EPSMor PSSM - "tying up syndrome"

Ryan · Active Member Joined: 10 Jan 2005 Posts: 321

Does anyone know which bloodlines maybe linked to this diesease Equine Polysaccharide Storage Myopathy or (PSSM/EPSM) I have heard up to 4 possible bloodlines in QH's are. Anyone know which lines?
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Ryan

one okie gal · Posted: Tue Feb 26, 2008 6:50 am Post subject:

Ryan,
PSSM isn't restricted only to quarterhorses. I checked the University of Minnesota web-site and there is probably more information available on their site. I did not see anything where they were identifying particular QH that were carriers.

Evidently there are two types and depending on the breed of the horse they have different ways on diagnosing. It is suspected that this mutation occurred before the modern breeds were established, hence its appearance in quite a number of breeds. They do acknowledge that there MAY be a familial pattern, but don't identify the family. QH, paint and appy & xbreds thereof appear to have the same test. Looks like this one is going to probably include some foundation folks.

Looks like they have a genetic test for type 1 and it is a dominant trait and not a recessive, so an inheritance pattern like HYPP as opposed to the inheritance pattern of HERDA. (This mutation is not related to the other two mutations just mentioned, just mentioned as example of how they pass to offspring.)

They have a huge list of publications for more information. Also, they list Dr. McCue's number and looks like they are trying to find subjects for more research.

Good Luck and please post anything pertinent that you find regarding this syndrome.

one okie gal · Posted: Tue Feb 26, 2008 9:24 am Post subject:

also, check out Purdue University newsletter from winter 2000. It has some good info so far as symptoms.

one okie gal · Posted: Tue Feb 26, 2008 9:36 am Post subject:

I still don't know identities, but here is a link to some work done at UC Davis and University of Minnesota that lists Stallions A, B & C, as well as some percentages that they came up with. Looks like their sample of horses they worked with was 23 horses, not all QH.

http://www.ncbi.nlm.nih.gov/pubmed/8669756?dopt=Abstract

danwilson · Posted: Sat Mar 01, 2008 10:24 am Post subject:

Taken from the Minnesota study, hope it helps.

"Researchers with the University of Minnesota have identified polysaccharide storage myopathy (PSSM) in 6-12% of overtly healthy Quarter Horses on six farms involved in a new study. They also said the disease could be more common within certain breeding populations.

The study, published in the Sept. 1 edition of the Journal of the American Veterinary Medical Association, explores one of many new findings concerning the disease, according to Molly McCue, DVM, MS, PhD, Dipl. ACVIM.

The disease stems from a genetic abnormality in muscle cell metabolism that leads to exertional rhabdomyolysis (tying-up). Horses with PSSM make and metabolize glycogen abnormally. This glycogen can build up in muscle, and when it cannot be burned as fuel it causes cramping and pain. There is no cure for the disease, but management changes, including elimination or reduction of concentrated feeds containing high levels of starch and sugar, and increasing exercise and turnout (such as keeping the horse on pasture), can minimize clinical signs.

Along with exploring PSSM in Quarter Horses, the researchers have also identified the genetic defect responsible for the disease, and they hope to have a genetic test commercially available within the next six months. They have also investigated the heritability of PSSM, which previous studies have shown is also common in draft horses and Warmbloods.

"We have identified the genetic defect that accounts for a large percent of PSSM cases in several breeds," McCue said. "PSSM is inherited in a dominant fashion. A horse with one copy of the mutant gene will have PSSM and pass PSSM on to its offspring 50% of the time. A horse with two copies of the mutant gene will have PSSM and will pass PSSM on to its offspring 100% of the time." "

It appears having the mutant gene has a fairly high chance of impacting multiple lines, but does not mean the trait will always be evident as their are many enviornmental factors influencing exhibition. Genetically the horse with a dominant gene (received the from both dam and sire) will always pass the gene on to offspring and if they are a recessive carrier 50% chance. Its been awhile since I thought about Mendel and his poppies.

one okie gal · Posted: Sun Mar 02, 2008 12:37 am Post subject:

Did Mendel have poppies? Don't know why but I thought it was peas. Oh, well, at least we have the idea and lots of folks with the bent for it are studying it. I think genetic testing is going to be the breeders handy tool of the future, and especially since they mapped the horse genome at UKY.

From what I gathered they are now thinking that HERDA may quite well be "more than skin deep", and that certain other genetic mis-steps are walking hand in hand with it, but not sure yet that these other things are because of the HERDA or if they are just other items that followed down some of these same lines. Not exactly the kind of jackpot that one would like to have.

How's the filly doing?

danwilson · Posted: Sun Mar 02, 2008 7:55 pm Post subject: one okie gal

Just read the string on "Do HYPP N/N horses get the AQHA World Titles? Please Share." The reader knowledge on this board is astute (in deference to horsetrainer89 dont want to use "impressive") and I am humbled. Your right, it was peas, glad I ended up in finance. The filly is improving, thanks for asking.