Protein, Fat, and Carbohydrates
Dogs evolved as carnivores and thrive on high protein diets for which bulk, in the form of carbohydrates, is no substitute. Protein provides many benefits: it contributes to a healthy skin and coat, aids wound healing, supports the immune system and the nervous system, and promotes lean muscle over fat. Increasing the amount of high quality protein in the diet can help both to calm hyperactive dogs and to energize sluggish overweight pets.
The right source of calories
Animal Protein is especially important for dogs. Plant proteins are incomplete and harder for carnivores to digest. Homemade diets should be at least half animal products (meat, eggs, fish, and dairy) and no more than half plant products (grains, vegetables, and legumes.)
Fat is also good for dogs, particularly animal fat rather than vegetable oils (cholesterol is generally not a problem for dogs) Fat is used for energy, so it's especially important for very active dogs that have trouble maintaining their weight. Less active and overweight pets need less fat, but do not need a very low fat diet unless your dog has a fat intolerance. Too little fat leads to skin conditions and dull, lifeless coat. It also leads to the dog feeling hungry all the time, which can introduce behavioral problems.
Carbohydrates and Canines
Carbohydrates, which come from plants such as grains, vegetables, and fruits, offer an inexpensive source of calories but have less nutritional value than foods from animal sources. Carbohydrates can also contribute to weight gain. Recent studies show that traditional high-carb-low fat diets are not the best choice for weight loss. Instead, feed a high protein, moderate fat, low carb diet if a dog is overweight, and increase exercise gradually.
Many health problems in dogs may be linked to high carb diets. If your dog suffers from allergies, arhtritis, seizures, urine leaking, chronic ear infections, or digestive disorders, omit grains and starchy carbs from the diet for a while and see if your dog improves.
Some dogs have a gluten intolerance and cannot handle certain grains. Gluten free substitutes for regular flour include chick-pea (garbanzo) almond, potato, tapioca, arrowroot, rice, millet, and quinoa flour. Buckwheat, rye, oat, and barley flours are not gluten free but can be used for dogs that have problems with wheat.
Source: The Healthy Dog Cookbook
