Carbohydrates in the Dog’s Diet

When it comes to human nutrition everybody talks about them. Yet to me it is amazing how few people really know what they are all about: Carbohydrates. But not just in human food, in pet food too these days there is a lot of discussion and controversy about them. What makes it even more difficult, as Steve Brown just recently told us in How much carbohydrate is in the dog and cat foods you feed?, pet food regulations do not allow the word “carbohydrate” on the label. Human foods are required to list carbohydrate on the label. This major difference makes it difficult to evaluate foods for dogs and cats. Concerned shoppers must do the calculations for themselves. Fortunately, pet food labels give you the information that you need to do those calculations. And why is this all so important? Choosing foods becomes much easier when you know what the balance of the animal’s natural diet really is! Almost all dogs and cats will do much better eating diets very close to that natural balance.
The biggest building blocks of dog and cat foods (the macronutrient content) are: Protein, fat, moisture and carbohydrate. Wellness, in it’s Nutrition 101 explains: “Carbohydrates almost always come from plant sources such as cereal grains. Carbohydrates, per se, are not a required nutrient and the body's need for glucose and other carbohydrates can easily be met by breaking down triglycerides (fatty acids) and amino acids. While an animal could survive without carbohydrates, they are helpful in adding bulk, variety and taste to the diet. The source of the carbohydrates and the way in which they are prepared are important factors in their digestibility and utilization. Carbohydrates are often classified into two groups: Digestible (sugars and starches) and indigestible (fiber).
1. Digestible: Sugars and Starches (Soluble)
Most types of sugars are digested easily by dogs or cats and are almost always quickly utilized for energy. Starches, on the other hand, must first be broken down into sugars in order to be usable. The primary sources of carbohydrates in most diets are cereal grains, such as: barley, brown rice, oats and rye. Proper grinding and cooking of cereal grains is necessary for the animal to efficiently digest cereal starches.
Recent work comparing the glycemic index* (the ability of the grain to raise blood sugar) of various grains in dogs has generated much interest. While likely of minimal importance for most healthy dogs and cats, the use of specific grains and the avoidance of others could prove useful. It is likely important in pet food formulation and in an owners ability to manage the diets of their diabetic animals, young and old.
Sugars and starches supply calories and make up a high percentage of most dry and semi-moist pet foods as well as many canned pet foods. The extrusion process used to make most dry pet foods and the baking process used to make biscuits requires some carbohydrates. Because of the calories they provide, sugars and starches help limit the use of protein for energy purposes. This allows the protein to be used to meet the animal's amino acid requirements rather than its energy needs. Carbohydrates exceeding the amount needed to meet the animal's energy requirements are stored in the body as fat, which may lead to obesity.
*Canine Caviar explains the “Glycemic Index”:
“The glycemic index indicates how fast and how high a given food raises blood sugar. It applies only to carbohydrates. Carbohydrates are sugars or starches.
Not all carbohydrate foods are created equal, in fact they behave quite differently in our bodies. The glycemic index or GI describes this difference by ranking carbohydrates according to their effect on our blood glucose levels. Choosing low GI carbs - the ones that produce only small fluctuations in our blood glucose and insulin levels - is the secret to long-term health reducing your risk of heart disease and diabetes.
Go easy on foods with a high glycemic index. Since these foods raise blood sugar to high levels shortly after eating them, the body has to release large amounts of insulin to keep blood sugar in the normal range. Foods with high indexes cause peaks and valleys in blood sugar. Such great fluctuations in blood sugar are not good.
A glycemic index of 70 or higher indicates a food with a high index; values between 56 and 60 are medium glycemic foods; values of 55 or less are low glycemic foods.
The only way to know a food's glycemic index is to look it up on a chart with such values. These charts are in nutrition books and on the Web. You can't guess at a food's index. For example, you would think that table sugar has a high glycemic index. It doesn't. It has a medium value. On the other hand, a baked potato has a high glycemic index. Low GI carbs improve diabetes control, reduce the risk of heart disease, reduce blood cholesterol levels, reduce hunger and keep you fuller for longer and prolong physical endurance” . (Note: Examples of Glycemic Index charts: Glycemic Edge, Mendosa)

2. Fiber
Fiber is well known (even in the human diet) for its role in regulating bowel function and transit time in diarrhea and constipation. Many apparently contradictory statements about fiber stem from the fact that there are different types of fiber all of which exert different effects. Unfortunately, pet foods are still required by law to list crude fiber, a method for measuring fiber that was developed in the 1800's, which is not very useful. In human dietetics, newer methods that measure dietary, insoluble and soluble fiber types are used and hopefully these will eventually find a place in pet food. Soluble fibers (hemicelluloses and gums) often help nourish the cells in the large intestine and encourage the growth of beneficial microorganisms. In contrast, insoluble fibers (cellulose and lignins) move rapidly through the gastrointestinal tract and provide bulk but no calories. For this reason, high fiber diets are useful for reducing the energy content of the diet and have been recommended for overweight animals. In contrast, diets high in fiber are not recommended for dogs and cats with high energy requirements (growth, late gestation, lactation, stress, and work).”
Dr. Lew Olson, PhD of Natural Health, with B-Naturals.com asks in his 09/08 newsletter: “Carbohydrates – Good or Bad?” (Make sure to visit his site as he also makes a number of product recommendations related to his own great supplement products, which I have left out here since as of this time we do not (yet) carry his product line).
