@DebraDownSouth Thanks Debra, you've given me a lot to think about. I think I'll start immediately with the "leave it" training at home and then get in touch with some trainers/behaviorists in my area. I'm not expecting any miracles here but, like you said, even just learning to ignore other dogs would make such a difference.
Hi, forum. My dog Ugo (almost 2 years old now) has a few behavioral quirks, but the worst by far is his constant, hair-trigger aggression towards other dogs. He's never shown aggression with people, he's playful with cats, and he shows the usual predatory instincts with birds and small mammals, but he becomes a snarling, bloodthirsty demon with other male dogs 100% of the time. He's usually fine with adult females, but he will lunge and nip aggressively at puppies of both sexes. This behavior is made worse when he's on leash (which is generally all of the time now), and much worse if we're in the park near my house, where he grew up (i.e. his territory). As a result of this it's become impossible to enter the dog park, so the only times I can really let him run free and therefore get the activity that he needs are when I take him somewhere very remote, like the mountains, or one of the really vast parks/nature preserves on the outskirts of my city. Even when I'm walking him around the city, the fur on his back goes up and he lunges immediately toward any dog that he sees.
When he was just under a year old he was bitten pretty badly (he needed some stitches) by a bigger dog around his age, after which his aggressive tendency worsened drastically. Therefore I don't know if he reacts this way out of fear or what. Does anyone have any experience in dealing with / resolving this kind of thing?