PSSM Hair Test - Worth It?

Does the PSSM hair test tell you anything beyond a horse has markers that could be associated with being symptomatic? I see a lot of people talking about hair testing but my vet is pretty adamant that the only way to have answers is the muscle biopsy.

Does the muscle biopsy cover I and II?

Hair test for PSSM 1 ABSOLUTELY worth it. You will find out if your horse has the gene or not. I have had a muscle biopsy give inconclusive results.
Hair test for PSSM 2-well…I chose to have it done and was happy to have it come back negative.

Type 1, absolutely, it’s a credible, validated test. That doesn’t mean they WILL become symptomatic, though a P1/P1 horse is far more likely to be symptomatic, and with worse symptoms, than a n/P1 horse. If you have symptoms, it’s a good place to start.

But type 2? Zero credibility in any results meaning anything about becoming symptomatic. It may have value in looking at which type when there are symptoms which may help dial in the diet and exercise more appropriately.

Muscle biopsy only has value once there are symptoms, as its sole purpose is to look for changes in the muscle fibers, which are what’s causing the symptoms. You can’t use a biopsy as a predictor