Oh Sharon! I am so, so sorry this has happened to you! And thankful from the bottom of my heart that you first survived it, then have been so courageous as to relate this experience to the rest of us. It is a reminder I'm sure we all need, as you're not the only one who has to multi-task at times. Our horses' pergolide becomes such a routine for us that I'm sure many of us don't give it the respect and caution that we might and should. You have probably saved at least one someone else from a similar awful experience, or worse. 
Again, many, many thanks. You have caused one owner to give a lot more thought when dosing my horse.
Melinda and Cato
IN  2010