There are many different intestinal parasites that can affect horses, so most people routinely deworm their horses. There are many different deworming products available that mostly focus on killing small strongyles, large strongyles, roundworms, pinworms, and bots. The most common dewormer used today is the chemical ivermectin as it is effective at killing most of the above parasites except roundworms and there are other dewormers effectively kill roundworms. However, tapeworms are a different story as the ivermectins and other routine products have no effect on them.
Fortunately, a drug called praziquantel was approved several years ago and it is effective against tapeworms and should be used in all horses at least twice yearly. Tapeworms are prevalent in Texan horses; a study in 2003 revealed that over 55% of the horses in Texas had tapeworms at some point. This number is even higher in the eastern and northern United States as percentages of infection in some of these areas were up to 95%.
Tapeworms potentially cause colic because they attach to the junction of the small and large intestines and can affect gut function in this area. The parasite is transmitted by a tiny mite that is ingested with the feed, and the immature tapeworm is released from the mite and then develops into an adult tapeworm. Praziquantel is available with ivermectin in two different deworming products so make sure that you choose a dewormer with praziquantel and use it at least twice a year.
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