114
Views
27
CrossRef citations to date
0
Altmetric
Short Communication

Probable multigeneric resistance to macrocyclic lactone anthelmintics in cattle in New Zealand

, , &
Pages 139-141 | Accepted 06 Nov 2002, Published online: 22 Feb 2011
 

Abstract

AIM: To establish the efficacy of topical formulations of eprinomectin and abamectin against naturally acquired abomasal and small intestinal nematode infections in cattle purchased from a North Island bull-beef property.

METHODS: A controlled slaughter trial, involving eighteen 6–8-month-old mixed breed calves, was conducted in May 2002. The animals were randomly allocated on the basis of faecal egg count to one of three equal-sized groups (n=6), consisting of an untreated control group and two treatment groups. One of the treatment groups was treated with a topical formulation of eprinomectin, the other with abamectin. Both anthelmintics were administered as a single topical treatment on an individual liveweight basis, at the manufacturer's recommended dose rates of 0.5 mg/kg. All calves were housed in separate groups with no access to pasture throughout the entire trial and were slaughtered 7–10 days after treatment.

RESULTS: Both anthelmintic treatments were highly effective (worm count reduction >98%) against Ostertagia ostertagi, Trichostrongylus axei and Cooperia punctata, but were not effective at reducing worm counts significantly of either Cooperia oncophora or Trichostrongylus longispicularis. Against these latter two parasites, worm count reductions of only 72% and 79%, and 81% and 76%, respectively, were recorded following treatment with eprinomectin or abamectin, respectively (all p>0.05).

CONCLUSIONS: These results demonstrate evidence of resistance to macrocyclic lactone anthelmintics by C. oncophora and probably T. longispicularis also.

CLINICAL RELEVANCE: As well as perhaps providing the first record of resistance to any anthelmintic by T. longispicularis, the present findings may also represent the first case of resistance to macrocyclic lactone anthelmintics exhibited by more than one parasite species at a time in cattle in New Zealand.

Reprints and Corporate Permissions

Please note: Selecting permissions does not provide access to the full text of the article, please see our help page How do I view content?

To request a reprint or corporate permissions for this article, please click on the relevant link below:

Academic Permissions

Please note: Selecting permissions does not provide access to the full text of the article, please see our help page How do I view content?

Obtain permissions instantly via Rightslink by clicking on the button below:

If you are unable to obtain permissions via Rightslink, please complete and submit this Permissions form. For more information, please visit our Permissions help page.