Seasonal alopecia affects animals, usually in winter months, when patches of hair fall out and the skin becomes darkened. The cause of seasonal alopecia is not known, but it might be connected to a lack of sunlight where harsh winters are common. Also called seasonal flank alopecia, the condition occurs more frequently in certain breeds and in regions with scant sunlight.
Season alopecia usually appears on the flanks, the front part of the rear legs, and typically both sides of the animal’s body. The hair might completely fall out, leaving dark, pigmented skin. It can also appear on the nose, ears, and base of the animal’s tail. In some cases, the hair grows back but is discolored.
Certain breeds of dogs are more prone to seasonal alopecia, including the boxer, bulldog, Airedale, and schnauzer. It is also common in Labradors, Akitas, Scottish terriers, and Doberman pinschers. Seasonal alopecia is diagnosed by skin scrapings. Some veterinarians believe the condition might be hereditary because it can appear in more than one animal from the same litter.
Animals might lose their hair a single time, or hair loss may be repeated each year in the same area of the body. Usually, the hair grows back once the animal is exposed to sunlight in the spring, but in some animals the hair loss is permanent. Typically, the area affected by the hair loss is not inflamed and does not itch.
Seasonal alopecia does not pose health risk to animals unless linked to symptoms of underlying diseases that causes hair loss. In some animals, injections of melatonin help the hair grow back more rapidly. Mink farmers sometimes use melatonin to promote thick coats during winter months.
Excessive shedding could indicate signs of other disorders. Cushing’s disease is a hormonal dysfunction that points to a problem with the animal’s pituitary gland. Hypothyroidism is the most common cause of hair loss in animals; it produces a thin coat and excessive hair loss. Animal diabetes, an immune disease, also provokes abnormal hair loss. A veterinarian can rule out these disorders through blood tests to determine if seasonal alopecia is present.