Originally, dog owners who fed their pets natural ingredients were attempting to replace the natural diet of the dog. Natural ingredients used today are no longer the foods eaten by an animal ‘naturally’ in the wild, but have become modifications of those original foodstuffs to more confinement or longer-lasting forms.
The human diet consists of a large selection of such modified natural foods, most of which have been tried for feeding a dog. Besides these human foods, there are still a few natural ingredients available to the dog owner that are not normally considered to be human foods. Examples of such foods are horse meat, hog livers, and bone meal.
Meat is, without question, the most common natural ingredient fed to a dog. It is also the most common source of protein. It is not the only source, however, nor is it the best. Eggs, milk, and plant proteins also make up a large reservoir of protein sources available to dog feeders.
All natural foods containing nutrients are energy sources, since most nutrients can become energy. Some natural foods supply more energy than others and are customarily used as energy sources. These are the foods containing the largest quantities of fats and carbohydrates. Fats are the primary energy source in any diet for a dog. Most meats come with the fat already attached, especially in the chopped and ground varieties. Fats also can be found in nature in the pure form as vegetable oils or as tallow and lard.
Carbohydrates, while not as concentrated an energy source as fats, are lower in cost. Carbohydrates are useful to dilute the protein in high-meat diets or lower the caloric density of diets containing too much fat.
Probably the most universally useful source of energy for a dog is corn oil. Corn oil supplies 9 calories in every gram, 250 calories in every ounce, 124 calories in every tablespoonful, and 62 calories in every teaspoonful. When used as the only fat in a food it also furnishes about ten times the amount of essential fatty acids needed by a dog. Corn oil is inexpensive, easily obtainable, and has a reasonably good keeping quality. Other vegetable oils that can be used satisfactorily as an energy source for a dog are olive oil, peanut oil, safflower oil and soybean oil.