Sheep ectoparasite control and animal welfare

The ectoparasites, sheep lice (Bovicola ovis), sheep scab (Psoroptes ovis), sheep ked (Melophagus ovinus) and the sheep blowflies (Lucilia spp., Hydrotea irritans, Calliphora spp.) are a major problem with respect to animal welfare in the sheep industry; not only do they affect the health and well-being of infested animals, but the treatments applied to prevent or control their effects can also raise animal welfare concerns. This paper will discuss the role of sheep veterinarians in reducing or eliminating animal welfare problems associated with sheep ectoparasites. It highlights the correct application or use of the correct chemical at the correct time to control these parasites, which is feasible on farm. The importance of improved farm biosecurity to prevent the reintroduction of infestations once they have been eliminated, will be emphasised. Blowfly strike is a serious animal welfare problem, often resulting in death of affected animals after severe stress and discomfort. The paper emphasises the importance of prevention rather than cure, with mention of strategic use of chemicals and other management strategies including time of shearing and crutching, genetic selection against fleece rot, control of dermatophilosis and surgical removal of skin folds in the breech region. With the increasing public concern in animal welfare issues within the livestock industries, there is a need to improve the health and welfare of sheep. Sound ectoparasite control and eradication programs are an important way of achieving this.