Hair loss is common in horses, and is a symptom of a wide variety of possible underlying causes. Causes range in severity from mild and easily treatable to serious conditions requiring extensive treatment. Horses with a patchy coat or bald spots require prompt veterinary attention in order to determine the cause and plan treatment.
The potential causes of hair loss typically relate to several basic issues.
In some cases, the horse is rubbing the hair off, usually due to something that is causing itchiness. Potential conditions include:
In some cases, the immune system is either overactive and sees the hair as a threat, or is underactive and allows an infection to take hold and kill the hair.
Other possible causes include
The main variation in severity of hair loss is the size and number of affected areas. Horses that have widespread, large patches of hair loss are more likely to have an immune-mediated disease such as an allergic reaction, whereas localized, multiple areas of hair loss are typically associated with infectious agents.
Hair loss also varies in whether the patches of missing hair are itchy. Horses that are itchy may self-mutilate or rub the itchy areas on objects, causing damage to the skin. Itchy hair loss is most commonly associated with infectious agents such as fungi or bacteria.
Horses with patchy coats or bald spots require prompt veterinary attention. Diagnostic tools include:
Treatment depends on underlying causes, and may include:
In some cases, a patchy coat is a result of seasonal shedding. During seasonal shedding, no areas of skin are hairless, but instead have a thinner layer of hair. Horses with truly hairless skin require examination by a veterinarian.