24 July 2000 - 24 July 2020

Twenty years online!

(Not tax deductible since I am a private individual)









Incidence of the Various Causes

Chronic Interstitial Nephritis

Hereditary or Congenital Abnormalities: PKD, Renal Dysplasia, Amyloidosis or Reflux Nephropathy

Infections: Pyelonephritis or Feline infectious Peritonitis (FIP)

Inflammation: Glomerulonephritis and Nephrotic Syndrome, or Dental Disease


Kidney Stones

Cancer, Particularly: Renal Lymphoma

Toxins: Lilies or Antifreeze

Non-Steroidal Anti Inflammatory Drugs (NSAIDs), e.g. Meloxicam

Perinephric Pseudocysts


Possible (Unproven) Causes:


Feline morbillivirus

Potassium Depletion

Proton Pump Inhibitors

Dietary Concerns: Dry Foods, Acidified Diets, High Phosphorus Foods, Free Feeding or Hunting

New Flooring





Site Overview

Just Diagnosed? What You Need to Know First

Search This Site




What Happens in CKD

Causes of CKD

How Bad is It?

Is There Any Hope?

Acute Kidney Injury



Phosphorus Control


(High Blood Pressure)



Potassium Imbalances

Pyelonephritis (Kidney Infections) and Urinary Tract Infections NEW

Metabolic Acidosis

Kidney Stones



Nausea, Vomiting, Appetite Loss and Excess Stomach Acid

Maintaining Hydration

The B Vitamins (Including Methylcobalamin)




Ways of Assessing Food Content, Including What is Dry Matter Analysis

How to Use the Food Data Tables

USA Canned Food Data

USA Dry Food Data

USA Cat Food Brands: Helpfulness Ratings

USA Cat Food Brands: Contact Details

USA Food Data Book



Coping with CKD

Tanya's Support Group

Success Stories



Important: Crashing

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.)



Early Detection

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



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)

Phosphorus Binders

Steroids, Stem Cell Transplants and 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



Nutritional Requirements of CKD Cats

The B Vitamins (Including Methylcobalamin)

What to Feed (and What to Avoid)

Persuading Your Cat to Eat

2007 Food Recall USA



Oral Fluids

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




Heart Problems



Polycystic Kidney Disease (PKD)


Dental Problems





USA Online

USA Local (Fluids)




The Final Hours

Other People's Losses

Coping with Your Loss




Feline CKD Research, Including Participation Opportunities

CKD Research in Other Species

Share This Site: A Notice for Your Vet's Bulletin Board or Your Local Pet Shop

Canine Kidney Disease

Other Illnesses (Cancer, Liver) and Behavioural Problems

Diese Webseite auf Deutsch



My Three CKD Cats: Tanya, Thomas and Ollie

My Multi Ailment Cat, Harpsie

Find Me on Facebook

Follow Me on Twitter

Contact Me

Home > What is CKD > Causes of and Risk Factors for CKD



  • I am including this information because so many people seem to blame themselves for their cat's illness, when in truth CKD is rarely avoidable - as the What Happens in CKD page mentions, around 10% of cats over the age of ten will develop CKD, with as many as 30% of cats over the age of 15 having the disease.

  • This page is divided into known causes of CKD and possible causes.

  • The possible causes section is just that at this point, possible causes. This section is not there to make you feel guilty about, say, your food choices. There is no hard evidence that any of these possibilities truly do cause CKD, although the anecdotal evidence is stronger for some than for others.

  • On the left is a list of this page's contents.



Many people who contact me want to know what has caused their cat's CKD because they are worried that they did something wrong, and want to ensure they do not do the same thing with their other cats.


CKD is not actually that simple. There are a multitude of possible causes, which I outline below, but in many cases you will never find out the most likely cause in your cat's case.


Try not to feel guilty because the cause is unlikely to be anything within your control. Most cats with CKD have changes in their kidneys known as chronic interstitial nephritis, and this is largely related to old age, affecting around 10% of cats over the age of ten, and as many as 30% of cats over the age of 15. So unless you have mastered the art of arresting aging in your cat (and if you have, please let me know immediately), the chances are it is just a combination of inflammatory processes, the passage of time, and bad luck. Renal fibrosis in feline chronic kidney disease: known mediators and mechanisms of injury (2015) Lawson J, Elliott J, Wheeler-Jones C, Syme H & Jepson R The Veterinary Journal 203(1) pp 18-26 says "It is thought that the intra-renal environment in CKD is significantly pro-fibrotic, leading to continued production of pro-inflammatory and pro-fibrotic cytokines and the perpetuation of the wound healing response rather than its resolution. The factors with the most influence on maintaining this state and which have undergone the most investigation to date are believed to be proteinuria, chronic inflammation, hypoxia, ageing and hyperphosphataemia."


Risk factors associated with the development of chronic kidney disease in cats evaluated at primary care veterinary hospitals (2014) Greene JP, Lefebvre SL, Wang M, Yang M, Lund EM & Polzin DJ Journal of the American Veterinary Medical Association 244 pp320–327 found that "Risk factors for CKD in cats included thin body condition, prior periodontal disease or cystitis, anesthesia or documented dehydration in the preceding year, being a neutered male (vs spayed female), and living anywhere in the United States other than the northeast."


