RISK-FACTORS FOR RESPIRATORY-DISEASES IN NEW-ZEALAND PIG HERDS

Aims. A survey of lung lesions and risk factors for respiratory diseas es was conducted in order to estimate the prevalence of respiratory di seases in the New Zealand pig population and to identify influential m anagement practices. Methods. Eighty-nine New Zealand pig farms with a minimum herd size of 50 sows participated in the survey, and risk fac tor data were collected using a mailed questionnaire. Abattoir data we re recorded once in winter 1995 and once in summer 1996. A total of 68 87 lungs was inspected. Results. The prevalence of enzootic pneumonia, pleuropneumonia and pleurisy in winter was 63,4%, 2.7% and 19.1%, res pectively. Enzootic pneumonia was significantly less frequent in summe r. Pleuropneumonia/pleurisy was found to be more prevalent in the Sout h Island. The univariate risk factor analysis was consistent with earl ier published evidence on the importance of environmental factors rela ted to housing and management of the farm. The multivariate models for enzootic pneumonia and pleuropneumonia or pleurisy had a reasonable g ood predictive power of 81-91% for farms with high disease prevalence. Conclusion. the results are useful to model the disease process on hi gh-risk farms, which account for a considerable proportion of the New Zealand pig population.