It depends, but most breeds will start their heat after they are about a year old. It's not recommended to breed a bitch on her first heat because she's a bit too young still. You could keep her outside in a secure area, but my brother has come up with a neat trick of putting his dog in old boxer-briefs and panty-liners. It works with his dog, but some dogs aren't going to allow it on them.
Answered by Anonymous - 11/11/2012 6:04:44 PM