Chronic kidney disease, a progressive condition that worsens at varying rates, affects an estimated 35 percent of cats over the age of 13. Although it has no cure, CKD is the subject of considerable research in the veterinary community.
Researchers at the Colorado State University College of Veterinary Medicine and Biomedical Sciences and the Animal Medical Center in New York City are evaluating the impact of stem cell therapies in cats with CKD. Although the studies differ in their approach to stem cell therapy, both are conducted in hopes that the findings might lead to novel treatments to stop the progression of kidney disease. Studies elsewhere are evaluating treatments for symptoms of the disease.
Complex Nature. While research continues, owners of cats coping with CKD need to understand and come to terms with the complexity of the disease. “The first thing I tell owners is, ‘The disease is chronic, we’re not going to cure it, and I don’t know how quickly it will progress,’” says Catherine Cortright, DVM, a resident in companion animal internal medicine at the Cornell University Hospital for Animals. “Some cats live with kidney disease for years and then die from something else. Others deteriorate quickly, so we simply must monitor the animal.”
The only treatment that has been shown to slow the disease’s progression is a special diet, Dr. Cortright says. “Diet doesn’t treat the disease process, but presumably the combination of the decreased protein, decreased phosphorus and omega 3 fatty acid supplementation helps slow the progression. The outcome, which has been shown scientifically, is that cats on the renal diet have longer survivals. We don’t know what aspect of the diet is most important in prolonging the survival or why.”
Treating Symptoms. Many drugs are available to treat symptoms of the disease — such as nausea, vomiting, lack of appetite, high blood pressure and anemia – but they don’t treat the underlying kidney disease.
Kidneys are responsible for removing waste and toxins from the body. When they become weakened or fail, wastes and toxins can start to accumulate in the blood and cause potentially severe complications.
The kidneys are susceptible to many disorders that can lead to kidney failure, also known as renal failure. “Acute” renal failure refers to a relatively sudden onset of problems in the kidneys, which can be caused by blockages or the ingestion of poisons, such as antifreeze or rodenticides. If recognized quickly, kidney damage from acute renal failure is potentially reversible.
Chronic kidney disease, on the other hand, is an incurable condition that progresses gradually, often over many months or even years. The exact causes of chronic kidney disease are unknown, although it can be linked to other conditions such as advanced dental disease and a variety of kidney infections.
The link between dental and kidney disease isn’t fully understood. It is thought that the buildup of bacteria in the mouth, combined with a potentially weakened immune system, can lead to higher incidences of kidney infection.
Although CKD is most prevalent in older cats, it can affect cats of all ages and breeds. Despite the fact that its severity builds over time, symptoms often seem to appear suddenly. In addition to the signs noted previously, others include excessive drinking and urination, lack of appetite and weight loss.
Both male and female cats appear to be equally susceptible to CKD. Certain studies have reported that Maine Coon, Abyssinian, Siamese, Russian Blue and Burmese breeds are more commonly affected, but those findings haven’t been consistent across all studies.
Blood Work. However, the condition can be detected before the onset of symptoms. “If we’re lucky, a veterinarian will catch kidney disease on routine blood work for an older pet,” Dr. Cortright says. When certain values in blood work are elevated, kidney disease might be suspected. But further tests need to be done to rule out other potential issues that can elevate those values, such as a urinary tract infection. Likewise, additional tests might be performed to look for an underlying cause for the CKD or to determine its severity.
The majority of approaches to chronic kidney disease focus on managing symptoms. Treatments might include dietary therapy, fluid administration, management of anemia and high blood pressure, and modification of calcium and phosphorus. The veterinarian might begin by prescribing certain treatments and then, based on patient response, add or subtract treatments.
Limited Protein. Feeding a special kidney diet is usually recommended. It contains less protein compared to other diets but the protein is high quality. Kidney diets also control the amount of substances that might be too high or too low in patients with CKD, such as phosphorous, salt, potassium, magnesium and B vitamins.
When a cat is diagnosed with a chronic condition like CKD, owners can become desperate for more extreme options. They commonly ask about the possibility of a kidney transplant, Dr. Cortright says. “Yes, there are places that do renal transplants for pets. But whether or not they’re a good idea is questionable.”
Although renal transplant survival rates are much higher in cats than in dogs, only about 60 percent of cats who have renal transplants are alive in six months, Dr. Cortright says. In addition, not all cats with CKD are candidates for a transplant, and the procedure is expensive (see sidebar below). A transplant requires cats to be on immunosuppressants for the rest of their lives, leaving them prone
to infections.
A Rare Option. Hemodialysis for cats with CKD is another available but rarely practical or affordable option, Dr. Cortright says. In hemodialysis, a cat is attached via catheter to a machine that filters toxins from the blood in the same way that a properly functioning kidney would. At the Animal Medical Center in
New York, the average estimate for the care of a hemodialysis patient is $20,000 to $25,000 for the first two
to three weeks.
The costs are often more justifiable for cases of acute kidney failure, in which long-term dialysis treatments aren’t necessary. But in cases of chronic kidney disease, treatments are necessary for the rest of the cat’s life, meaning costs continue to mount, and owners must live near the treatment center for regular visits. Furthermore, dialysis is feasible only for highly tolerant animals who will allow the placement of a catheter and remain still enough for the treatment, Dr. Cortright says.
Some cats with CKD can live many years in a stable condition and ultimately die for another reason. Other cats deteriorate quickly and might die within a few weeks or months after diagnosis.
The costs for treating CKD range widely depending on its progression. Dr. Cortright estimates average monthly expenses of about $200 for supportive treatments and special diets. However, that cost can be lower for cats whose conditions
are stable.
One of the biggest challenges is owners’ acceptance of the implications of a chronic disease. “People always ask, ‘Why did this happen?’” Dr. Cortright says. “There is no answer. The reality is that nearly every cat, if he lives long enough, will die of either kidney or heart disease. They’re degenerative conditions. The owners didn’t do anything wrong.”
However, through regular veterinary checkups, owners can hope to recognize the signs of CKD early and better control the effects on their cats. With proper management, Dr. Cortright says, some cats with CKD live long, full lives — sometimes as long as six to eight years after diagnosis. ❖
