Anthelmintic Resistance of Gastrointestinal Nematodes of Communally-Grazing Goats in Humbo District, Southern Ethiopia.

Background and aim: Anthelmintic resistance (AR) in gastrointestinal nematodes (GINs) is currently present worldwide and a major challenge to goat production. However, no updated information is available on this topic in the study area. Thus, this study evaluated the efficacy of commonly used anthelmintics on GINs in naturally-infected goats and assessed farmers' perception of anthelmintic utilization practices in Humbo district, Southern Ethiopia.

Materials and methods: The field experiments for routinely used anthelmintics, namely, albendazole, ivermectin, and tetramisole, were conducted from September 2022 to April 2023. Sixty naturally-infected goats with nematodes were selected based on egg count (≥150 eggs per gram of feces) and allocated randomly into four groups (15 animals per group). Then, fecal samples were collected pre- and post-treatment and examined for fecal egg count reduction (FECRT) to determine the AR status of goat GINs. The modified McMaster technique using standard floatation was used for quantifying the eggs. In addition, a questionnaire survey was conducted to assess anthelmintic utilization practices among goat owners.

Results: The FECR levels for albendazole, ivermectin, and tetramisole were 94.6, 95.9, and 97.3%, respectively. By coproculture, the nematode genera identified before treatment were Haemonchus, Trichostrongylus, Teladorsagia, Oesophagostomum, Bunostomum, and Chabertia Species. However, post-treatment fecal cultures showed that some Haemonchus, Trichostrongylus, and Strongyloides spp. did not respond to the treatments. The questionnaire survey revealed that albendazole was the most commonly used anthelmintic to treat nematode infection in goats. Respondents expressed that anthelmintic treatment was utilized based on veterinarian prescription (59%), availability (32%), efficacy (4%), and affordability (5%).

Conclusion: Tetramisole should be used cautiously to prevent the development of resistant strains, as it was still effective in the study area. Additionally, regular monitoring of anthelmintic effectiveness is necessary.