I have been caring for a neighbor dog a few weeks a year for several years, so I know him pretty well. I also foster for a local rescue and I've had my current dogs for a couple months. My dogs are small breed mixes (10+ pounds). The neighbor dog is more along the lines of a big lab mix. The lab has been getting along fine with me and one of my dogs, who mostly ignores him, but he will not leave the second one alone!!! He is constantly sniffing his butt, licking his "area", pawing at him, hooking one paw around his middle and situating like he's about to hump, following so he can harass some more and the cycle goes on... All the while he's doing this he is also whining. This is true at my home or his, on walks, on neutral ground hanging out, on leash, off leash, everywhere all the time. When my dog goes to give a cursory sniff back the lab quickly sits his butt tight to the ground and turns around to protect it. My dog has been pretty tolerant by just walking away when he's feeling harassed but the lab follows him and absolutely will not leave him alone. This has reduced my foster dog, who already has fear and trust issues, to a shivering ball of fear. Even when I hold him the way he likes or offer his favorite treat, he's scratching me and shivering and looking around like he does when he's really scared. I'm not afraid of him biting aggressively, I'm afraid he'll go from fixably skittish to permanently scared, eventually aggressive. He has tried to defend himself a couple times with low growls and a little tooth action but message not received and he is getting sick of it (me too). I stepped in when the dogs weren't sorting it out themselves but the neighbor dog completely ignores my existence until I physically take him by the collar and get his face away from my dog. This isn't normal- he's usually pretty happy to obey when I talk to him. I've separated them and I don't know what else to do. I want these dogs to get along! Both have behavior issues I am working on that will get worse if I have to leave either alone. Hopefully someone can offer some advice to get these two cohabitating without creating a phobia for my little one.