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The tapeworm life cycle. Courtesy Merial

Hoyt Cheramie, DVM, MS, is a member of the Merial Veterinary Service team. He has expertise in performance horse medicine, is a board-certified surgeon and has teaching experience at the Virginia-Maryland Regional College of Veterinary Medicine. He has practiced in Kentucky, Louisiana, Georgia and Illinois. Dr. Cheramie earned his doctor of veterinary medicine from Louisiana State University School of Veterinary Medicine. Below he responds to a question about tapeworms.

Question: With the temperatures getting colder, do I still need to worry about tapeworms?

Answer: Many people think that the risk of tapeworms disappears during fall and winter. Quite the opposite is true. Horse owners need to look at the entire life cycle of the tapeworm to understand their horses’ risk levels and treat them accordingly.

To thrive, tapeworms need both a definitive host (where they mature) and an intermediate host (where they reside while in immature stages). The horse serves as the definitive host for the tapeworm, while soil mites are the intermediate host. Mites, which can be infected with cysticeroid (larval tapeworms), are found in pastures.1

Once a grazing horse eats the infected mites, the cysticeroid develops into adult tapeworms in the intestine of the horse within four to six weeks. The tapeworms are then passed through the horse’s feces back into the pasture, allowing the tapeworm life cycle to continue.1 Currently, there is no reliable fecal diagnostic test for tapeworm infections as there are for most other equine parasites.2 However, selecting a deworming product that contains praziquantel, which has been approved for the treatment of tapeworms in horses, is a way to help remove them.3

Controlling tapeworms is important because studies have linked them, specifically Anoplocephala perfoliata, to spasmodic, impaction and intussusception-related colic.4,5 One study reported that 80 percent of ileal impaction colic cases examined were associated with tapeworms. Other findings from the same study showed 22 percent of spasmodic colic cases included tapeworm infection.2 These infections can also result in a life-threatening condition called intussusception, which occurs when the small intestine telescopes into the cecum, resulting in a blockage that can be fatal without surgical intervention.6

In addition to managing tapeworms, horse owners should control other parasites by working with their veterinarians to establish the most effective plans based on their individual horses’ needs.

1 Lyons ET, Tolliver SC, Drudge JH, Collins SS. Tapeworms in Horses. University of Kentucky, College of Agriculture. Cooperative Extension Services. Available at: http://www.uky.edu/Ag/AnimalSciences/pubs/vet32pdf. Accessed September 19, 2011.
2 Proudman, CJ, Trees AJ. Tapeworms as a cause of intestinal disease in horses. Parasitol Today. 1999;15(4):156-159.
3 Based on data provided on the ZIMECTERIN Gold label.
4 Proudman CJ, French NP, Trees AJ. Tapeworm infection is a significant risk factor for spasmodic colic and ileal impaction colic in the horse. Eq Vet Journal. 1998;30(3):194-199.
5 Barclay WP, Phillips TN, Foerner JJ. Intussusception associated with Anoplocephala perfoliata in five horses. JAVMA. 1982;180(7)752-753.
6 Dulany, J, Hubert J. Common equine parasites involved in colic. Louisiana State University, School of Veterinary Medicine. Available at: http://evrp.lsu.edu/healthtips/Parasitesandcolic.htm. Accessed September 13, 2011.
7 Based on data provided in the FDA Freedom of Information summaries.



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