Influence of the Route of Administration on Therapeutic Efficacy of Ivermectin in Saanen and Damascus Goats Naturally Infected with Trichostrongylidae spp.

The aims of this study were to compare the therapeutic efficacy of ivermectin after subcutaneous, per os and pour-on administration in Saanen goats naturally infected with Trichostrongylidea spp. and to evaluate the efficacy of ivermectin pour-on in Damascus goats with similar gastrointestinal nematodes. After body weighing and faecal sample collection on day 0 (pre-treatment day), 45 Saanen goats were weighed, faecal sampled and allocated on the basis of day -3 faecal egg counts (FEC) to four treatment groups (n=9 in each group). Saanen goats were then treated with a single dose of ivermectin at a dose rate of 0.2 mg/kg by subcutaneous injection or oral administration and 0.5 mg/kg or 1 mg/kg by topical application. Nine Saanen goats were kept as non-medicated control. Fifteen Damascus goats were divided two groups. The first group (n=9) received ivermectin pour-on as a single dose of 0.5 mg/kg and the second group (n=6) served as a non-medicated control. The efficacy was measured on the basis of the reduction of the egg output and the evaluation of the results from larval differentiation on 14 days post-treatment. In Saneen goats, ivermectin provided equally excellent (100%) therapeutic efficacy after subcutaneous or oral administration whereas ivermectin pour-on treatment at a dose of 0.5 mg/kg and 1.0 mg/kg reduced pretreatment FEC by 96.5% and 99.9%, respectively. No statistically significant difference was found between 1.0 mg/kg of ivermectin by topical application and the ivermectin subcutaneous and oral treated groups for post treatment FEC whereas the efficacy of ivermectin pour-on at 0.5 mg/kg was significantly lower than that for each of the other 3 treatment groups. In Damascus goat, the therapeutic efficacy of 0.5 mg/kg ivermectin pour-on was recorded as only 30.7%.