Maybe you can pull the listing and address the landscaping, maybe taller fence in the back (if allowed by city), fix concrete. (biggerpockets.com)
You will be amazed what little holes a big dog can get out of or what tall fences a dog can jump! (fohari.org)
Your male dog can smell a bitch in heat from a very long distance away, and some dogs will do anything to reach her - including scaling tall fences or digging underneath. (celiahammond.org)