Infographic: Sheep Scab – The Microscopic £8.3m Mite

Sheep scab is caused by the mite Psoroptes ovis, a non-burrowing, surface-feeding mite. Scab costs the UK sheep industry annually around £8.3 million, including £0.8 million in reduced animal performance1.



The severity of the disease is influenced by the stage of infection, the strain of P. ovis involved, the time of year, fleece length, sheep age, sheep breed and the individual host’s immune response.



Sheep scab is characterised by intense itchiness caused by the mite faeces.


Clinical signs are generally more severe in lambs and yearling sheep than in ewes. Sheep scab can be introduced to a flock by carrier sheep, including purchased animals, sheep returning from grazing and strays, or by exposure to mites in the environment, including contaminated fields, handling facilities, shared equipment, sheep transport and clothing.


Most sheep scab outbreaks occur during winter and spring months, in young and growing lambs, P. ovis infestation can result in rapid weight loss, debilitation and death. Low birth-weights and high mortality rates in lambs born to ewes with severe sheep scab during pregnancy probably resulting from an excessive loss of body condition in the ewes.

Key Facts:

  • Scab mites can survive for 17 days off the host in wool tags, on equipment or even under finger nails – this is why you need to move sheep to clean pasture with some treatments (pasture that has not had sheep on it for at least 3 weeks)
  • Scab mites do not feed every day so injectables may take time to kill the mites
  • Until the mite faeces is washed off the sheep, they may remain itchy
  • ML (Group 3 – clear) injectables are also wormers so ensure their use is necessary at this time of year and avoid repeat doses


What Do I Need to Know?

  • Am I using the product for treatment or prevention?
  • Can the sheep be moved to clean pasture?
  • Can the flock be treated in one day or does the farm system require a more persistent product?
  • Have the animals had a foot-rot vaccine?


What are my injectable options?

Always discuss your options with your local advisor or vet and make sure you choose the options that will fit your farm and needs. For more information about CYDECTIN®, check out the graph below to see how it stacks up.

CYDECTIN® 1% Sheep Injection

– For the prevention and treatment of psoroptic mange for (scab)
– Injection will protect against scab mite infestation for at least 28 days
– No need to move to clean pasture

CYDECTIN® 20 mg/ml LA Sheep Injection

– Allows a 6-week treatment window for scab

– No need to move to clean pasture

– A single subcutaneous injection treats and affords 60 days residual protection.


To explain the impacts of sheep scab clearly, we’ve created an infographic for you to enjoy. Take a look below:

For the latest news, be sure to follow @Sheep_Farmers on Twitter and Sheep Farmers UK on Facebook.


Nieuwhof, G.J. and Bishop, S. C. 2005. Animal Science, 81: 23-29

CYDECTIN® 20 MG/ML LA SOLUTION FOR INJECTION FOR SHEEP and CYDECTIN® 1% INJECTABLE SOLUTION FOR SHEEP contain moxidectin. POM-VPS For further information please see the product’s SPC or contact Zoetis UK Limited, Walton Oaks, Dorking Road, Tadworth, Surrey KT20 7NS. Customer Support: 0845 300 8034. Use medicines responsibly ( Date of preparation: August 2016