Kidney disease in your cat

Chronic kidney disease is a common health problem in middle-aged and elderly cats. A gradual reduction in the ability of the kidneys to do their job is an inevitable part of the aging process and occurs at varying rates in different animals. The damage is irreversible and for many cats it will eventually be fatal. Your cat may still have many months to years of good quality life after diagnosis of kidney disease if they receive effective treatment, however, some cats have quickly progressive kidney disease and this can be hard to predict without ongoing monitoring.

©Douglas McCallum

As part of the normal aging process, and sometimes in response to toxins, infections, kidney stones or other illnesses, the units of the kidney (“nephrons”) that usually filter waste products out of the blood become damaged. In time, so much kidney tissue is affected that these waste products can no longer be eliminated and build up inside the blood stream. This condition – which veterinarians call chronic kidney disease – is very common in cats over nine years old. Sudden or acute kidney injury can also occur as a result of poisoning, bacterial and viral infections, blockage of the tubes leading from the kidneys to the bladder or heart disease. These cases need emergency care and even if successfully treated by your veterinarian, your cat may still suffer long term kidney damage.

The kidneys have a lot of spare capacity for filtering blood, so symptoms only appear when about three-quarters of the kidney cells have stopped working. One of the first indications of disease can be weight loss, including muscle loss, but some cats show very few signs of kidney disease and requiring screening of blood and urine tests for it to be detected. Commonly, there is the loss of ability to produce concentrated (dark) urine. So to get rid of the same quantity of waste material your cat has to produce larger quantities of more diluted urine. Your cat will be thirstier than usual and have to pass urine more often. As the disease gets worse other symptoms may appear. Your cat may seem depressed and lose interest in food, vomit regularly, lose weight and its coat becomes dull. You may also notice bad breath and ulcers in its mouth.

Many of these symptoms also occur in other diseases such as diabetes. Your veterinarian will want to test samples of blood and urine +/- an ultrasound examination of your cat to show that the kidneys are not working properly.

Although damaged kidneys cannot be repaired there is much that can be done to make your cat feel better. In early stages of the disease your cat may feel well but some treatments are advised to help slow the progression of the disease and increase survival time (eg dietary changes, see below, and treatment for protein in the urine or high blood pressure). In later stages of the disease, your cat may start to feel nauseous, vomit or go off their food. Your veterinarian will advise on medications that can help treat these problems. Many cats that are producing abnormally large amounts of urine can become severely dehydrated. If this occurs, your veterinarian will want to give extra fluids to counter this and give medication to treat the secondary effects of the disease such as mouth and stomach ulcers. Anemia is a common problem in cats with advanced disease and in some cats this may require treatment if it is severe.

The most important thing in helping your cat is to reduce the workload on the remaining healthy kidney tissue. This can be done by altering your cat’s diet. There are special diets available from your veterinarian which reduce the waste products in the blood. They also have extra amounts of some vitamins and minerals. Avoid giving your cat leftovers or treats which may interfere with the new diet. Affected cats often feel sick and lose interest in their food. It may help if you warm up the food to stimulate your cat’s sense of smell or hand feed it while it is getting used to the new food. Feed it ‘little and often’ and throw away uneaten food. Change onto the new food gradually over 7-10 days. Always make sure your cat has plenty of fresh, clean water at all times, allowing your cat to go thirsty will make the problem rapidly worse.

Unfortunately, at present this can be very difficult to predict. Some cats have stable kidney disease for months to years, and some cats have rapidly progressive disease. The stage of kidney disease your cat has at diagnosis can help your veterinarian to give you some guidance on this. Additionally, monitoring of your cat’s kidney function, particularly during the first year after diagnosis will help to provide information on how rapidly the disease is progressing. Your cat will need regular check ups by your veterinarian and possibly changes to its medication. By weighing your cat often, watching its behavior and checking how much food and water it consumes, you will be able to provide your veterinarian with valuable information which help to manage the disease and maintain a good quality of life for your cat.