CASE REPORT: HOCK SWELLINGS AS A PRIMARY LESION OF SALMONELLA PULLORUM INFECTION IN BROILER

W ITHIN two months 9 cases were submitted to the diagnostic laboratory in which the principal complaint was a high incidence of lameness due to swollen hocks. All cases involved broiler chickens 3-4 weeks old, coming from several different chick sources. Losses to disease could not be established, for early chick mortality was only slightly above normal in these flocks, though several of them contained a considerable proportion of stunted birds. No medication was given before the outbreaks or diagnosis. On post-mortem examination the majority of the birds had no lesions other than articular and periarticular swellings at the hock joints. These swellings were either unilateral or else far more pronounced on one side than on the other. An occasional bird had a swollen foot-pad in addition to the hock lesion. The joint capsule was swollen, and the articular cavity contained creamy-white to yellow fluid. The periarticular swellings consisted of edematous tissue rather than free fluid. In one bird the distal portion of the tibia was enlarged on the affected side. A few birds from each flock exhibited some of the more orthodox internal lesions of pullorum, including nodules in the liver, gizzard, and heart, and an excess of pericardial fluid that was either turbid or contained floccular material.