What do my cat’s kidneys do?
The kidneys have many functions. They principally act to remove waste products from the blood stream, retain essential nutrients such potassium at the correct level, maintain hydration and produce urine.
What is chronic renal failure?
The kidneys have a large amount of spare capacity to perform their various functions so at least 70% of the kidneys need to be dysfunctional before any clinical signs are seen. In many cases this means that the damage to the kidneys has been occurring over a number of months or years (chronic) before failure is evident. Chronic renal failure (CRF) is most commonly seen in older cats. Only about 10% of the cases occur in cats less than three years old. Early signs of disease such as weight loss and poor coat quality are often dismissed as normal aging changes. In the initial stages of kidney disease, the kidneys cope with their inability to concentrate waste products by excreting them at a lower concentration over a larger volume. This is known as compensated renal failure. After approximately 70% of the kidney tissues are destroyed, there is a rapid rise in waste products in the bloodstream and an apparent sudden onset of severe disease.
What are the causes of CRF?
A large number of different disease processes can eventually lead to CRF including:
How is the disease diagnosed?
Renal failure is usually diagnosed by looking at the level of two waste products in the bloodstream, blood urea nitrogen (BUN) and creatinine, in conjunction with the urine specific gravity (USpG). Tests to measure the blood levels of other substances such as potassium, phosphorus and calcium as well as the red and white blood cell counts are important in order to determine the extent of failure and the best course of treatment.
Could the renal failure have been diagnosed earlier?
Unfortunately, this is very difficult as neither clinical signs of renal failure nor rises in BUN and creatinine are evident until significant loss of kidney function has occurred. In earlier stages of disease there are no clinical signs to indicate that sophisticated renal function tests, which can pick up early renal damage, are required. We recommend that all senior pets have at least a urinalysis performed every six to twelve months to diagnose kidney disease at it earliest detectable level. A low urine specific gravity may indicate that at least two-thirds of the kidney tissues are damaged.
How does CRF affect my cat?
Because the kidneys perform a variety of different functions, the clinical signs of renal failure can be somewhat variable. The most common changes seen are weight loss, poor hair quality, halitosis (bad breath), variable appetite which may be associated with mouth ulcers, lethargy and depression. Less commonly, cats are seen to drink and urinate more and some will have vomiting and diarrhea. Rarely, renal failure is seen as sudden onset blindness.
What treatments are available?
Depending on the results of blood tests your veterinarian may be faced with several problems that require different treatments. Don’t worry if the list below seems so long that you will never be able to administer all of the medications. The majority of cats can be effectively managed with diet change including supplementation and one or two other treatments.
IT IS IMPORTANT THAT FRESH WATER IS AVAILABLE AT ALL TIMES BECAUSE CATS WITH RENAL FAILURE CAN DEHYDRATE RAPIDLY.
What is the cost of treatment?
Treatment costs will vary with each individual case. In the majority of cases, long term management is generally inexpensive.
How long can I expect my cat to live?
Unfortunately, once the kidneys are damaged, they have very limited ability to recover. Most CRF cases progress very slowly. With treatment, your cat may have several years of good quality, active life ahead.