Livestock: Mystery of Bovine Respiratory Disease Continues — DTN

    Whether it’s called summer pneumonia or preweaning pneumonia, respiratory disease in beef calves is a leading cause of illness and death.

    Russ Daly, Extension veterinarian with South Dakota State University, said ongoing research into preweaning Bovine Respiratory Disease complex (BRD) is yielding clues about risk factors. But he added it remains difficult to pin down ways to prevent the disease.

    The USDA’s National Animal Health Monitoring System (NAHMS) reports BRD is responsible for 29% of all calf death losses in the U.S. The incidence of BRD in preweaned calves is 12%, with it peaking around the 120-day age mark. Organisms associated with BRD include infectious bovine rhinotracheitis (IBR), bovine viral diarrhea (BVD), bovine respiratory syncytial virus (BRSV) and Parainfluenza Type 3 (PI3).

    Bacterial agents that contribute to BRD are Mannheimia haemolytica, Pasteurella multocida, Haemophilus somnus and mycoplasma.


    Daly said calves that don’t get good colostrum (quantity/quality) are at risk. Some calves will be affected as early as 1 or 2 months of age.

    Exposure to older animals should be avoided, including fenceline contact. Calves still developing immune systems are more likely to contract a respiratory illness when exposed to animals shedding viruses.

    “I hear too many stories where fenceline exposure is a factor for me to not think there’s something going on,” Daly said. “The more separation between those animals the better.”

    Stress is another common factor. Anything that stresses calves can make lung problems worse. Moving calves to new pastures may seem like a good idea, but stress could make problems worse. Even gathering dams with their calves to artificially inseminate can lead to transmission of disease.

    “We want to minimize stress as much as we can,” Daly continued. “Understandably, if we need to administer an antibiotic, we are going to have to move and work them. But until your veterinarian decides you need to treat, it’s best to keep stress levels as low as you can.”


    There are vaccinations for calves and potentially for cows that may help. Many veterinarians recommend vaccinating calves for pneumonia pathogens at turnout.

    Cows can be vaccinated during pregnancy to boost immunity through colostrum.

    Daly stressed it is important producers work with their veterinarians to be sure products used are aimed at pathogens most likely to be problems in their individual herds.

    “We know that good vaccination programs don’t necessarily prevent all cases of calf pneumonia, but it still makes sense to do what we can,” he said. “There is increasing evidence that giving a modified live vaccine to very young calves can provide some immunity later on, so vaccinating at turnout makes sense.”

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