Risk factors for development of chronic kidney disease in cats (2016) Finch NC, Syme HM & Elliott J Journal of Veterinary Internal Medicine 30(2) pp602-10 concludes "Results of our study suggest there is no single risk factor, exposure, or predictor that can explain development of CKD in cats and therefore cumulative effects of multiple risk factors and interactive factors should be considered. Cumulative exposure to risk factors in certain possibly genetically predisposed cats may contribute to a decrease in renal function."


Management and treatment of chronic kidney disease in cats (2016) Caney S In Practice Oct 2016 pp10-13 states "CKD is the end result of a wide range of primary disorders that cause irreversible damage to nephrons, eventually leading to reduced glomerular filtration rate (GFR). In a minority of cases a specific underlying cause can be identified, for example, neoplasia, polycystic kidney disease, renal amyloidosis, hypercalcaemic nephropathy. However, in the majority of cases no primary cause can be identified; in these cases tubulointerstitial nephritis and fibrosis are the most common histological changes, likely to be the end result of a degenerative process initiated by factors including, but not limited to, repeated episodes of renal tissue hypoxia, exposure to toxins, glomerulonephritis, pyelonephritis and repeated transient ureteral obstruction due to ureterolithiasis." She also says "In the majority of elderly cats with CKD the primary cause of the problem cannot be identified. However, in selected cases further investigation may identify the underlying cause of CKD, which may be helpful to owners and in some cases may open avenues of treatment to address the primary problem. In general, seeking a primary cause is more likely to be rewarding in younger cats and in cats with enlargement of one or both kidneys."


Incidence of the Various Causes


Renal Disease (2006) Polzin DJ Delaware Valley Academy of Veterinary Medicine says that of cats with renal disease:

Renal diseases in cats (2002) Pagès JP Presentation to the 27th World Small Animal Veterinary Association Congress discusses the various causes of CKD.


Chronic Interstitial Nephritis


This is the most commonly seen type of kidney problem, so when a vet says a cat has CKD, s/he often means chronic interstitial nephritis.


Cats with chronic interstitial nephritis have small, shrivelled kidneys with scar tissue. The What Happens in CKD page explains why this occurs.


Hereditary/Congenital Abnormalities

There are a number of inherited or congenital conditions which may leas to CKD in cats.


Inherited kidney diseases in dogs and cats (2005) Lees GE Presentation to the Tufts' Canine and Feline Breeding and Genetics Conference has a good overview of these conditions.

Polycystic Kidney Disease (PKD)

Polycystic Kidney Disease, or PKD, is a condition in which cysts form on the kidneys. One of my Persians had PKD. There is detailed information about PKD on the Polycystic Kidney Disease page.


Renal Dysplasia and Renal Hypoplasia

In these conditions, there is a problem with kidney development:

  • renal dysplasia: the kidneys do not develop normally

  • renal hypoplasia: the kidneys do not develop completely

  • renal aplasia: the cat has only one kidney

These conditions are quite rare in cats but Feline hereditary and congenital kidney disease (2013) Suárez Rey M Veterinary Focus 23(3) pp17-25 states that renal dysplasia is more common in Persian and Norwegian Forest cats.


Cats who develop CKD at an early age often suffer from renal dysplasia or renal hypoplasia. These cats often are rather small, and may be noticeably smaller than their littermates. A small stature may also be a sign of FIP (see below). Unfortunately young cats who develop CKD are often diagnosed at a relatively late stage because nobody expects a young cat to develop CKD. Treatment is as for CKD generally.


Renal Aplasia (Only One Kidney)

Renal aplasia is a form of renal hypoplasia. Cats with only one kidney tend to be male, and for some reason it is usually the right kidney which is missing. Renal anomalies (2016) Fitzgerald SE The Merck Veterinary Manual says that it is always accompanied by a lack of the tube that connects the kidney to the bladder (the ureter).


Cats with one kidney may have a normal lifespan. Humans born with one kidney seem to do well: The congenital and acquired solitary kidney (2003) Shapiro E, Goldfarb DA & Ritchey ML Reviews in Urology 5(1) pp2–8 says "Unilateral renal agenesis is compatible with normal longevity and does not predispose the contralateral kidney to greater-than-normal risk; nevertheless, patients should have annual surveillance, including a blood pressure measurement, serum creatinine if not initially normal, and urinalysis to detect proteinuria." It goes on to say "Overall survival was not affected by URA unilateral renal agenesis]. URA is compatible with normal longevity and does not predispose the contralateral kidney to greater-than-normal risk."



Amyloid is a type of protein found in the body. In amyloidosis, amyloid is deposited in organs and tissues where it does not belong, causing inflammation and damage. In cats, the deposits are often found in the kidneys, and they eventually lead to CKD.


Amyloidosis is not particularly common, but familial amyloidosis may be found in Abyssinian cats in particular, while Siamese and Oriental cats may also have hepatic amyloidosis. Changes in serum and urine SAA concentrations and qualitative and quantitative proteinuria in Abyssinian cats with Familial Amyloidosis: A five-year longitudinal study (2009-2014) (2015) Paltrinieri S1, Sironi G, Giori L, Faverzani S & Longeri M Journal of Veterinary Internal Medicine 29(2) pp505-12 says "The disease course of FA is variable in the conditions of appearance, severity and progression. The deposition of amyloid may deposit within one year and cause kidney disease or slowly and kidney function may stay relatively stable for years."


