as much goodness from his/her food as is necessary for basic health; this is sometimes referred to as energy density. The University of Georgia says "protein quality is as important as quantity" (page 27, VIII, C, 1), so aim for high quality foods with high quality protein sources. Adding eggs to the diet may help for thin cats: cats: Washington State University College of Veterinary Medicine states: "Proteins with high biologic value can be readily converted to body proteins with minimal waste production. Animal proteins have a higher biologic value than vegetable proteins. Eggs have the highest biologic value." However, as obligate carnivores, cats do also need meat in their diets. Internet Vet - a vet who believes early restriction of protein is not critical. University of Georgia's Dr Scott Brown states "we found that other dietary factors, especially phosphorus, are much more damaging than protein". Ohio State University states that protein should never be reduced to less than 20% of calories (scroll down to the slides labelled Conservative Medical Management of CRF: Protein Restriction?).
In contrast to the protein debate, there is no dispute about the importance of controlling phosphorus levels for CRF cats. High phosphorus levels are very damaging to their health and can make the disease progress more quickly. This is because too much phosphorus can cause an imbalance of phosphorus and calcium in the body, which eventually can trigger problems with a hormone called parathyroid hormone (PTH), and lead to a condition called secondary hyperparathyroidism. In one recent Royal Veterinary College study (Barber PJ, Rawlings JM, Markwell PJ, Elliott J. 1999, Effect of dietary phosphate restriction on renal secondary hyperparathyroidism in the cat Journal of Small Animal Practice 40 pp62-70), 84% of cats developed this problem, so it really is important to try to deal with it. I feel Thomas might have managed longer if we had tried harder to control his phosphorus levels - in one 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(6) pp235-242, the cats who ate reduced phosphorus food or food with added phosphorus binders lived more than twice as long as those who did not.
In order to reduce the risks of secondary hyperparathyroidism, you need to feed your CRF cat a diet low in phosphorus. The prescription foods are designed to be low phosphorus, but if your cat will not eat them, consider feeding non-prescription foods which are low in phosphorus (see Tinned Food Data and Dry Food Data). 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% but you also need your cat to eat, so if necessary you may have to have a less ambitious goal, at least to start with, of less than 1% phosphorus. But the ultimate aim is to feed your cat a food containing as little phosphorus as possible. You can also use phosphorus binders if your vet agrees (see Treatments) but dietary restriction is usually a better place to start, because phosphorus binders are not 100% effective.
Whilst ideally you should be aiming to feed a diet low in both protein and phosphorus as CRF progresses, lack of appetite and weight loss are both common problems in CRF and it can be very hard to persuade a CRF cat to eat. Losing weight is not good for a CRF cat either, so you will often feel like you are walking a tightrope. There is more about persuading your cat to eat in the Persuading Your Cat to Eat page.
Cats only have a limited need for carbohydrates - a cat catching his/her own food would only eat the small amount of carbohydrate contained in a mouse's stomach. Some cat foods, particularly dry foods, do contain relatively high amounts of carbohydrate. In The carnivore connection to nutrition in cats (no abstract provided, but the document may be found here, or here in pdf format) (2002) Zoran D Journal of the American Veterinary Medical Association 221 pp1559-67, Dr Zoran writes:
"It is clear that cats have a greater need than dogs or other omnivores for protein in their diet. Cats also have several physiologic adaptations that reflect their expected low CHO [carbohydrate] intake... These specific differences do not mean cats cannot use starch. In fact, cats are extremely efficient in their use of simple sugars. However, it does underscore their development as carnivores and the expected low amounts of grain in their typical diet. These digestive differences may mean that high amounts of CHO in diets may have untoward effects on cats."
Therefore, if you are trying to reduce your cat's protein intake, I would recommend increasing the fat in the diet (see immediately below) rather than the carbohydrates. Of course, if you are feeding a prescription diet, this should be balanced, and in fact many of these diets increase the fat content rather than the carbohydrates in order to offset the reduced protein.
