A horse’s skin is vital to the animal’s survival. It serves as its anatomical boundary and as the principal organ of communication between the horse and the environment in which it lives. As is the case with other body components, the skin of a horse is subject to attack on a number of fronts, ranging from infectious bacteria to biting insects.

We will take a look at some of these skin afflictions, but first, let us set the stage by examining the way in which a horse’s skin is constructed. There are a number of resources available that provide information on equine skin problems. Two good ones–both were used in the preparation of this article, along with other sources–are Veterinary Notes for Horse Owners, first published in 1877 and revised and updated frequently through the years, and, on the more technical side, The Merck Veterinary Manual.

A horse’s skin is its largest body organ, ranging from 12-24% of the animal’s weight, depending on age.

The skin consists of various cellular and tissue components. There is an epidermis, an appendageal system, dermis, arrector pili muscle, twitch muscle (panniculus carnosus), and a fatty subcutaneous layer known as the panniculus adiposus.

Dermatitis on lower leg
Anne M. Eberhardt

Common signs of dermatitis are raised or bumpy spots on the skin.

The main activity of the epidermis is to produce two types of protein–keratin and melanin. Keratin is a scleroprotein, which is the principal constitue