Low protein dog foods can be controversial. Even though many veterinarians advise against feeding higher protein diets, recent research appears to support their safety — even for senior dogs with minor kidney issues.
In one study of dogs with kidney disease, researchers concluded…
“Results do not support the hypothesis that feeding a high protein diet had a significant adverse effect on renal function”.1
In another study, older dogs were divided into two groups.
One group was fed a low protein diet and the other a high protein diet for the next four years.
“Results of this study indicated there were no adverse effects from the high protein diet and mortality (death rate) was actually higher in the low protein group”.2
Does a High Protein Diet
Cause Kidney Disease?
The Veterinary and Aquatic Services Department of Drs. Foster and Smith addresses what it refers to as a false rumor regarding high protein diets:3
“High protein pet foods are NOT harmful to a normal animal’s kidneys. As an animal’s body digests and metabolizes protein, nitrogen is released as a by-product.
“The excess nitrogen is excreted by the kidneys. A high protein diet produces more nitrogen by-products and the kidneys simply excrete the nitrogen in the urine.
“While you may think this would ‘overwork’ the kidneys and lead to possible kidney damage, this is not true. The kidney’s filtering capabilities are so great that even one kidney is sufficient to sustain a normal life.”
Better Quality Protein
Fewer Nitrogen By-Products
So, then, why do so many veterinarians still believe a high protein diet is dangerous to older dogs and kidney health?
“The myth that high protein diets are harmful to kidneys probably started because, in the past, patients with kidney disease were commonly placed on low protein (and thus low nitrogen) diets.
“Now, we often put them on a diet that is not necessarily very low in protein, but contains protein that is more digestible so there are fewer nitrogen by-products.”
Animals with impaired kidney function are reported to do better by restricting phosphorus intake. However, limiting phosphorus on a preventive basis is not likely to delay the onset of kidney disease or benefit healthy older dogs.4
Drs. Foster and Smith conclude:5
“Unless your veterinarian has told you your pet has a kidney problem and it is severe enough to adjust the protein intake, you can feed your pet a high protein diet without worrying about ‘damaging’ or ‘stressing’ your pet’s kidneys.”
Apparently, one of the few justifications for a restricted protein diet is very high urinary nitrogen and elevated urinary protein.6
Or certain types of liver disease, such as hepatic encephalopathy.
The Bottom Line
Due to our respect for a dog’s natural carnivorous bias, we tend to favor dog foods rich in quality meat protein.
However, we also recognize there are medical conditions where a high protein diet can have a negative impact on kidney health.
For this reason, if your dog has been diagnosed with active kidney disease, please be sure to consult with your veterinarian before feeding any food to your pet.
- Bovee, KC, Influence of Dietary Protein on Renal Function in Dogs, Waltham International Symposium on Nutrition of Small Companion Animals, University of California, Davis, CA 95616, on September 4–8, 1990 ↩
- Finco DR, Brown SA, Crowell WA, et al, Effects of aging and dietary protein intake on uninephrectomized geriatric dogs, Am J Vet Res 1994; 55:1282 ↩
- Drs. Foster and Smith, “Are High Protein Diets Harmful to a Dog’s Kidneys?” ↩
- Thorpe-Vargas S, Cargill JC, Fortify the Food Bowl for the Aging Canine ↩
- Drs. Foster and Smith, Ibid ↩
- Straus, Mary, Is a Low-Protein Diet Desirable or Necessary for Dogs with Kidney Disease? ↩