The most successful treatment is prevention by applying fly repellent before open wounds from bites develop.
The effect of flies on the skin is usually minor, with irritation of the skin from fly bites being the most common problem. Attacks by stable flies and black flies are typically incriminated in skin wounds located on the ear tips or faces of outdoor dogs from late spring until first frost.
Horsefly, deer fly, and mosquito bites tend to be less irritating. The flies actually bite and open the skin creating multiple small ulcers oozing serum and blood or produce small red bumps covered with bloody crusts. Scratching or rubbing the ear flaps can be quite intense in those dogs with allergies to fly bites.
Treating Fly Bites in Dogs
Commercially available fly repellents, permethrin-containing products recommended for flea control on the dog, or a thin-coating of petroleum jelly applied to the affected skin reduces the potential for future bites. The products should be applied according to the manufacturers’ directions. More frequent applications will be necessary if the dog swims.
Avoid spraying the product directly onto the ear to prevent the possibility of contact with the eye and subsequent irritation. Spray the product on a soft cloth or make-up pad and wipe the surface of the ear avoiding direct contact with large open wounds. If open sores are present, they should be cleaned daily with soap and water. Coating with a triple antibiotic ointment will reduce the potential for infection and decrease the attraction of flies to the open wound.
Keep the dog indoors during the day until the lesions heal. When ear lesions are extensive or itching is quite intense, veterinary care is advised.