Protein is arguably the most important component of your dog or cat’s diet, and is often the most hotly debated aspects of pet foods. What is the best source of protein for dogs? For cats? How much protein should be in the diet and can you feed too much of it? How can you tell which foods have better protein sources? What about pets with food allergies? It’s a lot to ponder and leaves many guardians frustrated and confused about which of the seemingly endless variety of pet foods they should feed their companion.
During the last 5 to 10 years the rapid growth of the natural pet food market has significantly expanded the viable feeding options for responsible pet owners, but having more choices does not generally make a decision easier. On the contrary, the more options available, the more difficult the choice becomes. So let’s try and sort through some of the facts.
Evaluating Protein Sources
A protein molecule is made up of chains of amino acids. Different sources of protein contain different combinations of the 22 or so amino acids. Of these amino acids, 10 are considered “essential” amino acids; because dogs and cats cannot make them on their own, these particular amino acids must be present in the diet. When a dog or cat consumes protein, it gets broken down during the digestive process into its individual amino acids. Those amino acids are then reassembled into the building blocks of body tissues such as skin, hair, muscles, and organs. Amino acids are also utilized to produce metabolic enzymes that are necessary for many bodily functions including the regulation of antibodies within the immune system and the transfer of nerve impulses.
Protein from animal sources contains the most complete and most easily digested and assimilated amino acids for dogs and cats. Animal proteins are not only more bio-available and contain a wider array of amino acids – both essential on non-essential, they are also more palatable for you companion. The biological value of a protein is determined by how readily the amino acids broken down and used by the body. For dogs and cats, egg whites are at the top of the list with a biological value of 100, followed by muscle meat (beef, chicken, lamb) at 92, and organ meats at 90. Wheat and corn are way down the list with biological values of 60 and 54. Cooking meat at the high temperatures required for canned foods and kibble reduces it’s biological value, providing another reason to include raw or less processed foods in your companion’s diet such as freeze dried or dehydrated meals.
When evaluating the protein source on a bag of kibble, keep in mind that whole meats, such as an ingredient listed as “chicken” or “beef,” contains 75% water. So if a whole meat is listed first, the next ingredient should be a specific meat meal to insure the protein in the food is from animal sources, not grains (i.e. chicken meal or beef meal, not generic “meat meal” or by-product meals). The top-quality pet foods on the market use USDA sources (human grade) for their meat meals. If the ingredient lists “chicken” first followed by grains or grain by-products, you can be sure that much of the protein in the food comes from the grains and is less bio-available to your pet. Trying to force carnivores to derive their amino acid requirements from grain sources is one of the main contributors to the pet obesity epidemic facing our dogs and cats today.
Which Meat is Best?
Is chicken the best protein for cats? Is beef best for dogs, or is lamb better? While there are strong opinions among pet enthusiasts about the answers to those questions, the real answer is that it completely depends on your individual cat or dog. Some research, specifically that of William Cusick, suggests that dogs do better on a diet and protein source that most closely matches that of their ancestors: the food that was available in the region in which the breed developed. For example: Border Collies would eat lamb, fish and poultry as they originated in Scotland where these were staples in the diet. The Greyhound, originating in Egypt, would eat rabbit, pork, poultry and goat. German Shepherds would be fed beef, as they were originally bred in the Alsation Region of Germany.
While breed specific guidelines may be useful for some dogs, for many dogs their heritage is unknown. For another large group of dogs (and cats), food allergies will determine which protein sources are best, (see Novel Proteins below). Cats on the other hand, are assumed to have all developed on a similar diet of rodents – specifically mice, birds and the occasional rabbit.
So which meat is best? In the absence of food sensitivities or allergies, the answer is: at least three different ones. Rotation insures a broader nutritional base over time and helps reduce the incidence of food sensitivities and allergies. Many dogs and cats fed the same food for too long will develop signs of intolerance such as itchy skin or paws, or chronic digestive problems such as gas, loose stools or frequent vomiting. Rotating between at least three or four different foods with different protein sources, and preferably from a variety of manufactures, provides the ideal answer to “Which food is THE best for my companion.” Only you and your companion can really determine what is best by trying various high-quality foods and choosing those that your dog or cat thrives on.
How Much is Too Much Protein?
With the growing popularity of grain-free and low carbohydrate foods in recent years, we hear more questions from owners concerned about feeding too much protein. One reason for this question is the lingering myth that too much protein in the diet can cause kidney disease – especially in older animals. Nutritional research has disproved this falsehood, but still it lives on. This myth originated when veterinarians began to put animals with kidney disease on low-protein diets to minimize nitrogen levels. Today, holistic veterinarians, and increasingly even traditional veterinarians, are suggesting a diet for animals with kidney disease containing higher quality protein that is more digestible rather than low-protein foods. Better quality protein produces less waste through digestion, which creates less work for the kidneys and lower nitrogen levels in the body.
Excess protein in a healthy dog’s or cat’s diet typically would be either excreted in the urine, used as energy, or converted to fat. The one precaution when feeding a higher protein food is watching how much you feed to prevent unwanted weight gain. So the answer to “How much protein is too much?” is dependent on your individual cat or dog; his metabolism, activity level and lifestyle. If your feline friend spends most of the day on the window sill and rarely plays, feed her less of the same food you feed her brother who chases anything that moves and runs up and down the stairs a dozen times a day. They both can thrive on a high-quality, high-protein diet, they just require different quantities of the food.
Growing puppies and kittens, as well as pregnant and lactating animals and working animals require more protein than normal adult animals. Most of the premium pet foods provide adequate fat and protein levels for their needs provided they are fed larger portions for their size. Adding fresh meat or grain-free canned foods to some meals is a good way to provide extra protein.
Nutrition is the cornerstone of health, and high-quality protein is a critical part of proper nutrition. Read labels carefully to insure the protein your dog or cat is receiving is from meat, not grains. The best diet for your companion depends on their individual needs, but will ultimately include a variety of protein sources and optimally at least some portion of fresher, less processed foods. Feeding too much protein is rarely an issue, but feeding too much food IS – keep portions appropriate to each animal’s activity level and metabolism to avoid weight gain.
Resources and Helpful Links
Raw Meaty Bones by Tom Lonsdale
The Nature of Animal Healing by Martin Goldstein
Catinfo.org – Veterinarian Lisa A. Pierson on “Feeding Your Cat”
The Animal Adovocate – William Cusick on Breed Specific Nutrition