In some parts of the world, fly bites are a common problem for pets. Fly bites are a warm weather problem that primarily affects dogs confined to the outdoors in the summer and fall. These bites can be very painful and irritating. In upright eared dogs, the flies typically bite at the tips of the ears. In floppy eared dogs, the front edge of the ear gets the bites. In some severe cases, the face can also be involved. The signs are inflamed ear tips and edges, crusty scabs or wounds on the ears that leak blood or serum.
The first thing you want to do is soften the scabs. Soak a washcloth in warm water and hold against the dogs sore ear to soften the scabs and crusty material. This may take a few minutes until it is soft enough to be wiped away. Once the crusty material is gone, wash the raw areas with an antiseptic liquid soap like Betadine Skin Cleanser and be sure to rinse very well, dried soap can cause further irritation. Use an antibiotic ointment like Neosporin or Polysporin to help sooth the inflammation and prevent ears from getting infected.
Fly bites make the ears very sore and they'll continue to leak serum and crust up for several days, even without more bites. Keep the sores clean by wiping off the excess crust at least once a day. Use a soft cloth or gauze pad soaked in water or sterile saline contact lens solution. Apply the antibiotic ointment in a thick layer several times a day. It is best to keep the pet indoors while the ears are healing.
Another problem that flies can cause, is maggots. Flies can find sores that are hidden under the pet's thick fur or seek out the debris that collects in skin folds. They also target tumors, abscesses, healing inscisions from surgeries and infected ears. The flies lay eggs in less than 24 hours and the maggots (wiggling white worms) eat the dead tissue and drainage from the sore, which can become very large and serious very quickly. Most wounds infested with maggots need medical attention.
Don't spray fly repellent on the face, as it can get into the eyes. Insecticides can burn and sting the sores. Some people have success using Vaseline to coat the ears and others like to use Fly Repella by Troy, an antispectic cream that is also a insect repellant.
A great way to get rid of flies is RESCUE Disposable Fly Trap, $4.95, it is pesticide free. You just add water and the flies are lurded by the scent and go in the trap and drown. It works!