OregonBR - 2014-01-07 4:37 PM To increase the educational value of this thread.  There was a comment made about MH.  I wasn't totally sure but thought it was a dominant rather than a recessive so I looked it up.  It is dominant. It only requires one parent to be a carrier/affected to have a 50% chance to be a carrier/affected horse. 

 







Description

Malignant hyperthermia (MH) was initially recognized as a fatal syndrome in humans, and the term describing its occurrence in swine is known as porcine stress syndrome. MH is most prevalent in swine but this syndrome has also been reported in dogs (especially Greyhounds), cats and horses. In horses MH thought to be confined to Quarter Horses and members of related breeds such as Appaloosas and Paints. Less than 1% of Quarter Horses are affected, and those that are seem to trace to two specific bloodlines. The genetic disorder suggested to be an autosomal dominant trait.

MH is a potentially fatal disease of that could be triggered by factors that may include exercise, stress, breeding, illnesses, and concurrent myopathies. An additional genetic mutation in RYR1 gene (MH) influences PSSM and can increase the severity of the symptoms of PSSM in Quarter Horses and related breeds. The combination of PSSM and MH genetic tests are available at Animal Genetics.





 Wish I knew which 2 bloodlines it traces to. 

appycowgirl - 2014-01-08 4:30 AM

You were wondering about the 2 lines for Malignant Hyperthermia. The one research paper that I had read stated that they found it in a subset of bloodlines that they were researching. In Dr Molly McCue's 199 pagged dissertation she had outlined the bloodlines Eddie Cinco, another one with the initials of SDB who we believe to be Sonny Dee Bar, and another horse with the initials of PI who we believe to be Pretty Impressive.
Now, I have seen the pedigree of 4 horses that have tested to be MH positive. The one stallion's pedigree that I saw he was MH positive but PSSM1 negative and he traced back to Eddie 60. I'm not at liberty to reveal his name but his dam's name is Dry Fork Hancock.
The other three that I have seen that are MH positive along with being PSSM N/P1 are Oliver Sensation, Champagneinhollywood and Patch The Buck. All three of these horses trace back to Eddie Red Rose. Eddie Red Rose is sired by Eddie Cinco.

Now, Eddie Cinco and Eddie 60 are full brothers as they are both sired by Eddie and their dam is Miss Ogallala. Now, when they did the pedigree mapping they pointed an arrow at the mare, Miss Ogalla and in their explanantions they explain that were they put the arrow at, it was based upon eye witness accounts of the animal and that they believe that this animal was the source because of those accounts.

Personally, I would tell anyone, if you see the mare, Miss Ogallala in your horses pedigree, you better be testing.

All of these horses are on All Breed Pedigrees database so you can research their bloodlines. I just have trouble posting links to these horses with using my phone.