The primary function of the dog’s hair is as a protective and insulating coating.
But if the eyes are the gateway or the window to the soul, the skin and hair are both gateway and window to the embodiment of an animal’s inner health and well-being. Shiny hair, that is, a hair coat that exudes a healthy and lustrous sheen, is an indicator of overall health of the animal. In contrast, a dull coat that lacks luster is an indicator that the animal isn’t as healthy as she could be.
A dog’s coat color is determined by his genes. That said, a variety of environmental factors can somewhat alter the color of his hair. Specific nutrients may be involved in hair color. Cystine, methionine, arginine, tyrosine, and phenylalanine deficiencies are reported to induce hair discoloration. Protein malnutrition induces disturbances in hair growth and quality.
A 2004 study by the American Society for Nutritional Sciences reported that trace-element deficiencies or imbalances also affect hair quality. Suboptimal zinc levels, it said, induce graying of hair, and copper deficiency causes fading of brown- or black-pigmented hair. Other trace elements such as iron and iodine can also affect hair color, as well as vitamins A, B-2, and B-6, pantothenic, folic, and nicotinic acids, and biotin.
Too much exposure to sunlight can make the hair brittle and cause a black coat to redden or turn brown. After a dog has been clipped, the color of its hair is noticeably lighter, and scars often leave a mark of hair that remains white throughout the rest of the dog’s life.
In aged dogs, hair color tends to fade. As a dog ages, his hair turns gray, especially on the head, beginning with the muzzle.
For more information on what your dog’s skin and coat are telling you please refer to 10 Steps to Healthy Skin and a Silky Coat For Your Dog.