MSD Manual

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Pet Owner Version

Dermatitis and Dermatologic Problems of Horses


Karen A. Moriello

, DVM, DACVD, Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison

Reviewed/Revised Oct 2019 | Modified Oct 2022

Dermatitis is a general word for any type of inflammation of the skin. It is the word usually used to describe a skin condition before a specific diagnosis is reached. There are many causes of skin inflammation, including external irritants, burns, allergens, trauma, and infection (bacterial, viral, parasitic, or fungal).

Dermatitis may have many signs including any combination of itching, scaling, abnormal redness, thickening, and hair loss. The usual progression of a skin disease involves an underlying trigger that causes boils, scabs, scales, or blisters.

Abnormal itching, called pruritus, occurs in many skin diseases. As the inflammation progresses, crusting and scaling develop. If the problem reaches the deeper layer (the dermis), fluid discharge, pain, and sloughing or shedding of the skin may occur. Secondary bacterial and yeast infections commonly develop as a result of skin inflammation. If the dermatitis does not improve, the early signs of inflammation (such as redness) become obscured by signs of chronic inflammation (thickening of the skin, color changes, scaling, fluid discharge). Often the skin becomes drier and, if itching is not already a sign, it will often develop at this stage.

Resolving dermatitis requires that a veterinarian identify the underlying cause and treat secondary infections or other complications. A review of your horse’s history and a physical examination can more precisely define the problem.

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