Technical information for veterinarians

Dermatitis in horses

What is dermatitis?

Equine dermatitis is a catch-all term for inflammatory conditions of the horse’s skin that subsequently affect the overall health and sheen of the coat. The skin itself may be red and flaky or, in extreme cases, may ooze fluids

Etiology/pathology

Dermatitis is more of a reaction pattern than a disease classification and may be complicated with other respiratory and/or digestive conditions. Disturbances and/or damage to the dermal cellular production of ground substance glycosaminoglycans— collagen and elastin — negatively impact the skin structure and function. The skin adnexa (pilosebaceous system and the eccrine sweat glands), are complex structures that develop from the epidermis and remain in continuity with it but reside in the dermis. They are highly active structures metabolically and extremely sensitive to toxic and hormonal influences.

Symptoms and diagnosis of dermatitis

Equine symptoms of dermatitis may include superficial skin inflammation characterized histologically by epidermal edema and clinically by pompholyx when acute, poorly marginated redness, spongiosis (intraepidermal edema), oozing, crusting, scaling, pruritus, and lichenification caused by excessive scratching and/or rubbing.

Equine dermatitis may be caused by bacteria, viruses, or allergies/sensitivities to certain substances including insect venom. The primary types of dermatitis are perivascular dermatitis (acral lick dermatitis, flea bite hypersensitivity, sarcoptic mange, atopic dermatitis and other hypersensitivity to insect bites), irritant contact dermatitis, and Pemphigus foliaceus— a relatively rare condition caused by an allergic response to a substance in the horse’s own skin.

A horse with severe dermatitis will usually demonstrate scratching, rubbing, chewing and/or biting in the affected region. This is the horse’s attempt to relieve the itch that usually accompanies the condition. Other signs such as urtcaria, papules, scales and crusts are also indicative of dermatitis. Prolonged irritation of the skin is often accompanied by a loss of lustre in the horse’s coat.

Treatment options for dermatitis

Lifestyle modifications

Since equine dermatitis is likely to result from an allergy or other ongoing irritant, the horse’s lifestyle, food intake, etc. should be reviewed closely and discussed with the horse owner. If a horse is allergic to a certain substance/substances, then avoiding contact with or exposure to the substance will help alleviate symptoms. For example, a horse that is sensitive to the bites of gnats or midges should be kept in the stable before mid morning and after mid afternoon and insect repellent should be used.

Cortisone

Horses with severe or chronic skin conditions are sometimes given cortisone treatment, which may help alleviate the condition.

Use of natural substances

Bioflavonoids (plant-based, antioxidant substances with the power to protect plant and animal tissues), have been shown in many scientific studies to help the tissues maintain their health. Antioxidants from green tea (Camellia sinensis) and grapes (Vitis vinifera) have been shown to have particularly beneficial effects and may be employed preventively or therapeutically to help repair damaged tissues. Nutricol® (available to veterinarians as Recovery®SA (small animals) and Recovery®EQ (horses), is a proprietary formulation containing both these ingredients.*