Prenatal administration of persistent macrocyclic lactone anthelmintics can alter the behaviour of neonatal lambs *

The objective of this study was to evaluate the effect of anthelmintic drugs on ewe and lamb behaviour. We randomly allocated 60 pregnant ewes to one of three groups (n=20/group): 1) administered moxidectin 2-4 weeks pre-lambing, 2) administered a controlled-release capsule (abamectin and albendazole) 2-4 weeks pre-lambing, and 3) control group. The ewes were housed indoors one month pre-lambing until 1 week post-lambing. Ewe and lamb behaviour was recorded using video-cameras for up to 7 days post-lambing and birth data was recorded. There tended to be a difference between total labour length and ewe treatment (P=0.06). Control ewes were in labour for a median of 65.8 (IQR 33.2 to 139; maximum 420.4). CRC treated ewes were in labour for a median of 67.0 (IQR 55.4 to 159.21; maximum 407.3) minutes. Moxidectin treated ewes were in labour for a median of 47.4 (IQR 30.0 to 106.8; maximum 272.8) minutes. There were no differences between treatments for latencies (from birth) to perform behaviours: lamb to shake head (P=0.68), attempt to stand (P=0.57), complete stand (P=0.7), attempt to suckle (P=0.34) and complete suckle (P=0.84). Although LA drench may not have an affected lamb behaviour, they appear to affect length of labour.

* Conference abstract title: The effect of anthelmintic drugs on ewe and lamb behaviour