This is our 5 y/o pup. He was abandoned at a vet clinic on Christmas and we rescued him from the humane society in January. They had no history on him, but suspiciously he had these scars on the bottom of his jaw. Since we've had him, he's been gentle around kids and good around other dogs both bigger and smaller and of female/male breed. Last night we had another dog playdate that went horrible. Our dog latched onto the other dog's face and would not let go. It took 3 of us and a long 30 bloody seconds of struggle before he started passing out and we could finally pull his jaws apart. It's clear now, that those scars under his jaw are from previous attacks. I'm so heartbroken. We have kids and neighbor dogs come over all the time but I won't be able to trust our dog unless we follow the vet's advice and put him in a muzzle.