Can anyone please tell me what lines are carriers for any of the diseases on the 5 Panel test as well as PSSM2.
Am looking at purchasing a new horse, but am not as familiar w/ the all around bloodlines & I can’t seem to get anyone to tell me what lines are involved in most of these mutations. Will not necessarily nix the purchase, but will definately make the 5 panel part of the prepurchase (particular horse has not been tested).
I know about impressive & poco bueno. What are the others?
Some of the affected bloodlines are so prevalent in the stock horse breeds that they could pop up almost anywhere. On the other hand, not all descendants carry the problem genes, so they might not exist in certain lines that trace back.
Impressive is cited as the foundational source of HYPP, Poco Bueno for HERDA. But the PSSM varieties are more widely spread and not specific to QH.
I think my decision on a horse being an asymptomatic carrier would be different if it’s a gelding versus a mare that could potentially breed.
As Scribbler said, most of the five-panel (really six-panel at this point) genetic diseases aren’t limited to certain lines at this point. Certain diseases ARE more common in purpose-bred horses.
Info taken from UC Davis’ website.
-HYPP (traced back to Impressive) 1 or 2 copies will both affect the horse (2 worse than 1). Think this was more common in halter horses.
-HERDA (traced back to Poco Bueno) Needs 2 copies to be affected (1 copy = carrier). Metallic Cat (very popular cutting/cow horse sire) is n/HERDA so check any of his decedents.
-MYHM. 1 or 2 copies will both affect the horse (2 worse than 1).
-GBED (traced back to King-P234) 8-11% of QH population has. Highest percent in western pleasure and cutting. Needs 2 copies to be affected (1 copy = carrier).
-MYHM. Estimated that 4-7.5% of the QH population has at least one copy. More common in reining (13.5%), working cow (8.5%), halter (8%). 1 or 2 copies will both affect the horse (2 worse than 1).
-MH. 1 or 2 copies will both affect the horse (2 worse than 1). Not sure I’ve ever seen a horse affected with this.
-PSSM1. 1 or 2 copies will both affect the horse (2 worse than 1). General QH population has ~6-10%. More common in halter-bred QHs (28%) and least common in racing-bred QHs.
I don’t believe there’s a validated test for PSSM2 yet, but someone can correct me if I’m wrong. So it’s tricky to know which lines carry it.
Your best best is to ask if the horse has had a 5 panel done. If not ask about sire and dam’s panel. You can also check any registered horse on the AQHA website. Stallions are required to be tested now, so depending on the age of the horse you can at least know half the equation. Maybe even the dam sire too.
definately. I would require all neg if I was breeding, don’t know why that isn’t required for registration of any breeding stock, but that’s another can of worms. As long as the dominant ones were neg (HYPP, PSSM 1, & MH) I would be OK w/ the recessives being a carrier since this is a gelding
You are mostly correct. there is a test for PSSM 2, but it requires muscle biopsies. They have not figured out the genetics of it yet.
My current plan is to have the horse 5 panel tested as part of his prepurchase if we get that far. I just don’t know where the PSSM 2 tends to show up, so not sure how concerned I need to be with it. No one in their right mind would let me do a biopsy as part of a prepurchase…
HYPP is relatively prevalent in the WP and HUS world as well, as Impressive was a very good “using horse” as well as a winning Halter horse, so was also bred for horses to do more than just stand and look “pretty”
And yes, as that list implies, several diseases’ origins are either not known, or not outed
Actively affected horses can be IDd through proper muscle biopsy. BUT there is no credible to test to determine if an asymptomatic horse has the disease. EquiSeq is the only place doing hair testing for several variants, but there is zero credibility to their insistence that any positive horse actually has the disease, and not only that, there IS evidence, through Dr Valberg’s fairly extensive research, that there’s no correlation between ES’s testing, and confirmed positive (muscle biopsy) horses. ES is only potentially useful to try to narrow down which variant a symptomatic horse has to see if tailoring a diet to that variant helps
If you wanted to wade into the madness, you could join the PSSM2 group on FB to see if people (think they) know which lines are actually diseased (which is NOT the same as simply testing positive for P8, for example), but honestly I wouldn’t bother, it’s just a lot of fear mongering in that group.
IMHO, if the horse is older than 5/6, is in reasonable work, and is asymptomatic, that’s not high on my list of concerns
Unless he’s symptomatic, it’s a useless test anyway, the muscles have to have damage
Yes, Impressive was a leading sire of performance horses back in the day, so you’ll still find his name in the pedigrees of a lot of riding horses.
There is a top reiner that is Impressive-bred on the bottom, so its in lots of pedigrees. Current thought is that it descended from Impressive’s dam, Glamour Bars. There are half siblings to Impressive that have passed the disease down. Very rare, but still not exclusive to Impressive bred horses.
Related to this one maybe? https://www.allbreedpedigree.com/jesses+impression
Though I’m sure he isn’t the only Impressive bred reiner going. I’ve seen some really good Impressive bred barrel horses too at the local circuit.
I’ve never seen a vet recommend the 5 panel test on a prepurchase exam for a QH. Is the 5 panel recommended before purchase, if you don’t know the status of the stallion and damn? Or if the horse is a grade? Thanks!
I would say if you think the horse has stock horse blood, a 5 panel is a good idea since there is QH in Paints and Appaloosas too. If the horse is registered and parents are negative/negative then you are OK.
Thanks Scribbler! Have others had the 5panel done on a QH PPE?
No but I ran a HYPP test on my Paint mare after we had a single wierd muscle twitching episode. She came back negative so no idea what that was about. Knowing what I do now, I would in future if I was buying another stock horse.
No, but they weren’t a thing when I bought my last QH 25+ years ago if I recall. 
She’s 28 now, so I’m not too concerned about it.
It takes a while to get the results back, depending on your location. So it may be difficult to have one done as a condition of sale depending on how accommodating the seller is.
I definitely look up status of sire and dam on the AQHA site though. There was one gelding for sale I enquired about and asked the 5 panel status. Seller “couldn’t remember”. When I looked the horse up, both him and sire were positive for PSSM1.
That is smart!! What about an unregistered QH? What would you do?
I would want it even more on a grade horse. There might be a reason the horse is being listed as grade.
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