Will we ever get on top of sheep scab?
Sheep scab remains a constant battle for producers up and down the country, and without joined-up thinking and a proactive approach to tackling the disease, it is set to remain a bugbear.
What’s more, independent sheep vet Chris Lewis says we are looking at a “very disappointing picture” with incidences of the disease on par with what they were over a century ago.
So what’s to blame? According to Mr Lewis it’s a combination of some farmers and shepherds viewing the disease as an “acceptable nuisance”, topped with problems associated with long withdrawal periods for the treatments used. In some cases this can be in excess of two months, causing serious problems for those finishing lambs.
“Sheep scab costs the industry a lot, it’s certainly not cheap to treat. So farmers must not just accept it as a nuisance, they must do something about it,” adds Mr Lewis.
“I think if there was a really concerted effort and everybody with sheep decided ‘we are going to get rid of sheep scab’ then it could happen. You could do it on a small scale with regional, local type schemes, but farmers really need to band together and put peer pressure on those not treating in their area.”
Although sheep scab is a difficult disease to quantify in terms of what it costs the UK sheep industry every year, Kath Dun from the Royal School of Veterinary Studies, Edinburgh, says the losses lie in lower productivity of the animals, and the cost of treating the disease on farm.
“Sheep scab is still fairly endemic in a lot of areas up and down the country; it’s a real threat to the sheep industry because of its welfare and economic impact,” adds Ms Dun.
Alike Mr Lewis, Ms Dun says there is an opportunity to get on top of the problem, but only if farmers work together and everyone works to treat the problem.
“I would encourage farmers to speak to their vets to get proper advice on the products that can be used that are best for their situation. And I would also encourage them to work with their neighbours to try and treat together at the same time,” she adds.
“Farmers need to start doing risk assessments for their individual flocks. And when buying in stock, always assume they are buying in infected animals and quarantine accordingly. The critical thing is to make sure to quarantine for long enough – 10-14 days – and that stands for other diseases too.”
Another problem arising from the persistent problem of sheep scab, is the fact many farmers are being forced to treat for the disease several times in one year – something which could lead to further anthelmintic resistance, warns Mike Glover from Torbridge Veterinary Group.
“In an area where sheep scab is endemic, it spreads fairly quickly so farmers may have to treat several times in one year,” says Mr Glover.
“We are very concerned that not being able to treat the disease with single annual doses of a drug will lead to frequent use of those medicines used to treat both internal and external parasites, which put a selection pressure on the worms the sheep are carrying at the time, and leads us down the route of further drench resistance,” he says.
He also encourages farmers to get involved in local control schemes and work to treat their sheep together, as a means of reducing the risk of re-elimination of the disease.
“Scab control has never been easy; it is a constant threat especially in any area with a large population of sheep. But locally with the co-operation of farmers I think we would eliminate the disease.”
Sheep scab: what you need to know…
• Sheep scab is caused by the Psoroptes ovis mite, which feeds on a sheep’s dead skin causing an allergic reaction
• Adult mites can live for up to 40 days and the lifecycle of a female mite is approximately 11-19 days from egg to egg
• Mites pass easily between animals and can survive away from the host for up to 17 days
• Scab is less of a problem in hill sheep and more prevalent in breeds with tightly packed fleece such as Suffolks and Dorsets
• Initial symptoms are a dampness in the wool around the shoulders, which leads to large, itchy red patches on the sheep’s back and shoulders
• Sheep suffering from scab have a drop in productivity, with ewes producing smaller lambs and lower milk production; the growth rates of fattening lambs are affected as a result of lost protein through the lesions
• Scab is best identified by a vet – this can be done with sticky tape on the skin to pick up mites and/or skin scrapings around the lesions. Presence of the disease is confirmed under a microscope
• Scab can be treated by full-plunge dipping in organophosphate (OP) solutions – this kills all mites for 28 days and must be done correctly as per regulations. A licence is required to use and thereafter dispose of the product, which must be used with protective clothing
• Alternatively, scab can be treated with injectables offering between 17 and 60 days protection – producers should seek advice from their vet on what product is suitable for their farm
• Bought-in stock should be quarantined and treated for sheep scab
The Legislation
• In England and Wales, the Sheep Scab Order 1997, states it is a criminal offence for owners or keepers of sheep to fail to treat sheep visibly affected with sheep scab. As a result, local authorities have the authority to control the movement of sheep that are affected by the disease, and force treatment of those sheep if necessary.
• In Scotland, the Sheep Scab (Scotland) Order 2010, means sheep scab is a notifiable disease. Farmers are required to report any cases of the disease, and failure to treat or slaughter infected sheep can result in action being taken against owners and keepers to arrange and pay for a vet to either confirm or rule out the presence of the disease.
Treatment essentials: Top tips for effective control
Dipping in OP solution
• The solution must be made up and replenished to the correct concentration. This is crucial to remember when topping up.
• Keep the solution clean – mud and faeces bind up the OP product, stripping out the dip. Dag animals beforehand and pass them through a water footbath in front of the dip.
• Each animal must be immersed for at least one minute, with the head dipped under the surface twice.
• Sheep should never be dipped when hot, tired or thirsty and should be stood in a drainage pen after dipping until the dip ceases to run from their fleeces.
• Abide by the regulations – you need a licence to purchase and dispose of the product and correct protective clothing must be worn. Seek advice and follow label recommendations.
Injectables
• Calibrate the gun correctly – dose for the heaviest animal you will treat as under-dosing is ineffective.
• Pass your flock through a race or equivalent to ensure you have treated every animal. Omitting one or two sheep can be easily done when injecting.
• Make sure you inject properly – there is a high risk you may fail to penetrate the skin.
• Assume your flock is still carrying live mites for seven days after treatment and handle them accordingly. The same goes for bought-in stock.
• Good training and skills will help ensure treatments are effective.
For more information on sheep scab and to test your knowledge of the disease go to the sheep scab academy.