OregonBR - 2017-09-07 12:32 PM Actually Barrelhorseusa has some valid points. Most people under dose their horses with wormer. I have said it over and over that you need to accurately estimate your horses weight and DO NOT UNDERDOSE the wormer given. If they spit any out, give them more. I give 20% more than the highest possible weight of any of my animals. Weight tapes are not very accurate if you don't know where to put the tape. Any horse that is 15 hands and in good flesh is going to weigh at least 1200#. I worm for 1500#.