Cats with amyloidosis often have proteinuria.


International Cat Care discusses amyloidosis.


Pet Place has some information.


Universities Federation for Animal Welfare has a detailed discussion of amyloidosis.


Cornell University College of Veterinary Medicine has some information about amyloidosis.


Overview of amyloidoses (2016) Tizard I The Merck Veterinary Manual has an overview of amyloidosis.


Strategies for protein losing nephropathy (2001) Wallace MS Presentation to the Atlantic Coast Veterinary Conference in which she discusses glomerulonephritis and amyloidosis.


Lyons Feline Genetics Laboratory at the University of Missouri reports on a research project in the USA and Europe where you can provide blood or buccal samples from Siamese and Oriental cats to assist with research into feline amyloidosis.


Reflux Nephropathy

This is a rare condition in which the kidneys are damaged by urine flowing backwards into the kidney. A genetic form of this has recently been identified in Ragdolls by researchers in Finland.


Health and behavioral survey of over 8000 Finnish cats (2016) Vapalahti K, Virtala A-M, Joensuu TA, Tiira K, Tähtinen J & Lohi H Frontiers in Veterinary Science 3(70) pp1-16 states that Ragdolls were the only breed reported to have the disease.




Pyelonephritis is inflammation of the kidneys which is usually caused by a bacterial infection. In many cases this will have started as a lower urinary tract infection which has risen into the kidneys.


 If your cat has a kidney infection and also has high bloodwork values, the bloodwork may improve once the infection is under control.


There is more information about pyelonephritis on the Pyelonephritis and Urinary Tract Infections page.


FIP (Feline Infectious Peritonitis)

Feline infectious peritonitis is a virtually always fatal illness that develops in a small number of cats who catch a type of virus known as a coronavirus, which then mutates into FIP. (Although it belongs to the coronavirus family, FIP is not the same as Covid-19).


FIP occurs in two forms, effusive (wet) and non-effusive (dry). The wet form is generally considered harder to treat, but both forms can be fatal. It commonly affects kittens, but mature cats are more at risk too.


FIP is notoriously difficult to diagnose, and testing positive for the coronavirus does not inevitably mean that the cat will develop FIP (the majority of cats test positive for the coronavirus but never develop FIP).


Possible signs in bloodwork include elevated neutrophils and elevated total protein. You will usually see a low albumin:globulin ratio combined with very high globulin levels. An A:G ratio below 0.4 combined with elevated globulins, indicates that FIP is quite likely, assuming other causes of a low A:G ratio have been ruled out, whereas an A:G ratio over 0.8 rules out FIP.


Symptoms of FIP include a raised temperature on more than one occasion and poor growth in kittens (an affected kitten is often much smaller than his/her littermates). Cats with the wet form of FIP often have ascites (fluid build up in the abdomen). Cats with the dry form may develop other symptoms, depending upon the area affected in the body. Commonly affected areas are the eyes, brain, abdomen and kidneys. Cats whose kidneys are affected may develop enlarged kidneys and CKD.


Very few cats on Tanya's Feline CKD Support Group have FIP, but I've had three CKD cats and one PKD cat, and fate decided I needed to experience FIP too. I lost the most adorable kitten in the world to dry FIP. You think CKD is bad? Well, FIP was worse, because there was so little I could do and so little hope.


Until very recently, there were very few treatments available for FIP, and those that were available worked for some cats (often only for a short while) but not for others, so FIP was generally considered to be fatal. (I tried feline interferon and polyprenyl for Lily, but without success).


This changed when a treatment known as GS-441524 was assessed in 31 cats with FIP, as discussed in Efficacy and safety of the nucleoside analog GS-441524 for treatment of cats with naturally occurring feline infectious peritonitis (2019) Pedersen NC, Perron M, Bannasch M, Montgomery E, Murakami E, Liepnieks M & Liu H Journal of Feline Medicine and Surgery 21(4) pp271-281. Four of the cats were put to sleep within 2-5 days of starting the study, and a fifth was put to sleep during the study. However, of the 26 cats who completed the study, eighteen remained healthy after one 12 week course of treatment, and although the eight other cats relapsed, repeated courses of treatment were effective, to such an extent that 24 cats remained healthy (one cat died of heart disease, and the other of neurological problems caused by the FIP).


GS-441524 therefore is widely considered to be a breakthrough treatment for FIP, being both safe and effective, but tragically it is not commercially available as yet and, since it is patented by Gilead Sciences, which is currently focusing on treatments for Covid-19 in humans, it is not known whether it ever will be. Some people are therefore purchasing illegal versions of the treatment, usually from China, with varying degrees of success.


If your vet suspects your cat has FIP, please join the FIP Support Group where you can obtain help and support and learn about the latest research from people experienced with this dreadful disease.


Cat Virus is the website of Dr Addie, a lecturer in veterinary virology and an expert on FIP. Her site is available in a number of different languages.


