What is kidney disease?
Veterinary specialists estimate that 30% of cats over the age of 10 have chronic renal (kidney) disease. That’s a scary number and, though there are a variety of treatments available, there is no known cure for this condition. Thankfully, veterinary diagnostics have become more sensitive over time, allowing your veterinarian to detect subtle signs of renal disease earlier. Combined with rapid detection and advanced treatment, many cats can live long lives with this condition. Though renal disease can occur at any age, it is most commonly diagnosed in cats over 7 years of age.
The kidneys are a particularly important organ, contributing to metabolic factors like blood pressure, electrolyte balance, hydration, and red blood cell production. Your veterinarian can work with you to perform blood work, check your cat’s blood pressure, discuss diet changes, increase fluid intake, control symptoms, and even supplement electrolytes that may be out of balance.
What is the difference between chronic kidney disease and renal failure? What causes it?
Given how important kidneys are to the body, cats (and most species) are born with a reserve supply. 60-70% of the kidneys must be dysfunctional before a cat displays signs of this disease. Names like chronic kidney disease (CKD), chronic renal failure (CRF), chronic renal insufficiency (CRI), and chronic renal disease (CRD) are frequently used interchangeably. As we begin to diagnose CKD earlier, however, we should note that renal failure occurs when >75% of the nephrons (the kidney’s filtration units) are depleted. Your veterinarian will be able to determine if your cat has reached this point.
Most of the time, the cause of CKD is unknown. Some factors can contribute to the advancement of kidney disease, such as congenital changes (birth defects), infection, hypertension (high blood pressure), and neoplasia (cancer).
What are the clinical signs of chronic kidney disease?
A cat with renal disease may start to drink more, urinate more, have a change in appetite, vomit, lose weight, or seem weak. Many owners notice their cats’ coats appearing more dull than usual. Prolonged hypertension (high blood pressure) can lead to sudden blindness in severe cases.
How do we detect and stage kidney disease?
The blood value that is most specific to the kidneys is called creatinine. Creatinine is used to stage kidney disease, which is a valuable tool in determining appropriate treatment and predicting prognosis. Blood urea nitrogen (BUN) is also often elevated in cats with CKD. Your veterinarian may also notice protein loss through the kidneys into the urine, along with dilute urine. In some cases, your veterinarian will be able to palpate changes to the shape of your cat’s kidneys.
Creatinine will not be persistently elevated until the kidneys have reached the 60-70% tipping point. Recently, additional markers have been developed to detect renal disease earlier. As one of these values, your cat’s serum symmetric dimethylarginine (SDMA) may be elevated for over a year before creatinine increases. A diagnostic laboratory has also developed a tool called RenalTech, which uses predictive modeling to determine whether an individual cat is likely to develop CKD.
How is kidney disease treated?
One of the most important treatments of kidney disease is a prescription diet. These specially formulated foods contain low amounts of highly-digestible protein, are low in phosphorus, and contain additional vitamins to support your cat. Cats with severely elevated phosphorus levels may require phosphate binders, while those low in potassium may need oral supplementation of this electrolyte. Some cats will also need medications to lower their blood pressure, treat anemia (low red blood cells), or control nausea. Your veterinarian may further recommend supplements, such as omega-3’s, to support the kidneys. Once renal disease has advanced, many cats will require subcutaneous fluid administration at home. Your veterinarian can discuss when this is appropriate and show you how to administer fluids to your cat.
What should I do to prevent my cat from developing kidney disease?
As discussed above, this disease is very common in older cats, and the underlying cause is often unknown. Just like in any other aspect of your cat’s health, your veterinarian is the best source of information. Always be sure to schedule yearly physical examinations and maintain preventative medical care for your cat. As your cat ages, your veterinarian will let you know when annual or more frequent bloodwork is appropriate.
Your BetterVet veterinarian will be happy to discuss further details of kidney disease at your cat’s next visit!