Chronic renal failure occurs due to a progressive loss of functional renal tissue. This may occur due to one of many possible underlying causes. By the time signs of renal failure are noticed in a cat there may have been a loss of around three quarters of its normal kidney function. Obviously this is a problem which we see mostly in older cats; often these animals are over 10 years of age. Younger animals can be affected as well, especially if they have some kind of congenital problem which would impair their kidney function in some way.
Cats with renal disease are often observed to be drinking excessively. We often do not see healthy cats drinking very much, especially if they are fed on moist food, so any increase in drinking should be noted easily. As cats drink more they also have increased urinary output so they begin to need to urinate more frequently. Urine will be passed in normal to larger volumes, unlike in cystitis, where urination is frequent but the volumes are small. These signs of drinking and urinating more than usual should always ring alarm bells with owners because they are a sign which may occur in many serious diseases and your cat should be seen by a vet if he or she is doing this.
Cats with renal disease may also vomit, lose weight, not want to eat, become dehydrated and suffer from mouth ulcers. Sometimes cats with renal failure may become anaemic or have dental problems due to the metabolic effects of renal disease.
If your vet suspects that your cat may have chronic renal failure he or she may need to carry out some tests. Often your vet will take a urine and blood sample from your cat, both of which can provide useful information regarding kidney function. It may also be useful occasionally to perform an ultrasound examination or X-rays.
If your cat does have chronic renal failure there is much which can be done to help, although unfortunately there is no cure and the condition will get progressively worse over time. The treatment which can be given aims to increase your cat's quality of life and slow down the rate of progression of renal disease.
Access to water is very important to cats with renal disease and you should never restrict this for any reason. Your cat should always have a bowl of fresh, clean drinking water available. Many cats do not like the "chemical" smell of tap-water; to help this disperse you can store tap-water in a glass bottle in the fridge for 24 hours before use, this helps the chemical gasses come away and makes the water more palatable to cats. Some people do give their cats spring water but take care that you do not use something with a high concentration of minerals as this will not be good for your cat. Something like Evian is usually OK. Many cats prefer to drink running water from taps and if this is the case for your cat you should not discourage it. Commercial drinking fountains for cats are available and your pet may appreciate this.
Attention should be paid to the diet of cats with renal disease. The diet should be low in protein and minerals especially phosphorus. Of course cats still need protein in their diet but this should be a very high quality protein.
There are many commercial diets available on prescription which are formulated for cats with renal failure. In my view, cats with renal disease should not be fed a dry diet as they need plenty of water and some of this will come from their food if they are fed a moist type of diet.
Cats may sometimes be given vitamin B to help to compensate for the loss of vitamins which occurs in renal failure. Anabolic steroids may also help your cat. Often cats with renal failure also have high blood pressure and this can be treated by your vet if necessary. Occasionally i/v or subcutaneous fluids will be needed if your cat becomes too dehydrated. Some other treatments may also be necessary depending upon the clinical condition of your cat.
In the United States vets are performing renal transplants for cats with chronic renal failure. However, there are risks to both the donor and the recipient animal with this type of surgery and it also raises some very serious ethical questions since a healthy cat must be used to provide a kidney. This healthy cat must undergo surgery from which it does not benefit in any way and it loses half its own renal function into the bargain. Although the donor cats which are used are often strays which must then be homed by the owners of the recipient cat, it still seems ethically challenging to me.
Unfortunately chronic renal failure is a progressive disease, so with time (a few months or possibly years) affected cats become more and more unwell. Eventually despite all our best efforts it may be necessary to euthanase the cat in order to prevent undue suffering in their final days of life.