Bacillary Hemoglobinuria in Cows: Redwater Disease Signs and Prevention

Bacillary hemoglobinuria is a severe bacterial disease of cattle caused by Clostridium haemolyticum. You may also hear it called redwater disease because affected cows can pass dark red urine. This color usually comes from hemoglobin released when red blood cells are rapidly destroyed.

The bacteria can live in the liver as dormant spores for long periods. Trouble starts when part of the liver becomes damaged and oxygen levels drop in that area. That creates the right conditions for the spores to activate, multiply, and release a toxin that causes liver injury and sudden destruction of red blood cells.

This disease often appears suddenly in adult cattle on pasture, especially in areas where liver flukes are present. Some cows are found dead with few warning signs. Others show fever, depression, pain, weakness, and red or brown urine over a short period. Because the course can be so rapid, quick veterinary involvement matters.

The underlying cause is infection with Clostridium haemolyticum, a soil-borne clostridial bacterium. Cattle usually become infected by swallowing spores while grazing. Those spores can travel to the liver and remain dormant without causing immediate illness.

Disease develops when liver tissue is damaged and becomes low in oxygen. In many regions, liver flukes are the classic trigger because migrating flukes injure the liver and create the anaerobic conditions the bacteria need. Once activated, the bacteria produce a toxin that damages the liver and causes severe intravascular hemolysis, meaning red blood cells break apart inside the bloodstream.

Risk tends to be higher in cattle grazing wet or marshy areas where fluke exposure is more likely. Outbreaks are often sporadic, but multiple animals can be affected if herd conditions favor both clostridial exposure and liver damage. Your vet may also consider other causes of hemoglobinuria or sudden death while working through the case.

Your vet usually starts with the history, pasture conditions, vaccination status, and a physical exam. Dark red urine, fever, weakness, anemia, and sudden death in a grazing cow raise concern, especially in fluke-prone areas. Because this disease can move so fast, treatment may begin before every test result is back.

Diagnosis often combines clinical signs with laboratory and postmortem findings. Bloodwork may show anemia and evidence of red blood cell destruction. Urine may contain hemoglobin. In animals that die, necropsy can reveal a characteristic area of liver damage along with widespread jaundice or dark kidneys. Your vet may submit liver tissue, blood, or other samples for fluorescent antibody testing, PCR, or other lab methods when available.

Other diseases can look similar, so ruling out differentials matters. Depending on your region, your vet may consider babesiosis, leptospirosis, bacillary hemoglobinuria, postparturient hemoglobinuria, copper toxicity, or toxic plants and chemicals that damage red blood cells.

Prevention usually focuses on vaccination, liver fluke control, and pasture risk management. In areas where bacillary hemoglobinuria is known to occur, your vet may recommend a clostridial vaccine program that includes protection against Clostridium haemolyticum when available in your region. Vaccine schedules vary by product and herd risk, so it is worth reviewing timing before turnout, breeding, or seasonal pasture changes.

Because liver damage often triggers disease, controlling liver flukes is a major part of prevention. Your vet may suggest strategic deworming or flukicide use based on geography, grazing conditions, and local parasite patterns. Wet, marshy, or irrigated pastures can increase exposure to the snail hosts involved in the fluke life cycle, so drainage improvements or grazing adjustments may help in some herds.

If you have had one case, ask your vet about herd-level risk right away. Review vaccination records, recent pasture moves, and any history of sudden deaths or red urine. Prompt necropsy of unexplained deaths can also help confirm the problem and guide a more targeted prevention plan for the rest of the cattle.