Just as cats need a diet relatively high in protein, so they also need relatively high levels of fat compared to a human or dog. Fat does not result in a lot of waste products like protein, so processing it is not a strain on the kidneys; plus cholesterol is not an issue for cats the way it is for humans (see What Do All Those Test Results Mean?). Thus, a diet relatively high in fat can help an older cat to maintain his/her weight while placing less strain on the kidneys.
In most CRF prescription foods, the fat content is increased to compensate for the lower protein levels; but many senior cat foods also have relatively high levels of fat and relatively low levels of protein; as a bonus, they often also have low phosphorus. Therefore, if your cat won't eat prescription foods, it is worth considering senior foods.
The kidneys cannot process sodium so effectively in CRF cats, which is thought to increase the risk of hypertension (high blood pressure). It is therefore helpful to restrict sodium intake, though if you do this, you should do so gradually, so as to give the kidneys time to get used to the reduction. The prescription foods for CRF cats have low levels of sodium; if you are feeding another food, you should ask your vet what is a suitable level to aim for.
Effects of sodium chloride on selected parameters in cats (2006) Kirk CA, Jewell DE, Lowry SR Veterinary Therapeutics: Research in Applied Veterinary Medicine 7(4) pp333-346 found that there was actually no change in blood pressure in the CRF cats in this study, but levels of BUN, creatinine and phosphorus were higher in the cats eating a high sodium diet compared to those eating a low sodium diet. Around 30% of CRF cats have low levels of potassium, since potassium is easily lost through increased urination and vomiting. Low potassium levels can cause muscle weakness and some vets believe it can cause CRF to progress more quickly. The prescription foods have extra potassium added (all cat foods need some potassium), but if your cat refuses to eat these, your vet can give you a potassium supplement instead, if appropriate; some cats need a potassium supplement whether or not they eat the prescription food.
Please note that a lot of commercial cat foods are acidified in order to reduce the risk of FLUTD (feline lower urinary tract disease, which includes bladder stones and blockages, and which is sometimes known as FUS). These foods often say that they are designed to maintain urinary tract health; or they may contain cranberries or additional Vitamin C. However, they are actually designed to treat a different kind of problem to CRF and may have the effect of increasing the amounts of potassium lost in the urine, which is bad for CRF cats. It is therefore best not to feed these acidified foods to CRF cats, who tend to have quite high acid levels anyway.
Fibre can be helpful for CRF cats because it reduces the risk of constipation, a common problem in CRF cats. Most commercial cat foods have sufficient levels of fibre for a healthy cat, but if your cat suffers from constipation you may wish to add more fibre in the form of something like baby peas. Please see Treatments for more information on dealing with constipation. A 1999 study Role of Fermentable Carbohydrate Supplements With a Low-Protein Diet in the Course of Chronic Renal Failure: Experimental Bases, (Younes H, Alphonse JC, Behr SR, Demigné C, & Rémésy C) indicates that the use of fermentable fibre may help reduce urea/BUN levels. This is because the use of such fibre may "trap nitrogen" by diverting excretion of urea/BUN from the kidneys to the large intestine/faecal route to some extent. Iams has patented beet fibre for this purpose, their Nitrogen Trap Fibre System being used in their renal failure diet. Fermentable carbohydrate supplementation alters nitrogen excretion in chronic renal failure (2006) Younes H, Egret N, Hadj-Abdelkader M, Remesy C, Demigne C, Gueret C, Deteix P, Alphonse JC Journal of Renal Nutrition 16(1) pp67-74 is a more recent study into the use of fibre to reduce BUN/urea levels. The authors suggest that this method appears to have similar benefits to protein restriction without the drawbacks of protein restriction. Too much fibre may prevent your cat from absorbing sufficient nutrients or calories from his/her food. In humans, fibre may also bind calcium in the small intestine and lead to an increase in calcium levels in the body (hypercalcaemia). I would therefore recommend discussing the use of additional fibre with your vet before doing so, and perhaps avoiding it in a cat who already has high calcium levels. Baton Rouge Abyssinians – references for research into the use of fermentable fibre in CRF. Effect of fermentable fibre blends on nitrogen repartitioning in the feline (2000) Sunvold GD is a presentation to the North American Veterinary Conference 2000 by an employee of Iams. Scroll down to page 21. Iams – information on Iams patented beet fibre. PDR Health mentions how fibre binds calcium in the small intestine.
