RESEARCH CONFIRMS Resistance to Panacur® PowerPac (fenbendazole) in the United States is widespread while QUEST® (moxidectin) remains effective for controlling the most common equine parasites.1

Comparison of a single dose of moxidectin and a five-day course of fenbendazole to reduce and suppress cyathostomin fecal egg counts in a herd of embryo transfer-recipient mares

OBJECTIVE: To compare the two approved larvicidal regimens for the treatment and control of cyathostomins for reduction and GEOGRAPHIC ORIGINS OF RECIPIENT HERD suppression of fecal egg counts (FEC) in a transient herd of embryo transfer-recipient mares. PROCEDURES: • Study qualifying mares were randomized via complete block design into 2 treatment groups: • Group 1 received a single dose of QUEST®, Group 2 received Panacur® PowerPac (PPP). • FEC data were analyzed 14, 45 and 90 days following treatment. RESULTS: • Mean FEC reduction was 99.9% for moxidectin treated mares and 41.9% for fenbendazole treated mares 14 days post-treatment. At the time of the study initiation, the resident herd was composed of 120 individual mares that had arrived from the 21 states highlighted within the previous 16 months. • By 45 days, fenbendazole group mean FEC There is no history of fenbendazole or moxidectin use on the farm. exceeded pre-treatment levels and were 10x those of moxidectin. • Moxidectin group mean FEC levels remained MEAN FECAL EGG COUNTS suppressed throughout the study. Statistically significant FEC differences were observed between 1700 1600 90 day 1500 groups 14, 45 and 90 days post-treatment. 1413.2 1400 CONCLUSIONS: 1300 1200 45 day • Failure of the 5-day regimen of fenbendazole to 1100 1033.9 1000 Pre Tx adequately reduce or suppress FEC suggested Pre Tx 857.3 900 807.3 inadequate adulticidal and larvicidal effects. 800 • In contrast, a single dose of moxidectin effectively 700 600

reduced and suppressed FEC for an extended period. # of eggs per gram 500 14 day 90 day • Given the diverse geographic origins of study 400 346.6 352.8 300

mares, these results are likely representative of 200 45 day 100 14 day 97.2 cyathostomin-infected mares in much of the United 0.6 0 States, confirming previous findings indicating Fenbendazole group Moxidectin group that fenbendazole resistance in cyathostomins is widespread and that moxidectin remains an effective treatment for control of these important parasites. One dose of QUEST® (moxidectin) was more than 2x as effective as Panacur® PowerPac (fenbendazole) in reducing fecal egg counts and without intestinal inflammation.3

Characterization of the inflammatory cytokine response to anthelmintic treatment in ponies

OBJECTIVE: CONCLUSIONS: Because anthelmintic treatments have been associated • There are pronounced differences in theinflammatory with intestinal reactions3 and these inflammatory cytokine responses to anthelmintic treatment. reactions may play a role in the development of • QUEST successfully reduced FEC without producing parasitic disease post anthelmintic treatment (larval signs of inflammation, whereas PPP failed to adequately 4 cyathostominosis) , this study was developed to reduce FEC and stimulated proinflammatory gene determine the effect of different anthelmintic classes expression. on the proinflammatory response post treatment. • Such inflammatory reactions may play a role in the PROCEDURES: development of parasitic disease post anthelmintic • Ponies were divided into 4 treatment groups: treatment. Group 1 (n=4) were untreated controls; Group 2 (n=5) received 5 daily doses of fenbendazole GEOMETRIC MEAN FECAL EGG COUNTS (10 mg/kg bwt); Group 3 (n=4) received daily [Significance (*) based on pre-treatment counts] treatment of pyrantel tartrate 2x (2.65 mg/kg 1600 Moxidectin treated bwt); and Group 4 (n=5) received a single dose of 1400 Fenbendazole treated moxidectin (400 g/kg bwt). 1200 • Blood samples were collected daily for 2 weeks 1000 to determine the effect of deworming on 800 proinflammatory gene expression. 600

• Fecal egg counts were used to evaluate the 400 * efficacy of each drug. # of eggs per gram 200 0 * * * * RESULTS: Day 0 Day 7 Day 14 Day 21 Day 28 • While treatment with Panacur® PowerPac (PPP) was the least successful in reducing fecal egg FECAL EGG COUNT REDUCTION POST TREATMENT counts, it stimulated the most pronounced systemic proinflammatory cytokine gene Moxidectin Pyrantel Tartrate expression. 100 Fenbendazole Untreated • Treatment with pyrantel salt also reduced fecal 80 egg counts with less of a proinflammatory response. 60

• Treatment with QUEST was the most successful in 40

reducing fecal egg counts and produced no signs % Reduction of increased proinflammatory cytokine expression. 20

0 7 14 21 29 Day post treatment

Do not use QUEST Gel or QUEST PLUS Gel in foals less than 6 months of age or in sick, debilitated and underweight horses. These products should not be used in other animal species, as severe adverse reactions, including fatalities in dogs, may result. 1 Mason ME, Voris ND, Ortis HA, Geeding AA, Kaplan RM. Comparison of a single dose of moxidectin and a five-day course of fenbendazole to reduce and suppress cyathostomin fecal egg counts in a herd of embryo transfer-recipient mares. J Am Vet Med Assoc. 2014;245. 2 Betancourt A, Lyons ET, Horohov DW. Characterisation of the inflammatory cytokine response to anthelmintic treatment in ponies. Equine Vet J 2014; DOI: 10.1111/evj.12280 3 Steinbach T, Bauer C, Sasse H, Baumgartner W, Rey-Moreno C, Hermosilla C, Damriyasa IM, Zahner H. Small strongyle infection: consequences of larvicidal treatment of horses with fenbendazole and moxidectin. Vet Parasitol 2006; 139:115-131. 4 Reid SW, Mair TS, Hillyer MH, Love S. Epidemiological risk factors associated with a diagnosis of clinical cyathostomiasis in the horse. Equine Vet J 1995;27:127-130.

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