Canine nutrition has been the subject of much research in recent years. Since prepared dog food accounts for a greater volume of supermarket sales than any other single grocery item, the commercial incentive is tremendous. As a result, American dogs are the best fed in the world, probably the most expensively fed, and certainly the most often overfed.
Biologists describe the dog as a carnivorous mammal. But modern authorities say that his cohabitation with man has caused him to become like us, omnivorous. Dogs are remarkably adaptable to different kinds of diets, including diets that are high in vegetable content.
The dog's digestive system is not exactly like ours. The general process is the same, but the timing is different. First of all, mastication is less important in canine digestion. The dog's teeth and jaws are designed for tearing meat and grinding bones with amazing efficiency and up to 300 pounds of force. Dogs chew little and swallow rapidly. They cannot chew with their mouths closed.
The dog's taste buds are situated under his tongue, but his food passes quickly, practically untasted, through the pharynx and esophagus into the stomach, where the principle digestive process takes place. The dogs gastric juices are much stronger than ours, allowing him to digest matter which would give us a severe stomach ache, to say the least.
Your dog's stomach is very elastic, and can expand to a capacity of one pint in a small lap dog, while large dogs make room for 8 quarts of food. The gastric juices in his stomach are high in acid and food remains there longer than it does in ours. This is why they require a richer, more concentrated diet than we do. Digestion takes place mostly in the stomach, very little in the mouth.
The dog's nutritional requirements are similar to ours. However, puppies, since they grow and mature faster than we do, need a richer diet than do babies, with more protein and less bulk. Baby food, except for all-meat products is unsuitable for puppies. Adult dogs need a balanced diet including proteins for body building, fails and carbohydrates for supplying energy and heat, bulk for elimination, vitamins and minerals to catalyze various body processes, and a total caloric intake that corresponds to individual living conditions, age, weight, metabolism, and activity.
Water is very important, representing an estimated 70 percent of the dog's weight. Protein content can be provided by meat, fish, cheese, milk, and eggs. Fat is an important source of calories, valuable in cold climates, and during winter. It also helps to maintain a healthy coat and skin. Dogs housed out of doors may be given as much as 20 percent fat in their diet to provide calories and promote a heavy growth of fur, while 10-15 percent is sufficient for most pet dogs.
Carbohydrates include sugars and starches, both of which are sources of quick energy. Dogs assimilate sugar easily, although it is often an acquired taste. Their gastric juices are less efficient in digesting starches, unless they have been cooked very well. Commercially prepared dog biscuits are specially processed and enriched in order to fill the dog's nutritional requirements. On the other hand, potatoes, white bread, treated rice, and pasta are not advisable for dogs, partly because of indigestibility, but mostly because they provide little to no nourishment.
In addition to starches, the cellulose that is found in greens and vegetables provides bulk and favors elimination. Green vegetables are actually indigestible to dogs, which eat grass for this very reason in order to purge themselves. If your dog has as obsession for grass, you might examine his diet to make sure that it agrees with him. Carrots and spinach provide useful vitamins and minerals, while cooked vegetables and greens in the diet of obese or inactive dogs can satisfy their hunger temporarily without providing fattening calories.
The principle canine vitamin requirements are those of the B group, and vitamins A, D, and E. Oddly enough, dogs do not need Vitamin C, because their body produces it naturally. Liver and milk are particularly rich in these essential vitamins. Carrots are a natural source of vitamin A, and whole wheat cereals supply the B group. Cod liver oil is the richest source of Vitamin D, essential for growing puppies, and adult dogs that don't get a lot of sunshine.
Finally, there are the minerals, the most important of which are calcium and phosphorus, especially for growing puppies. The principal decision an owner has to make is whether to give his dog commercial dog food, a homemade diet plan, or a combination of the two.