Stillbirth/perinatal weak calf syndrome: a study of calves infected with Leptospira

Leptospiral infection has been reported in calves which were either stillbo rn or dead from perinatal weak calf syndrome; 356 such calves were examined for evidence of associations between leptospiral infection and macroscopic , histological and microbiological findings, and the parity of the dam. Cal ves in which leptospiral antigen was detected in the placenta were signific antly lighter by an average of 6 to 10 kg than calves with no antigen in th e placenta. Calves infected with Leptospira were more likely to be infected by Actinomyces pyogenes or Bacillus species. No other significant associat ions were detected. The adrenal gland, lung and placenta were the most usef ul organs to examine for leptospiral antigen. The placenta was the only ant igen-positive tissue 8.9 per cent of the calves submitted with their placen ta.