Equine Wellness: Summer Sores

Habronemiasis, more commonly known as summer sores, is a common condition in horses. Summer sores form when larva from bot flies accidentally invade fresh wounds or moist areas on the body. The horse’s body reacts to this larva infestation by forming a large amount of proud flesh. These non-healing skin lesions are extremely itchy, and have white calcified material in the wounds. Summer sores most commonly occur in the spring or summer. It is extremely important that your veterinarian differentiates a summer sore lesion from a pythium lesion. Treatment for summer sores involve administering systemic oral ivermectin or moxidectin. The dewormer used must contain these active ingredients, or it will not be effective. Sometimes surgical removal of the proud flesh may be required. The lesions are treated topically with a steroids/ivermectin/antibiotics and DMSO to reduce inflammation and itching. The key to preventing summer sores in your horse is fly control. It is extremely important to remove manure, excess feedstuffs, wet straw and other materials to prevent fly breeding sites and hatching of fly larvae. Compost piles should be properly managed to maximize heat production to kill hatching fly maggots. Insecticide fly traps/baits, residual fly sprays, face masks and fly repellents are all beneficial.

More information available on Dr. Kurtz’s Equine Wellness:  Anhidrosis and Other Summer Medical Issues video.