This longitudinal randomized field trial evaluated egg count levels, bodyweight, and equine health under defined parasite control protocols in foals and mares at four stud farms in New Zealand.
The article was titled, "Monitoring equine ascarid and cyathostomin parasites: Evaluating health parameters under different treatment regimens" and was authored by Nielsen, Martin K.; Gee, E.K.; Hansen, A.; Waghorn, T.; Bell, J.; and Leathwick, D.M.
Foals (n = 93) were divided into two treatment groups; group A were dewormed at 2 and 5 months of age with a fenbendazole/ivermectin/praziquantel product, while group B were dewormed monthly, alternating between the above-mentioned product and an oxfendazole/pyrantel embonate product.
Mares (n = 99) were divided into three groups; group A were dewormed twice (early summer and winter) with fenbendazole/ivermectin/praziquantel, group B were dewormed with the same product only when egg counts exceeded 300 eggs per gram, and group C were dewormed every 2 months, alternating between the two products. Health data was collected at two-month intervals for a total of eight months.
Foals in group A had significantly higher ascarid and strongylid faecal egg counts compared to group B, but no significant differences were observed between mare groups. One foal in group B developed diarrhea during the monitoring period. No colic signs were reported in any group during the study.
Bottom line: Reducing anthelmintic treatment intensity can lead to higher ascarid and strongylid egg counts in foals on stud farms; however, no negative health consequences were observed within the timeframe of this study. Longer monitoring periods are needed to assess the effect of increased endoparasite burdens and the effects of increased egg shedding on subsequent foal crops.
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