Cornell University College of Veterinary Medicine has a good overview.


The Winn Feline Foundation has information about FIP.


Newman Veterinary has information on FIP.





The glomeruli are very fine blood vessels in the kidneys that act as filters of waste products to produce urine. When they become inflamed, it is known as glomerulonephritis.


Glomerular disease is an immune-mediated disease and is actually relatively rare in cats, though Feline hereditary and congenital kidney disease (2013) Suárez Rey M Veterinary Focus 23(3) pp17-25 states that there is a hereditary form that may be seen in Abyssinian cats. Otherwise it is usually secondary to some other condition such as an infection, inflammatory disease, dental disease, chronic pancreatitis, FIP, cancer or diabetes.


When glomerulonephritis occurs, proteinuria may result, so affected cats will often have low albumin levels. They may also have blood in the urine and occasionally a high urine specific gravity: Glomerular disease in small animals (2016) Brown SA Merck Veterinary Manual states "Although uncommon, urine specific gravity may be inappropriately high for the degree of renal dysfunction, a condition referred to as glomerulotubular imbalance."


In severe cases, the resulting low levels of protein in the blood may cause weight loss and a build-up of fluids under the skin (subcutaneous oedema). 


The ideal treatment is to find and treat the cause of the inflammatory process. Using medications to suppress the immune system may help, though in some cases this may make things worse. Chronic kidney disease (2007) Polzin DJ Delaware Valley Academy of Veterinary Medicine discusses glomerulonephritis and has a table (Table 1) showing possible causes and discusses the pros and cons of using immunosuppressants.


If the cause cannot be found, then the goal is to control the proteinuria as much as possible. ACE inhibitors may be used for this purpose. One study found that amino acids may help.


Mar Vista Vet has very helpful information, including information on how to treat glomerulonephritis.


University of Georgia College of Veterinary Medicine has some helpful information about glomerulonephritis.


VCA Hospitals has a good overview of glomerulonephritis in cats.


Pet Place has a helpful overview of glomerulonephritis.


Strategies for protein losing nephropathy (2001) Wallace MS Presentation to the Atlantic Coast Veterinary Conference in which she discusses glomerulonephritis and amyloidosis.


Nephrotic Syndrome

In the worst case, glomerulonephritis may result in nephrotic syndrome. Nephrotic syndrome is not a disease in itself, but rather a collection of symptoms that may be seen as a result of the glomerular problems.


The primary symptoms of nephrotic syndrome include proteinuria, oedema and/or ascites, low albumin levels and high cholesterol levels. You may also see diarrhoea, reduced urine output, anaemia and occasionally an arterial thromboembolism (a blood clot in the leg).


However, just as glomerulonephritis is relatively rare in cats, so is nephrotic syndrome.


Update on nephrotic syndrome 2010 Pressler B CVC in Washington DC Proceedings discusses nephrotic syndrome.


Immune-mediated elements of renal disease (2007) Sellon RK Presentation to the World Small Animal Veterinary Association Congress 2007.


Dental Problems

It appears that dental problems may be linked to an increased risk of other health issues. Although the precise mechanism is not known, it appears that in humans there may be a link between the oral bacteria associated with poor dental hygiene and heart disease. Colgate reports on this.


A similar link is thought to exist in cats. Littleton West Animal Hospital states that dental disease "not only affects the mouth, but can also lead to more serious health problems such as heart, lung, and kidney disease."


Risk factors for development of chronic kidney disease in cats (2016) Finch NC, Syme HM & Elliott J Journal of Veterinary Internal Medicine 30(2) pp602-10 states "It is possible that oral inflammation may lead to kidneys damage through unknown mechanisms" and concludes "Our study suggests independent associations between both vaccination frequency and severity of dental disease and development of CKD" but states that further studies are necessary to investigate why this might be the case.


Some cats with periodontal disease who need dental treatment under anaesthesia may develop CKD shortly afterwards. Risk factors associated with the development of chronic kidney disease in cats evaluated at primary care veterinary hospitals (2014) Greene JP, Lefebvre SL, Wang M, Yang M, Lund EM & Polzin DJ Journal of the American Veterinary Medical Association 244 pp320–327 found that "Risk factors for CKD in cats included ... prior periodontal disease or cystitis, anesthesia or documented dehydration in the preceding year."


A more recent study appeared to support these earlier findings. Survival analysis to evaluate associations between periodontal disease and the risk of development of chronic azotemic kidney disease in cats evaluated at primary care veterinary hospitals (2018) Trevejo RT, Lefebvre SL, Yang M, Rhoads C, Goldstein G & Lund EM Journal of the American Veterinary Medical Association 252(6) pp710-720 evaluated cats at 829 hospitals over a period of more than eleven years, comparing cats with periodontal disease to cats without periodontal disease. The study found that periodontal disease (PD) "was associated with increased risk of CKD; risk was highest for cats with stage 3 or 4 PD. Risk of CKD increased with age. Purebred cats had greater risk of CKD than mixed-breed cats. General anesthesia within the year before study exit and diagnosis of cystitis at any point prior to study exit (including prior to study entry) were each associated with increased CKD risk. Diagnosis of diabetes mellitus or hepatic lipidosis at any point prior to study exit was associated with decreased CKD risk."


