Bacillary Hemoglobinuria

C haemolyticum is a soilborne organism naturally found in the GI tract of some cattle. It can survive for long periods in contaminated soil or in bones from carcasses of infected animals. After ingestion, latent spores ultimately become lodged in the liver. The incubation period is extremely variable, and onset depends on the presence of a locus of anaerobiosis in the liver. Such a nidus for germination is most often caused by liver fluke (Fasciola hepatica) infection, rarely by high nitrate content of the diet, accidental liver puncture, liver biopsy, or any other cause of localized necrosis. When conditions for anaerobiosis are favorable, the spores germinate, and the resulting vegetative cells multiply and produce β toxin (phospholipase C). This causes intravascular hemolysis, resulting in hemolytic anemia and hemoglobinuria.

Cattle may be found dead without premonitory signs. Usually, there is a sudden onset of severe depression, fever, abdominal pain, dyspnea, dysentery, and hemoglobinuria. Anemia and jaundice are present in varying degrees. Edema of the brisket may occur. Hgb and RBC levels are quite low. The duration of clinical signs varies from ~12 hr in pregnant cows to ~3–4 days in other cattle. Mortality in untreated animals is ~95%. Some cattle suffer from subclinical attacks of the disease and thereafter act as immune carriers.

The general clinical picture and postmortem findings usually permit a tentative diagnosis. The most striking sign is the typical port-wine-colored urine, which foams freely when voided or on agitation. The presence of the typical liver infarct is sufficient for a presumptive diagnosis. The normal size and consistency of the spleen serve to exclude anthrax and anaplasmosis. Bracken fern poisoning and leptospirosis also should be considered. Diagnosis can be confirmed by isolating C haemolyticum from the liver infarct, but the organism is difficult to culture. Rapid and accurate diagnosis can be made by demonstrating the organism in the liver tissue by a fluorescent antibody or immunohistochemical test or by demonstrating the toxin in the fluid in the peritoneal cavity or in a saline extract of the infarct. PCR has also been used to diagnose clinical bacillary hemoglobinuria in a cow in Japan.

Early treatment with penicillin or tetracyclines at high doses is essential. Whole blood transfusions and fluid therapy also are helpful early in the disease. C haemolyticum bacterin prepared from whole cultures confers immunity for ~6 mo. In areas where the disease is seasonal, one preseasonal dose is usually adequate; where the disease occurs throughout the year, semiannual vaccination is necessary. Cattle in contact with animals from areas where this disease is endemic should be vaccinated, because the latter may be carriers.