Kidney Disease in Cats and Dogs

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Kidney Disease in Cats and Dogs

By Dr. Jean Hofve, Veterinarian Advisor


Only Natural

Kidney disease is a frequent problem in older cats and dogs. Kidney failure can develop in young animals, but it is far more common in pets over age 10. It is the leading cause of death in older cats.

In the Pet Food Recall of 2007, melamine contamination of pet food caused tens of thousands of cats and dogs to develop Acute Renal Failure (ARF). Many of the pets who got sick but recovered likely suffered some kidney impairment, and may ultimately develop Chronic Renal Failure (CRF). In that case, age makes no difference; animals of all ages were affected.

The kidney filter out and excrete toxins from the body through the urine. Healthy kidneys conserve water and concentrate toxins into a smaller amount of liquid to be urinated away. The kidneys have a very large reserve capacity, and symptoms of failure are not seen until approximately 75% of kidney tissue is nonfunctional. When the kidneys are damaged, they become less able to concentrate the urine. Because they’re losing water in the urine, they need to drink more—but because they’re drinking more, they urinate more. So the first and most noticeable symptom is usually an increase in water consumption and urination ("drink-a-lot, pee-a-lot syndrome").

As the kidneys lose function, other signs of CRF may occur, such as weight loss, nausea, constipation, low energy, fatigue, and poor appetite. A blood test and urinalysis should be done if you notice these symptoms, as there are many conditions that can cause them. A blood test and urinalysis are necessary to accurately diagnose CRF.

The measurement of urine concentration is called Urine Specific Gravity (USG). If the USG is low (less than 1.035 in cats, and 1.030 in dogs) and there are abnormal levels of two other compounds, then kidney function is reduced. The first, BUN (blood urea nitrogen), may be high if the animal is dehydrated, or eats a very high protein diet. However, as long as the kidneys are able to concentrate the urine, small elevations in BUN are usually not a cause for alarm. The second is a protein called creatinine.

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Creatinine is a more sensitive measurement of kidney function; an increase in creatinine usually means that the kidneys are having problems. In advanced disease, an increase in phosphorus is also seen, and indicates that 85% of kidney tissue is damaged.
     
Treating CRF

No conventional or alternative medical treatment can reverse CRF, since the disease involves the death of kidney cells and replacement by scar tissue. The rate of progression in any individual pet may be slowed, but not stopped, by various treatments. When the process is advanced, the kidneys become scarred, small, and lumpy, and the amount of functional tissue is greatly decreased. 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 of the best and simplest treatments include:
Diet: The Protein Controversy
You may have heard that restricting protein is recommended for pets in kidney failure. This has been the "standard" treatment for decades in dogs and humans. However, in cats, it remains controversial.

The real culprit is not protein but phosphorus, which combines with calcium and gets deposited in the kidneys, causing further damage. Meat contains a lot of phosphorus, so the easiest way to restrict phosphorus is to restrict meat protein. Decreasing phosphorus intake (by restricting protein) can help some pets feel better, so it may be worth a try if the symptoms are a problem.

However, some studies have suggested that excessive restriction of protein in cats 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 for cats until the BUN (Blood Urea Nitrogen) is at least double what it should be normally (about 60-80 mg/dl), and should never be fed to kittens or healthy cats.
For many animals, a diet with HIGH QUALITY protein will be better than a low-protein diet. Low-protein diets, if not carefully managed, can lead to malnutrition. If a low-protein diet is necessary, bear in mind that non-prescription canned foods are much higher in protein than similar dry foods, but prescription-type foods typically contain poor quality ingredients.
Canned foods universally contain higher levels of protein than dry foods. Since dogs are more omnivorous and are better at keeping themselves hydrated than cats, they may do well with mostly dry food. For dogs, these dry foods contain less protein:

Over-the-counter canned foods vary tremendously in phosphorus content, from less than 150 mg to over 600 mg! Veterinary low-protein diets are severely restricted, containing less than 100 mg of phosphorus per 100 Calories.

Cats are exclusively carnivorous and, because they tend not to drink enough water, don’t do as well with dry food as a mainstay of their diet. Canned cat foods containing about 200 mg or less of phosphorus include:

"I and Love and You" Pate Canned Cat Food

EVO 95% Venison, 95% Chicken & Turkey

Wellness Cat Food – Turkey and Chicken Varieties
Nature’s Variety Beef, Chicken & Turkey, Lamb

Because water balance is so crucial, it is best to feed cats a high-moisture diet to help maintain good hydration; do not feed only dry food. Feeding mostly or only canned, raw, or homemade food, even though they tend to be high in phosphorus and protein, provides the moisture and calories they need, in a very palatable form that most cats will happily eat. If your veterinarian insists on a protein-restricted, low-phosphorus renal diets, get the canned version. Adding egg whites, which contain very little phosphorus, will provide extra protein without causing harm. Dry cat food causes dehydration even in healthy cats, and is not appropriate for CRF cats (see the posts on Switching Foods for help).
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 switch! There are several good books on home cooking for animals, including Dr. Pitcairn's Guide to Natural Health for Dogs and Cats, by Richard Pitcairn, DVM, and Susan Pitcairn (Rodale Press. ISBN 075962432 and 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. For an easy starter diet, check out the Little Big Cat website.