So I’m looking at a lovely horse with pssm. It is managed by his owners and he’s in full work/showing. What are people’s thoughts on purchasing a horse with pssm if it’s manageable?
What’s his age?
“Managed” at 8 is a no thanks.
Managed at 18 and I’m ok with it
Is he hetero or homozygous? Type 1 or 2?
He’s 12. Can you educate me on the hetero homozygous - type 1 or 2? These are questions I need to ask the. seller (:
Hetero means one gene for an issue. Homozygous means two. If it’s a dominant trait you get effects with one gene and possibly stronger effects with two.
A Palomino is heterozygous for the creme gene. A cremello is Homozygous.
For HYPP, symptoms are way worse for Homozygous compared to heterozygous. I don’t know a lot about PSSM.
PSSM 1 has a definite test and treatment protocol. PSSM 2 has no accepted test yet.
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Definitely find out if it’s type 1 or type 2 and how was the diagnosis made- blood/hair or muscle biopsy. What is the current owner doing to manage the condition? What is the horses current diet and is that something you’re able to continue? What is your turnout situation like, will you be able to keep the horse turned out for at least 8-10 hours or will it mostly be stalled?
I have a horse with moderate type 2 PSSM and it’s very well controlled with diet, exercise and turnout. If you can replicate what the current owners are doing to manage the condition then I would consider it.
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I would never take a horse with pssm. Never ever again. I had a paint on lease- beautiful and sweet mare. She rode perfectly and was the most calm/laid back horse you would meet. But something was off. She was thin. I was feeding peanut hay which was similar to alfalfa, and grain, and a cup of oil a day. Still was barely gaining weight. I thought it must be ulcers and started treating for that without any change. She would feel depressed when ridden, to the point I would get off due to concern something was wrong. She had some minor colic like episodes - a short ride in the trailer and she would be back to normal. Then one day she tied up badly, just out in the paddock. Her owner took her back without getting her checked by the vet and was talking about breeding her. I would guess that was type 1 because it didn’t match the symptoms of type 2. But she tied up so badly she looked like she was going to fall over dead. Could not walk- uncoordinated, severely tucked up abdomen with muscle spasms. The only other time I saw a horse look that sick was an impaction colic requiring euthanasia.
My paint is suspected pssm type 2. She’s only asymptomatic if you can ride her every day for 2 hours… She has never been able to canter without swapping leads behind and has been this way since age 2. I’m sure some people would euthanize, but she’s a total sweetheart and she will be with me for life. Unlike the above horse, she doesn’t tie up while out in the pasture and she is pain free - it’s more like a mechanical lameness. She has only tied up 3 times in 14 years and that was when she finally was diagnosed. It was assumed by the 3 vets that looked at her originally that she had lameness issues that they could not diagnose. They suggested a nuclear bone scan but I didn’t see any point in further diagnostics. Only much later, did the puzzle pieces start fitting together - she gets sounder the more you work her. But always somewhat off behind.
She is perfectly happy as a trail horse, but I have to either commit to keeping her fit, or not ride her at all. She also does poorly in hot temperatures - exercise intolerant. And when she does tie up- she goes down dramatically. It looks like colic, but about 15 minutes later, it passes and she’s bright eyed and chipper again. And the last thing you want to do is be out in the middle of nowhere with your horse on the ground. Terrifying to watch until I realized what it was. I had emergency dialed the vet but they were in the middle of colic surgery and couldn’t come. By the time we walked back to the trailer- she was clinically fine again. Every episode has lasted approximately 15 minutes.
In the summer, she crawls along at the slowest walk possible - definitely more symptomatic in summer. It’s possible this will get worse as she gets older.
I would not take a pssm horse for free - it’s a serious defect and the horse is never going to be healthy.
It will break my heart if I have to retire my paint mare- she’s a lovely trail horse and I have had so much fun with her, but now I worry every time I go out that she might tie up. Especially with it being hot for 7 months of the year. Cooler weather comes and she feels better.
She is absolutely stunningly beautiful - great conformation and beautiful markings. I don’t blame the breeder- they didn’t ride their horses and didn’t know.
You also need to know his exact current management. A 12yo who is in solid work without issues doesn’t bother me nearly as much as if he were 5, or 12 but is a light trail horse and you want more work out of him.
The hetero/homo has been addressed. Pass if he’s homozygous.
So really you need more details if you love everything about what you know about him so far.
What exactly is his diet
Type 1 or 2
What was the test
What is his workload - not just “we ride 5 days a week”, that’s frequency, not load. What does a week’s worth of rides look like, and is he consistently ridden.
If you want to do to substantially more work than he’s been doing for the past couple years, pass.
If you want to do substantially LESS work in the frequency area, pass - these horses don’t do well sitting around and then being pulled out for some work.
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Another thing to add to the decision process - are you able to keep this horse if the PSSM thing makes it not work for what you want it for?
