Bichon beginning to be aggressive?

[cherrypieplum]

My younger sister has just returned from walking my two dogs and her dog and said that my bichon has bitten another dog!

I can't understand as he's really not an aggressive dog normally. A large dog went for him recently so could he be associating any new dog with a threat or could it be down to the introduction of a new dog into the house? Also the bichon tends to stay on the lead (he's not the best at listening) whereas the other two come off.

You've probably heard this before, but there's a lot of sense in it:
dogs are much more fearful and defensive if they're restained - and this might be even more so if they've had a bad experience.
If you're worried that your dog's fear-aggressive, then a muzzle is a safer and kinder way to try and safeguard against aggression than keeping the dog on lead, which is quite likely to contribute to your dog's insecurity/defensiveness, as it will make the dog feel disadvantaged and prevent it from interacting with other dogs.

Can you give any more detail about what actually happened? Was your dog charged at or cornered by the other dog?

And does your dog get to have regular off lead playing time with other dogs?

IMO, people can make a bit too much of the idea that their dog has become aggressive after a bad experience with another dog. Generally dogs get over this quicker than their owners do, and it can be that owners restraining their dogs because they think the dog must have become fear aggressive actually exacerbates the problem. I'm not saying you're doing this, just that it's best not to do it.

Also, does the dog get picked up and carried around other dogs? I know this happens to a lot of small dogs and it seems that this can mess up their communicating with other dogs so that they go quite snappy and moody.

He's always been on a harness and lead when out and about. He's never been great off the lead as he is quite impulsive.

He doesn't get picked up an awful lot epsecially around other dogs- he doesn't like being fussed in general. He does have play time with my other dog, my sister's dog and my in law's dog too.

I wasn't actually there during the incident but my sister took the three dogs out and had a natter with another owner. My dog began growling and then bit the other dog. My instinct would've been to take him out of the situation once he even began growling but there we are...

The incident where he was growled at was just us passing a larger dog and the other dog growling at mine. He's always been so soppy I'd hate for him to get nasty. He's been bitten/jumped on by others dogs befroe but we've never had a problem like this :(