A herd of cattle on pasture had two adults die suddenly; necropsy shows hemoglobinuria and a large liver infarct. Which causative agent is on the top of your list?

• A. Weaponized anthrax
• B. Clostridium chauvoei
• C. Bacillus anthracis
• D. Clostridium hemolyticum

Answer: (D)

Bacillary hemoglobinuria caused by Clostridium haemolyticum best fits these findings. In cattle, spores reach the liver and germinate in preexisting hepatic lesions (often from liver fluke migration), producing toxins that cause intravascular hemolysis. The resulting hemoglobinuria combined with hepatic necrosis leads to large liver infarcts seen at necropsy. The sudden death on pasture with red, hemoglobin-rich urine is a classic clue pointing to this disease.

Other agents don’t align as well with this pattern. Clostridium chauvoei (blackleg) causes severe muscle necrosis and gas production rather than liver infarcts and intravascular hemolysis. Bacillus anthracis (anthrax) can cause sudden death and hemorrhagic lesions, but the characteristic liver infarcts with hemoglobinuria are not typical of anthrax.