Below are just some interesting dog "high" protein studies that show "high" protein levels cause no adverse effects for dogs with certain pre-existing conditions as believed by some. In contrast some studies show that dogs with certain pre-existing conditions do better on higher protein diets than lower ones, and in fact hat too little protein causes harm in many cases. There is also a study that shows higher protein diets (along with other factors) actually work better for weight loss in dog. For whatever it's worth..below are links to the studies. Personally I believe it's not really the protein % that one is to worry about but the quality of ingredients where the protein comes from. With a that being said there is also no "studies" that show high protein diets cause kidney disease (as believed by some), or studies that show feeding a low protein diet slows the progression of kidney disease or prolong life (reducing phosphorus does both, however)!
One study showed that dogs aged 7 to 8 years with just one kidney who were fed a diet with 34% protein or four years suffered no adverse effects, and the mortality rate was lower than for dogs fed 18% protein (
Effects of aging and dietary protein intake on uni... [Am J Vet Res. 1994] - PubMed result).
Most dogs with liver disease do not need a reduced protein diet, and too little protein is harmful to the liver (
http://jn.nutrition.org/cgi/reprint/128/12/2733S.pdf).
Most dogs prone to forming bladder stones of various types do not need a low protein diet, and those who are fed ultra-low-protein diets such as Hill's Prescription u/d for extended periods are prone to developing dilated cardiomyopathy (DCM).
High protein diets do not lead to hip dysplasia or other orthopedic problems in puppies (it is too much calcium and too many calories that are the culprits, not protein). (
Growth-calcium-energy,
Eukanuba premium pet food,
ADVANCE Pet Foods)
A study published by Dr. Dodman in 1996 "concluded that a reduction in dietary protein is not generally useful in the treatment of behavior problems, with the possible exception of those with territorial aggression that is the result of fear." (
Summary of Tufts University study on the effect of dietary protein on dog behavior). The conclusions of the 2000 study were, "For dogs with dominance aggression, the addition of tryptophan to high protein diets or change to a low protein diet may reduce aggression. For dogs with territorial aggression, tryptophan supplementation of a low protein diet may be helpful in reducing aggression." (
AVMA - Journal of the American Veterinary Medical Association - 217(4):504 - Abstract).
Veterinary behaviorist Dr. William Campbell, author of Behavior Problems in Dogs, believes that it is carbohydrates that are linked to aggression and other behavioral problems, and recommends higher protein diets for most dogs. See his "Case of the Month" archives at
BehavioRx: Pet Behavior Resources Case of the Month for more info (especially April 1999, February, June, August and December 2000, February 2001, November 2001, February 2003).
Recent studies have shown that high-protein low-carb, moderate-fat diets work better for weight loss in both dogs and cats than the traditional high-carb, low-fat diets (
High-Protein Low-Carbohydrate Diets Enhance Weight Loss in Dogs -- Bierer and Bui 134 (8): 2087S -- Journal of Nutrition). One study done on English Pointers aged 7 to 9 years showed that those dogs fed a diet with 45% protein for several years maintained a directionally higher percent of lean body mass and lower percent of body fat compared to dogs fed a diet with 15% protein (
http://web.archive.org/web/200703300...ionProtein.pdf).
"The very early research that pointed a finger at protein as being a cause of kidney failure in dogs wasn't even done on dogs. It was done on rats fed unnatural diets for a rodent... diets high in protein. Rats have difficulty excreting excess protein in their diets because they are essentially plant eaters, not meat eaters. Dogs are quite able to tolerate diets with protein levels higher than 30% on a dry weight basis. Dogs are meat eaters; that's how Nature made them! Rats are not. So some of the early research on rats was assumed to be true for dogs... and the myth of "too much protein in a dog's diet causes kidney damage" was started. And just like any seemingly valid rumor or assertion, it derived a life of its own and is only recently being accepted as untrue. "
"Here is just one of many references that recently have appeared asserting the lack of data indicating that reducing the protein level in a food helps to protect the kidneys... Kirk's Veterinary Therapy XIII, Small Animal Practice, page 861, written by Finco, Brown, Barsanti and Bartges "...restriction of protein intake does not alter the development of renal lesions nor does it preserve renal function. Considering these (research) findings, the authors do not recommend reduction of dietary protein in dogs with renal disease or reduced renal function in order to achieve renoprotective effects." They do recommend, though, that once a Blood Urea Nitrogen (BUN) level reaches 75, which is very elevated, that some restriction of protein intake be considered for beneficial effects unrelated to kidney function dynamics. These authors point out that Phosphorus blood levels can play a major role in the health status of dogs with compromised kidney function."