The Moredun Research Institute has been awarded a £1.2 million grant to explore resistance to sheep scab treatments.

The three-year grant will see Moredun Research Institute collaborate with project partners from the University of Glasgow, Scotland’s Rural College (SRUC) and the Sustainable Control of Parasites in Sheep (SCOPS) industry group.

The project will explore the mechanism of resistance to the macrocyclic lactone (ML) injectables in the sheep scab mite Psoroptes ovis, and how this resistance has spread across the UK.

Project lead, Dr Stew Burgess of Moredun Research Institute, said the £1.2 million grant is a “pivotal investment” in the mission to combat the growing challenge of ML resistance in the sheep scab mite.

“Sheep scab remains a significant threat to livestock health and welfare, imposing substantial economic burdens on farmers across the UK.

“With this funding, we aim to decode the genetic basis of resistance and its spread, providing the agricultural community with vital tools and updated strategies to manage this pervasive issue effectively.

“This project strengthens our collaborative efforts with partners at the University of Glasgow and SRUC and reinforces Moredun’s commitment to pioneering research that drives real-world impact.”

Sheep scab

Sheep scab represents a significant welfare and economic concern for UK livestock production, costing the industry between £80-200 million annually.

Current control strategies rely on organophosphate (OP) sheep dips and ML injectables (ivermectin, doramectin, and moxidectin).

However, overreliance on ML injectables for controlling gastrointestinal nematodes (GIN) and sheep scab has led to the emergence of ML-resistant parasites, posing a “significant threat” to sheep health and welfare, Moredun Research Institute said.

While OP dipping is an effective alternative, it is associated with more complex safety requirements for both operators and the environment and, if overused, scab mites could also develop resistance to OP.

Resistance to treatments

Lesley Stubbings of SCOPS said maintaining two effective control methods is essential for the sheep industry’s ability to control scab in the future.

“Understanding the basis of resistance in the MLs, together with the potential for early detection, will allow the industry to develop strategies to manage and slow resistance,” she said.

Part of the research team at the University of Glasgow, Dr Jenni McIntyre, said: ML resistance is complex and poses a real challenge to farmers in controlling both GIN and scab.

“This exciting project will be the first to apply cutting-edge genomic tools to understand ML resistance in sheep scab mites.”

To produce this new guidance, the project will use new tools, including samples of Psoroptes ovis mites that are either resistant or susceptible to ML treatment and a detailed map of their genes.

The project team will study these samples to understand how ML resistance has developed and then track how this resistance has spread across the UK.

Project partner Jack Hearn of SRUC said: “Translating basic research on the understanding of drug resistance in parasites to improve control strategies has undergone huge progress in recent years.

“We can now target parasites of veterinary importance like the mites that cause sheep scab with a variety of research methods.

“This will lead to much swifter recommendations for improved scab management than previously possible to the benefit of animal welfare and farmers.”