Kidney Disease in Cats  - Chronic Renal Failure 
By Jean Hofve, DVM  littlebigcat.com

Signs of Renal failure in cats. Increased thirst is often the first symptom

Kidney disease, in the form of chronic renal failure (CRF), is a common problem in older cats. I have seen kidney failure in cats as young as 4 years, but far more frequently in much older cats. The most noticeable symptom is an increase in water consumption and urination ("drink-a-lot, pee-a-lot syndrome"). A blood test should be done if you notice these symptoms, as there are several conditions that can cause this. The increase in drinking and urinating in CRF is due to loss of the kidney's ability to concentrate the urine. The kidneys have a very large reserve capacity, and symptoms of kidney failure are not seen until approximately 75% of kidney tissue is non-functional. In my experience, kidney failure is the most common cause of death in older cats.

Diagnosing CRF

Laboratory tests are needed to definitively diagnose CRF. A blood test alone is usually not sufficient; a urinalysis must be taken at the same time the blood is drawn. Kidney disease is likely present when the cat is “azotemic” AND the urine is not sufficiently concentrated. “Azotemia” means that there is an increase in particular compounds in the blood; specifically blood urea nitrogen– BUN–and/or creatinine. The measurement of urine concentration is called Urine Specific Gravity (USG). If the cat’s USG is less than 1.035 (1.030 in dogs) AND azotemia is present, then kidney function is abnormal. BUN and/or creatinine may be high if the animal is dehydrated (common in cats who eat a lot of dry food, or during hot weather or after a stressful car ride). They may also be increased in animals on a high protein diet. As long as the kidneys are able to concentrate the urine, small elevations in BUN and/or creatinine are usually not a cause for alarm.

Causes of Chronic Renal Failure

Recent research suggests a link between vaccination for feline distemper and immune-mediated inflammation of the kidneys, which is thought to be the cause of CRF. Annual boosters for distemper are completely unnecessary. Be sure to discuss all recommended vaccines with your veterinarian. A cat with kidney disease or kidney failure should not be vaccinated at all.

Long-term feeding of an all-dry-food diet is also suspected as a factor in Chronic Renal Failure. Cats' kidneys are highly efficient and adapted to life in the desert, where they would get most or all of their water from eating their prey. Cats eating dry cat food take in only half the water that cats on a canned or homemade diet get; this chronic dehydration can cause stress on the kidneys over time. Dry diets also predispose cats to lower urinary tract disease (FLUTD, LUTD, FUS, crystals, stones, cystitis) because they force such a high degree of urine concentration.

Chronic or recurrent bladder disease may also be a factor in the development of CRF.

Treatment of Chronic Renal Failure

Chronic kidney failure is progressive and incurable. No conventional or alternative medical treatment can reverse its course, since the disease involves the loss of kidney cells and replacement by scar tissue. The rate of progression in any individual cat probably cannot be slowed to any significant degree. When the process is advanced, the kidneys become small and lumpy, and the amount of functional tissue is greatly limited. The most significant problems caused by the loss of function are build-up of blood toxins, and anemia. These can cause weight loss, lethargy, vomiting, loss of appetite, weakness, and other signs of illness. 

Some cats are able to maintain their body weight and live relatively comfortable lives for months to years, while others succumb to the disease more quickly. In conventional medicine, there are drugs that can minimize anemia, and phosphate binders to prevent phosphorus precipitates from further damaging the kidneys. However, these may not be palatable, and may cause adverse reactions. They are also of little or no value unless the cat is eating a restricted protein/low phosphorus diet exclusively. It may also be important to supplement potassium in the food.

However, because the study has not yet been published, it is impossible to evaluate the data, which is contradicted by other research. The real culprit is actually phosphorus, which meat contains in large amounts. Decreasing phosphorus intake (by restricting protein) can help some cats feel better, so it may be worth a try in a symptomatic cat.

Some studies have suggested that excessive restriction of protein may actually cause further damage to the kidneys and other organs, because there is not enough protein for normal body maintenance and repair. Experts say that these diets are not appropriate until the BUN (Blood Urea Nitrogen) is at least double what it should be normally (about 60-80 mg/dl).

