Hereditary, immune-mediated condition of the skin and muscles in dogs and humans.
Like humans, horses can be allergic to pollens, spores, and other allergens that appear in the environment seasonally, as well as substances found within the barn such as dust, mites, and animal dander. While people tend to respond to these various allergens by sneezing and developing watery eyes, while horses react by getting very itchy skin or developing hives. This leads to constant scratching and chewing which can cause trauma to the skin and extreme discomfort. Generally, symptoms worsen with age and can be controlled, but not eliminated.