real examples of HYPP attack while being ridden?

So I am writing a speech on the whole HYPP controversy, and I keep coming across the same secondhand warning about the risk of an HYPP horse collapsing while being ridden and injuring/killing the rider. Does anyone have any examples of this actually happening to back this up?

Nope, I’ve ridden two. One was a school horse who had to be tacked while moving as a way to mitigate stress. The other was a paint that had terrible episodes in his stall around turn-in and feeding time. The hardest part was getting him up and on his feet.

I saw a halter horse lined up to enter his class start having what looked like mild seizures.
The handler turned him around and tried to take him back to the stables.
The horse was wobbling and shaking some as it kept trying to follow him.
Once away from the lineup, the handler had to stop and let the horse stabilize itself for a bit, before it could slowly and tentatively keep walking away.

You would have had time to get off if you had been riding him when that started.

I had a gelding who was N/H, so he didn’t have full blown episodes, but if you tried to make him stand still while you were mounted, he’d start with this weird jerky flinging leg twitch. And if you didn’t let him walk right that second, he’d rear pretty violently. Went over backwards once, and thankfully I only had a concussion. Flopped over on his side once, too, though he didn’t have trouble getting up. Also lots of third eyelid flashing, and the first trail ride or two in the spring, he’d be just a touch excited and make all these weird breathing noises.

So I’d say that he qualified as dangerous, though it seemed to be less of a complete physical loss of control, and more like his symptoms would make him panic and explode.

I did keep riding him, but I stopped showing so that whenever I needed to I could just let him walk it off.

Thanks guys! The more I’m reading about this the more it seems like these episodes aren’t as sudden as they’re made out to be. I guess learning is the point of writing about this stuff. Still definitely not pro-breeding N/H horses, but I’m glad I can take a more realistic stance. If you all have any other HYPP experiences that you think may be insightful, let me know.

Circa 1977 or so, had one colt, 2 or 3 yo, collapse on the hot walker. Went down pretty quick but we did not know at the time exactly what was wrong, just that some horses of that lineage had weird episodes, think this one was an own grandson of I with related lineage on the damside.

Few years later, maybe 82 or so, was showing at a Paint show in Oklahoma, one Jr WP colt (meaning the horse was under 4 years old) went down in a schooling ring and the guy on it was hurt, another trainer had to sub for him in the class. I didn’t see it but enough reputable people told me about it there’s no doubt it happened. Heard about a few others abruptly going down while being led or ridden from same type reputable witnesses so convinced it did happen. These were all young males with I very close up on the topside.

But that was 35 years ago. Used to see them occasionally with the siezures go down. Terrifying but handler/rider had time to get out of the way or off. Out of QHs for some time but friends still active haven’t mentioned it in years.

Certainly not in a BNB/Ts interest to share any such incidents. Back then it was more public and information was shared since the cause was not yet confirmed as genetic within a specific line. There’s no way of knowing what actually goes on at the home barn, no vet reporting system. Even at shows, they can keep things pretty hush hush when it’s a direct reflection on their breeding program, and income.

Just doubt there’s enough hard scientific evidence to base any meaningful conclusions on with no records available and a good bit of temptation to keep breeding that line for "The Look’ since that look has been the winner for decades.

IIRC, there are now additional steps in place with the registry to be sure it gets bred out whether some breeders like it or not.