RMR News - Pfizer Animal Health QUEST PLUS Dewormer

Madison , NJ – There was a time not too long ago that tapeworms in horses were thought to be innocent bystanders and caused no real problems for the horse. However, research over the last decade has determined that as high as 22 percent of spasmodic colic and nearly 80 percent of ileocecal impactions are associated with tapeworms¹. Fortunately, today there are effective dewormers on the market, including Pfizer Animal Health’s QUEST^® PLUS (moxidectin/praziquantel) that help protect against tapeworms. Parasitologists also have a better understanding of tapeworm prevalence and their potential risk to the horse.

Tapeworms can pose a medical threat to horses across the United States . A ground breaking study in equine parasitology, done in 2003 by Dr. Craig Reinemeyer of East Tennessee Clinical Research, uncovered a high prevalence of equine tapeworms throughout the United States . Updated data from Pfizer Animal Health showed tapeworm prevalence on west coast farms as 17.3% in California , 36.5% in Oregon and 25.3% in Washington².

“Tapeworm infections can be very difficult to detect in horses, because many horses fail to show any clinical signs until a colic episode occurs,” said Tom Lenz, DVM , MS , Diplomate ACT and Senior Director, Equine Veterinary Services for Pfizer Animal Health. “Horses across the country may be exposed to oribatid mites that are infected with tapeworm larvae. As a result, a better understanding of the lifecycle of the oribatid mite can help veterinarians and horse owners to combat tapeworm infections before they lead to bigger issues, such as colic.”

Research suggests that oribatid mites may be the key link to the tapeworm threat. As the intermediate hosts to Anoplocephala perfoliata – the most common species of tapeworm infecting horses in the United States – these insects are highly prevalent worldwide. As microscopic decomposers, these mysterious mites can exist by the thousands or even millions per square meter of soil. Any horse that grazes on pastures, eats hay or is bedded with straw or wood products is likely exposed to oribatid mites, which could potentially translate into tapeworm infections.

As decomposers, mites ingest tapeworm eggs passed in equine feces. The eggs hatch inside the oribatid mites and the infective stages of the parasite, also known as cysticercoids, develop within the mite’s body cavity in about two to four months³. Horses become infected with A. perfoliata when oribatid mites are consumed along with forage. The digested mites release the cysticercoids in the horse’s intestinal tract and the immature parasites then develop into adult tapeworms that attach to the ileocecal junction– the meeting place of the small intestine and the cecum³. The tapeworms mature and reproduce inside the horse. Eggs are released through the feces and the cycle starts all over again³.

Active tapeworm infection is difficult for veterinarians to diagnose. There are two approaches to tapeworm diagnosis (1) coprologic (fecal) testing using a centrifugation/flotation technique, and (2) serologic testing using an ELISA format to detect tapeworm antibodies as evidence of prior exposure. Both tests can be labor intensive and a poor indication of the actual tapeworm burden in the individual horse and in the herd overall^3,4. This limitation often contributes to an underestimation of the true prevalence of tapeworm infection in a herd, which in turn can encourage negligence in tapeworm control. In many cases, horse owners will simply resort to routine deworming instead of performing a diagnostic test that can confirm active tapeworm infection. Also, horse owners may mistakenly assume that broad spectrum dewormers such as macrocyclic lactones (avermectins), such as ivermectin alone or moxidectin alone, or benzimidazoles will control tapeworms, unaware that neither of these classes has any effect on the tapeworm parasite⁵.

Horse owners can ensure their herd is protected by incorporating a praziquantel dewormer, such as QUEST PLUS into their deworming program⁶. This class of anthelmintic has been proven effective against tapeworm infections and is commercially available. Be sure to consult a veterinarian before making any changes to your deworming program.

QUESTPLUS (moxidectin/praziquantel) is a long-lasting, effective dewormer that helps protect against a broad range of parasites including large and small strongyles, roundworms, pinworms, hairworms, stomach worms, bots, and encysted small strongyles (bloodworms). QUEST PLUS contains the same active ingredients as QUEST^®(moxidectin) gel, but with the additional feature of praziquantel for treatment and control of tapeworms (A.perfoliatum). Both dewormers provide up to 84 days of protection from strongyle egg reinfection and 14 days without inflammation in just one dose^[^i].

