Why do we wait until after the first frost to deworm in the Fall?
With the cooler temperatures setting in it’s time to start thinking about fall deworming protocols. The life cycle for most equine internal parasites involves eggs, immature larvae, and adult worms that then release more eggs into the environment through manure. Eggs or larvae shed in manure will accumulate in the environment, and if horses are turned out on these same pastures throughout the grazing season they can acquire large parasitic burdens by ingesting the eggs and larvae on the grass. The goal of any deworming protocol is to focus treatments at times of the year that are most optimal for larval development and egg transmission, ultimately reducing the parasite load both internally and in the grazing areas. As temperatures cool down and we start to see frost, the eggs on the ground are no longer viable, and this is an ideal time to deworm because the horses won’t pick up more live parasite eggs and larvae and carry them through the winter. A few weeks after the first frost we recommend using an ivermectin or moxidectin product that also contains praziquantel to additionally target tapeworms – a serious internal parasite that is widespread and has the potential to cause disease (including colic).