I realize that any horse can become unsound for use at any time. But when you (general you) are in a situation where you board and can only afford one horse at a time, best to start with a horse that is less likely to have a problem. If you have your own place and having a horse around that does not have a job is no issue then heck… go for it.
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I have a suspected PSSM2.
If I were buying a horse again, and knew it had PSSM (either type), I’d pass. Managing the disease is very difficult.
I also had a PSSM Paint. He was adorable and had a lovely temperament. He’d been shown in halter and longe line futurities as a yearling and had exhibited symptoms… but this was kept from me, which I why I ultimately was able to send him back and get a full refund.
When I started my colt under saddle, the tying up and paralysis-like episodes were both startling and unpredictable. My vet did the biopsies and I followed all the dietary and exercise protocols. Yet that didn’t stop the episodes 100%. I was nervous about schooling too long or too hard in the arena for fear he’d tie up. Then I stopped trail rides for fear he’d have an episode and I’d be stranded in the middle of nowhere. He was a gorgeous, sweet guy but I’m just not cut out to deal with that type of issue.
While I know care and management of PSSM horses has undoubtedly improved since I had my colt, I still would not knowingly take one on.
I own a N/P1, carries one copy of PSSM1, from his dam, did not know he had it, was told he was 5 panel clear, my bad for taking someone’s word for it, rather than seeing the test results.
I love this horse unreasonably, in the first unsymptomatic months he was everything I wanted, then things went down hill, and it feels like we are now in a constant battle to stay ahead of his condition.
I would NEVER knowingly buy another carrier, the roller coaster is just so hard. It’s a fickle ever changing condition, some horses just seem to sail on through life with no issues. Some have scary episodes, mine is just a constant always a little something…
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I would not knowingly buy one unless it was…
- Properly diagnosed (hair test or muscle biopsy for type 1, muscle biopsy for type 2)
- Well maintained with a performance record tantamount to what I planned to do and a management/feed routine I could easily mimic
- I could afford to lose the purchase price and retire/rehome the horse for peanuts if it didn’t work out for me
So I would buy one under EXTREMELY limited circumstances.
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Muscle biopsy is an accepted test for type 2. You might have meant no accepted hair/blood test, which is correct, but muscle biopsy is a pretty definative way to diagnose type 2.
Just adding some info for completeness - unfortunately you can’t muscle test for an asymptomatic but positive horse. Yet, anyway. The biopsy is conclusive when there are muscle changes to be seen, which means they’re symptomatic (even if just mild)
I know what you meant, I just didn’t want anyone to think they could muscle test a 2yo who isn’t symptomatic 
Yes, sorry, that is correct and a good clarification. Biopsy cannot predict whether a horse is an asymptomatic carrier but can explain why a symptomatic horse is having symptoms.
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This is SUPER helpful - Thank you!
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I just bought my friend’s horse who has Type 1 PSSM. He’s an older draft cross who is in full work (4-5 rides a week) and is a first field foxhunter. We discovered he had it last year when he tied up badly and had the testing done. He’s been well managed with diet, vitamin E supplement, and specific/controlled exercise for the last year without any reoccurrence (hunted all last season for 3+ hrs). If the horse is managed and going and do the job you want right now I wouldn’t necessarily pass. That said I think Type 2 is 'nother ball of wax: My friend’s horse has Type 2 PSSM and he was never right and/or consistently rideable.
I have a 23 year old horse with PSSM who. I have managed for the last 15+ years. It did take time (several up/down years) to figure out what he needed to stay active and symptom free, but we have had very few episodes over the last ten years. I found one of the hardest parts was learning to do the opposite of what one might do with a non PSSM horse - for example if your horse is not quite right you might do a lighter ride or cut it short, but mine needs to be worked to clear the stored glycogen.
I got lucky in that most of my management was already what he needed when he got diagnosed. The variants weren’t recognized at the time so I never did get him tested. I will say that his required management requires extra diligence when selecting a new barn because there are some compromises that simply can’t be made.
Having the experience, if the horse’s management was something I could continue and the horse’s workload was similar to what I would do I would buy the horse.
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I’m glad you brought this up, because it speaks so directly to actually understanding as much as you possibly can about the disease. It’s not simply about “feed this way”. It’s also (in the case of type 1) likely blanketing heavier and/or earlier than a “normal” horse, it’s about exercise consistency being paramount (whatever it has to look like on a given day), etc.
I wouldn’t take a well-managed PSSM1 horse who’s on full turnout and put him in a 12/12 in/out (let alone more hours in) situation
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You’re spot on. I manage him a bit differently. He wears heavier blankets in winter, always in a quarter sheet, I hack him out before we start hunting so everything is warmed up before we start, use BOT sheets, etc. When we hunt I ride 4, 5 times that week and then he always goes for an hour hack the day after hunting. That proved very successful for him. If we travel to hunt, I make sure I can get turnout for him overnight or we don’t go. Movement is the key for these horses and it seems counterintuitive when I think of how I handle my non-PSSM horse. Before I got him and he was coming back from a bad tie up, it was great he went out with my horse who herds him around some. Forced movement.
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