The influence of the oesophageal groove in goats on anthelmintic efficacy

Abstract

Twenty-four 1 and 2 year old goats carrying natural gastrointestinal nematode infections (mean faecal egg count (FEC) = 3333 epg) were allocated to one of three treatment groups: intraruminally injected (n = 8) or in capsule form (n = 8) Synanthic R.I. (Coopers Animal Health NZ Ltd, New Zealand. 225 g/l oxfendazole; 1 ml/l0 kgBW) or orally administered (n =8) conventional volume Systamex™ (Mallinckrodt Veterinary, New Zealand. 22.65 g/l oxfendazole; 1.0 ml/5 kgBW). Treatments administered in conjunction with glucose (0.110g/kgBW). Blood samples collected over a three hour period post treatment administration showed a similar area under the curve (AUC) of plasma glucose concentration following conventional volume orally administered anthelmintic to those goats known to have anthelmintic deliberately placed in the rumen. Regardless of treatment allocation, FEC collected from goats -1, 4, 8, 12, 16, 20 days after anthelmintic administration showed a similar pattern of reduction in egg counts until day 8, egg counts from then on increasing until the completion of the trial. The similarity of FEC and glucose AUC between the treatment groups indicates that when goats are drenched in such a way that the anthelmintic is administered over the tongue and directed into the oesophagus, activation of the oesophagus groove does not occur. A significant age/faecal egg count interaction (p = 0.024) was observed prior trial commencement, suggesting that there may be an age-immune interaction in goats to gastrointestinal parasitism.