Essential fatty acids are so called because the body cannot synthesise them, so they have to be obtained from food. The two main types of EFAs are Omega-3 and Omega-6. The modern diet tends to contain far more Omega-6, partly because Omega-6 EFAs are cheaper and more stable, but this may create a potentially harmful imbalance. What is the correct balance is not yet known, though some believe it is probably around 5:1 (Omega-6:Omega-3). The first signs of an imbalance or deficiency are usually a dry coat, itchy skin or matted fur. The usual form of supplement is fish oil, which contains Omega-3 fatty acids in the form of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). However, oils from the liver, such as cod liver oil, are not suitable because they contain too much Vitamin A and D - look for an oil pressed from the flesh only. If fish oils are given, extra Vitamin E is also required in
order to avoid steatitis.
Vitamin E requirement of adult cats increases slightly
with high dietary intake of polyunsaturated fatty acids (2002)
Flax seed oil is not recommended, because it does not contain all the essential fatty acids which a cat needs, see Holistic Treatments for more information on this. Whether to supplement essential fatty acids in CRF cats is a grey area. Recent research in rats and humans appears to indicate that the addition of omega-3 fatty acids to the diet may delay the progression of CRF. However, in Nutrition and renal function: effects of dietary lipids on renal function (1999) Polzin DJ, Osbourne CA, James K, Purina Research Report, adapted from articles presented at the 1998 Purina Nutrition Forum, Dr Scott Brown suggests that Omega-3 supplementation might be of some use and is probably safe for healthy cats, but that further studies are required on cats with CRF regarding such supplements. In a later paper, Diet and renal disease: myths and realities (2003), a Presentation to the 28th World Congress of the World Small Animal Veterinary Association, Dr Brown suggests that Omega-3 supplementation might be of some use for dogs but states that "no information is available on PUFA [EFA] supplementation in cats with renal insufficiency."
Essential fatty acids can turn rancid quite easily. Keep them in the fridge, and check them regularly to see if they smell off before using them.
Washington State University College of Veterinary Medicine does provide a protocol for dietary lipid modification. I would therefore recommend that, if you do decide to supplement, you only do so with your vet’s input and approval and with reference to WSU’s protocols. Pet Education provides a general overview of EFAs. Consumer Lab has a summary of its findings with regard to the quality of EFAs, including the names of some of the US products which met with its approval.
Since early January 2007, I have received several enquiries about a new product called Astro's CRF Oil, which was created by a human doctor to treat his own CRF cat. This product is basically a combination of essential fatty acids and CoQ10 (ubiquinon) but in a concentrated formula.
Astro's CRF Oil contains approximately 510mg EPA, 330 mg DHA, Ubiquinon (CoQ10) 15mg and natural Vitamin E (D-tocopherol) 200 IU per 1.5ml dose. It is claimed that combining these ingredients creates a synergistic effect. The intention is for the product to have a strong anti-inflammatory effect, which it is hoped will help the kidneys.
The manufacturer states that the product has been tested on an informal basis on 18 CRF cats in the Montreal area over a period of about eight months. There is a possibility that more formal trials may be run at the University of Montreal in due course.
The product's website states that using this product may enable you to stop other treatments such as sub-Qs, but I cannot see why an anti-inflammatory product might help prevent dehydration. I certainly would not recommend stopping any of your cat's current treatments, particularly sub-Qs, without your vet's knowledge and approval.
EFAs do have an anti-inflammatory effect. However, one kidney specialist vet has informed me that oversupplementation can throw off the correct ratio of Omega-3s to Omega-6s, and might be detrimental in some cases. I do know a number of people who have ordered the product, however, and I will report back on their experiences in due course. At the moment (July 2007), the feedback I have received is favourable, with people reporting that their cats seem "better", albeit in some unmeasurable way.
