Ok it is WAYYYY to late for this reply but. Dogs can smell the hormones that cats release when they are in heat but they don't act on it normally because it's not supposed to atract male dogs. Dogs have a really good sense of smell, they can even smell tumors that are inside people for example. And also, humans are not the only ones that masturbate you know? Other animals do too. Dogs use anything they have near them, a blanket, a pillow or even a cat, to masturbate if they are feeling horny. It's best to give your dog a blanket for him to do his business so he doesn't use your cat and possibly hurt him. Again WAY to late for this reply but you can use this for future reference.
