Dogs do indeed need a variety of vitamins to maintain a healthy well balanced diet. However, it is imperative that you realize that most of the commercially prepared dog foods you find in the local stores contain all the vitamins and nutrients your pet needs to fulfill his dietary needs. There are several vitamins you should look for to make sure your choice of food offers them in the necessary quantities.

1. Vitamin A is very important as it has a number of functions. It helps aid the development of normal vision for dogs, helps aid their growth and development from puppies to mature dogs, contributes to immune system functions, and aids the reproduction process.
2. Vitamin D, which is also known as cholecalcifero is also considered a hormone. It is one of three major hormones involved in the regulation of calcium in the body. It´s primary function is to help the mineralization of bone and to increase absorption of calcium and phosphorus. It can be acquired in diet or, in most species can be produced in the skin following exposure to ultraviolet radiation from sunlight.
3. Vitamins D and K are also important to a canine´s health. Lack of vitamin E can cause damage to the wall or membrane of cells throughout the body. Vitamin K functions primarily as a clotting agent with in the blood.

All of these vitamins are in what is known as the fat-soluble group. This means that when consumed they are absorbed and stored in the fat cells throughout the body. Then, they are released gradually as the fat dissolves them slowly as the body needs them. You should not have to supplement your dogs diet with any of these vitamins. Sufficient amounts can be found in a good quality dog food.