Back in September, I wrote a blog post entitled, “Kidney Disease in Dogs and Cats.” One question I received from this post was about the use of supplements in cats diagnosed with chronic kidney disease. I decided to respond to this question by writing another post since this is an important feline disease and many readers will appreciate the answers to this question.
Chronic Kidney Disease
The inability of feline kidneys to properly filter waste products from the blood, maintain water and electrolyte balance, and even make red blood cells is one of the most common disease processes seen in the geriatric feline. In the early stages of disease, cats compensate well for the decrease in kidney function, but as the disease progresses, more interventions are required to keep your cat with kidney disease feeling well. Many of these interventions provide supplemental nutrients, vitamins, minerals and fluids.
I am interpreting the reader’s question to be asking about treatments for chronic kidney disease that are not drugs and thus am including food. Practically every pet food company manufactures a kidney-friendly diet. These diets contain less protein than maintenance diets in order to spare the kidneys from working hard to excrete the byproducts of protein metabolism. These diets are also low in phosphorus and supplemented with B vitamins and potassium. Elevated phosphorous has been linked to a shorter survival in cats with kidney disease; consequently, lowering phosphorus is beneficial. Prescription diets developed for management of kidney disease also frequently contain omega-3 fatty acids and antioxidants, which, along with vitamins and minerals, are discussed separately below. The most important feature of feeding your cat with chronic kidney disease a kidney-friendly diet is the diet’s ability to extend survival in cats diagnosed with chronic kidney disease.
Vitamins and Minerals
Because cats with chronic kidney disease make large volumes of urine, they are also excreting large volumes of water soluble vitamins, like B vitamins and potassium. Supplementation of B vitamins, orally or as part of a prescription diet, helps to maintain adequate levels of these important nutrients. Since low potassium levels are so prevalent in cats with chronic kidney disease, several commercial potassium supplements are available in formulations designed to appeal to the most finicky felines. Many of the potassium supplements also contain B vitamins and other ingredients designed to support kidney function. Iron deficiency is a common mineral deficiency in cats with chronic kidney disease. Cats may lose iron due to bleeding ulcers or may not take in enough dietary iron if they have a poor appetite. Oral administration of iron can cause stomach upset, so most often injections are the favored method of iron supplementation in cats.
Omega-3 Fatty Acids and Antioxidants
Inflammation and oxidation play a role in the progression of chronic kidney disease. In dogs, omega-3 fatty acids have beneficial anti-inflammatory effects in chronic kidney disease and are often included in kidney-friendly diets by the addition of fish oil. The impact of omega-3 fatty acids on cats with chronic kidney disease is less clear. Vitamin C, Vitamin E and rosemary are typical natural antioxidants added to kidney-friendly pet food. Omega-3 fatty acids and antioxidants can also be supplemented separately from kidney-friendly diets.
Often, reduction of dietary phosphorus does not correct elevated phosphorus levels. When this occurs, veterinarians often prescribe phosphate binders to trap phosphorus in the intestines where it is excreted in the feces. To be effective, phosphate binders need to be administered with every meal. Several manufacturers have developed feline specific phosphate binders in supplement form.
When kidneys can no longer regulate water balance, a sick cat may not feel up to drinking adequate amounts of water and will become dehydrated. Even the most squeamish owner can be taught to administer supplemental fluids under the skin (subcutaneous) to keep their cat well hydrated.
With such an array of supplemental nutrients, vitamins and minerals available for cats with chronic kidney disease, cat families should discuss any supplements or diet changes with their cat’s veterinarian to ensure optimal treatment of their cat’s chronic kidney disease.