Kidney Stones in Cats

There are several common underlying causes of kidney disease.

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.

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.

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. Toxins such as antifreeze can very quickly damage the kidneys and cause renal failure. 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.

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.

How is it diagnosed?

Usually a physical examination followed by blood and urine tests are sufficient to diagnose the disease; sometimes more detailed testing including ultrasound and biopsies are required to rule out other diseases such as kidney tumours.

How is it treated?

There is no cure but treatment can help to slow the progress and prolong your cat's life and maintain a good quality of life. This can be very helpful if we detect the disease early on.

It is very important that your cat has access to fresh clean water.

Diets can be changed, especially by introducing a low protein diet - there are now a number of different dry and canned low protein diets on the market. If your cat won't eat these as sole diets, they can be incorporated as part of the diet.

Cats with kidney failure often have hypertension or high blood pressure; this can be measured and medication to help control this can be instituted. Your cat's blood pressure can then be monitored on an ongoing basis.

In more advanced stages, anabolic steroids, medications to control elevated phosphorus and medications to control vomiting may be required. Also in severe cases, your cat may need hospitalisation and intravenous fluid therapy.

If you have concerns that your cat may have some signs of renal disease, please either ring to discuss the condition with one of the vets or arrange an appointment for a checkup.

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.

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.

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.

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.