Producers should keep three things in mind when controlling M. Bovis in feedlot cattle
According to South Dakota State University Extension and State Public Health Veterinarian Dr. Russ Daly, in order to effectively control infectious diseases in cattle, producers need to address one or more of the three components in the disease process – the germ, the animal and the environment.
“For many reasons, Mycoplasma bovis (M. bovis) is a challenging component of respiratory disease in feedlot calves,” Daly explains. “Understanding the factors that help it become established in calves is a good first step in formulating a plan to help diminish its effects on health and productivity.”
The first consideration when mitigating M. bovis in feedlot cattle, according to Daly, is to address the germ. This can be done by using antibiotics to kill the germ or to slow down progression once it has entered the body.
“Antibiotics are the hallmark of treating bacterial infections in calves, but M. bovis infections present some challenges due to the bacteria’s ability to become well established in body tissues,” explains Daly.
He notes there are several injectable antibiotics approved for use against M. bovis, including enrofloxacin, florfenicol, gamithromycin and tulathromycin.
“However, regardless of the antibiotic used, once clinical signs begin in the animal, results can be variable and often disappointing,” Daly states.
“Tissue damage caused by M. bovis, whether in the lungs or in the joints, makes it difficult for an antibiotic to reach high enough concentrations for a long enough time to slow down or kill the bacteria,” he explains. “Treating calves early with a product that reaches high blood and tissue levels for long periods of time is important.”
Daly notes metaphylaxis, which involves treating incoming cattle with full therapeutic doses of antibiotics upon arrival, has been successful at decreasing illness and death rates in high-risk calves.
“Antibiotics approved for metaphylaxis are prescription injectable drugs, to be used only under direction of a veterinarian,” Daly says. “Feed-grade antibiotics are not considered effective, nor are they labeled for use against M. bovis.”
In Daly’s opinion, when controlling M. bovis infections, the animal is the second component of the disease process producers should address. He encourages boosting animals’ defense mechanisms in order to neutralize the infectious agent before it starts causing clinical illness.
Although there are several commercial vaccines on the market for M. bovis, Daly notes they are fairly un-effective and some studies have even shown to indicate more severe illness in vaccinated animals versus unvaccinated animals.
“In many situations, M. bovis infections are already well established prior to vaccination,” he says, further noting vaccinating calves against other bovine respiratory disease (BRD) pathogens is generally a good practice to reduce the instance of M. bovis and other respiratory disease.
Daly’s third strategy for mitigating M. bovis involves taking steps to ensure animals don’t encounter the disease agent in their environment.
“For many cattle diseases, biosecurioty is an important aspect of prevention,” Daly says. “However, isolating and testing incoming cattle for M. bovis isn’t very viable, especially in feedlot situations.”
“Not much is known about the potential for M. bovis to be transmitted from environmental sources as well,” he continues. “While M. bovis can survive for extended periods of time in cool, moist conditions, it’s largely unknown how important that is for overall transmission. We do know the bacteria is not very resistant to disinfection and is inactivated by drying and sunlight.”
With this in mind, Daly suggests separating sick animals from non-infected animals as well as partaking in strategies to reduce stress and promote immunity in feedlot calves to reduce the effects of M. bovis.
Hannah Bugas is the managing editor of the Wyoming Livestock Roundup. Send comments on this article to firstname.lastname@example.org.