Abstract
Histopathological examination revealed multiple white nodules on the myocardium and diaphragm of a sick head of Japanese Black cattle at a slaughterhouse to consist of many tiny abscesses containing gram-negative bacteria. The ID test H/N Rapid identified the organism as Histophilus somni (Haemophilus somnus). The 16S rDNA sequence of the organism taken from the abscesses demonstrated 97% homology with that of H. somnus. Immunostaining with the H. somni antiserum detected the H. somni antigen in degenerated neutrophils within the abscesses. These results confirmed the diagnosis of myocardial and diaphragmatic abscesses cased by H. somni.
