Dry and coarse coats can indicate nutritional deficiencies, and there are several ways to enhance coat health through nutrition. | Getty imagesQ: My 4-year-old gelding is losing hair in tiny half-inch spots around his face, jaw, and under his tail. Last year he almost lost his tail hair completely. This year I see signs of him rubbing both his mane and tail, but so far it hasnt fallen out.My vet thinks it might be a nutritional deficiency because his coat is coarse and dry. What could be causing this, and what can I do to improve his coat quality?A: Dry and coarse coats can indicate nutritional deficiencies, and there are several ways to enhance coat health through nutrition. Because your horse is losing hair, ask your veterinarian to help you identify the underlying cause; many potential causes require medical intervention.Alopecia, or hair loss, in horses is acquired (they are not born with the condition) and can have a variety of causes. Based on the information you provided, it sounds as though your veterinarian has ruled out the causes that would necessitate medical care such as bacterial infections, allergies, skin cancer, hormone imbalances, and parasites.Regarding your horses diet, healthy hair growth depends onadequate nutrition. Many nutrients play a role in coat health; therefore, a balanced diet is critical. If your veterinarian suspects a nutritional deficiency, consult a qualified equine nutritionist to ensure you are supplementing required nutrients in adequate amounts. Once you have completed that step, you can add additional coat support such as an omega-3 supplement or additional biotinto help improve your horses coat.A horses hair coat is primarily composed of the protein keratin, so for coat growth and maintenance, its important to supply an adequate amount of this essential amino acid. Other critical nutrients include fatty acids, vitamin A, zinc, copper, and, again, biotin. These nutrients all play imperative roles in coat health.Zinc and copper both impact the production of melanin, which is responsible for the pigmentation of the hair coat. Additionally, a hair coat lacking in melanin is at increased risk for oxidative damage? Zinc is critically important for the repair and maintenance of epithelial cells (cells that line the internal and external surfaces of the body), and copper plays a crucial role in maintaining structural integrity and collagen production. These two minerals are present in the forages your horse eats but typically not in adequate amounts, and they often need to be supplemented.Vitamin A deficiency can also result in a dry, brittle hair coat. Healthy pastures normally contain adequate amounts of this vitamin, but you should supplement it if your horse is maintained on hay. You need to supply other nutrients, such as the potent antioxidants selenium and vitamin E, in adequate amounts to prevent excess oxidative damage that can affect coat health.Biotin is a B vitamin that is also well known for improving hoof health. Hooves are also composed largely of keratin, which is the same protein found in hair and skin tissue. For the average-sized horse, supplementing 20-30 milligrams per day of biotin is ideal for additional support above and beyond a balanced diet.You can also supplement omega-3 fatty acids to enhance coat health and shine. Horses do not have a set requirement for omega-3 fatty acids, but adding 2-4 ounces per day of an omega-3 rich oil such as flax or camelina can improve your horses hair coat appearance.To meet your horses essential amino acid needs, as well as vitamin and mineral requirements, you will likely need to add a high-quality ration balancer to his diet. Ration balancers normally have a high protein content and are designed to fill the nutritional gaps in hay. Evaluate thebalancers ingredient list carefully to be sure it contains significant amounts of high-quality protein such as alfalfa meal, whey protein, or soybean meal; this will be evident by these ingredients appearing close to the top of the list.Take-Home MessageIf you notice your horse losing hair, first consult your veterinarian and determine the underlying cause. Many causes for equine hair loss require medical treatment, but once health issues have been ruled out, investigating the diet is the next step. When feeding to improve coat health, first ensure that your horses basic nutrient needs are met with a high-quality ration balancer, then consider an additional supplement of biotin and an omega-3 fatty acid source. If you are unsure if your horses current diet is meeting his nutrient requirements, reach out to a qualified equine nutritionist.