Nutritional adequacy of diets formulated for companion animals.

D ogs and humans share a unique relationship that has existed throughout the world for centuries. The evolutionary nature of this relationship and information about the early days of domestication are unknown. However, one may assume that some efforts were made by humans to feed their canine companions , and symbiotic relationships developed. As domestication emerged, humans continued to share food with dogs, even though it was unknown how the food nourished and sustained them. Cats, which were domesticated more recently than dogs, also have a unique history, but their story is even more uncertain. The Scientific Method The scientific method was born during the Renaissance as humans began to increasingly question the world around them. The advent of the germ theory of disease elicited great excitement, because it seemed that every disease could be explained on the basis of causative agents. However, a few diseases defied this theory. For example, scurvy was the first disorder to be linked with diet rather than a bacterial agent. Beri-beri, pellagra, and rickets soon were added to the list. 2,3 For the first time, the groundwork was laid for the identification of relationships between diet and certain diseases , which led to the discovery of essential vitamins. Certain essential nutrients could be used to treat companion animals and humans afflicted by recognized disorders attributable to lack of specific nutrients, and a new era of nutritional discovery had begun. During the 20th century, another category of diseases began to appear. Heart attacks, hypertension, and diabetes seemed to be linked with excesses of nutrients , rather than deficiencies. Advances in scientific techniques allowed various aspects of these diseases to be studied at the molecular level, and today these techniques are being applied to determine genetic components of those diseases. Modern scientific inquiry and exploration will continue to provide information concerning the 2 recognized forces of nature and nurture. Throughout the course of our scientific advancements , dogs have remained faithful companions. Many early and current discoveries were made because of dogs. For example, one of the early studies 4 conducted in dogs found that the B vitamin niacin was a treatment for pellagra. Also, in the 1920s, investigators conducted historic studies 5 that involved the use of dogs to document the relationship of insulin and diabetes mel-litus. Although our understanding of human nutrition has been advanced as a result of responsible scientific investigations that involved …