I'm no expert but have you tried a "Halti?" instead of a muzzle? It looks like a muzzle but helps you control the dog- it doesn't cover the nose it straps around it. You can give the command "no barks" or whatever as you give a yank on the leash and Nikki can eat, drink, pant, and bark but it's a good training tool. Funny that my Cody really dislikes men he doesn't know (some neighbors and relatives he's fine with)since we got him as a wee pup and he was not exposed to cruelity or mistreatment. I think cause 2 females did most of the training, he's very protective. When I walk Cody and we pass people, I still hold his leash gently but I know his every move so if I feel he's about to go crazy, I give a gentle yank, say "leave it" and walk normal. I found if I get too nervous and scared, he gets worse. I've been trying this for a month or so and he seems better. Nikki seems soo sweet. I hope everything turns out ok in time. maybe you should muzzle and chain the previous owner, the jerk.