A horsefly has a scissorlike mouth and a bite that can be painful for you or your dog, but the harm is usually short-term minor irritation of the dog's skin. Larger breeds are most susceptible to horseflies. The regions of the dog targeted are the abdomen, legs and neck.
Horseflies are capable of transmitting anthrax, anaplasmosis, Lyme disease, tularemia and the virus of equine infectious anemia. The flies' saliva entering the open wound can cause an allergic reaction. Male horseflies do not feed on blood, so not all horseflies are a threat.
There is little you can do to control horseflies around your dog. One way to minimize horsefly bites is by limiting your dog's outside time on warm, sunny days when there is no breeze. Windy days are perfect days for dogs to be outdoors for longer periods of time since horseflies cannot overcome strong air currents to reach a target. Keeping the dog's environment dry minimizes the risk of horsefly bites. Repellants are generally ineffective against horseflies.
- Ryan McVay/Stockbyte/Getty Images