Sarcoptic mange and production performance of swine: a review of the literature and studies of associations between mite infestation, growth rate and measures of mange severity in growing pigs.

Cost-effective control of sarcoptic mange requires knowledge of the effects of the disease on production. This paper presents a critical review of the literature on the association between sarcoptic mange and reduced production performance of swine. One of the difficulties in interpreting inconsistent findings among studies is lack of information about the severity of disease, which is likely to vary considerably. Lack of standard methods and failure to quantify disease severity preclude meaningful interpretation of experimental results in commercial production. Three experiments with growing pigs were conducted to evaluate associations between sarcoptic mite infestation and growth rate, and to assess pruritic behaviour and mite-induced lesions at slaughter as indices of mange severity. Sarcoptic mange was associated with increased pruritic behaviour and the presence of papular dermatitis at slaughter. Pruritic behaviour decreased over time despite reinfestation and may be subject to numerous behavioural influences. Growth rate tended to be slower in mange infested pigs, but a significant effect of mange infestation on average daily gain was found in only one trial, in which the severity of skin lesions at slaughter was greatest. These observations suggest that the production effects of mange infestation of growing pigs are variable. Evaluating dermatitis lesions at slaughter may be an objective means for assessing the severity of mange infestation and for relating experimental results to commercial swine production.