This topic is covered in detail on the Dental Problems page.




For many years it was thought that hypertension in cats was the result of another condition, such as CKD - this is known as secondary hypertension. According to Cornell University College of Veterinary Medicine, other conditions that may cause hypertension include hyperthyroidism, diabetes and heart disease.


Whilst it is true that hypertension is more common in cats with these conditions, it is gradually becoming clear that primary hypertension does exist in cats, and may in fact contribute to the development of CKD. If the blood vessels within the kidneys are damaged because of hypertension, eventually CKD can result. The National Institute of Diabetes and Digestive and Kidney Diseases explains more about this.


Feline hypertension: Part 1 (2012) Atkins C says "adding to the confusion in understanding the pathogenesis of hypertensive renal disease, renal disease begets hypertension and hypertension begets renal disease."


This topic is covered in detail on the Hypertension page.


Kidney Stones and Obstructions


Kidney stones may cause kidney problems. The stones may calcify, and cause damage that way, or they may lodge in the ureter, thus allowing waste products that would normally be excreted by the bladder to build up in the kidneys - this is called obstructive nephropathy.


If a cat's kidney bloodwork suddenly becomes extremely high, a kidney stone blocking the ureter may be the cause. The diagnosis can usually be confirmed via ultrasound. The ultrasound may show one small kidney and one enlarged kidney (see renomegaly).


There is more information about kidney stones on the Kidney Stones page.


Cancer - Renal Lymphoma (Lymphosarcoma)


Lymphoma (lymphosarcoma) is a type of cancer in which white blood cells called lymphocytes become cancerous and produce tumours. Some cats with lymphoma also have feline leukaemia.


Lymphoma may be found in several parts of the body; if it occurs in the kidneys, it is called renal lymphoma. It is the most common type of renal cancer in cats.  As renal lymphoma progresses, it may cause kidney disease.


BUN may be elevated because of internal bleeding (which may eventually also cause anaemia), as may lymphocytes. Renal lymphoma may cause the kidneys to become enlarged (see renomegaly) but this is not always visible on x-ray because it is a soft tissue type tumour, though it may  show on ultrasound. A biopsy is necessary for a definitive diagnosis but many people do not bother and treat presumptively.


There are two types of lymphoma:

  • Small cell lymphoma is slower growing and very treatable. The cat can normally be treated using chemotherapy tablets at home which reduces the cost.

  • Large cell lymphoma is more aggressive but may still be treatable, though this normally requires weekly visits to the vet for intravenous chemotherapy to start with, with the frequency reducing and treatment stopping once the cat is in remission.


Cats tend to cope far better with chemotherapy than humans do, especially if they are given anti-nausea treatment before, during and after each chemotherapy session, so I would seriously consider this treatment if you are offered it.


Renal diseases in cats (2002) Pagès JP Presentation to the 27th World Small Animal Veterinary Association Congress. Section 2.5 discusses renal cancer.


The Veterinary Society of Surgical Oncology has an overview of the most common types of renal tumour.


There are more links about feline cancer, including lymphoma, on the Other Illnesses page.


Toxins: Lilies and Antifreeze


Common nephrotoxins include lilies and antifreeze, which cats may lick or eat accidentally (the taste of antifreeze is unfortunately very attractive to cats).


In most cases these cause Acute Kidney Injury, but in some cases, if the cat recovers, there may be residual kidney damage resulting in CKD.


Non-Steroidal Anti-Inflammatory Drugs (NSAIDs)


Non-steroidal anti-inflammatory drugs are very effective at controlling pain and inflammation in cats, but unfortunately cats cannot metabolise them very well. Meloxicam is an NSAID available in both injectable and liquid (oral) form. It is approved in the UK for the ongoing treatment of arthritis in cats (and I myself used it successfully for my PKD but not CKD cat who had severe arthritis), but there are concerns that it may cause kidney problems in some cats, primarily when used at higher doses, as tends to happen in the USA where cat-sized formulations are not available.


Having said that, a study is underway at Kansas State University College of Veterinary Medicine into whether meloxicam might slow the progression of CKD in cats. You can read more about that here.


You can read more about meloxicam and other NSAIDs in the Treatments section, which includes a protocol for what to do if your cat experiences an adverse reaction.


Perinephric or Perirenal Pseudocysts


Perinephric or perirenal pseudocysts are large fluid-filled sacs that form around one or both of a cat's kidneys. They are called pseudocysts because they do not have the membrane that true cysts have. True cysts may be seen in another condition associated with CKD called polycystic kidney disease, so if your vet mentions cysts, be sure you know which type is meant.


Perinephric pseudocysts appear to be more common in male cats, and the cat may appear healthy apart from having an abdomen that is increasing in size but not usually tender to the touch. Upon examination, which is usually performed via ultrasound, the kidneys are usually enlarged.


The cysts may be treated by draining the fluid, but this is often only a temporary measure. Clinical exposures: a perinephric pseudocyst in a cat (2005) Morrow BL Veterinary Medicine states "Because of continual fluid production, needle drainage provides only temporary relief to the patient, lasting from days to months, and should be repeated as needed." However, one cat on Tanya's CKD Support Group did only need to have his cyst drained once and it never filled up again, so draining can sometimes be an effective treatment option.


