In contrast there was a decrease in both the mean proportion of lung with lesions and the mean lung score for Beaufort challenged pigs on day 28 compared to day 21.However data may have been skewed by the fact that one of the pigs euthanased 21 days post-challenge had evidence of secondary bacterial infection, with subacute pneumonia and a Goodwin lung score of 31. Overall, the highest prevalence of lesions was found in Hillcrest challenged pigs 28 days post-inoculation. No visible pneumonic lesions
were observed in the unchallenged pigs on day 21 or 28.