Contributed by Sarah Wooten, DVM, CVJ.
Why All Cat Parents Should Know About Cat Kidney Disease
Cat kidney disease, the leading cause of death in elderly cats, is a frustrating condition for pet parents and veterinarians alike. The cause of cat kidney failure has not been determined, and cat kidney disease doesn’t cause cats to act sick until it is too late.
When it comes to acting healthy, cats are masters of disguise. They will look and act healthy until they are physically unable to do so because of their instinct to survive. Unlike dogs, who have been evolving alongside humans for multiple millennia, cats are not so far removed from their wild ancestors. If a cat in the wild showed that she was sick, she would be easy prey to larger predators. That instinct drives a cat to act normal even when they are sick and to hide themselves when they can no longer do so.
Kidney failure in cats is typically a slowly progressive disease. What this means is that no signs of kidney failure in cats will show other than your cat drinking lots of water and peeing more until the cat kidney disease is far advanced.
The kidney’s job is to filter toxins out of the blood. In cat kidney disease, the kidneys become scarred and damaged, and the microscopic filters start to shut down, one by one. A cat can lose up to 75% kidney function and still eat and act normally, which is why many cat owners don’t notice any signs of kidney failure in cats until it is too late. Once kidney function is lost, it usually does not come back, and toxins building up in the blood start to affect other organs in the body. Cats that have end-stage kidney failure usually fail within a couple of days of this happening. It is heartbreaking to see alarmed pet parents in the exam room with their dehydrated, debilitated, and very, very sick kitty who seemed perfectly normal last week.
A cat drinking lots of water and peeing excessively are the classic and earliest signs of kidney failure in cats. Other symptoms include weight loss, loss of appetite, vomiting, decreased energy and in emergency cases, ulcers in the mouth that smell very bad. Cats that are in end-stage kidney failure are suffering, and unless they are a candidate for dialysis and kidney transplant, are unfortunately humanely euthanized because of poor quality of life and lack of a cure. Kidney failure in cats frustrates veterinary professionals to no end.
There is good news, however. Cat kidney failure is usually very slowly progressing, and if treated appropriately, your cat can have a good quality of life for years—even with cat kidney disease. Veterinary researchers are finding new ways to detect cat kidney failure earlier, and early diagnosis leads to early intervention, which can prolong length and quality. I recommend that all my cat patients over the age of 7 have annual blood work drawn to test for kidney disease. One of the most promising tests is a blood test for SDMA, a sensitive kidney biomarker, which can detect kidney disease earlier than standard blood tests for kidney function. This test can either be run at your veterinarian’s hospital or it can be sent to the local laboratory. SDMA can detect a decrease in the kidney’s ability to filter the blood earlier, and allow you to pursue treatment earlier.
I have several feline patients that get their blood tested yearly. On their bloodwork, the BUN and creatinine, which are historically used to determine kidney function in cats, are normal, but their SDMAs are abnormal. Kidney changes was caught early in these patients because of SDMA, and would have been missed if we were just checking BUN and creatinine. Because we caught them early, we can start treatment earlier and preserve kidney function for longer.
If your cat has been diagnosed with cat kidney disease, there are several treatments available that depend on the stage of disease. Cats with early kidney insufficiency can benefit from a high-quality, high-protein diet. In the past, cats with kidney insufficiency were immediately switched to a protein-restricted diet, however this is no longer the case. It is important to keep cats with kidney disease in good body condition—which means feeding your cat a diet high in protein to fuel strong muscles to drive metabolism and support the body. For my patients with early cat kidney disease, I recommend feeding a combination of high-quality canned and dry cat food, and lots of fresh water. Cats with kidney disease dehydrate easily, so providing some moisture in the form of canned food is a good idea. Cats with kidney disease also benefit from a high-quality fish oil supplement, like Nordic Naturals Pet Cod Liver Oil. In humans, fish oil has shown to have a protective effect for kidneys.
Cats with advanced kidney disease have different dietary needs. In these cases, food really is the best medicine for these cats. Feeding your cat a kidney diet, like Hill’s Prescription Diet k/d Kidney Care with Chicken, is appropriate to prevent toxins from building up in the blood. The problem with many kidney diets is that sick cats become very picky, and it can get hard to switch their food or get them to eat at all. For cats that will not transition to a kidney diet, I recommend supporting them with an intestinal phosphate binder, like the Vetoquinol Epakitin Supplement, under the supervision of your local veterinarian.
The most important thing you can do for a cat with kidney disease is to work closely with your veterinarian. Cats with kidney disease need to be seen every 3-6 months for exam, weight check, blood work and nutritional recommendations. Do not give cats with kidney disease any supplements without the supervision of your veterinarian.