Unfortunately, whilst virtually everyone I have heard from is positive about Astro's CRF Oil, many of them have mentioned that their cats hate the taste and smell of it. It may help to build up to the full dose gradually, using the syringe that comes with it. Alternatively, you could try mixing it with food, but there is then a risk that your cat will not receive the full dose.
If you do use Astro's CRF Oil, please see the advice about not stopping products containing CoQ10 here.
If your cat is eating prescription food, additional vitamins should not be necessary, since suitable extra vitamins are added to these foods. However, if your cat is not eating these foods, or if your cat has anaemia, additional vitamins may be necessary. Discuss this with your vet who can prescribe a suitable supplement if necessary - one popular brand is Pet-tinic (apparently now also known as Pet Tabs Iron Plus), which also contains iron and may be helpful for CRF cats with mild anaemia. Do not give vitamins to your cat without your vet's approval because excess vitamin intake can be very dangerous. This section discusses: Vitamin B is a water-soluble vitamin, and is often lacking in CRF cats, who lose much of their Vitamin B through urination. A lack of vitamin B may in some cases be related to a lack of appetite, or occasionally may cause twitching or itching. Vitamin B deficiencies are also known to cause non-regenerative anaemia. Your vet may therefore suggest a supplement in order to avoid these problems.
Vitamin B12 may be particularly helpful. Vitamin B12 in the form of methylcobalamin (rather than the more commonly available cyanocobalamin) is the neurologically active form of Vitamin B12, and is used by the body to correct neurological problems. It appears to help cats with diabetic neuropathy, and in addition has been found by Feline CRF Information list members to be very helpful for various CRF-related problems, including incontinence and constipation. A possible starting dose would be 500mcg (0.5mg) a day, though some people give twice as much. Be guided by your vet. Methylcobalamin is often sold in the form of fruit-flavoured lozenges which some people do use to pill their cats successfully, though plain methylcobalamin tablets are also available, though less easy to find.
PDR Health has some information about methylcobalamin (this is a human site). Vitacost sells 200 plain methylcobalamin 500mcg (0.5mg) capsules for US$11.99. I ordered these myself on a Sunday evening, and received them on the following Tuesday. Bayho sells 180 1000mcg (1mg) plain methylcobalamin tablets for US$26.81. Although the site states that it only sells to health professionals, they will normally sell to individuals if you tell them it is for veterinary use. Vitamin UK sells a number of different types of methylcobalamin, click on Search, then type in methylcobalamin. Methylcobalamin Resources has details of suppliers in USA, UK, and New Zealand, some of whom will ship worldwide. Please note this site is recommending methylcobalamin for cats with diabetes, and the doses given may be too high for a CRF cat; ask your vet.
B Vitamins are sensitive to heat and light so are best kept in a cool dark place. Some vets add Vitamin B to the sub-Q fluids bag, but this is not a good idea because it can make the fluids sting; it can compromise the sterility of the bag; and giving vitamins in this way is very expensive.
I would avoid using multi-vitamin products, particularly two products called Hi-Vites and Felovite II, as a source of B vitamins. These products tend to be too high in Vitamins A and D for a CRF cat, and Felovite II also contains phosphorus. Several cats on the CRF List have not done well on Hi-Vites in particular.
If you are in the UK, you may be offered a newish product called Kaminox. This is a combination of B vitamins, iron and potassium. Alfamedic provides a list of the ingredients. There is a similar product in the USA called Amino B & K, available from Emerson Ecologics. I would not recommend using Kaminox unless your cat has low potassium levels, which not all CRF cats do; giving potassium when it is not needed can be very dangerous. Please also be aware that ACE inhibitors such as Fortekor may make potassium levels rise; so if your vet has prescribed Fortekor, as so many British vets do, it might be wiser to use a different type of B Vitamin without the potassium.
Vet UK sells Kaminox for £29.49 for 120ml, with free UK shipping. Caledonian Cat Clinic sells Kaminox for £30.55 for 120ml. Vetscriptions sells Kaminox for £30.99 for 120ml.