Removing the wall of the cyst may be more effective, and a couple of people on Tanya's CKD Support Group have had this done successfully, but in more severe cases it may be necessary to remove a kidney. This is a last resort because it may lead to CKD, since many cats with these cysts tend to have compromised kidneys (they are often already in early stage CKD) and/or urinary tract infections. Clinical exposures: a perinephric pseudocyst in a cat (2005) Morrow BL Veterinary Medicine states "Nephrectomy should be avoided, if possible, when underlying renal disease is present or suspected because of the potential for rapid progression of underlying chronic renal failure in the remaining kidney." However, one member of Tanya's Support Group's cat did have the surgery performed and it was a success, despite the cat already having CKD.


Pet MD says "Perirenal pseudocysts are usually not life-threatening and some cats need no treatment whatsoever. Otherwise, the fluid is surgically drained from the capsule, especially when the cat's abdomen is distended." It recommends check ups every 2-6 months.


Pet Place has some information about pseudocysts.


Perinephric pseudocysts in the cat: a retrospective study and review of the literature (1999) Ochoa VB, DiBartola SP, Chew DJ, Westropp J, Carothers M, Biller D Journal of Veterinary Internal Medicine 13(1) pp47-55 reports on thirteen such cases.


Berkshire Vet tells how cysts were successfully removed from a young cat called Daisee.


Suspected Causes (Not Proven)


These are areas where research has indicated there may be a correlation between the presence of a particular factor and the development of CKD but this does not necessarily mean these factors have caused the CKD. Imagine a bank robbery: just because you happened to be present does not mean you were the robber. However, you might well need to be interviewed and ruled out as a suspect. Further research is needed.


Risk factors for development of chronic kidney disease in cats (2016) Finch NC, Syme HM & Elliott J Journal of Veterinary Internal Medicine 30(2) pp602-10 followed 148 cats in the UK between 2005 and 2009. 27 of the cats developed elevated kidney values. It concludes "Epidemiological studies, as conducted in our study, do not necessarily imply causality, but simply suggest associations."

A Vaccination Connection?

In 2002 a tentative connection between feline vaccinations and CKD was mooted. The connection arises because feline vaccines are grown on kidney cells known as Crandell Reese Feline Kidney (CRFK) cells. It has long been known that growing the vaccines in this way produces some unidentified antibodies in addition to those required for the vaccine, but it was only discovered in 2002 that the unidentified antibodies were to renal tissue. These additional antibodies occur in all modified live or killed vaccines, but do not occur with intranasal vaccines. In the UK, live vaccines are usually used.


Investigation of the induction of antibodies against Crandell-Rees feline kidney cell lysates and feline renal cell lysates after parenteral administration of vaccines against feline viral rhinotracheitis, calicivirus, and panleukopenia in cats (2005) Lappin MR, Jensen WA, Jensen TD, Basaraba RJ, Brown CA, Radecki SV, Hawley JR American Journal of Veterinary Research 66(3) pp506-511 concluded that "hypersensitization with CRFK cell proteins did not result in renal disease in cats during the 56-week study."


A later study, Interstitial nephritis in cats inoculated with Crandell Rees feline kidney cell lysates (2006) Lappin MR, Basaraba RJ, Jensen WA Journal of Feline Medicine and Surgery 8(5) pp353-6, found that 50% of the cats in the study who were given normal vaccines developed interstitial nephritis according to biopsies. However, these cats were vaccinated 12 times in 50 weeks, which is obviously far more often than is normal (the current US guidelines are for cats to be vaccinated only once every three years). One group of cats in the study were given intranasal vaccines, and they did not develop any signs of interstitial nephritis.


Antibodies against Crandell Rees Feline Kidney (CRFK) cell line antigens, a-Enolase and Annexin A2 in vaccinated and CRFK hyperinoculated cats (2010) Whittemore J, Hawley J, Jensen W & Lappin M Journal of Veterinary Internal Medicine 24 pp306–313 was able to identify a number of CRFK antigens in cats vaccinated with four commercially available FVRCP (standard vaccinations) vaccines. Further research is required to determine the clinical relevance of the findings.


Risk factors for development of chronic kidney disease in cats (2016) Finch NC, Syme HM & Elliott J Journal of Veterinary Internal Medicine 30(2) pp602-10 states "A large proportion of the feline population receives regular vaccinations and, based on findings from previous studies described above, this practice may be considered a potential risk factor for CKD in cats." It concludes "Our study suggests independent associations between both vaccination frequency and severity of dental disease and development of CKD" and states that further studies are necessary to investigate why this might be the case.


in 2012 Dr Lappin stated that in his research cats who developed antibodies did not go on to develop CKD. He recommends that core vaccines should continue to be given to healthy cats in accordance with the American Association of Feline Practitioners vaccination guidelines. 


Please see the Treatments page for more information on the use of vaccines in cats, and discuss what is appropriate for your own cat with your vet.