QUEST and QUEST PLUS are approved for use in all breeds of horses and ponies. QUEST is safe in breeding mares and stallions, and foals six months of age and older. Reproductive studies evaluating safety of use of QUEST PLUS in reproductive mares and breeding stallions have not been conducted. For more information on QUEST and QUEST PLUS, visit www.Questhorse.com.

Important Safety Information

Extreme caution should be used when administering QUEST and QUEST PLUS to foals, young and miniature horses, as over dosage may result in serious adverse reactions. Do not use in sick, debilitated or underweight animals. These products should not be used in other animal species, as severe adverse reactions, including fatalities in dogs, may result. For more information on QUEST or QUEST PLUS visit www.QUESThorse.com.

About Pfizer Animal Health

Pfizer Animal Health, a business unit of Pfizer Inc, is a world leader in the discovery, development and manufacture of innovative animal health vaccines, medicines, and diagnostic products. Pfizer Animal Health invests more in research and development than any other animal health company. We work to assure a safe, sustainable global food supply from healthy beef and dairy cattle, swine, poultry and fish while helping dogs, cats and horses live healthier longer lives. We strive to be the animal health company that provides full healthcare solutions to veterinarians, livestock producers, and pet owners. To learn more, visit www.us.animalhealth.pfizer.com.

References:

1 Tom, Lenz DVM, MS. Tapeworms. April 5, 2004. Available at:

http://www.aaep.org/health_articles_view.php?id=256. Accessed: October 17, 2011,

2 1 C.R. Reinemeyer, A.W. Farley, S.A> Kania, B.W. Rohrbach and R.H. Dressler, 48^th Annual Meeting of the American Association of Veterinary Parasitologists, Denver, CO, July 2003. Updated West Coast Farm prevelance of tapeworm infection data. Data on file. Pfizer Inc. 2009.

3 Williamson RM, Beveridge I, Gasser RB. Coprological methods for the diagnosis of Anoplocephala perfoliata infection of the horse. Aust Vet J 1998; 76:618-621.

4 Proudman CJ, Edwards GB. Validation of a centrifugation/flotation technique for the diagnosis of equine cestodiasis. Vet Rec 1992;131:71-72.

5 Lyons , E.T., Tolliver , S.C. , Drudge, J.H., Collins, S.S. Vet 32: Tapeworms in Horses. University of Kentucky College of Agriculture. 1997; p. 6.

6 Slocumbe JO, Heine J, Barutzki D, et al. Clinical trials of efficacy of praziquantel horse paste 9% against tapeworms and its safety in horses. Vet. Parasitol 2007; 144; 366-370.

[i] Pfizer Animal Health in conjunction with Maxwell H. Gluck Equine Research Center and the University of Kentucky performed an study to better understand the inflammatory responses first noted in a 2006 European study comparing two anthelmintic treatments against encysted small strongyles². Along with the findings came statistically significant evidence showing QUEST^® (moxidectin) to be more effective against parasite egg shedding than PANACUR^®PowerPac (fenbendazole) without inflammation².

The Gluck study included three treatment groups of ponies infected naturally with small strongyles and other parasites. The groups included a control, a group of ponies given 5 daily doses of fenbendazole (20mg/kg/day) and a group given a single dose of moxidectin (400 µg/kg)³. By day 7, through day 28, all ponies treated with moxidectin tested negative for parasite eggs, meaning a 100% fecal egg reduction³. Ponies treated with moxidectin also showed no significant proinflammatory cytokine gene expression prior to day 14³. The lack of significant proinflammatory cytokine gene expression was consistent with the findings in the original 2006 study that revealed no severe inflammatory intestinal lesions associated with encysted strongyle death in moxidectin treated horses².

The ponies treated with fenbendazole showed only an average 65% fecal egg reduction by day 7², and this sub-optimal efficacy was short-lived. By day 14, strongyle fecal egg shedding was statistically identical to pre-treatment levels. In other words, after the five dose PANACUR PowerPac was administered, ponies were shedding eggs at a rate no different than before treatment. Additionally concerning was the finding that fenbendazole treated horses with encysted small strongyle infections experienced an inflammatory response detectable in the peripheral circulation.

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