CHRONIC RENAL FAILURE IN CATS
The kidneys are an important organ whose function is to remove waste products from the blood while conserving water. They also play a part in electrolyte balance and red blood cell production.
Cat’s usually show no signs of disease until 75% of their kidney function is gone. For this reason by the time your cat shows signs of disease he or she is usually already in the advanced stages.
WHY DO KIDNEYS FAIL?
There are many reasons why kidneys fail. Unfortunately, damaged kidneys look the same no matter what the cause and so it can be difficult to diagnose a cause.
Possible causes of kidney failure are; toxic damage (eg. snake bite, lily posioning), chronic infections, renal calculi (ie. Mineral deposits or stones stuck in the kidneys or the urethra and bladder), immune-related diseases (these effect the entire body but can specifically target and damage the kidneys), amyloidosis (a type of protein which ‘clogs up’ the kidneys damaging normal tissue), kidney tumours and congenital and hereditary disorders (Abyssinian cats can carry a hereditary nephropathy in their lines).
CLINICAL SIGNS
Cats with kidney failure tend to have an unkept coat, bad breath and an inconsistent appetite, this progresses to weight loss, mouth ulcers, vomiting, lethargy or depression and an increase in drinking and urinating. These signs usually become apparent gradually over weeks or months.
Sometimes the signs appear suddenly due to an incident, which stresses an already damaged kidney. For example, a cat with renal disease that is lost without water for 24 hours may suddenly get very ill. A healthy cat would be able to cope with this.
DIAGNOSIS
A physical examination by your vet is the first step. A urine sample to assess how well the kidneys can concentrate urine and a blood test to check kidney function and the electrolyte balance will also be required.
TREATMENT
1. Diet – the kidneys filter the waste products from the blood and most of these waste products come from the food your cat eats. Therefore, the workload of the kidneys can be significantly reduced by the type of food you feed your cat and should be thought of as a medication just as tablets are prescribed.
2. A diet low in phosphorous and protein and high in potassium and other essential nutrients can make a major difference in preventing or reducing the loss of more kidney cells. Special prescription diets are now available to make this easier for you as the owner. They come in tinned and dry food and are usually palatable although it can take some cats a little while to get used to them. These foods should be fed exclusively with no extras given.
3. Antibiotics – if an infection is complicating the renal failure. It is relatively common for cats to get urinary tract infection as their urine is less concentrated than it should be and therefore easier for bacteria to grow in. For this reason a urine culture and sensitivity may be recommended every 6 months.
4. Angiotensin Converting Enzyme inhibitors – these help to reduce protein loss in the urine and lower blood pressure. Whether these drugs will be useful can be determined by a urine test – a urine protein creatinine ratio.
5. If blood pressure is high other drugs can also be used to help reduce it.
6. Fluid therapy – the patient should be encouraged to take in as much water as possible by the use of wet food, flavoured water, water fountains etc and if this is not sufficient then subcutaneous fluids can be used.
PROGNOSIS
Kidney cells that have already been damaged cannot be repaired. The progression, however, can be slowed down with appropriate treatment. This can improve the cat’s well being and extend his/her lifespan quite significantly. Each case should be assessed individually by you and your veterinarian and the prognosis judged by serial blood and urine testing.