ORNITHOBACTERIUM RHINOTRACHEALE INFECTION IN TURKEY BREEDERS

A sequence of outbreaks of respiratory disease separated by intervals of about 2 wk occurred on three turkey breeder ranches. The last two r anches affected belonged to different companies and were separated by a distance of 11 km. Mortality on the last ranch was particularly seve re among certain segregated groups of turkeys that included toms; heav ier birds, and birds undergoing a stressful event such as artificial i nsemination. On this ranch, percentages of mortality within an 18-day period were 5.2% in toms, 2.4% in hens, 7.4% in heavy toms and 5.4% in heavy hens. Turkeys from 27 to 42 wk of age were examined during the outbreaks. Gross lesions included severe lung consolidation with fibri nous exudate on the pleura and air sacs, petechiae on the epicardium, and increased cloudy fluid in the pericardial sac. Liver and spleen we re moderately enlarged. Histologically, there was severe fibrinohetero philic inflammation in the airways, pleura, and air sacs and severe pe rivascular interstitial edema in the lungs. Liver had acute coagulativ e necrosis of hepatocytes associated with occasional thrombosis at the periphery of the liver lobes. Ornithobacterium rhinotracheale was iso lated from tissues of the respiratory system, such as infraorbital sin us, trachea, lung, and air sacs, but not from the liver, spleen, or bo ne marrow. Escherichia coli was isolated less often from lung, air sac , and trachea.