New figures highlighting an estimated 8.6% of the national sheep flock suffers from scab point to an ever increasing need for farmers to take control of this extremely debilitating disease to eradicate if for good.

The story of the rise of scab in the UK makes for depressing reading and is a tale of a nation that came close to scab eradication, only to see all its good work undone when compulsory dipping ceased.

Reports show that since the end of compulsory dipping in 1992, the incidence of sheep scab incidence increased at a staggering rate. Industry reports outline that by 2007, scab incidence was 60 times higher than it had been in 1999 and by 2017 the rate had increased 100 fold.

In 2006, synthetic pyrethroid plunge dips were banned, leading to a further increase in the group 3-ML wormers to target scab.

Add to that the confirmation of three cases of resistance of the sheep scab mite to the Group 3-ML wormers, and the industry was knocked even further, leading to calls to prioritise this group to be used to treat scab when also targeting internal parasites.

In the interests of slowing down the rate of the development of resistance, at times when only external parasites need to be targeted, it is therefore advisable to consider using a product which targets only external parasites, such as OP dip.

How to step up control measures

Biosecurity is key – Scab can be difficult to prevent as in the early sub-clinical stages of disease, there may be no visible clinical signs. This means that animals which appear perfectly healthy, with no skin lesions, bald patches or pulled wool, can in fact be carrying scab mites. This is why sheep scab can be so easily introduced into the flock when buying animals in, and adequate quarantine procedures are vital.

Hence, new sheep should be kept separate from the flock, at the periphery of the farm, with bio-secure double fencing.

Diagnostic-led approach – It can be hard to distinguish between some parasites, such as scab and lice. However, it is vital that treatment is diagnostic-led. Speak to your veterinarian about appropriate diagnostics, such as a skin scrape for clinical ecto-parasite disease, or an ELISA blood test if subclinical scab is suspected.

Speak to your vet or SQP about what is right for your flock – Vets and SQPs have a wealth of knowledge to help you make informed treatment and prevention choices.

Where only external parasites are likely to need treating, consider using OP sheep dip – The macrocyclic lactones (3-MLs) are a broad spectrum parasite treatment and will also target gastrointestinal worms. When macrocyclic lactones are used to treat scab, it inadvertently exposes internal worms to them. Where only low worm burdens are present, this creates the perfect conditions for the development of resistance. By striving to preserve 3-MLs for when internal worms are present, the industry slows down the rate of development at which worm resistance can occur to the 3-MLs.

The benefits of OP plunge dipping

• Targets only external parasites so will not contribute to the development of anthelmintic resistance of internal parasites.

• As well as treating scab, dip can help prevent it! OP dips such as Gold Fleece have activity for longer than the 17 days that the sheep scab mite can survive off the fleece, meaning that it can also prevent reinfection.

• OP plunge dipping is licensed for the treatment and prevention of both summer and winter external parasites, including blowfly, lice, scab, ticks and keds.

• OP dips such as Gold Fleece have a short, 49 day meat withdrawal.