Benzimidazole resistance of equine stronygles–critical tests of six compounds against population B.

This research investigates the effectiveness of six benzimidazole compounds in treating horses infected with large and small strongyles from population B. The study finds that all tested drugs completely removed large strongyles but demonstrated varying effectiveness against five species of small strongyles. Furthermore, the tested drugs did not effectively remove immature forms of the parasites.

Study Overview

The study involved critical tests on eight horses naturally infected with several species of large and small strongyles from the population labeled as B. Six benzimidazoles, including thiabendazole, mebendazole, cambendazole (two formulations), fenbendazole, oxibendazole, and oxfendazole, were tested.

• The tested compounds varied in their mode of administration, strength and approached the disease with different compounds.
• Except for cambendazole, which was provided as an intra-oral paste, the rest were administered through a stomach tube.

Efficacy of the Tested Drugs

• The research reported total (100%) removal of larger strongyles varieties and two specific species – Strongylus vulgaris and Strongylus edentatus by each of the tested drugs.
• However, the effect was not uniform when it came to five species of small strongyles – Cyathostomum catinatum, Cyathostomum coronatum, Cylicocyclus nassatus, Cylicostephanus goldi, and Cylicostephanus longibursatus. These exhibited varying degrees of resistance against the tested compounds. Oxibendazole was found to be effective against these.
• Similarly, a total of 19 other species of small strongyles from seven genera were mostly removed by the six benzimidazoles.
• However, the tested compounds were ineffective in removing the immature or larval stages irrespective of the strain.

Conclusions

The study sheds light on the effectiveness of benzimidazoles against different species of strongyles and emphasizes the role of drug variety and dosage. It also raises concern about varying degrees of resistance and challenges presented by immature stages of the parasite. More research is needed to identify solutions for these issues.