I use the Safflower oil mixed with OOO, two drops in my cat's dinner every day. I started out with one drop till she got used to the taste. It seems to pretty effectively keep bugs off her. I also put one drop in all my water that is stored, and she drinks that water too, so she gets a tiny amount that way. Her fur is unbelievably soft too!
So in your case I would get a little bottle and mix a small amount of the OOO with Olive Oil and give that to your pet.