“Commercial dog foods all contain carbohydrates. These foods offer fiber (to help with firm stools), a less expensive food ingredient and to aid in the ability for dry foods to maintain a longer shelf life. While they serve a purpose in this regard, they also add some liabilities. Carbohydrates make stools larger and have more odor, and they offer less nutrition. It is important to do your research if you use commercial food. Shop for a food with the least amount of carbohydrates offered and with a good primary animal based protein. Some foods are now being offered as grain free. But remember, other sources offered are still carbohydrates, and the most often used is potato. This can be of benefit to dogs with certain grain allergies or gluten intolerance. Some dogs can have digestive issues when fed food with gluten. And commercial foods that are grain free can be a novel food source to try for dogs with allergies.
Carbohydrates are also used in home cooked recipes. The main reason for this is to offer a fiber source. Most carbohydrates are high in fiber and this helps keep the stool firm. When using vegetables sources, fully puree, blend or cook them. Dogs cannot digest grains or vegetables that aren’t fully cooked or pureed. They do not have the ability to break down the cell wall of carbohydrates, nor digest them well in their short and simple digestive tracts. When using carbohydrates in home cooked diets, I generally recommend using about 75% animal based protein, and 25% carbohydrates.
High Glycemic (Sugar Content) Vegetables: Equally important to note is that the type of carbohydrate used affects stool size. In most of the recipes I offer in the B-Naturals articles (in the newsletter directory) use low glycemic carbohydrates. These are vegetables, which offer the lowest sugar content. Dogs are carnivores, and genetically speaking, they do not have systems that need or adapt well to a constant influx of high sugar foods. Dogs need fat and animal protein to survive and thrive. High sugar foods contain more calories and also add unneeded and unnecessary weight gain. They may also offer poor health conditions, such as diabetes, allergies, yeast growth, propensity for urinary tract infections and may contribute to seizure activity in dogs with epilepsy. For more information, see the article on low glycemic recipes.
Carbohydrates are not necessary in raw diets. Raw diets contain bone, which offer fiber and help create firm stools. Some may wish to add some vegetables to the diet for variety, but I would feed no more than 10% of these of the total diet. They may not add to the nutrition of the diet, but they aren’t harmful either. Adding more than 10% of carbohydrates to the diet will only increase stool size and in some cases may cause gas. (Further information on carbohydrates and more references)
It is also thought that grains and starches may aggravate incontinence in spayed females and senior dogs. Incontinence is leaking of urine, and chronic conditions can lead to rashes, irritation and urinary tract infections. Removing grains from the diet can alleviate the problem and sometimes completely stop the incontinence, without having to resort to prescription medications.”
Jenifer Boniface of Aunt Jeni’s in her Health Column expands on incontinence: “The pesky condition of "leaky" dogs is otherwise known as incontinence. Sometimes dogs, especially females, have a tendency to leak or dribble urine. This usually happens while they are sleeping and unaware of what is happening. You may notice that your dog wakes up embarrassed at what she has done. She should not be punished for having this kind of accident; it's not her fault! Some breeds, such as Dobermans, commonly suffer from what has been termed "spay incontinence," which begins sometime after the spay surgery. There is no "usual" time period between the surgery and the onset of incontinence symptoms. Neither does there seem to be any link between the age of the dog when spayed, and the onset of symptoms; they may begin immediately or not until years later. It is a very individualized thing. Older dogs also tend to develop incontinence as a function of aging, regardless of breed or spay status. It is very important that you rule out the possibility that your dog's incontinence is indicative of a bladder or urinary tract infection. Infections usually require medical treatment. An infection left untreated will not only bring your dog much discomfort, but it could turn into an even more serious health problem. Dietary changes can help prevent recurrence by building the proper pH in the body to ward off future attacks.”
Dr. Olson continues: “Dogs with arthritis or other inflammatory affected problems need to avoid grains and starches. The sugar content of these foods may aggravate inflammation and cause pain. This would include avoiding fruit, as well as vegetables in the nightshade family, such as tomatoes, potatoes, peppers and eggplant. I have had many emails from people over the years testifying that moving their dogs to a raw diet or a low glycemic cooked diets has reduced arthritis pain in their dogs.”
Dr. Olson also made another attempt explaining the subject matter with his article “Carbohydrates” describing them in a lot more detailed and scientifically referenced manner. Please make sure to read it as he makes a great number of good points. I also ask you to visit his B-Naturals.com website to check out the wide variety of supplements he has developed and, if everything goes well, possibly soon to be found at our store as well.
He concludes the above article: “While carbohydrates are not necessary in a dog’s diet, they can be useful in certain conditions. This would include the benefit of adding fiber to a home cooked diet and in certain liver or renal issues that need carbohydrates to add calories, absorb ammonia or reduce phosphorus in the diet. Using too many carbohydrates can cause larger stools with more odor and gas. They are composed of chains of sugar, so they add calories, and can adversely affect dogs with diabetes, seizures, arthritis, dogs with incontinence and dogs with hypothyroid conditions. It is important to know these variables, to make the best decisions on whether carbohydrates can help or hinder your dog’s health. It is not a question of ‘good or bad’, but rather about the individual needs of your dog.”