This is Boyboy's behavior when we accessed him yesterday, he was extremely fearful and aggressive.
After discussion, we learned that Boyboy was so aggressive because of the ex trainer recommending choke chains to his family, who had just gotten their first dog and thought that it would benefit his growth to consult a trainer. Not soon after, Boyboy started to choke and even vomited, the trainer then said that it was perfectly normal for dogs to vomit while on the tool. Having doubts, Boyboy's owner stopped the course. But it was too late, he started getting very aggressive especially when the neck area is touched, then not long after he used the same aggression on every other things that he was afraid of, which led to paws, tail and ears.
Boyboy had stayed with us for regular boarding previously and we managed to just work on his aggression towards paws. Now he is here for the full program and we will do our best to eliminate all other issues.
I am not saying that choke chains are bad, but it should never be applied to every single dog going for basic lessons, choke chains in my opinion are NOT suitable for small dogs and puppies.
"If a tool doesn't work, don't blame the tool, blame the user."
Many schools in Singapore are still continuing to enforce choke chains in their basic obedience program no matter the size of dog or behavior they possess. I have personally seen countless dogs becoming aggressive because of this, many had also developed trachea issues. If you do encounter such trainers, leave before it's too late.