Veterinarians recommend therapeutic diets for dogs with chronic kidney disease (CKD) because these foods contain lower amounts of certain nutrients than over-the-counter adult maintenance dog foods. One of those restricted nutrients is protein. (The others are phosphorus and sodium.) If you’ve ever wondered why lower protein levels are recommended for kidney-friendly dog foods, you’re not alone.
The reasons might surprise you.
A “diet effect,” not solely one nutrient
Kidney-friendly diets are the cornerstone of CKD management for a very good reason: Research has shown that therapeutic kidney diets are better than adult maintenance diets for managing dogs with CKD. Compared to dogs with naturally occurring CKD who were fed an adult maintenance food, dogs with CKD who ate a kidney-friendly diet went for a longer period of time before they experienced a uremic crisis (a toxic condition caused by elevated levels of nitrogen-containing wastes in the blood). The dogs who were fed the therapeutic kidney diet also lived longer.
While the therapeutic kidney-friendly diets are formulated with less protein than typical adult dog foods, they are also different in other ways. Kidney-friendly dog foods also tend to be lower in phosphorus, higher in fat and supplemented with more omega-3 fatty acids. These differences along with lower protein levels may contribute to the diets’ effectiveness. These differences also mean that the benefits associated with feeding therapeutic kidney diets can’t be attributed to changes in any one nutrient.
Why limit protein level?
According to veterinary nutritionists, there are two key reasons why a kidney-friendly diet should have a lower protein content than an adult maintenance dog food. That said, it’s important to realize that kidney-friendly pet foods provide enough dietary protein to meet your dog’s maintenance needs, while avoiding excess protein that could contribute to CKD signs.
The first reason to limit protein is to minimize buildup of nitrogen-containing waste products that are created during protein and amino acid metabolism. When these wastes accumulate in the blood, they depress your dog’s appetite and make him or her feel listless or lethargic and can cause vomiting and diarrhea as they continue to rise. By decreasing dietary protein, the amount of protein- and amino-acid-related waste products that diseased kidneys need to remove is reduced.
A second important reason for reducing protein in foods for dogs with CKD is that protein is a major contributor of phosphorus to the diet. By lowering the amount of dietary protein, the phosphorus level in food can also be reduced. Many veterinary nutritionists now believe phosphorus is the more important nutrient to restrict because elevated blood phosphorus levels can damage kidneys further. Protein, on the other hand, typically doesn’t damage canine kidneys like it does in people or rats.
Type and quality of protein matter
Although the protein content of kidney-friendly diets will be lower than that of adult maintenance foods, therapeutic kidney diets aren’t protein deficient. Veterinary nutritionists agree that therapeutic kidney diets contain more than adequate levels of protein and do meet protein and essential amino acid requirements of dogs with CKD. However, the type and quality of that protein is critical in terms of amino acid composition, digestibility and phosphorus content. Using high-quality protein that’s well-balanced for essential amino acids enables a lower overall dietary protein level while preventing protein malnutrition.
Talk with your veterinarian
The right food is an important piece of your dog’s CKD treatment plan, and the nutritional changes that need to be made will depend on the severity of your dog’s kidney disease. While changing your dog’s diet can’t cure CKD, it can minimize clinical signs and contribute to your pet’s health and longevity. Your veterinarian can recommend a therapeutic kidney diet, such as Diamond CARE Rx Renal Formula for Adult Dogs, that’s right for your dog.