I'll warn you that it's a little unnerving to watch, but it's also obvious that the dog is not in pain and perfectly happy.
Miss Ruby has only had one episode, which scared us half to death, but she's never had another and seems none the worse for her experience. Some dogs have a more acute form than others - a few can collapse just from excitement without much exertion or heat. But that's the exception not the rule.
They've seen it in other retrievers, but most cases are in high-bred, high-strung field Labs. They think the gene is VERY common, but if the dogs are not pushed to the limit they never have an attack, so your average couch potato retriever is not going to be doing repetitive 200 yard blinds in hot weather with multiple whistle stops and collar corrections. That's generally what brings it on.
Yes, I saw your explanation. I guess I had not heard it referred to by the initials and my brain was too lazy to decipher! I had one golden who collapsed one day, chasing a ball in the hot E TX sun. I wasn’t there, my son was, he called his dad and was told to hose her until she got better. By the time I got home she was fine. I *think* it was heat stroke (she is a ball fanatic and will not stop and my son didn’t know she would keep going no matter what).
Later, when I first heard about that, I wondered if it was something like that instead of heat stroke, but she’s never had another episode. Then again, she is an indoor couch potato. FWIW she was never bred.