Provet in the UK sells a Vitamin B supplement that is phosphorus-free, which costs £8.32 for 30 tablets. Pet-tinic, apparently now also known as Pet Tabs Iron Plus, is both an iron supplement and Vitamin B supplement. The usual dose for a 10lb (4.5kg) cat is 1 ml twice a day (which equates to 5.4mg of iron a day), but do check with your vet in case your cat needs a different dose. KV Vet Supply will ship Pet-tinic to the UK. Click on Pet under Complete Catalogue, then click on Vitamins and Nutrition, then click on Supplements for Cats, and finally click on Blood Support for Cats; or just search for Pet tinic. It costs US$6.85 for 4 oz, but shipping is relatively expensive. California Veterinary Supply sells something similar to Pet-tinic called NutriVed for $6.99 for 4 oz, which has the advantage of containing folic acid, which Pet-tinic lacks. It is also available from Healthy Pets at a cost of US$9.99 for 4 oz. Natural Pets also sell Nutrived for US$9.99 and will ship to the UK. Shipping via USPS Express Mail for one or two bottles costs around US29.
David Jacobson's Pages provide details on many Vitamin B supplements in the USA, which you may prefer to use instead of Pet-tinic if your cat does not need iron.
These vitamins are fat soluble, and are stored in the body rather then excreted. For this reason, there is a risk of toxicity when supplementing these vitamins. Vitamins A and D also promote calcification, which is a risk with CRF cats who have a tendency towards calcification anyway.
In any event, deficiencies in these vitamins are extremely rare, so it is highly unlikely that your cat requires supplementation of any kind; plus care should be taken when considering the use of multi-vitamin tablets, which may contain these vitamins.
Dr Katherine James mentions (Section K, Dietary Management) that Vitamins A and D may cause toxicity in CRF cats. DVM News Magazine states on page 2 that fat soluble vitamins should not be given to excess.
Additional vitamin C is not a good idea for CRF cats, because it is acidifying and CRF cats already have a tendency towards acidosis. Medline Plus mentions that Vitamin C may also interact adversely with products containing aluminium, such as phosphorus binders.
Vitamin C-induced hyperoxaluria causing reversible tubulointerstitial nephritis and chronic renal failure: a case report (2007) Rathi S, Kern W & Lau K Journal of Medical Case Reports 1 p155 reports on a case where a man developed CRF after taking large doses of Vitamin C, which proved to be reversible following proactive treatment and stopping the Vitamin C.
In any event, unlike humans, cats are able to produce their own Vitamin C, so it is unnecessary to add it to their diet.
We used to just have one bowl of water out but once Thomas was diagnosed we switched to three, including one placed upstairs so Thomas didn't have to go too far for a drink in the night. Even now, we leave a bowl of water out downstairs and another out upstairs in order to encourage our other (non-CRF) cats to drink.
Some people give their cat bottled or distilled water. The taste of chlorine in normal tap water doesn't taste too good to cats, so this is worth considering but not essential. We give our cats filtered water, at room temperature, and change it several times a day.
Some people have tried a fountain with running water in order to encourage their cat to drink more. The best known is probably the Drinkwell Water Fountain. Pet Planet in the UK sells the Deluxe Freshflow Fountain for £44.99. Pet Planet also sells the Cat-It water fountain for £22.99. Pampered Pet Mart sells the Drinkwell for US$34.95. Valley Vet sells the Petmate Freshflow Water Fountain in the USA for US$25.95 or US$29.95 for the larger model. My cat have the large (deluxe) version of this and they love it (see photo above). Drs Foster and Smith sell the Cat-It fountain for US$39.99. Miles Kimball sells a small water fountain for US$14.99. Real Canadian Superstore sells the Petmate Freshflow Water Fountain in Western Canada for CAN$29.98.
Please note that if a CRF cat is on sub-Qs, he/she will most probably drink much less; but it is still important to provide water. You may also wish to give your cat homemade chicken broth to drink.
