I’ve never, ever heard of a breakaway dog collar. Cats are the ones jumping off stuff, squeezing through small spaces, climbing and having a much higher risk of strangulation via a caught collar. Dogs don’t typically do that, so their risk is very, very low.
I've never seen a breakaway on a dog. My trainer recommended a martingale, though two dogs now are "special" and were abused rescues that bite the shit out of me.
I haven't either, and I just did some searching and I'm not seeing vets saying you should use one. I'm seeing a lot of companies that sell them claiming that vets say that, but I'm not seeing it anywhere. I've had four dogs in my life and I've never been in a situation with any of them where a breakaway collar would be needed.
Someone above mentioned that boarding places want them sometimes. That seems reasonable. Less likely that the dog will escape and more likely it will hurt itself when there are no staff. I wish I could find a boarder that was staffed 24/7. There was a huge fire in Austin a while ago at a boarding place and every single animal perished.
That's what I do. She still wears the martingale and I suppose if she is being a dick I could hook up to that, but I have a nice 3 point harness with a handle so if she gets in to trouble I can just pick her up like a suitcase 🤣