I own a 17 year old QH cross and we do mostly 1st level dressage. He came to me about 8 years ago with some mild arthritic changes to his right hock that as of last year, had not progressed. He’s on 2x/yr Adequan IM loading dose injections as well as MSM and SmartFlex Rehab pellets by SmartPak. He and I both had health challenges in 2017 … he was turning up a bit lame, off and on, in his right front during 2016. After a series nerve blocks didn’t tell us much, I opted to do an MRI in January 2017 of his right front. He had some areas of degenerative joint disease and we opted to do 6 months of stall rest to start out. At the 6 month mark, the veterinarian was really pleased with his progress and we came to a plan that the horse could lightly return to work and we would evaluate how it went. We did some very light work and in one of the rides, at the trot to the left, he stumbled and fell all the way to the ground and rolled to his right side when on the ground. Thankfully, he’s a saint and while he did roll on me, he quietly and calmly stood up while I dusted myself off. I got back on and he seemed fine. No swelling or soreness following in the next few days. Unfortunately, about the time we were lightly starting back to work, I ended up needing emergency back surgery, requiring 1 year recovery (but I got my surgeon to agree to let me ride at 6 months). Now, my horse and I are both on track to start work again. We’ve been doing some very light rides intermittently. Yesterday, we had a more traditional ride with walk/trot/canter, shoulder in, leg yields, etc. It went really well, neither of us were visibly sore and I think we both enjoyed having purpose again to our ride. Today, I was about done riding and at the canter, traveling left, he suddenly stumbled and fell to the ground. Again, he landed on his side and while I’m not entirely certain of what happened, as all I remember is him suddenly falling and me pitching my reins away in hopes he could find his balance. We ended up with him laying on his left side and me slightly under him. I am again thankful for his mind as he was rattled but chose to remain calm and stood up quietly. He was not visibly sore after. I got on and got all 3 gaits, both directions without issue. He has had bouts of what I call “falling out behind” … almost like he has stepped in a hole. I attribute this to weak stifles from not being worked for a year. But now the falling all the way down twice in a year has me concerned for him and for me. I have a call into my veterinarian to see what is going on but was curious if anyone else has been or known of a similar circumstance. When I look up why horses could fall down while being ridden, more often times than not, I’m presented with diagnosis of neurological problems. Would those issues suddenly arise at 17 years of age? Or, is this just a case of rider error … I asked for too much work on weak stifles? Any thoughts or ideas are welcomed and appreciated!
If it was me, I’d be doing some free longe work in a contained area not only
to help get him back into shape, but to see if I could spot what’s actually occurring. But personally, if I had a horse fall on me more than once I’d give very serious thought to retiring him. You get one back and one head. A horse can be substituted.
My old guy fell at the canter on top of me three years ago. He also had been having some arthritic changes. We were both hurt pretty good in the fall - though he was definitely worse off. He was pretty lame for some time.
One of the things the vet thought contributed to the problem was his eyesight. This was how I found out he was mostly blind in one eye.
My old buddy is moving about a lot better now, and looked sound enough for light work last year, I’m just not sure it is safe enough to risk.
With a surgically repaired back, I don’t think riding this horse is a risk worth taking right now. (Actually not worth taking at all)
Unless you can get a diagnosis and effective treatment from the vet, I would consider the horse unrideable.
I hate to mention the “N” word (“neurological”, folks 
), but, since you are already thinking of it, I can agree. My horse, Waldo, began tripping badly, and for no reason. He never went down, but he would go to his knees and I would go off.
At the necropsy (several years later, when he became a danger to himself and others), the pathologist found that every cervical vertebrae was abnormal.
If you want to pursue it, maybe get x-rays of his neck. Your horse has no proprioception anymore, and that is usually a neuro problem. The signals from his brain are not reaching his legs. No bone or soft tissue problem would cause that response.
I am so very sorry that you and he are going through this. 
I’m also with MsM. Sure sounds like you love riding him and he loves have a job but IMO, I wouldn’t be riding him given your back surgery and his history of falling (since he’s done it more than once). Not saying not to ride, just may not him at the moment.
He needs to be diagnosed to understand why he keeps falling and deciding if you want to treat or not and continue to risk your back.
