Horses experience hair loss for a number of reasons. Uneven shedding of winter coats can cause a patchy appearance. Blankets and tack may need adjusting if they leave rub marks. More seriously, hair loss can be a sign of an underlying skin disorder requiring treatment.
Complex hormonal actions regulate hair growth in horses. Individual follicles form a varied pattern of growth, transition and rest. Seasonal shedding usually happens over the course of several weeks, but sometimes the cycles become less coordinated. The coat can then take on a patchy look and even exhibit areas of baldness.
Hair loss in horses can have a number of physiological causes. Stress from conditions such as pregnancy, chronic illness or even a change in environment can cause horses to lose hair and exhibit bald spots. The condition should resolve itself once the contributing factor is removed.
Hair follicle infection, dermatitis, mites and parasitic fungi, such as ringworm, are among the more common conditions affecting skin health in horses that also can lead to hair loss. Diagnosing and treating any suspected skin condition early is important to avoid secondary skin infections and more serious lesions and loss of hair.