Anthelmintic (dewormer) resistance is a major issue in the small ruminant industry and an emerging problem in other segments of animal agriculture. Drug resistance exists when an anthelmintic treatment fails to reduce fecal egg counts by more than 95 percent. It is inevitable. Severe resistance exists when treatment fails to reduce worm egg counts by more than 60 percent. Currently, there is resistance to all of the anthelmintics used to treat small ruminants (in the US). The level of resistance varies by geographic region and farm.
Dewormers and dewormer resistance; part 4 in a six part series on worm control in goats. Steve Hart, Langston University, and American Consortium for Small Ruminant Parasite Control. Orginally published in The Goat Rancher Magazine [June 2008].
Dewormer resistance on farms in the Mid-Atlantic Area. D.J. O'Brien, Delaware State University. [May 2010].
Do you know which dewormer(s) are effective on your farm? E. Nelson Escobar, University of Maryland Eastern Shore. [Timely Topic, July 2013]
More on-farm dewormer resistance testing needed: do an LDA!; Dahlia O'Brien, Virginia State University [Timely Topic, October 2015].
Potential solutions to highly resistant worms in sheep and goats; Steve Hart, Langston University [Timely Topic, October 2013].
Test your knowledge of the management practices that affect dewormer resistance. Michelle Arnold, DVM. University of Kentucky [September 2015].
Biology of Anthelmintic Resistance: These Ain't Your Father's Parasites; Dr. Ray Kaplan, Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia; 10th Anniversary Conference of the American Consortium for Small Ruminant Parasite Control, Fort Valley, Georgia [May 2013].
Determining the Level of Efficacy in Anthelmintics; Dr. Ray Kaplan; W4: What Works With Worms Congress, Pretoria, South Africa [May 2015].
How and Why Resistance to Worms Develops; Dr. Ray Kaplan; W4: What Works With Worms Congress, Pretoria, South Africa [May 2015].
Sequential Dosing as a Possible Way of Slowing AR; Dave Midgley; W4: What Works With Worms Congress, Pretoria, South Africa .
Drench Resistance and Sheep Worm Control. By Stephen Love, Veterinarian/State Worm Control Coordinator. New South Wales Government, Australia.
Best Management Practices for Controlling Internal Parasites in Small Ruminants: Managing Dewormer Resistance; Dr. Dahlia O'Brien, Virginia State University [May 2018].
Prevalence of anthelmintic resistance on sheep and goat farms in the mid-Atlantic region and comparison of in vivo and in vitro detection methods. E.K.Crook, D.J. O’Brien, S.B. Howell, B.E. Storey, N.C. Whitley, J.M. Burke, and R.M.Kaplan. Small Ruminant Research [September 2016].
Anthelmintic resistance on sheep and goat farms in the southeastern United States; S.B. Howell, J.M. Burke, J.E. Miller, T.H. Terrill, E. Valencia, M.J. Williams, L.H. Williamson, A.M. Zajac, and R.M. Kaplan; Scientific Reports: Journal of American Veterinary Medical Association [December 2008].
An inconvenient truth: global warming and anthelmintic resistance; Ray Kaplan and Anand N. Vidyashankar; Veterinary Parasitology .