Nutritional Requirements: Veterinary Links The 'Catkins' diet - the feline diet: an historical look (2003) is a paper by Dr Deborah Greco presented to the American Veterinary Medical Association in July 2003 which discusses a cat's needs for relatively high amounts of protein and fat and low requirement for carbohydrates, the so-called 'Catkins diet'. The carnivore connection to nutrition in cats (no abstract provided, but the document may be found here, or here in pdf format) (2002) Zoran D Journal of the American Veterinary Medical Association 221 pp1559-67 discusses feline nutritional requirements in great detail.
The National Academy of Science has recently done some in-depth research into canine and feline nutrition. It states (page 12) 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."
Free feeding a CRF cat has an additional benefit, namely that feeding little and often may reduce the problem of stomach acid, a common problem in CRF cats.
Fluid intake is very important in a CRF cat so as to reduce the possibility of dehydration. The catfood manufacturers produce their CRF diets in both a dry and a tinned (canned) version. However, if you possibly can, I urge you to feed your cat tinned food in preference to dry food, whether prescription food or otherwise. As desert animals, healthy cats do not naturally drink a lot, instead they obtain moisture from their prey (a mouse, for example, is around 65-70% water); and whilst cats who eat dry food do tend to drink more than cats fed on wet food, they simply cannot take in as much moisture overall as a cat fed on tinned food. This was known back in 1986, when the US Board of Agriculture stated in an article entitled Nutrient Requirements of Cats:
"cats given dry food do not voluntarily consume water to equal the ratio of water to dry matter of cats given canned diets containing about 75% moisture."
This paper is being updated and a detailed book entitled Nutrient Requirements of Dogs and Cats will be published in 2004; in the meantime, a few snippets are available at the National Academy of Science.
More recently, an article entitled The carnivore connection to nutrition in cats (no abstract provided, but the document may be found here, or here in pdf format) (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".
I know that persuading your cat to eat tinned food in preference to dry is often easier said than done. My cat with multiple health conditions used to only eat dry food, and would have starved rather than eat tinned (strangely enough, he switched voluntarily almost exclusively to wet food after a dental in 2004). You may also feel uncomfortable leaving tinned food out all day while you go to work, particularly if the weather is hot; in this instance, you might wish to try a timed automatic feeder which keeps food cool and fresh.
Unfortunately, a recent 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 tinned food, particularly from pull-ring tins, appear to be at increased risk of developing hyperthyroidism. It is thought that this may be related to the lining used in these tins, 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 tins. If you do use tins, be sure to store any leftover food in glass containers in the fridge rather than in the tins themselves. The Food Standards Agency has more information on this. Pet Planet sells an automatic feeder in the UK for £28.90. Pets Direct sells an automatic feeder in the UK from £34.99, click on Cats, Feeding Accessories. Drs Foster and Smith in the USA sell one for US$44.99. Mighty Pets sells an eight day automatic feeder for US$71.99.
Sometimes we just have to juggle and do the best we can. But if you can persuade your cat to switch from dry food to foil pouch food, it would probably be a wise move.
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This page last updated: 10 January 2008 Links on this page last checked: 23 January 2008 Copyright Tanya's Feline CRF Website 2000-2008. All rights reserved. You may print out one copy of each section of this site for your own information and/or one copy to give to your vet, but this site may not otherwise be reproduced or reprinted, on the internet or elsewhere, without the permission of the siteowner, who can be contacted via the Contact Us page. If you wish to link to this site, please feel free to do so, and to use the banner ad on the Contact Us page if required. Please make it clear that this is a link and not your own work. I would appreciate being informed of your link. This site is best viewed using Internet Explorer. If you wish to print out the pages, I have found it works best if your margins are set to zero. |
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Water is critical for CRF cats. In order to
maintain hydration, a cat generally needs around 24-30ml of water per pound
bodyweight per day (though this amount will be affected by activity levels
and climate): for a 10lb (4.5kg) cat, this would mean 240-300ml of water a
day (a cat in congestive heart failure may need less). However, a cat does
not need to obtain this by drinking alone, some of his or her intake will
come from tinned (canned) food, which contains a lot of water and which is
therefore the food of choice for CRF cats (see