Such a tough dilemma for sure. I’d also concur on looking at a possible neuro cause.
Agree re neuro - cervical arthritis. And it doesn’t show up suddenly, really; its been brewing. and now he’s back to doing some work, more obvious. The stifle feeling may not be a weak stifle, it may be nerve pinching. My TB had C. arthritis; he was rideable for a while after injections, but then the stifle reared its head. First in corners, then more often. He did not do it when lunged, untacked, in the round pen. Weight on his back seemed the trigger.
Get a vet who can do a neuro exam - they aren’t invasive or complicated - and hopefully vet can shoot some pics of his neck.
Dont be putting yourself at risk…
For your own safety, I would strongly recommend not riding this horse. He has done his darndest to not hurt you when he fell, but there would appear to be a severe medical problem since this has happened twice now. I suspect whatever medical findings there are will result in a diagnosis of no more riding. I am sorry you are in this position… Big hugs for you both.
A friend recently had to put down a young horse with cervical deformities causing extreme hind end weakness (vets didn’t agree exactly which ones were causing the problem but nonetheless there was no treatment option). She had only had the horse 1-2 months, but when put in regular work the hind end weakness started… I still feel horrible for her.
yes, a neurologic issue can come on over time.
VERY very much of concern that he has fallen, so sorry for you and him, but he is a safety risk to himself and to you.
Besides checking his neck/back, someone I knew whose horse fell a few times (twice while riding) ended up positive for PSSM and was so compromised by it I think she retired him.
It is not usual for a horse to stumble and end up on its side. It has happened twice. I wouldn’t risk a third.
Sounds neurological. And highly dangerous, I would NOT ride this horse. You need to find out what is wrong, for your safety and his
Thank you all for your thoughts and sharing experiences. Super helpful and a lot to think about/research. Especially the comment about the weight of a rider triggering the issue. While he’s cross fired and “fallen out behind” on the lunge a few times, he’s never fallen to the ground outside of the two times with me in the saddle. We have an appointment scheduled with the veterinarian/surgeon who has overseen his care for the past few years. We will put riding on hold for now and go back to groundwork to give us both a job to do together until we figure out what’s going on. If my horse needs to be retired, I’ll be greatly disappointed because he’s such a joy to ride and tries his absolute hardest for me. But, even without the riding, he’s my buddy and will always have a home with me.
I am puzzled why someone would ever again think of riding a horse who has fallen completely down and on top of you? You were very fortunate both times you were not crushed and now that you have had back surgery? Retire him from riding and keep watch for stumbles while walking because you could also be looking at a disease progression as well as arthritic changes.
be careful when you are doing groundwork with him. If he were to have a “falling out” while you are leading him he could fall on you. My boy started having very similar symptoms to your boy on the lunge about 2 months ago. We stopped riding him immediately and he was diagnosed as neurologic, most likely cervical arthritis by my vet a month ago. He is worse now than he was a month ago. His walk is still fine, but my concern is that if he were to spook at something, that his legs would go out and he would fall on me. In fact, he did spook last night, and he pulled back. I’m not sure if he pulled back or his hind end went out making him LOOK like he was pulling back. He has NEVER done that maneuver before. So, PLEASE, be very careful on the ground, wear a helmet, and keep a few feet away from him. be safe.
What’s your footing been like in these two situations?
I’ve had horses fall with me in the canter several times (never the same horse, never the same place), and footing has always been a contributing factor. Particularly when arena footing starts to get a bit thin in just that spot and no one noticed, and horse slips on hard base hiding underneath. Hoping it’s something as simple as this for you.
Also my immediate thought was footing. I have seen many a horse go down from bad footing in an arena. Usually they face plant but sometimes go down sideways, and for a horse who isn’t as fit I could see him stepping wrong with one foot and going down sideways.
Have you tried backing him up? Other neuro tests are subjective; experienced horse people or vets can tell if he is mildly or grossly abnormal. But the backing up test is easy to see.
In order to back up, the signals from the brain need to reach all 4 legs. A horse who is neurologically compromised will not be able to back up correctly.
I have, over many years, had 2 neuro horses. I am now requesting that the ‘backing up’ test be part of PPE’s.
