We have one outside dog that is being bitten unmercifully by the flies this year. She is bleeding on her back and ears. Skin so Soft did not work. I had heard rubbing rosemary on the dog would help and I tried that, but it only gave brief relief. I had made some rosemary and garlic oil out of olive oil. I was desperate and rubbed some of this over her and all afternoon the flies have left her alone. Is this safe to continue using?