All incoming and returning stock to a farm should be quarantine drenched to reduce the risks of resistance to multiple wormers, which is becoming a growing problem in certain areas.

In a study conducted in the South West, led by vet, Mike Glover, multiple examples of resistance to older active wormer groups on almost half of the farms tested were found.

Out of 25 farms involved in the study, 40% (10 out of 25 farms) had resistance to all three groups of wormers (BZ, LV, IVM) deeming them ineffective, which Dr Glover said, highlights the need for all sheep farmers to have an effective quarantine strategy in place.

Instead vet, Emily Gascoigne from Synergy Farm Health, highlighted the importance of quarantine drenching in order to protect the resistance status of individual flocks and maintain performance.

“Buying sheep can be like Russian roulette. Not only do you not know what diseases they are carrying, but you also don’t know the resistance status of any worms present.

“Whether it’s breeding ewes, rams, or lambs that have been purchased or brought home from grazing, all incoming sheep should be wormed,” she says.

Independent sheep consultant Lesley Stubbings, who is a member of the Sustainable Control of Parasites in Sheep (SCOPS) group says there are still a lot of farmers taking a big risk by not isolating and treating sheep coming into their flocks.

Current advice is that the dual active Startect® or the group 4 wormer, monepantel should be used, as these are the most efficacious wormers in the UK. To align with SCOPs ‘gold standard’ treatment the above would be used alongside a moxidectin product, such as Cydectin® .

“We know that the gold standard using SCOPs Quarantine Treatment Options matrix, will ensure all worms are killed, but the SCOPS silver or bronze options, which are less expensive, but still involve the use of either a group 4 or 5 wormer, will provide very good protection for their flock,” said Ms Stubbings.

Backing up the importance of quarantine drenching, Innovis, which sells more than 2500 rams around the UK, now treat all their tups at the point of sale.

Izzy Willison, veterinary consultant at Innovis said: "When we sell so many tups the potential to spread resistant worms is huge.

“We have now brought Startect into our programme and as rams are leaving the sale they are wormed with the recommendation that they are then housed for 24-48 hours,” she says.

“It’s as much about protecting your land from resistant worms as it is about protecting your stock,” she adds.

The Sustainable Control of Parasites in Sheep (SCOPs) guidelines say all sheep arriving on farm should be wormed and housed on a hard standing for 24-48 hours before being let out to graze. This makes sure any potential worm resistant eggs being shed in faeces are not shed onto pasture.

SCOPs also recommends more than one active worm ingredient is used, to make sure that all worms in the sheep are killed.

Zoetis vet Dr Dave Armstrong says: “The benefits over using one active ingredient at quarantine are vast because it not only kills worms resistant to other products, but also protects the individual actives. This will ensure successful drenching of your flock now and into the future.”

In addition, sheep should also be treated as if they are carrying sheep scab unless there is absolute assurance they are not, as the disease is becoming more of a problem and more widespread.

Dr Armstrong added that farmers not wishing to dip, can instead use a combined wormer and scab product, such as Cydectin® long acting injection for sheep.

“Used alongside one of the newer groups of wormers such as Startect or monepantel it will add a belt and braces approach to remove resistant worms and sheep scab at the same time preventing their introduction into your flock,” says Dr Armstrong.

Following quarantine treatment, sheep should ideally be moved to pasture which is contaminated with resident worms. This helps to ensure that any worms surviving the quarantine treatment are then diluted by other susceptible worms already on the pasture. This is known as refugia, which plays a critical part in delaying the development of anthelmintic resistance.