I have another piece of the puzzle! I'm excited, even though it's about bad test results. It's a result and it (possibly) confirms what I've thought for years. (Why did I doubt? I think I needed proof, I was never really sure.) I stopped by the vet today and got a copy of Tonka's blood test results. I'm trying to think of how to relate this coherently.
Dr. Valentine, the vet who discovered EPSM, said that a blood test done 4-6 hours after exercise that shows elevated CK and AST is indicative of muscle damage and possibly EPSM. I was thinking, "Oh darn," because I didn't exercise Tonka before his blood test. But it turns out the AST is the only thing on his blood test that was abnormal. Anything over 420 is too high, and his was 577. Unfortunately the test we had done doesn't show CK. If I had done my research before doing bloodwork I would have had him do a test more geared toward EPSM.
Here is an explanation of what CK and AST are, and why they are indicative of a problem (note that this college calls the disease PSSM, not EPSM, but we're talking about the same thing):
"Two muscle proteins often used as a measure of muscle damage include creatine kinase (CK) and aspartate transaminase (AST). When muscle cells are damaged, they release these proteins into the bloodstream within hours. A blood sample taken to measure these proteins can determine how much muscle damage has occurred. This is not a specific test for PSSM as the presence of CK and AST in the blood occurs with any muscle damage. With many forms of tying-up, blood CK activity returns to normal within days if horses are rested. It is very common for horses with PSSM to have high CK activities even if they are rested for weeks after an episode of tying-up." Quoted from http://www.cvm.umn.edu/umec/lab/PSSM/
I sent in Tonka's DNA for testing today. This test is easy, using just hairs pulled out by the roots, and it's only $65. It is only accurate for one of the two types of EPSM, but I do not want to do a biopsy. They cut out a one inch cube of muscle! Ouch.
Even with this new information, I am going to do the allergy test. I feel like there is more going on here than the EPSM. His appointment for the blood draw is on Friday and it might be a week or more before we get results.
I also took in a fecal sample today. I assume I'll know more on that when I go in on Friday unless there's something alarming.
It's good to feel like I'm starting to work my way through to some answers.