Feline Morbillivirus (FeMV)

Researchers have found that a recently discovered virus may be present in some cases of interstitial nephritis in cats. To date the virus has been found in Asia, Europe and the USA. Feline morbillivirus, a previously undescribed paramyxovirus associated with tubulointerstitial nephritis in domestic cats (2012) Woo PC, Lau SK, Wong BH, Fan RY, Wong AY, Zhang AJ, Wu Y, Choi GK, Li KS, Hui J, Wang M, Zheng BJ, Chan KH & Yuen KY Proceedings of the National Academy of Sciences of the United States of America 109(14) pp5435-40 discusses the initial findings. Yahoo! News reports on this study.


Epidemiological and pathological study of feline morbillivirus infection in domestic cats in Japan (2016) Park ES, Suzuki M, Kimura M, Mizutani H, Saito R, Kubota N, Hasuike Y, Okajima J, Kasai H, Sato Y, Nakajima N, Maruyama K, Imaoka K & Morikawa S BMC Veterinary Research 12(1) p228 looked at tissue samples obtained at random from 100 deceased cats in Japan. It found that 29% of the cats had the morbillivirus or antibodies to it. However, the study could not find a correlation with CKD.


Chronic infection of domestic cats with feline morbillivirus, United States (2016) Sharp CR, Nambulli S, Acciardo AS, Rennick LJ, Drexler JF, Rima BK, Williams T & Duprex WP Emerging Infectious Diseases 22(4) pp760-2 found the virus was also present in around 3% (ten cats) in the survey in the USA. Three of these ten cats had CKD. The strain appeared to be closely related to those in Asia.


Discovery of new feline paramyxoviruses in domestic cats with chronic kidney disease (2015) Sieg M, Heenemann K, Rückner A, Burgener I, Oechtering G & Vahlenkamp TW Virus Genes 51(2) pp294-297 found several new feline paramyxoviruses in urine samples from cats with CKD, whereas none were seen in the control group of cats. One of these viruses was similar to the form of feline morbillivirus found in Hong Kong and Japan. The researchers state that it is not yet known whether the virus is a potential cause of CKD or if the inflammation stemming from CKD merely enabled the virus to take hold.


Novel feline viruses: emerging significance of gammaherpesvirus and morbillivirus infections in cats (2019) Beatty JA, Sharp CR, Duprex WP & Munday JS Journal of Feline Medicine and Surgery 21(1) pp5-11 reviewed earlier studies and says that morbillivirus has been found in up to 52.9% of cats, both healthy or with CKD, in one study in South America. "Naturally acquired FeMV may be an asymptomatic and self-limiting viral infection, or it may result in disease in cats that has previously been attributed to other causes or considered to be idiopathic," but add that causation has not yet been proven.


Potassium Depletion


Chronic kidney disease (2007) Polzin DJ Delaware Valley Academy of Veterinary Medicine says "A particularly intriguing concept is that hypokalemia may be a cause of CKD in cats, rather than simply a consequence of it." This is because of several studies, including Chronic renal disease and potassium depletion in cats (1992) Dow SW & Fettman MJ Seminars in Veterinary Medicine and Surgery (Small Animal) 7(3) pp198-201, which suggested that all cats with CKD should be supplemented with potassium, even if they do not appear to have low potassium levels. Some people go further and believe that all older cats should be supplemented with potassium, whether they have CKD or not. 


Whilst it is true that blood tests for potassium may not accurately reflect potassium levels at the cellular level, where the potassium is needed (see Potassium for more on this), this does not automatically mean that every cat would benefit from potassium supplementation. Muscle potassium content and potassium gluconate supplementation in normokalemic cats with naturally occurring chronic renal failure (1997) Theisen SK, DiBartola SP, Radin MJ, Chew DJ, Buffington CA, Dow SW Journal of Veterinary Internal Medicine 11(4) pp212-217, found that CKD cats with normal potassium levels who were given potassium supplementation did no better than CKD cats who received a placebo.


Overall there is not sufficient evidence to support the theory that low potassium levels may cause CKD. Chronic kidney disease (2007) Polzin DJ Delaware Valley Academy of Veterinary Medicine says "These findings support the concept that reduced renal function precedes development of hypokalemia."


Feeding potassium-restricted acidified diets (see below) to cats with normal renal function reduces gastrointestinal absorption of potassium and may lead to potassium depletion. I therefore would not recommend feeding such diets to older cats; and these diets should not be fed to CKD cats anyway (see Nutritional Requirements).


Do not give your cat a potassium supplement without your cat's knowledge and approval, because high potassium levels may develop quickly, particularly as the CKD progresses, and are potentially very dangerous (see Potassium).


Proton Pump Inhibitors

There is some evidence that proton pump inhibitors (such as omeprazole, sometimes used in CKD cats) may be a factor in the development of CKD in humans. This is discussed in more detail on the Appetite Loss, Nausea and Vomiting page.


Dietary Concerns

Dry Food Diet

It is thought that feeding an exclusively dry food diet may cause chronic dehydration, which in turn may contribute to the development of CKD. This is not proven, in fact Risk and protective factors for cats with naturally occurring chronic kidney disease (2017) Piyarungsri K & Pusoonthornthum R Journal of Feline Medicine and Surgery 19(4) pp358-363 found that feeding dry cat food might actually be "a potential protective factor against CKD in cats."


