I have two chessies. One will run the other way when the warning sound goes off but the other one would go right through if a squirrel or cat is on the other side. I put the invisible fence collar and an e collar on the dog and managed to catch her going through the fence and I had TT collar up to a 6. She hasn't gone through it again. I still do not trust the invisible fence. I'm always outside with my dogs. Any other animal can come into your yard and that is the downside of the fence.