I also had this problem with my horse. He suddenly seemed terrified of things that he had been exposed to millions of times (like saddle pads). He tore up cross ties, crashed through his pasture fence. He was not mean or aggressive, it was like his flight response became hypersensitive. He then started to show some neuro symptoms that mimicked EPM. However, the frustrating part was that all of the symptoms were transient. On Monday he was a sick horse, then on Tuesday fine, Wednesday weird, sick horse again. After several vets, and tests (EPM was ruled out) we found out that his liver was out of whack and his white count was low. No one had an explanation for this except possible poisioning. The horses that share his pasture were not affected. He was started on immune boosting and anti-inflammatory supplements. When he received his fall shots all of his lab work came back normal, and I have my horse back again.
So, I definetly agree with Dr. Berger when she says rule out a medical reason. Changes in behavior are not always behavioral porblems.
