The horse in this picture was diagnosed with Cutaneous Habronemiasis, commonly known as “summer sores.” Cutaneous Habronemiasis is a condition in horses caused by the deposition of fly larvae in open wounds or moist areas on the skin. The larvae migrate through the tissue and irritate it resulting in an ulcerative granulomatous lesion. It is believed that the lesion is the result of a hypersensitivity reaction to the dead or dying larvae. The hallmark sign of summer sores is the presence of yellow calcified granules within the lesion. Summer sores often become chronic and healing is very slow. Most commonly we find these around horses eyes, lower limbs, and their genitalia. In this case, the primary lesion is located on the urethral process with smaller lesions located on his sheath. Fortunately, the urethral lesion does not seem to affect his ability to urinate.
Treatment of summer sores is very lengthy and difficult. In this case, treatment involved both topical and systemic therapies. First, this gelding was treated with a larvicide. One dose was administered after the initial exam, and a second dose was given two weeks later. We also examined this horse twice per week and treated the lesions with topical medications. After three weeks of treatment, the lesion is improving.
There are some measures that you can take to help prevent summer sores from occurring. Most importantly, you should maintain a regular deworming program using larvicidal drugs. We can help you implement and execute a proper deworming protocol. In addition, controlling the fly population on your farm can help reduce the incidence of summer sores. This is easier said than done, especially in the warm Florida climate.
Be sure to examine your horses regularly for any suspicious skin lesions. There are many other skin disorders in addition to summer sores, some of which can be very serious and require extensive treatment. If you notice something that looks abnormal, please call us so we can examine your horse as soon as possible. Early diagnosis and treatment are essential to your horse’s health.