Efficacy of four broad spectrum anthelmintics against gastrointestinal nematodes in goats
Chartier, C.; Pors, I.
Veterinary Record 134(20): 523-524
1994
ISSN/ISBN: 0042-4900 PMID: 8085312 Document Number: 425561
In 1992, a faecal nematode egg count reduction test (FECRT) performed using febantel on 28 goats in an Alpine herd of 130 milking goats in western France suggested a high level of resistance (19% at 10 days after treatment). PM examination of 4 goats showed a low level of infection with gastrointestinal strongyles (average 3500 worms), almost exclusively represented by Trichostrongylus colubriformis (>98%). A study of the efficacy of 4 anthelmintics was carried out using FECRT in 94 dry goats on the farm. The goats were randomly assigned to 6 groups; the first acted as untreated controls and the other groups received 0.2 mg/kg bodyweight ivermectin (IVM) once orally, 88.8 mg/kg thiabendazole (TBZ) as 2 doses 24 h apart, 11.4 mg/kg levamisole (LEV) orally as 2 doses 24 h apart, thiabendazole and levamisole (TBZ + LEV) at the same doses and schedule as before and 34 mg/kg pyrantel tartrate (PYR) as 2 doses 24 h apart. Faecal egg counts were measured at treatment (day 0) and 7 and 28 days afterwards. Decreasing efficacies, as measured using two different formulae were recorded at day 28 for IVM and TBZ + LEV (more than 99%), LEV (less than 82%), PYR (less than 73%) and TBZ (less than 24%). Calculations of 95% confidence limits indicated that resistance was present in the TBZ, PYR, LEV and TBZ + LEV groups. The predominant use of benzimidazoles on the farm for a long time at dose rates recommended for sheep may have contributed to the development of resistance.