Clinicopathological Observation on Haemophilus somnus Infection in a Dairy Cow

Abstract

Haemophilus somnus infection occurred in a 6-year-old Holstein dairy cow in Gifu Prefecture in June, 1984, a month after delivery. The cow was condemned within a day.
Opisthotonus and clouding of consciousness were noticed. When the cerebrospinal fluid was examined, its pressure was high and its color yellowish red. The count of floating cells was 198/mm³. Pandy's reaction was four plus. The concentration of total protein was 100mg/dl, glucose 80mg/dl, inorganic phosphorus 2.7mg/dl, and calcium 7.0mg/dl. An increase in staff neutrophils was seen.
Microscopy revealed hemorrhagic meningoencephalitis, thrombosis, vascular degeneration, and perivascular necrosis of the brain and subdural and subarachnoideal hemorrhage of the spinal cord.
H. somnus was isolated from the brain and the spinal cord. It was very sensitive in vitro to aminobenzyl-penicillin and oxytetracycline. The titer of the micro-plate agglutination test against H. somnus was 1: 1, 280.