Horse Skin Allergies

Some horses are very susceptible to skin allergies.

Horses, like humans, are susceptible to allergic dermatitis, or swelling of the skin. Allergic reactions can cause a myriad of uncomfortable symptoms and can vary greatly in severity. When horses are exposed to antigens, or foreign substances, their bodies normally react by producing antibodies. Typically, these antibodies handle the foreign substance with ease. But, when the body overreacts to an antigen, the body produces excessive antibodies, causing swelling and irritation.

Symptoms

Skin allergies in horses can produce a wide range of symptoms including inflammation, itching, thickening, scabbing, oozing, flaking and broken or raised skin. Every horse responds differently to an allergen.

Types

Pasture plants can cause skin allergies.

Culicoides hypersensitivity, also known as summer itch or sweet itch, is an allergic reaction to insect saliva or parasitic worm larvae. Ventral midline dermatitis is a reaction to insect bites, usually from horn flies. It causes swollen, oozing skin most commonly on the horse's belly. Contact dermatitis is a reaction to an irritating substance on the horse's skin. Typically, this irritant is a chemical found in soap, topical medications or fly spray. It can also be a naturally occurring substance such as a plant or feces. Hives, or wheals, are characterized by raised, swollen bumps. They usually come from insect bites, plants or ingestion of pollens or poisons.

Treatment

Optimal treatment involves removing the allergen from the horse's environment when possible. Treating the symptoms of skin allergies can be difficult, but options include cooling gels that contain aloe and/or tea tree oil. You can treat extreme cases with cortisone injections.

Prevention/Solution

Avoid turnout during humid weather.

Modifying your horse's lifestyle is the best prevention for skin allergies. This could involve removing irritating plants from pastures, avoiding turnout during times when insects are rampant (dawn and dusk are particularly bad times) and during extremely humid conditions, and using fly sprays and masks (so long as your horse is not allergic). Also look at your horse's nutrition program to make sure he is not reacting to an ingredient in the feed. Adding probiotic or enzyme supplements to his feed may help as well.

Considerations

Typically, skin allergies appear in the spring, summer and fall and often come and go with the seasons. You can distinguish skin allergies from nonallergic reactions (such as skin swelling due to exposure to an irritant) by the cyclical pattern of the reaction. Usually the source of the irritation and the symptom of the irritation are in two different locations. For instance, sweet itch may manifest around the tail, neck and withers, but the insect bites usually occur between the legs or on the belly.

References

• Thoroughbred Times: Skin Allergies in Horses
• Peter Fention Equine: Sweet Itch