First report of multiple drug resistance in trichostrongyles affecting sheep under field conditions in Italy

Abstract

Drug resistance in sheep gastrointestinal trichostrongyles is a cosmopolitan major constraint to small ruminant production. Despite reports that anthelmintic drug resistance has become common, there are limited information on the presence of drug resistance in Italy. The purpose of this study was to determine the effect of four anthelmintics to control infection in sheep in central Italy. Fifty sheep with fecal egg counts (FEC) > or =150 eggs per gram were selected on each of three farms (n = 150 total sheep) which were randomly allocated to one of five groups. Groups were treated with febantel, levamisole, ivermectin, or moxidectin while the fifth group acted as the control group. A FEC reduction test (FECRT) was conducted on each animal and the mean FEC of each treatment group was compared to that of the control group within farm. Resistance was declared when percentage reduction (R) <95% and the lower 95% confidence interval was <90%. Levamisole (mean R = 89%) resistance was found on all farms and ivermectin (mean R = 93%) resistance was found on two of the three farms. Posttreatment larval cultures showed the presence of Teladorsagia (Ostertagia) circumcincta and Trichostrongylus spp. larvae. Febantel (mean R = 96%) and moxidectin (mean R = 100%) remained effective. This study suggests that drug resistance in sheep gastrointestinal trichostrongyles is present in central Italy and a potential problem which would justify a broader nationwide geographical investigation.

The effect of moxidectin 0,1% vs ivermectin 0,08% on milk production in sheep naturally infected by gastrointestinal nematodes

Abstract：

Background: Gastrointestinal nematode (GIN) infection is one of the main constraints to sheep production both in temperate and tropical countries. Economic losses caused by GIN are related to decreased production, treatment costs and even animal death. The present paper was aimed at assessing the anthelmintic efficacy (based on faecal egg count reduction) of moxidectin and ivermectin both administered per os at dose rate of 0.2 mg/Kg body weight and the benefit of anthelmintic treatments on milk production in a commercial dairy sheep farms in central Italy whose animals were naturally infected by GIN.

Results: The treatment with moxidectin was highly effective (> 98%) from day 7 until day 75, and effective (90-98%) until day 105. The treatment with ivermectin was highly effective (> 98%) from day 7 until day 14, effective (90-98%) at day 28 and moderately effective (80-89%) on day 45. The milk productions in the treated groups were significantly higher than those of the control group.

Conclusion: In conclusion, the results of the present study demonstrated that moxidectin and ivermectin administered per os according to the manufacturer's instructions were both effective and safe anthelmintics in sheep. The total milk production was higher in the treated groups than the control group. Overall, animals treated with moxidectin had a milk production 40.8% higher than control group; whereas animals treated with ivermectin had a milk production 32.2% higher than control group.