@summersolstice43
Just a bit of context, he pulls while wagging his tail, gets nose to nose with the other dogs and is fine, no negative behaviour at all until today. Hes always been good with other dogs but today has worried me and he won't be going for walks near other dogs anytime soon unless its unavoidable like it was today.
I appreciate all advice. Ive looked at videos on muzzle training which looks easy enough. Ive also enquired about behaviourist but at £80 a session it seems a bit expensive. Not sure if that's the average price?
I wonder if it was just this dog he took a dislike to. Sometimes you do just get a personality clash for no good reason.
I've got a reactive terrier (main triggers aren't dogs, thankfully) and while he is lovely with most dogs, he has a pathological hatred of two very specific breeds, and one specific individual dog in the local park (who is lovely, and doesn't deserve it!). He also has a tendency to be a bit of a git on lead, so I avoid on lead greetings. 99% of the time when we're in the park he's off lead, but if we spot one of his least favourite breeds or individuals we give them a wide berth or he goes on a lead if they're too close for comfort.
Thankfully most of it involves him standing a metre or so from the other dog and barking (probably shouting "come and have a go if you think you're hard enough") at a dog four times bigger than he is (cos he's well 'ard). On the few occasions he's got into a scrap it's been all noise and no damage, which is like 99% of dog fights tbh. Handbags at dawn you might say.
If it is just one dog or dog breed he hates (and the jury should still be out on that one) then I wouldn't be condemning him to a life on lead and muzzled.
There is such a concept as a frustrated greeter - basically they're so keen to get to the other dog to say hello that they get frustrated when they can't because of the lead. The way they deal with the frustration is to start kicking off...
You'd do well to watch some YouTube videos on dog body language - starting with the canine ladder of aggression by Talk to the Paw.
£80 a session is very cheap for a qualified behaviourist. Unfortunately literally anyone can call themselves a behaviourist, so it's important to go for an APBC, CCAB or ABTC qualified one. It's also worth knowing that there's a big difference between a trainer and a behaviourist, and this is a behaviourist issue. You will need to get a vet referral for the behaviourist - and it's a big red flag if they don't ask for one.