A field evaluation of anthelmintics for control of cyathostomes of horses in Brazil.

This study investigates the effectiveness of different anthelmintics medicines, specifically ivermectin, piperazine citrate, and fenbendazole, used alone or in certain combinations, for controlling strongyles (a type of worm) in Mangalarga equids, a breed of horse common in Brazil. The study suggests some level of resistance among the worm population to fenbendazole and piperazine citrate.

Anthelmintics Under Investigation

• The anthelmintics studied include ivermectin (IVM), piperazine citrate (PPZ), and fenbendazole(FBZ).
• The study looked at these anthelmintics both individually and in combinations with varying dosages of PPZ and FBZ.

Research Method and Observations

• Strongyle egg counts per gram of faeces (EPG) before and after treatment were taken into consideration.
• In all positive cases, cyathostome larvae with eight gut cells were consistently observed in faecal cultures.
• Faecal Egg Count Reductions (FECR) were evaluated between Day 7 and Day 56 after treatment.
• Beyond this, the mean EPG values of IVM were compared with those of the other anthelmintics.

Results

• Significant differences were found between Day 7 and Day 49 when comparing the mean EPG values of IVM with those of the other anthelmintics.
• PPZ alone and in combination with FBZ showed no significant differences during the trial; both groups exhibited a greater than 90% FECR.
• Horses treated with various combinations of FBZ and PPZ, as well as FBZ alone, showed an FECR of less than 90% after 2 weeks of treatment.

Implications

• The final results suggest a degree of resistance emerging in certain segments of the cyathostome population (worm population) to both FBZ and PPZ.