By T. J. Dunn, Jr., DVM
Protein requirements of dogs is an important and often misunderstood aspect of pet nutrition. "You are what you eat" is a saying we've all heard and it surely has some truth to it.
Every responsible dog owner I’ve talked to has real concern about feeding a high quality diet to his or her dogs. Remarkably, though, no two dog owners seem to agree as to which dog food is “the best”. A large part of the disagreement regarding “the best” food to feed centers on the often ambiguous, mysterious and sometimes incorrect information we all see regarding the substance we call protein.
Let’s get the facts straight about the importance of protein in the dog’s diet. Then we can better judge which food would be “the best” for own dogs.
Unlike felines (go here to see some of the differences between feline and canine metabolism) dogs are classified as omnivores. They can survive on a diet of either plant or animal origin if it is balanced and diverse. But to thrive and not merely survive, dogs should have a source of animal protein -- MEAT! -- in their diets.
There is a huge difference between survive and thrive! Nature made the rules of biochemistry and nutrition and we mortals have no power (and no business, for that matter) to try to bend those rules. For that reason there are truly no adequate vegetarian diets for cats. For that reason dogs thrive on diets based on meat.
Every single day in practice I see dogs that are not thriving because nature's rules are not being followed. Overweight dogs, dogs with itchy, flaky skin, dogs with coarse and brittle coats, dogs with poor energy levels and resistance to infection -- 95 percent of the time these dogs will be consuming diets low in animal origin tissues and high in grain-based products. Inexpensive, corn-based diets are some of the worst.
|FOODS OF ANIMAL ORIGIN
||FOODS OF PLANT ORIGIN
|Meat by-products: heart, liver, spleen, intestines (emptied of their contents), blood, kidneys
||Grains... corn, wheat, rice, barley, soybeans, oatmeal
||Fiber... The non-digestible cellulose parts of plants such as peanut hulls
||Nuts and seeds
|Fish... salmon, herring
|Poultry... chicken, turkey, duck
|Dairy... eggs, milk, cheese
Dogs need meat! Dogs thrive on meat-based diets. (Caution: an ALL meat diet is hazardous too!) Dogs can and do assimilate grains such as corn, barley, oats, wheat and soybean meal. Remember, though, that grains provide mostly carbohydrates and only limited amino acid (protein) profiles. Extra carbohydrate intake, above the immediate needs of the dog (which occurs often with grain-based diets) prompts internal enzyme factors to store that extra carbohydrate (sugar) as fat.
Give that same dog extra protein and it is excreted through the kidneys and NOT stored as fat. Knowing this, what do you think would make a better "weight loss diet" for a dog ... one with grain as the main ingredient or one with a protein-rich meat source as the main ingredient?
Ahhhhhh ... I know what you're thinking! Too much protein! Kidney damage! Well, guess what? 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. (Were we tinkering with Nature during these “tests”?) 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 percent 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:
"...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."
-Kirk's Veterinary Therapy XIII, Small Animal Practice, page 861, written by Finco, Brown, Barsanti and Bartges
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.