Cutting Through the Tape

An explanation of the new spotlight on tapeworms. Are they cause for concern?

Gaze at photographs of tapeworms and their equally unappetizing cousins in the parasite family, and as a concerned horse professional, you’re sure to renew your commitment to deworming.

Tapeworms—scavengers in equine bodies—have always been around. So why is there so much hullabaloo about the lowly but obviously troublesome tapeworm now?

Because now we can eliminate these parasites with comprehensive, effective dewormers that pack one powerful punch. Put these on your list: Merial’s Zimecterin Gold (1.55% ivermectin, 7.75% praziquantel), Pfizer’s Equimax (1.87% ivermectin, 14.03% praziquantel) and Fort Dodge Animal Health’s Quest Plus Gel (2% moxidectin and 12.5% praziquantel).

If you feel remiss that you didn’t worry so much about tapeworms previously, you’re not alone. Experts tell us that tapeworm infection is easily and frequently missed using routine diagnostic methods…and that tapeworm eggs are rarely seen on standard fecal examinations, even in horses shown to be heavily infected.

Veterinarians frequently discovered tapeworms during equine abdominal surgery, but thought them to be relatively harmless when compared to the legions of other harmful parasites. However, one recent study showed that 22 percent of spasmodic or gas colics were caused by tapeworms, while 81 percent of ileocecal impactions were associated with the parasite. Ileocecal intussusception, which can be fatal, is almost always caused by tapeworm infection.

Tapeworms wreak health havoc like this: They congregate at the ileocecal junction, where the small intestine, cecum and colon meet. Pfizer Animal Health reports that a tapeworm “attaches itself to the sensitive mucosa of this area with strong hooks, creating inflammation, swelling and even ulcers at the site of attachment.”

Pfizer, maker of Equimax, cites research by Dr. Craig Reinemeyer of East Tennessee Clinical Research, who found that an average of 54 percent of horses have been exposed to the parasite. The study provided an exposure range of 12.6 percent of horses on the Pacific coast to a troublesome number of 95.8 percent of horses in the upper Midwest. Bottom line: tapeworms are a factor to be reckoned with all across the U.S.

As horse professionals, we’ve relied on ivermectin for years in our battle against parasites; now praziquantel joins the war on the lowly anoplocephala perfoliata, a.k.a., the most common tapeworm.

In terms of administration, a discussion with your veterinarian is in order if you collaborate on deworming. Merial says its Zimecterin Gold “is presently indicated for and proven to have a wide margin of safety in all horses five months of age or older; the company is exploring the possibility of expanding the Zimectrin Gold label to include horses younger than five months of age.”

Pfizer has long recommended “a regular parasite control program with particular attention being paid to mares, foals and yearlings. Foals should be treated initially at four weeks of age and routine treatment repeated as appropriate.”

The latest advances against tapeworms provide hope for further advances against parasites. Dr. Rocky Bigbie, director of field veterinary services for Fort Dodge Animal Health and its all-in-one Quest Plus Gel dewormer, weighs in on a “what if”: May we soon expect an equine all-in-one anti-parasite medication?

Take ticks for example: “None of the products on the market are labeled for use against ticks, says Dr. Bigbie, “although some products that people use are extra-labeled, though not approved.”

As science marches resolutely on, it’s only a matter of time…






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