Kidney disease in cats is quite common and takes two main forms. Acute inflammation of the kidney tissues (nephritis) can arise as an extension of an infection elsewhere in the body; chronic nephritis is insidious in its onset and affects cats in their old age.
In the acute disease, the cat becomes suddenly very depressed, may vomit, refuse food and be very tender when handled around the abdomen. The urine may be very dark and often contains blood. Usually the cat has been in a fight and may have a badly infected wound or abscess. Acute nephritis can result from infections of the teeth.
The treatment of acute kidney disease consists of keeping the cat in hospital and giving it fluids by injection and administering antibiotics until the kidney tissues show signs of recovery.
Chronic nephritis is a disease a veterinarian frequently encounters. As aged cats seem less prone to develop cardiovascular disease than dogs, the organ that seems to fail first in old animals is the kidney.
The onset of the disease is quite gradual. The affected cat tends to drink more water but this may go undetected for a long time until the cat is observed going into the bathroom and licking the wet tiles or jumping up and drinking from the kitchen sink. Gradually the cat loses weight, although it may continue to be bright and eat well.
The increase in thirst and loss of weight continues until the cat becomes extremely thin and spends most of its days close to the water dish. It starts to lose interest in food and may approach the food apparently hungry, only to quickly lose interest and return to the water bowl.
In the final stages the cat refuses all food, may start to vomit and is reluctant to move. Its gums may be quite yellow and there is an unpleasant smell from the mouth.
Unfortunately, chronic nephritis is not curable. Vital tissues in the kidney have been destroyed and will not regenerate. There are some measures that can be taken that should slow the progress of the disease and prolong the active and comfortable life of the pet.
Changes in the diet are aimed at reducing the overall protein level and substituting other sources of nutriment. Cats are probably prone to kidney disease because their preferred diet is extremely high in protein, the waste products of which must be excreted by the cells of the kidney. Such foods as liver and kidneys should be avoided.
Cats usually will not eat large quantities of carbohydrates but will accept quite high levels of fat. The addition of vegetable or animal oils or lean meat or chicken may allow the overall amount of meat to be reduced. Cheese, yogurts and milk also are useful low-protein additions to the diet.
Extra vitamins in the form of the Vitamin B group are usually prescribed and anabolic steroids help reduce the amount of protein broken down and therefore excreted by the kidney.
The cat must be allowed free access to water, as it is by increasing the urinary flow through the kidneys that the waste products are removed and are prevented from building up in the bloodstream and producing the toxic effects already described.
The cause of chronic nephritis in the cat is not known. It is suspected that bacterial infections from fighting may play a part in the destruction of kidney cells early in the cat’s life.