Semi-moist foods include chemicals such as propylene glycol, color enhancers, and lots of sugar, also making them poor choices for a total diet in spite of their convenience. Either, however, can be used to top-dress dry food or as occasional snacks. Some go so far as to say that supplements can unbalance the diet by disrupting the necessary relationship between vitamins and minerals. Some breeders disagree and regularly supplement their dogs with one of a variety of products promoted for healthy coats and skin, bone growth, reproductive capacity, etc. Some owners who have dogs with dry skin may add a teaspoon or tablespoon of corn oil to their pet's dinner, but many nutritionists think that this adds only calories and that a food higher in essential fatty acids will take care of the skin.
Some owners purchase essential fatty acids in a bottle and add that to the food.
Some owners think growing puppies need extra calcium and add it in the form of bone meal. But this can do more harm than good, for calcium must be in balance with phosphorus and magnesium in the diet, and an overabundance of calcium can cause a myriad of problems. Those owners who would like to cook their own food at home should contact a nutritionist for a recipe to make sure the ration is balanced. The Collins Guide to Dog Nutrition by Donald R. Collins DVM, from where much of the information in this article came, includes homemade diets. The book is available in many public libraries and can be ordered by most booksellers.