Following last week’s post, this is the next installment of interesting nutritional information that was presented at the Annual Clinical Nutrition and Research Symposium. The symposium is organized by the American Academy of Veterinary Nutrition and is held in conjunction the annual American College of Veterinary Internal Medicine scientific conference. It features oral and poster presentations of abstracts of recent or soon to be published scientific studies. This year’s venue was held at the Washington State Convention Center in Seattle.
Dietary Protein and Kidney Disease
For years, dietary protein restriction has been the hallmark management tool for veterinarians treating chronic kidney disease in dogs and cats. This is a result of an old study that determined that the survival time was three times longer for dogs fed a low protein diet compared to dogs fed a regular protein diet.
The study had several flaws but without sound research to the contrary, it has remained the “gold standard” of kidney disease management. Many veterinarians, myself included, have questioned the wisdom of this approach but substantiating research has been lacking. A new study questions this age old practice.
The double-blind, randomized study compared actual kidney function, creatinine (a blood marker for kidney function), body condition and survival time of dogs fed a low protein diet (16%) and those fed a normal diet (22.5% protein). Both diets had the same restricted phosphorus content. What they found was no significant difference in kidney function, blood creatinine levels or survival time between the two groups. As expected the body condition scores were greater for the normal protein group as they maintained more muscle mass. The main determinant of survival time was the level of kidney dysfunction at the time of diagnosis, not the diet.
What is interesting is that the low protein diet in this study was 2-3 percent greater than most of the veterinary diets formulated for kidney disease. That means that muscle loss would be expected to be even greater for pets being fed veterinary kidney diets. The maintenance of muscle mass has implications for maintaining an active lifestyle. Since quantity of life is no different it would make sense to feed kidney patients a normal protein diet to maintain their quality of life. This study also suggests that phosphorus control is more important than dietary protein in kidney patients.
The Protein Needs of Cats
A poster presentation featured a study to determine the necessary protein requirement for aging cats to maintain lean body mass. Researchers matched four groups of ten cats and fed them diets of varying protein content. The cats were fed adequate calories to maintain their weight for the six month study.
Each cat’s lean body mass was determined by a special technique called DEXA (dual-energy X-ray absorptiometry) at the beginning of the study, at three months and at six months. They found that cats needed at least 2.5 grams (.09 oz.) of protein per pound of body weight daily to maintain ideal lean body mass. Cats fed less protein than this necessarily replaced muscle with fat in order to maintain the same body weight. These finding are greater than the present protein recommendations of both the National Research Council (NRC) and Association of American Feed Control Officials (AAFCO) guidelines.
This suggests that many cat foods are not meeting the protein requirements necessary to promote optimum lean body mass for older cats. Pet food labels are not required to give detailed information about protein, fat and carbohydrate content. Finding how many grams of protein your cat is getting from its diet will require researching the company’s website or talking to a company nutritionist. Even after that, the exact amount of protein may require further mathematical calculations. We really need pet food labels like those on our food!
Dr. Ken Tudor