Oh my They really should be kept totally separate until she is without a doubt out of heat. Male dogs will do ANYTHING to breed a female in heat.

When I was younger once, my Mom and I ran across a stray female in heat... Unfortunately it was a better than good chance she had already been mated, but we locked her up tight in the garage anyway before taking her to a local no-kill shelter (They said she would be fostered out until they knew for sure whether she was pregnant or not).

Anyway, the next morning, the rubber seal at the bottom of the garage door was completely ripped off, and the wood chewed and gnawed all along the bottom . Still too much for the male dog or dogs to get through, but they made an extremely determined effort.

Male dogs have been known to escape/climb out of high fenced areas or even go through electric fencing to get to a female in heat, so a cloth diaper would be nothing but an annoyance for the few seconds it would take to rip it off. Even if it was sewn shut around the dog, he'd chew it off.

Please separate them and keep them totally separate until she is out of heat.