Kidney Disease in Cats

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Unfortunately, kidney disease is very common in cats, with as much as 18% of the UK cat population being effected. As any cat owner will have noticed, most cats don’t drink nor pee much. This is because cats’ kidneys work very hard through their lives concentrating their urine, much more than dogs or people can, so it is not surprising that older cats are frequently seen with kidney or ‘renal’ disease - however young cats can occasionally develop problems as well.

There are several common underlying causes of kidney disease.

  1. In older cats Interstitial Nephritis is most frequently seen. This is basically old age scarring, although there are many factors involved. Diet and genetics don’t appear to play a role and there is nothing that can be done to prevent the disease.
  2. Polycystic Kidney Disease (PKD) is a very common problem in Persian cats - 20-30% of them can be affected. Basically, kittens are born with cysts in their kidneys which gradually enlarge, eventually destroying the normal surrounding renal tissue by the time the cat is between 2 and 8 years old. Most Persian breeders have their animals scanned when they are about a year old to detect the problem before it is passed on to their offspring.
  3. Tumours are occasionally seen in middle-aged and older cats. These are normally a type called lymphoma, and can respond well to chemotherapy if caught early.
  4. Toxins such as antifreeze can very quickly damage the kidneys and cause renal failure.
  5. Infection in the kidney (pyelonephritis) can occasionally occur, while any chronic inflammation or infection in the body can cause a condition called amyloidosis - complexes of antibodies form in the kidney tissue and destroy the normal cells.

What to look for

As most people know the commonest signs seen with kidney failure are increased drinking and urination. These tend to be quite marked although may develop over many months and therefore go unnoticed. Cats will also tend to have a reduced appetite and show weight loss.
As the condition progresses, regular vomiting of bile can occur and leg weakness with disorientation may develop in extreme cases. Animals with terminal kidney failure are very depressed, and eventually progress into a coma and death.

Diagnosis of Kidney Disease

Diagnosis is normally best done by looking at a urine sample from the cat and testing a blood sample. The blood sample will show an increase in Urea, Creatinine and sometimes Phosphate levels. The cat may also be a little anaemic. The urine is checked to see how concentrated it is by measuring the specific gravity and also to look for any signs of infection or protein loss. Repeat blood and urine samples should be taken 3-4 times a year to monitor the condition.


Treatment depends on how ill the cat is when the diagnosis is made.

  1. Fluids
    Very weak cats that are dehydrated and off their food, benefit from the administration of fluids for a few days - either under the skin or by the intravenous route i.e. dripping. Fluids flush kidney toxins out of the cat’s system making them brighter and hopefully getting their appetite back. If the cat doesn’t start eating well, it will start going downhill again within a few days or weeks.
  2. Diet
    The mainstay of treatment is diet. A low protein, low phosphate diet will reduce the workload for the kidney and so reduce the build up of toxins in the cat’s bloodstream. There are several wet and dried prescription diets available, so hopefully your cat will find something he likes. Studies have shown that cats with kidney failure that eat renal prescription diets will live 2-3 times longer than those that don’t, so it is well worth trying to change them over. Unfortunately trying to cook a low protein diet at home is often not successful - cats tend to pick out only the meat which is obviously high in protein. Fish and chicken is not good for cats with kidney disease either.
  3. Medications
    There are several medications that may be given to your cat in renal failure. Fortekor is the most frequently used. This daily tablet reduces the blood pressure in the kidneys, thereby slowing progression of the disease and improving function. Most cats on this medication show an improvement in appetite and gain weight. Antacids may be used to reduce vomiting.
  4. Antibiotics
    Antibiotics may be used if the blood or urine sample shows signs of infection in the kidneys.

The outlook for a cat with kidney failure is very variable. A single blood test and urine sample will tell us how bad the disease is but will not tell us how fast it is progressing. Repeat samples after 2-4 weeks will give us a better idea of how things are going and how well the cat is responding to treatment. The severity of the disease when it is first diagnosed, whether there are any concurrent infections and if the cat will eat the special diets and medications, all contribute to the outcome. It must be remembered however that the problem is not curable - treatment will only slow or stabilise the progression for a while. However survival times of anything between 6 months and 3 years can be achieved in most cases. Renal transplants are not being carried out in this country at present - rightly we feel. Please read our article on this topic for more information.