In the past we would deworm at two to three month intervals but as resistance in parasites is increasing were starting to realize that practice may be part of the problem. It is now recommended that we do several fecals to determine your horses carring load of eggs. Some horses are low shedders an never have many eggs, others are moderate and still others are very high in numbers. The horses with little to no eggs will only need to be dewormed a few times a year. The other two categories may need to be dewormed more often and it’s best if checked with a fecal first so the right medication can be chosen. When controlled, you can almost eliminate contamination of your fields and reinfection of other horses.
The feces we need needs to be fresh, less than 3 hours old. We only need 2-4 fecal balls to check for parasites. We can also check for blood and sand with these samples. Both those problems can also lead to weight loss and ill thrift. We have lots of problems in our areas with sand. If your horse ever spills his/her food at all they should be checked. Ulcers are another major problem in our are probably in part because they can’t graze they way they were meant to. Both endoscopy and fecal blood tests can be used to check for ulcers. A physical exam checking sore points can also be helpful.