Furthermore, there is one big problem with using the protein-restricted commercial diets: many cats don't like them, and won't eat them. Obviously, it does little good to provide a special diet if the cat is going to starve to death! Experts emphasize that it is much more important to feed the cat what he likes and will eat, and maintain weight and body condition, than to be overly concerned about protein content. (Please note that if you add any other protein source to the diet, it will completely negate any possible beneficial effect from the low-phosphorus renal diet. It is useless to feed both a renal diet and a normal protein food or meat-based treats at the same time.)

Let me say this again, because it is the single most important thing to know about CRF: feed the cat anything she will eat! IF THE CAT WON'T EAT IT, IT WON'T HELP THE CAT! Weight loss is your cat's worst enemy in this disease; so let the cat eat what she wants!

Because water balance is so crucial, it is best to feed a high-moisture diet to help keep the cat hydrated; do not feed only dry food. Feeding mostly or only canned food, even though it is high in phosphorus and protein, provides the moisture and calories that these cats need, in a very palatable form that most cats will happily eat. You can also get low-phosphorus renal diets in canned form. Dry cat food causes dehydration even in healthy cats, and is not appropriate for  CRF cats (unless, of course, it's the only food he will eat!).

The best thing you can do is feed a home-prepared diet; but only if the cat will eat it! If the cat has never eaten homemade food, or does not have a hearty appetite, this is not a good time to make this switch! There are several good books on home cooking for animals, such as Dr. Pitcairn's Guide to Natural Health for Dogs and Cats, by Richard Pitcairn, DVM, and Susan Pitcairn. (Rodale Press. ISBN 075962432.) They discuss why a diet made from fresh, raw foods is important, and provide recipes, including a special recipe specifically designed for animals with kidney disease. Another excellent book is Home-Prepared Dog and Cat Diets: the Healthful Alternative by Donald R. Strombeck, DVM. (Iowa State University Press. ISBN 0813821495.) If you choose to use Dr. Strombeck's recipes, I suggest substituting 1 capsule of taurine (250 mg) for the canned clams, since clams do not contain enough taurine for proper maintenance.

Special Nutrition for Chronic Renal Failure

Several nutritional supplements may be helpful for cats with kidney disease. Omega-3 fatty acids have been shown to be beneficial in CRF. Antioxidants are also important. Both of these are contained in the highly digestible algae, Biosuperfood. A nutritional supplement called "Renafood" from Standard Process, is a good renal detoxifier and helps to maximize kidney function in cats. Give one or two a day. Most cats eat them readily if they are crushed into the food. Call Standard Process at 1-800-558-8740 to find a distributor in your area. Remember, though, that the basic diet is the most important factor in your cat's health, and no supplement will make up for poor quality nutrition. For more info on feeding, choosing a good food, and switching to a better diet, see the many nutrition articles in our Library.
 

Supplemental Fluids

Your veterinarian can give your cat subcutaneous fluids in the clinic, or teach you how to give them at home. This is the least intrusive and most beneficial treatment you can give your cat. Cats in chronic renal failure drink a lot of water, but they cannot drink enough to compensate for the loss of water through the kidneys. Subcutaneous fluids are an excellent way to help keep the toxins flushed out of the bloodstream and make the cat feel much better. If the cat is sick or not eating, it may be necessary to hospitalize it for a few days for intravenous fluid therapy, followed by subcutaneous fluids at home as needed.  A semi-permanent "port" that can be inserted in the cat's skin has taken much of the hassle out of this procedure; talk to your vet about having this installed. It is best to have this procedure done by a veterinarian who has lots of experience with these ports since there can be many complications.

Holistic Veterinary Care

While no treatment can create new kidney cells when scar tissue has already formed, homeopathy, herbs, flower essences or acupuncture may be able to help your cat feel better and live a better quality of life. Click on this link for a directory of holistic veterinary practitioners by state.

Other Resources

The Feline CRF Information Center is an incredible website devoted to cats in renal failure. You can find out just about everything there is to know about this disease here, as well as explore a host of excellent links to other feline health sites. You can also sign up for their email list, which can be a great resource and support for guardians of CRF cats.

Pet Loss Support

Ultimately, fighting CRF is a losing battle, and may carry a great emotional cost to the family.
Losing a beloved cat to CRF is just as traumatic as losing a human family member, but friends and
family don’t always understand. There are many resources to help you through the difficult times and
tough decisions you will have to make for your cat, and to support you afterward. Many of these are
listed on the Feline CRF pet loss support page.

This copyrighted article is reprinted with permission courtesy of Little Big Cat: www.littlebigcat.com