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A model for the control of psoroptic mange in sheep
  1. N. D. Sargison, BA, VetMB, PhD, DSHP, DipECSRHM, FRCVS1 and
  2. V. Busin, DVM, MRCVS, DipECSRHM2
  1. 1Royal (Dick) School of Veterinary Studies, Easter Bush Veterinary Centre, Roslin, Midlothian EH25 9RG, UK
  2. 2Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Midlothian EH26 0PZ, UK
  1. e-mail: neil.sargison{at}

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SHEEP scab became a common cause of animal suffering and production loss in British sheep flocks leading up to and following the deregulation of its statutory control in 1992 (Rose and others 2009). Failure to recognise and treat the disease promptly, or improper treatment of affected groups, compromises animal welfare. Clinically affected animals display abnormal behaviour due to pruritus and discomfort caused by acute and chronic inflammatory lesions (Corke and Broom 1999) and show illthrift due to exudative and endogenous albumin loss, becoming debilitated. Furthermore, perinatal lamb mortality of clinically affected hypoproteinaemic ewes is high due to low birthweights and poor colostrum accumulation (Sargison and others 1995). Sheep scab causes additional economic losses through abattoir carcase condemnations or trimming, downgrading of pelts and the perennial cost of prevention and treatment (Nieuwhof and Bishop 2005).

The high prevalence and risk of sheep scab have led to a high level of dependence on acaricidal drugs. However, the use of macrocyclic lactones can lead to problems with the control of other parasitic diseases, for example due to their broad spectrum of action (Wall and Strong 1987), potentially allowing for selection for anthelmintic resistance (Sargison and others 2007a).Acaricide plunge dips can also be toxic to people or harmful to the environment.

Coordinated sheep scab control schemes

In some regions with a high density of sheep farms and inevitable contact between neighbouring flocks, increasing concern about the unsustainability of a high prevalence of sheep scab prompted coordinated control schemes, with the aims of eradicating the disease in defined areas and removing dependence on acaricidal drugs. The schemes involved individual farmers first deciding whether Psoroptes mites could be present in carrier sheep or introduced to their flocks with purchased animals, sheep returning from grazing or strays (Sargison and others 2006). Psoroptes mites can survive away from their sheep host and …

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