It is the best spray to cover open wounds since the flies can't get through the aluminum spray. Make sure to cover the eyes when spraying. I use it on horses, dogs and sheep.
BTW, you can use the permethrin fly spray for horses on their ears and head (cover the eyes) and it helps to keep flies off. I used it on the sheep when they lambed in the summer to keep flies off the in the jugs. I just bought some that is supposed to be for horses, cattle sheep, goats, etc.