Carbohydrates, Grains and Your Dog's Diet

I wrote this article as part of a series on dog nutrition for our local club newsletter. I will post more from this series later.

Last time, we talked about reading parts of the label on dog food packages and we casually referred to carbohydrates as something whose amounts in food can sneak up on you. Let’s examine how carbs and grains pertain your dog’s diet.

First of all, it’s important to recognize that the importance of carbohydrates in the canine diet is still widely debated. Carbs are almost impossible to avoid even in home-prepared foods and there are situations where carbs have been thought to provide an advantage to the dog(pregnant and lactating bitches for example). Nearly all dog food contains some carbohydrates with dry foods (kibble) possessing the most, on average. As we stated last time, kibble needs binding agents, and grains and plant-based food derivatives fill this requirement nicely. When you use grains, starches and plant-based ingredients, you get carbohydrates galore. Even in “wet” foods (canned) there are typically 15% to 20 % carbohydrates depending on whether the food is grain-free or not, and which types of grain or starch it utilizes.

Second, while dogs do not need carbohydrates in their diet, they do need sources of glucose (which the body converts to glycogen) to fuel their energy requirements. If a dog had a zero-carbohydrate diet, they would have to get the glucose needed from food proteins or fats (from the glycerol in fat). If the glucose in the diet is insufficient to meet the energy needs of the dog, their bodies will “steal” glucose from amino acids in proteins in lieu of building muscle or bone. Minimizing amino acid conversion is why lactating bitches and puppies should have some carbohydrates in their diets.

“Feeding Your Dog for Life” (Diane Morgan, 2002) gives four uses for carbs in a dog’s diet. Ominously the third reason listed is to create a store of glycogen but excess ends up being converted to fat. It is that last phrase that unfortunately is the most common result of high carb diets. Note that proteins and fats can also perform the four things in a dog's diet just as well as carbs. (Also remember that proteins and carbs have the eaxact same caloric content- 4 calories per gram). Another use for carbs in dog food is as an inexpensive protein source. The book “K9 Kitchen” (Monica Segal, 2002) lists several grains along with their carbohydrate, protein and mineral content. Most grains possess 2% to 4 % protein and 20% to 30% carbohydrate. Since grains are cheap relative to meat and fish, and since dry foods need binding agents anyway, plant-based foods are an inexpensive way to augment the protein content of a food while providing teh binding agents necessary for it's production. Lastly, cheap foods use sugars to improve taste; something that all owners should try to minimize. Even good, highly rated foods sometimes use beet pulp and other plant sources as a binder. Others use berries and fruits as a source of anti-oxidants (this is GOOD!- albeit these are sugar rich). And low-end foods utilize a lot of corn which contains significant sugars. If a dog food contains 40% or more carbohydrate (from grains and sugars), the amount of glucose the dog could potentially derive from that much carbohydrate far exceeds their daily need. Thus the excess carbohydrate is turned to fat. Interestingly, if the protein content of a food far exceeds the needs of the dog, the excess can be removed from the body through urination although at some strain on the kidneys.

Grains are problematical because many dogs have allergies to certain grains. Wheat and corn are the most common allergens. Grains must be cooked or processed to be digested by the dog. Well, I say that tongue in cheek because my dogs eat the raw wheat kernels from the horse hay that falls on the driveways here. They enjoy the crunchiness I guess! Mostly the grain kernels pass right through undigested but they must get some carbs from eating the raw grain because their weight is harder to control when they eat a lot of grain kernels!
Another issue with grains is that some grains bind certain minerals and prevent their assimilation. Grains, like carbs, are difficult to avoid in food, although today there are more “grain-free” foods available. However, many of these foods include other starches like potatoes and tapioca. Starches, like grains, must be cooked for a dog to assimilate them and they are less digestible than grains like rice and corn. By the way, rice is the most digestible of the common grains and is one reason why a “bland” diet (chicken broth and rice- with their respective protein and glucose sources) is often used to feed a dog with an upset digestive system.

I have had good success in managing my dogs’ weight (apart from the hay issue above!) with daily exercise and diets that minimize carbs and grain. Their diets consist of about 25% (by weight- possibly 40% by kilocalories of energy provided) high-quality, grain-free, low-carb kibble. Raw and cooked protein sources such as meat, green tripe, fish and chicken make up the remainder of my dogs’ diets.