USING SLAUGHTER INSPECTIONS TO EVALUATE SARCOPTIC MANGE INFESTATION OF FINISHING SWINE

Sarcoptic mange is one of the common swine diseases worldwide. Althoug h mange-free populations can be established with caesarean derived sto ck, by herd repopulation programmes or by eliminating mange with iverm ectin, mange remains prevalent in many countries, Field and experiment al studies indicate that hypersensitive mange is detrimental to perfor mance of growing pigs, Typically, producers tolerate mange infestation in their herds and control measures are often haphazard, This toleran ce to mange infestation is attributable to the covert nature of the lo sses (reduced growth rate and feed efficiency without mortality) and t o the fact that clinical signs of hypersensitive mange (pruritus) are usually viewed as normal. Lack of tools to evaluate mange severity in pigs and to demonstrate its importance has hindered the efforts of vet erinarians to control the disease, Traditionally, veterinarians have u sed slaughter inspections to assess respiratory diseases such as enzoo tic pneumonia and atrophic rhinitis. Much of the value of slaughter in spections is as a tool with which veterinarians can educate and motiva te their clients to improve disease control measures. The potential fo r evaluating hypersensitive mange by inspecting slaughtered pigs for l esions of papular dermatitis was recognised some time ago, but quantit ative evaluation of the reliability of this approach has been lacking, We have conducted several studies in Australia, the USA, Canada, Euro pe and Latin America to evaluate associations between Sarcoptes infest ation and the severity of papular dermatitis at slaughter, using a sim ple ordinal scale for classifying carcasses, Our initial field and exp erimental data in Australia indicated the specificity of localised der matitis to be in the order of 75-80%, but that the generalised dermati tis was highly specific (> 98%) for mange. Subsequent studies in the U S Midwest yielded almost identical results, and indicated that the met hod may also have some utility for surveillance of mange-free herds. R esults from other locations invariably have shown significant associat ions between dermatitis lesions and mange infestation. Relative to oth er methods such as skin scrapings and monitoring pruritus, this method is simple and relatively objective, and should be considered for rout ine inclusion in slaughter Inspection protocols.