breeding

Question
We have an 8 year old TB mare that was diagnosed with EPM at 3 after noticing the jaw muscle on the right side of her face shrinking. She was treated with that very expensive paste whos name escapes me at the moment. She  seems in fine health and no further testing has been done because they say all it proves is exposure at some point. How wise is it to consider breeding a mare with this history? Thank you so much for your time. Dave.

Answer
David:

Im sorry to say that having done alot of research in EPM as an internist myself, this is not a well substantiated case of EPM. JAw muscle atrophy is a VERY poor indication of EPM alone, and contrary to what you were told, diagnostic testing is VERY important in looking for EPM in that the test HAS to be positive for the disease to be diagnosed. If it is negative, the disease is very unlikely. Not having tested your horse, there is no way to know if your horse could have been negative and maybe the treatment was wasted money. there are about a thousand other explanations for jaw muscle atrophy, most of which are much more likely to occur than EPM. Your mare can be bred whether she had EPM or not. The limiting factor would be ataxia, or inability to walk normally that might suggest she is too weak to carry a foal. Nowhere did you mention this which would be unlikely since EPM causes primarily ataxia in the horse long before any other signs, especially somehting as rare as jaw muscle atrophy due to EPM and without any other signs of it. Im afraid as an intenist, I feel you recieved less than ideal recommendations in this situation if I have all the facts. Good luck. Breed her without concern. Feel free to contact me again.