ABSTRACT
Field tests were performed on Thoroughbred yearlings (n=143), evaluating efficacy of moxidectin (MOX) against ascarids and strongyles and the efficacy of an ivermectin (IVM)-praziquantel (PRAZ) combination against those nematodes and tapeworms on a farm in Central Kentucky. The study was started on March 1, 2016 and completed on August 23, 2016. Fecal samples were collected from yearlings every two weeks for counts of ascarid and strongyle eggs per gram of feces (EPGs) and for determining the presence of tapeworm eggs. MOX was given to 88 yearlings on March 1; 55 yearlings were nontreated controls on this date but were treated two weeks later with MOX. On June 15, 2016, all yearlings (n=87) remaining on the farm were treated with IVM-PRAZ combination. Ascarids were present in low numbers for MOX-treated horses, and the drug had virtually no effect. The low number of ascarid infected horses before any treatment during the study was most likely due to age related immunity. Efficacy against strongyles was alike for both MOX and the IVM- PRAZ combination. At two weeks post-treatment, strongyle EPG values were reduced over 90%, started increasing at four weeks post-treatment, and returned to near pre-treatment values at six weeks post-treatment. Tapeworm efficacy of the IVM-PRAZ treatment was 96% at two weeks and was maintained for the entire ten-week post-treatment examination period.
ABSTRACT
REASONS FOR PERFORMING STUDY: Nocardioform placentitis in horses is poorly understood, and the development of an experimental model would be of help in understanding the pathogenesis of the disease. OBJECTIVES: To investigate whether (1) intrauterine inoculation of Crossiela equi during the periovulatory period or (2) i.v., oral or intranasopharyngeal inoculation of C. equi during midgestation would result in nocardioform placentitis, and (3) before and after mating endometrial swabs present evidence of nocardioform placentitis-associated organisms (C. equi or Amycolatopsis spp.). METHODS: In Study I, mares (n = 20) received an intrauterine inoculation of C. equi 24 h after artificial insemination. Endometrial swabs were obtained 24 h post inoculation for PCR analysis. In Study II, pregnant mares (at 180-240 days of gestation) were inoculated with C. equi by intranasopharyngeal (n = 5), oral (n = 4) or i.v. (n = 4) routes. Sixty contemporaneous pregnant mares maintained on the same farm served as control animals. In Study III, privately owned Thoroughbred mares (n = 200) had endometrial swabs collected before and within 24-48 h after mating for detection of nocardioform microorganisms. RESULTS: In Study I, C.equi was identified by PCR in 3 of 20 mares following intrauterine inoculation. Pregnancy was established in 19 of 20 treated mares. There were 2 embryonic losses and one abortion at 177 days of gestation (undetermined cause). Sixteen mares delivered a normal foal and placenta. In Study II, one mare (oral inoculation) aborted at 200 days of gestation (unidentified cause). The remaining mares delivered a normal foal and placenta. In Study III, none of the mares yielded positive endometrial PCR for nocardioform microorganisms. CONCLUSIONS: We were unable to induce nocardioform placentitis, and there was no evidence of nocardioform microorganisms in endometrial swabs of broodmares before or after mating. These findings suggest that nocardioform placentitis is not induced simply via the presence of nocardiform actinomycetes and that route, insufficient duration of exposure and dose may play a role in the development of disease. Additional predispositions may also be involved in the development of nocardioform placentitis.
