During the 2008 Midsouth Stocker Conference, attendees had an opportunity to hear from
According to the presenters, M. bovis infections can result in pneumonia, joint swelling and middle-ear infections in stocker calves. There are several strains that vary in their ability to cause disease and more than one strain can infect a calf.
The risks of commingled cattle become magnified when there is an M. bovis infection present, as the organism can be spread through aerosol droplets, close contact, as well as contaminated watering troughs or feeders. An outbreak will typically occur two to four weeks after the arrival of new cattle.
Most cattle are exposed to this bacterium at some time in their lives and may spread the disease for weeks after exposure, and, according to
Detecting an M. bovis infection can be challenging as symptoms can be difficult to recognize early in the disease and hard to differentiate between other causes of pneumonia. You should watch for the following:
- Low-grade fever
- Calves that will still eat, but come to the bunk more slowly
- Calves that are not as depressed as other calves affected with pneumonia
- Rapid breathing and a moist cough
- Clear nasal and eye discharge
- Swelling along the back
- Tilted head and dropped ears
- Stiffness and lameness, especially in the upper joints, appears in about 25 percent of affected calves
- Poor treatment response.
If your calves do become infected with M. bovis, you can expect up to a 30 percent death rate with many calves becoming chronic poor doers. M. bovis infections can be difficult to treat because it mutates easily and many commonly used antibiotics act on bacterial cell walls, while M. bovis does not have a cell wall. The presenters recommend focusing treatment on other sources of pneumonia infections, so that the calves’ immune systems are better able to deal with the M. bovis infection.