Anthelmintic resistance in cattle nematodes in the US

Area of Science:

• Veterinary Parasitology
• Antimicrobial Resistance
• Livestock Management

Background:

• Macrocyclic lactone resistance in cattle gastrointestinal nematodes is a growing concern in the US.
• Resistance in Cooperia and Haemonchus genera affects over half of examined operations, causing economic losses.
• Current detection methods for anthelmintic resistance are limited, often requiring animal necropsy.

Purpose of the Study:

• To address the increasing incidence of anthelmintic resistance in cattle nematodes.
• To explore strategies for sustainable parasite control in cattle production.
• To evaluate methods for detecting and managing drug-resistant parasites.

Main Methods:

• Review of current literature on anthelmintic resistance in cattle nematodes.
• Analysis of the impact of parasite control programs on resistance development.
• Discussion of potential strategies for sustainable parasite management.

Main Results:

• Anthelmintic resistance has increased alarmingly, with significant prevalence in key cattle parasite genera.
• Effective parasite control programs have inadvertently increased selective pressure on parasite genomes.
• The fecal egg count reduction test (FECRT) can be adapted for screening resistance.

Conclusions:

• Sustainable parasite control programs are crucial to mitigate anthelmintic resistance.
• Integrated strategies, including targeted treatments and rotation of drug classes, are essential.
• Balancing productivity with reduced selective pressure on parasites is key for long-term herd health.