How Your Veterinarian Can Help with Summer Sores

Your horse's sores could be caused by habronematidosis, or summer sores, a painful parasitic infection most likely to affect horses during warm weather. Fortunately, your equine veterinarian offers treatments that help your horse's skin heal and prevent new sores.

What Causes Summer Sores?

House flies carry the larvae of three species of the Habronema worm, a type of roundworm responsible for summer sores. Adult Habronema worms live in your horse's stomach and are usually harmless. Larvae and eggs from the worms are shed in manure. Horse flies land on the manure, pick up the larvae, and land on your horse's nose or lips. Your horse eats the larvae, which develop into worms in its stomach.

Flies may also deposit larvae on small wounds or scratches on the skin or on mucus membranes, like the eyes, lips, mouth, and genitals. The skin doesn't provide the ideal environment for the larvae to turn into worms. Instead, the larvae burrow into the layers of skin, causing irritation and inflammation. The resulting sores may be as small as a dime or larger than an orange.

D. G. Pugh, DVM, a professor at the Auburn University College of Veterinary Medicine, told Practical Horseman that some horses may be more likely to get summer sores than others, due to a possible genetic susceptibility or an extreme sensitivity to the larvae.

What Do Summer Sores Look Like?

You may notice a red, raised, open wound if your horse has a summer sore. The middle of the sore may be yellow or white, and it may contain bumpy red tissue that resembles proud flesh, according to PetMD. Some sores may ooze blood or bloody liquid. The inflammatory reaction may trigger intense itching as the larvae burrow into your horse's skin. Unfortunately, scratching can worsen the sore and lead to a bacterial infection.

How Are Summer Sores Diagnosed and Treated?

Before your veterinarian can diagnose habronematidosis, he or she must determine what caused the sore. Skin scrapings from a sore may be examined under a microscope to confirm a diagnosis of summer sores.

Depending on the severity of your horse's condition, your veterinarian may recommend one or more of these treatments:

• Steroids. Oral or topical (placed on the skin) steroid medications ease itching, pain, swelling and inflammation, allowing healing to occur.
• Antiparasitic Medication. Antiparasitic drugs, like Ivermectin, kill worms in your horse's stomach, preventing the shedding of eggs and larvae. According to Practical Horseman, Ivermectin may also be applied on the sore.
• Debriding. Your veterinarian may need to remove dead or damaged tissue from the sore in some cases.

How Can I Prevent Summer Sores

UC Davis Veterinary Medicine notes that summer sores can continue to occur year after year once a horse has an initial bout of summer sores. Preventing new sores involves these simple steps.

• Practice Good Fly Control Management. Promptly remove manure, wet bedding, and old feed to reduce flies. Repair holes in screens promptly. Use fly sprays, traps, and foggers if flies become a problem. Outfit your horse with a fly mask to keep flies away from its eyes and face.
• Deworm Your Horses. Talk to your veterinarian about establishing a regular deworming schedule to kill any worms your horse may ingest.
• Treat Wounds Promptly. Examine your horse's body for new scratches or wounds, especially during the spring and summer months when flies are most active. Clean and cover wounds to prevent flies from landing on them.

Are you worried about a sore that won't heal? Contact our office to schedule an appointment with the equine veterinarian.

Sources:

Practical Horseman: How to Treat and Prevent Summer Sores in Horses, 6/26/2024

https://practicalhorsemanmag.com/health/summer-sores-28596/

PetMD: Summer Sores in Horses, 2/16/2024

https://www.petmd.com/horse/conditions/skin/summer-sores-horses

UC Davis Veterinary Medicine: Summer Sores, 4/14/2022

https://ceh.vetmed.ucdavis.edu/health-topics/summer-sores

The Horse: Summer Sores in Horses: Causes, Clinical Signs, and Diagnostics, 4/19/2024

https://thehorse.com/1126590/summer-sores-in-horses-causes-clinical-signs-and-diagnostics/