What is sheep scab and what can you do about it?

Sheep scab is an allergic dermatitis which is caused by the mite Psoroptes ovis. It is a highly contagious condition as the mites live and feed on the skin and so they are easily spread onto in contact sheep.

Clinical signs such as scratching and rubbing are caused by an allergic response to the saliva and faeces of mites. This is important to note as clinical signs may persist after successful treatment as the saliva and faeces can continue to cause irritation even after the mites have been killed.

 Chewing lice infestation has similar clinical signs to sheep scab but different treatments may be required so a definitive diagnosis is vital before treatment begins. This can be done either with a skin scape or a blood test.

• Biosecurity: Good biosecurity practices will help to reduce the risk of scabs by preventing them from getting on to farm
• Quarantine: Treat sheep for scab on arrival at a farm or leave in isolation for 2 weeks and use the blood test
• Clean and disinfect all equipment and trailers after use
• Avoid contact with infected sheep. Ensure all visitors to the farm (shearers, contractors, etc.) disinfect their protective clothing
• Fencing: good quality fencing will help to prevent contact with neighbouring flocks

Once scab is confirmed, ALL animals should be treated including any sheep that may have been in contact (including from neighbouring farms). Treatment options are an ML injection or plunge dipping. It is important to note that organophosphate dips are only authorised for use as plunge dips. The use of organophosphate dips via showers and jetters is not authorised and not fully effective against scab, which could lead to resistance.

Scab mites do not feed every day and can survive for 17 days off-host. If a non-persistent treatment is used then sheep need to move to a clean pasture. ML injectables are also wormers so try to avoid dose and move strategies that could lead to increased worm resistance.

It is very important that the correct dose is used when treating for scab as underdosing can speed up the spread of resistance.

CYDECTIN 20 MG/ML LA SOLUTION FOR INJECTION FOR SHEEP
contains moxidectin. To treat and prevent mixed infections of gastrointestinal nematodes, respiratory nematodes, and certain arthropod parasites in sheep.

POM-VPS For further information please see the product’s SPC or contact your medicine supplier or Zoetis UK Limited, First floor, Birchwood Building, Springfield Drive, Leatherhead KT22 7LP www.zoetis.co.uk. Customer Support: 0845 300 8034. Use medicines responsibly (www.noah.co.uk/responsible). Date of preparation: July 2020 MM-10014