The hair coat is composed almost entirely of protein. If the animal's diet doesn't contain adequate protein quantity and quality, hair may fall out or become dry, weak and brittle.

Skin is made up of squamous cells--flat cells tightly packed together. These cells have tough membranes composed of proteins and fats. Without proper amounts of these nutrients, cell membranes weaken, allowing water to escape and bacteria and viruses to enter more easily.

Essential Amino Acids and Fatty Acids

Proteins are found in both animal-based and plant-based ingredients. Animal-based proteins contain all the essential amino acids dogs and cats need, whereas plant-based proteins may contain only some essential amino acids. Dogs and cats need animal-based proteins to achieve optimal health.

Fats can also be found in both animal-based and plant-based ingredients. They are incorporated into skin cells as fatty acids. There are two essential fatty acids for skin and coat health. Linoleic acid maintains skin and coat condition in dogs and cats. Without enough linoleic acid dogs and cats may experience dull, dry coat, hair loss, greasy skin and increased susceptibility to skin inflammation. Cats also require arachidonic acid for normal skin and coat health.

Both of these are omega-6 fatty acids and are found in animal tissues like chicken fat and in vegetable oils (corn and soybean).

However, most commercial dog and cat diets contain more than adequate amounts of omega-6 fatty acids. Because these fatty acids can be converted to compounds that promote skin inflammation, it is important to balance the amount of omega-6 fatty acids in the diet with omega-3 fatty acids, which do not promote inflammation.

Omega-3 fatty acids are found in oils from fish and some plants (canola and flax).

Research has found that combining fat sources in the diet at a ratio of five to ten omega-6 fatty acids to one omega-3 fatty acid results in excellent skin and coat health.

Vitamins and Minerals

Vitamins and minerals are essential for the development of healthy skin and hair coat. The best way to provide these nutrients is through a complete and balanced diet containing appropriate amounts of essential vitamins and minerals rather than through supplements.

Vitamin or Mineral	Importance to Skin and Coat Health
Vitamin A	Necessary for growth and repair of skin
Vitamin E	Protects skin cells from oxidant damage
Vitamin C	Helps heal wounds
Biotin	Aids in the utilization of protein
Riboflavin (B2)	Necessary for fat and protein metabolism
Zinc	Necessary for fat and protein metabolism
Copper	Involved in tissue, pigment and protein synthesis

Changes in Coat Condition

Diet is believed to be a factor when changes in skin and coat condition are noticed. The most common causes of these changes, however, are season and lifestage.

As cold weather approaches, most dogs and cats grow a thick coat to help keep heat in and cold air out. As the weather begins to warm up, they shed the thick, heavy coat.

Most puppies and kittens are born with soft fuzzy hair, but as they age, a coarser coat grows. Pregnant or lactating bitches and queens also may experience a change in coat condition or hair loss. And, as with humans, the hair on dogs may thin out and become coarser and white as they reach their senior years.