Most people underestimate their horse’s weight by as much as 20%. Underestimating a horse’s weight can lead to underdosing. Giving a horse less than the required dose of wormer can leave them at risk of worm-related disease as potentially worms will be left untreated within the horse. Underdosing can also encourage the development of resistance in your horses by exposing the worms to sub-lethal doses of wormer. It is therefore vitally important to correctly estimate your horses’ weight when deciding on the correct dose of wormer to give them. It is in fact preferable to give horses a slight overdose rather than an underdose. There are several methods for finding out a horse’s weight, the most accurate obviously being a set of scales. As most horse owners to not have easy access to horse scales, there are several other methods that horse owners can use to get a good estimate of their horses’ weight. The use of the weight estimation formula will give a reasonably good estimation of most horses’ weight. The formula is:
Another method that can be used to estimate weight is by using one of the commercially available weight tapes. Unfortunately, some of these tapes are far more accurate than others so it is a good idea to calibrate the tape using the formula first to check that it is measuring accurately. Weight tapes are also not suitable to use in immature horses as they have a different body composition to older animals.