Leptospira interrogans serovar Pomona infection associated with carcass condemnation of swine at slaughter

This report describes a clinical case of Leptospira interrogans serovar Pomona infection in finishing pigs, associated with multifocal interstitial nephritis that resulted in carcass condemnation at slaughter. Clinical signs of leptospirosis were not observed. On gross examination, kidneys varied from slightly shrunken to 1.5 times normal size, with pale mottling extending through the cortex and into the medulla. Microscopic examination revealed tubulointerstitial nephritis with lymphoid nodules in affected kidneys. Renal lymph nodes were three to 10 times normal size, often having a cystic appearance. Diagnostic results indicated that, in this herd, serovar Pomona infection had been introduced into the finishing barns with resulting widespread endemic infection in these buildings. Clinical management included antibiotic therapy for the grower and finisher pig inventory, site depopulation with cleaning and disinfection of the facilities, and strict rodent control.