Flies and mosquitoes belong to the same insect order known as Diptera. The house fly and other types of flies can be nuisances similar to mosquitoes. However, flies also spread disease to humans and your dog.
Fly strike is a disease seen in outside dogs (or those residing near livestock farms) in the warmer summer and fall months. Flies in these areas, such as the stable fly, can cause painful bites when feeding on human or animal blood.

Control Flies with a Fly Repellent Ointment
Flys-Off is a specially formulated product used to kill and repel flies such as the horse fly, stable fly, face fly, and horn fly from wounds and open sores on dogs, horses, and ponies.