Which Foods to Feed has more information on dry food versus wet.


Acidified Diets

Over the last twenty years many commercial diets have been reformulated to promote "urinary tract health", or words along those lines. Essentially, these diets are acidified, so as to reduce the risk of cats developing feline lower urinary tract disease (FLUTD). Cats with FLUTD tend to have urine that is too alkaline, and are therefore at risk of developing struvite crystals, which develop in an alkaline environment. Feeding an acidified diet reduces this risk.


Unfortunately, feeding these diets to cats who are not at risk of FLUTD may lead to urine that is too acidic. It is thought that acidified diets may be a factor in the increase in kidney stones (calcium oxalate stones), which develop in an overly acidic environment, and which in turn are a risk factor for developing CKD. Urolithiasis in Small Animals (2913) Brown SA Merck Veterinary Manual states "Common management schemes that involve feeding urine-acidifying diets with reduced magnesium have reduced the incidence of feline struvite urolithiasis. Magnesium has been reported to be an inhibitor of calcium oxalate formation in rats and people; thus, the reduced magnesium concentration in feline urine may partially explain the increase in calcium oxalate stones in cats." These stones, unlike struvite, cannot be dissolved by diet - they can only be removed by surgery.


Acidified diets may also contribute to low potassium levels. I therefore would not recommend feeding such diets to older cats; and these diets should not be fed to CKD cats anyway (see Nutritional Requirements).


Foods Containing Fish

Mineral analysis of complete dog and cat foods in the UK and compliance with European guidelines (2017) Davies M, Alborough R, Jones L, Davis C, Williams C & Gardner DS Scientific Reports 7 17107 found that some fish-based foods in the study contained high levels of arsenic. The study states "Arsenic is water soluble and accumulates in organs such as the liver and kidney, where it is relatively toxic either by itself or via interactions with other catalytic metals such as iron and copper. High urinary arsenic is associated with increased risk of CKD... Arsenic may therefore bio-accumulate in the tissues of animals such as fish that inhabit these waters and in the animals that consume these fish sources such as the domestic cat. It remains to be determined if relatively high, long-term arsenic intake predisposes the domestic cat to chronic kidney disease or whether high intake of other metals that are also prevalent in fish may also have an effect, such as mercury."


Foods With a High Phosphorus Content

Although it is well documented that a high phosphorus intake is not appropriate for CKD cats (it can make the CKD progress faster, can make the cat feel unwell, and may lead to secondary hyperparathyroidism), in recent times there is also some debate as to whether a high dietary phosphorus intake may be a factor in the development of CKD. This is discussed in more detail on the Prevention page.


Free Feeding

A 2002 study, Diet and lifestyle variables as risk factors for chronic renal failure in pet cats (2002) Hughes KL, Slater MR, Geller S, Burkholder WJ, Fitzgerald C Preventive Veterinary Medicine 55(1) pp1-15, compared cats in three groups:

  • free feeding with fibre;

  • free feeding with Factor-2 (a composite variable composed of fibre, magnesium, protein, sodium and ash);

  • and fibre alone.

The researchers concluded that free feeding was associated with increased odds of developing CKD. However, they did not simply free feed the cats; they also gave them additives. It is therefore not known whether free feeding alone would give similar results.


I myself have always free fed, and will continue to do so. In the wild, cats naturally feed multiple times a day. See Which Foods to Feed for more information on this topic.



Case control study of risk factors associated with feline and canine chronic kidney disease (2010) Bartlett PC, Van Buren JW, Bartlett AD & Zhou C Veterinary Medicine International Vol 2010, Article ID 957570 states that "There was a nonsignificant finding that the percent of diet from hunting might be positively associated with CKD, and further investigation may be warranted. This question was asked because infectious or toxicologic agents associated with hunting, such as hantavirus in rodents, may contribute to renal destruction as a hidden cause of CKD."


New Flooring


Some people on Tanya's CKD Support Group believe that new carpets and floors contain potential toxins for cats - several people have noted that their cats developed CKD shortly after new flooring was laid.


Carpets and other floor coverings may contain various volatile organic compounds, particularly in the backing. Carpet and indoor air quality (1996) Maxwell L & Hedge A Facility Planning & Management Notes, Cornell University 1(2) recommends ventilating the area where new carpet is installed for 48 - 72 hours.


Cats appear to be particularly sensitive to smells; essential oils, for example, are toxic to cats, who lack the metabolic pathways to process them. I therefore would recommend keeping cats away from new carpets and floors for several days after installation, if possible.


Back to Page Index

This page last updated: 13 November 2020


Links on this page last checked: 24 April 2020








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.



Copyright © Tanya's Feline CKD Website 2000-2020. All rights reserved.


This site was created using Microsoft software, and therefore it is best viewed in Internet Explorer. I know it doesn't always display too well in other browsers, but I'm not an IT expert so I'm afraid I don't know how to change that. I would love it to display perfectly everywhere, but my focus is on making the information available. When I get time, I'll try to improve how it displays in other browsers.


This site is a labour of love, from which I do not make a penny. Please do not steal from me by taking credit for my work.

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.