Starting to have issues on-leash
Seems to be a very common problem, I'm hoping to nip this in the bud. Jupiter, 7.5 months, does not generally seem aggressive, although he does sometimes bark at the other dogs in obedience class if I don't keep his attention (he's been in classes almost continually since we got him at 10 weeks). He goes to the dog park nearly every day, where he gets along and only seems to have issues when he does the chase/nip too hard behavior. Then they yip and I have to redirect, because he doesn't back off very well once he starts that.
Anyway, he has never shown much interest in dogs on the leash, but the last two days there have been two alarming incidents. There was this girl with a pointer who seemed to _really_ want her dog to meet Jupiter. They sniffed each other, and all was well, but the dog had a tennis ball (oops), and Jupiter wanted it. It got to the point that Jupiter started growling at the pointer. I'd never heard Jupiter growling at another dog.
When we walked home, there was some yippy foo-foo dog doing the normal plant and yip, and again Jupiter growled at it. Again, this is new territory.
Tonight, pointer girl found me and again, really wanted Jupiter to meet her pointer. They sniffed and everything seemed fine... but then Jupiter kind of jumped up on the pointer's back (I've seen him do this wrestling before) and then started growling, barking and pulling on the leash (prong collar). He seemed pretty agitated, although there were no hackles.
It seems a shame that he's just developed this leash aggression, whereas before he'd been fairly well-behaved. The standard advice seems to get his attention before he has a chance to stare/lunge, but is there anything else that might correct this in a more "natural" way?