They may not be fire ants. If they are, I don't know of a spray that will get rid of them. There are a couple of ways, but you have to be careful with dogs. The best to use is the one that is granules that you put a TON of water on. The other ones have granules that stay out...those are dangerous to pets.
If they persist, maybe you should call an exterminator. Any ant bite can be irritating. I only mentioned the fire ants because you said they are red. Those things do kill small dogs...they are just awful pests.
