FAQ for Newcomers!
What are symptoms of PSSM?
Symptoms of PSSM are often basic horse behaviors - the difference with a PSSM horse is they do them predictably and consistenlly. Examples would be biting at the cinch/girth, getting antsy when tightening the cinch/girth, throwing the head up when tightening the cinch/girth. All of these behaviours can easily be the result of poor saddling technique, poor saddle fit, and learned habits from old BUT with a PSSM horse you can try on saddles til the cows come home and you will see little improvement.
Other Symptoms include intermittent lameness, difficulty holding up back feet for the farrier, a Jekyl and Hyde type of personality (perfect one day and nasty the next) bucking, trouble holding leads, crossfiring, acting colicky and many more. Again many of these are common horse behaviours, but a warning bell should go off if you can't train them out of it and there seems to be no real reason for the behavior.
How is it dignosed?
There are genetic tests available to confirm or deny your suspicions. You can pull hair and test for P1 and PSSM2 variants: P2, P3, P4, P8, and K1 - the P2-K1 tests are not peer reviewed and there are a lot of people who discount the results of those tests but there are an overwhelming number of people who have had the PSSM2 variant tests and have found the answers they needed to help their horse based on the test results. Some people prefer muscle biopsies but muscle biopsies cannot give a definitive answer other than saying what is seen in the muscle at the time of biopsy. Some have been diagnosed as having PSSM2 via a muscle biopsy and then a couple months later with a new biopsy been declared not to have PSSM2.
There are other genetic conditions (testable via hair sample) other than PSSM that can cause similar symptoms - these include MH, IMM, RER (tested as PX as an indicator) and even HYPP. All of the above (including PSSM) are what are known as dominant defects and only need one copy from one parent to exhibit symptoms. In most cases a double positive horse will have more severe symptoms.
Could my 8 year old horse have PSSM? He has never shown any signs before hand.
Yes, Most definitely. Especially the PSSM2 variants and RER which often only show symptoms after 6 years old.
How can I decide what to test for?
IF you are planning to breed, test for everything unless both parents are nn for any particular issue, that issue you do not need to test for.
IF you are wondering about symptoms your horse is having, start with the pedigree. More and more info is coming to light every day. If there is PSSM or something else in your horse's background then test for that issue. With pedigree analysis you can often rule out many things and target your testing so you are not wasting smoney on test you don't need. eg. Should you 5 panel test your horse? IF breeding yes. If just trying to diagnose - then HERDA and GBED are not an issue as the symptoms for HERDA are very obvious and double positive GBED foals don't live. One copy of HERDA or GBED does not affect the horse. MH and HYPP bloodlines are known so can be ruled out via pedigree analysis. So instead of spending over $80 you can spend $40 and just test for PSSM1.
What can I do once I know my results?
My best recommendation is the facebook group called PSSM FORUM. You will find very good advice from people who have horses with these variants and what has worked for treating them. Often vets are behind on this information. If your vet is knowledgable, by all means be thankful and follow his advice!