Chronic Kidney Failure In Cats

One of the most common diseases that we see at our clinic is kidney (renal) disease in cats.  Kidneys are a vital part of a normal functioning body.  They filter the blood and help to excrete urea and other toxins, as well as maintaining fluid and electrolyte balance and helping to produce some hormones.  A failing kidney cannot reabsorb fluids or excrete toxins, resulting in a very dehydrated and unwell cat.  Once the kidney’s filtering components are damaged they do not regenerate and will stop functioning.  The kidney can function efficiently until up to about 70% is lost, then they start to decompensate and we start to see clinical signs develop in cats.

There are two different forms of kidney disease that are classified as acute (sudden) or chronic (long-term).  Chronic kidney disease is by far the more common form. With regular monitoring we aim to discover kidney disease in its early stages, in many cases even before our cats start to show signs of ill health.

Causes of Chronic Kidney Disease

There are numerous causes of chronic kidney disease. Some can be prevented or effectively treated if detected early enough.

  • Degenerative kidney disease associated with ageing
  • Congenital malformations of the kidneys (eg. Polycystic kidneys in Persian cats)
  • Bacterial infections (can ascend from the bladder or be filtered from the blood)
  • Kidney tumours (most commonly lymphosarcoma which is an infiltrative tumour of white blood cells)
  • High blood pressure
  • Viral infections (Feline Immunodeficiency Virus or Feline Infectious Peritonitis)
  • Deposition of amyloid in the kidneys

Clinical Signs

Early detection of any of the following signs can help to treat kidney disease early and preserve the remaining functioning part of the kidney.

  • Increased thirst/urination
  • Weight loss
  • Poor coat quality
  • Lethargy
  • Bad breath (halitosis)
  • Mouth ulcers
  • Loss of appetite
  • Vomiting
  • Diarrhoea
  • Sudden onset blindness (retinal detachment)


The clinical signs are quite vague and are indicators of many possible disease processes occurring. The aim of monitoring senior cats is to discover disease before they show signs of significant ill health. To confirm a diagnosis of kidney disease as well as determine the best course of action the following should be performed:

  • Clinical examination.  This is where your vet can palpate your cat’s kidneys and check their size and shape as well as for any discomfort. The other clinical signs mentioned above will also be investigated.
  • Blood test.  To check the levels of urea and creatinine (toxin indicators), red and white blood cells, potassium, phosphorus and other electrolytes.
  • Urine sample.  To see if the urine is concentrating well (thus giving us information on the functioning ability of the kidneys), also to check for protein levels and evidence of infection (the presence of red and white blood cells as well as bacteria in the urine sample.) A further test may be performed to check where the damage has been done in the filtration unit of the kidney.  This is called a urine protein creatinine ratio (UPCR). This can help guide any medications that may help your cat’s kidneys function improve.
  • Abdominal ultrasound.  This may be recommended to assess the kidneys further and can allow for sampling of the tissue if a tumour or amyloidosis is suspected.


Depending on the results of the clinical examination, blood tests and urine sample (+/- an abdominal ultrasound), appropriate treatments can be implemented.

  • Intravenous fluids.  This is the first treatment recommended if your cat presents as inappetant and dehydrated.  The fluids help to flush the kidneys and reduce the levels of toxins in the body as well as replace the fluid that your cat has lost.
  • Appetite stimulants and anabolic steroids.  These help get inappetant cats eating again and to build up muscle reserves that have usually been depleted.
  • Dietary changes.  A prescription kidney diet has reduced levels of protein and phosphorus to reduce the levels of toxins in the blood stream.
  • Phosphate binders.  These help by binding phosphorus in the intestines so it does not cross into the blood stream.
  • Antibiotics.  If a urinary tract or kidney infection is detected.
  • Potassium supplementation.  Excessive loss of potassium when kidneys fail result in muscle weakness and poor coat quality, replacing this can improve cats well being.
  • Vitamin B and C supplementation.  These are required as levels are rapidly depleted by failing kidneys.  These vitamins are important for cells to function normally and to help cats feel well.
  • Blood pressure reduction/ monitoring.  To reduce the chance of further damage to the fine blood vessels in the kidneys.
  • Treatment of anaemia (low red blood cells).  These can be achieved with the replacement of the hormone that stimulates red blood cell production (erythropoietin).
  • Provide lots of water to encourage your cat to drink as they are at a higher risk of dehydrating.

Kidney disease can be detected early if regular veterinary checks are made of senior pets (those aged over 7 years old) and if clinical signs are recognised early.  The sooner kidney disease is detected, the better the outcome, as monitoring and appropriate treatments can be put in place to protect the remaining portion of the kidney, and thus ensuring your cat’s quality of life is optimised, and in many cases considerably increasing their life expectancy.