Hello

I have a 6 yr old belgian who gets muscle tremors in the fore-quarters with exertion in the spring as we begin field work. It doesen't take much to exertion to see this. No heavy breathing or blowing. He has had this for a couple of years, and it goes away later in the season, seeming to only appear in the spring. Last year he did this while we were trimming his feet, those muscles over his shoulders wer "flapping". He looks anxious when it happens. I was suspecting EPSM. Any way after i saw this I had the vet out right after an episode, and we drew lab for muscle enzymes (cpk, sgot, etc) which were all normal.

I was wondering if this could be equine 'grass tetany' which comes from hypomagnesium when animals get on fresh grass in the spring. Or could it just be simple lack of conditioning.

How should i proceed. BTY I have an older mare with EPSM, Ruby, so I know what it looks like.

wally

Wally, this sounds very much like EPSM to me. There is quite a range of things you can see in a horse, especially a draft, with EPSM. They can be very different, although in the end we can relate them all to muscle issues. And, most drafts with EPSM have normal muscle enzymes, although occasionally the CK (CPK) will be slightly over 350 and/or the AST (SGOT) can be over 420. There is a genetic test at Minnesota now that identifies some (but not all) EPSM horses (they call it PSSM, but it is the same thing.
http://www.cvm.umn.edu/umec/lab/Advances_in_PSSM/home.html

Easy ienough to do from pulled mane or tail hairs so you might want to try it. Otherwise, I would definitely be feeding him the same way you are feeding Ruby.