The most important nutrients for maintaining a healthy coat in dogs are the amino acids tyrosine and cysteine. These primal amino acids play an important role in the synthesis of melanin, which are responsible for the color of the coat, including dark eumelanin and yellow and orange pheomelanin. Insufficient intake of these amino acids can adversely affect the synthesis of eumelanin, leading to coat depigmentation. Therefore, it is crucial to ensure that your dog's diet contains sufficient amounts of tyrosine and cysteine to maintain a healthy coat. Other important nutrients for a healthy coat include omega-3 and omega-6 fatty acids, biotin, and zinc.