Twenty years ago, infectious disease caused by Mycoplasma bovis (M. bovis) was on few bovine veterinarians’ and producers’ top 10 lists of health concerns. Not anymore.
“It’s really kind of exploded the last 20 years or so in the dairy industry,” says Geof Smith, DVM and a dairy technical services veterinarian with Zoetis. (Smith shares his insights on M. bovis and how to address it in the brief video.)
Beef animals aren’t off the hook, either. The bacteria routinely contributes to disease and related issues in cow/calf herds as well as in backgrounding operations and feedlot cattle.
Mycoplasma bovis is widely distributed throughout feedlot cattle populations, according to Russ Daly, South Dakota State University Extension veterinarian and State Public Health Veterinarian. “Most calves first encounter the germ before weaning, but if not, they usually become rapidly colonized upon mingling with other calves on their arrival to the feedyard. It only takes about 100 organisms to colonize (become established in) a calf’s nasal passages,” he says in an online article here.
Large Percentage of Dairies Affected
Zoetis reports M. bovis is a cause of mastitis, arthritis and bovine respiratory disease (BRD). Respiratory disease caused by M. bovis can be chronic, leading to irreversible lung damage, mortality and high costs.
“I would say 60% to 70% of dairies have mycoplasma at least as a component of the respiratory disease that they deal with,” Smith says. “I talk with a lot of veterinarians who don’t think (their clients have) had it in their herds, and then it shows up as a major component of a problem they’re dealing with. So, I think it’s known but underrecognized,” he adds.
“Unlike most bacteria, it’s a very small, simple organism that doesn’t have a cell wall,” Smith says.
As a result, he says some products – penicillins and cephalosporins – are ineffective, because they are designed to attack the cell wall. Likewise with sulfonamides-trimethoprim which stop folic acid production, something that most bacteria need but not Mycoplasma. The same is true for vaccines historically, which have been aimed at antigens or components of the cell wall.
“One of the other tricky things about this organism is it doesn’t grow in regular culture conditions,” Smith says. “So if we take a sample and send it in to the lab and you specifically request a mycoplasma culture, you might still not find out it’s there.”
Instead, Smith says what veterinarians are likely to hear from a producer is: “I’ve got a lot of pneumonia that doesn’t respond to treatment, and I can’t figure out what the problem is.”
Smith says there are still a lot of unknowns about the various ways M. bovis is transmitted, which researchers continue working on to understand.
“We know it’s transmitted through milk and by nose-to-nose contact, but there are dairies that manage to prevent those factors yet still have mycoplasma in their calves,” he says. “There is the theory that you can have chronic Mycoplasma bovis carrier cows in herds that are able to transmit it to their calves, and then those calves spread it to the rest of the herd.”
Treatment And Prevention
Active ingredients such as macrolides, oxytetracyclines, fluoroquinolones and florfenicol are licensed for treatment of M. bovis.
For prevention, Smith recommends using the cattle industry’s first modified live vaccine for M. bovis: Protivity. It can be used in calves 1 week of age and older.
“Protivity is a great option for producers who want to limit antimicrobial usage, improve herd health, optimize productivity,” Smith says. “We’ve seen really good success with it.”
In addition, Smith advises pasteurizing milk and limiting stressors, such as transportation and commingling.
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