Ear infections caused by Mycoplasma bovis are stubborn and often deadly interruptions in the lives of young calves. John Kirk, DVM, MPVM, Extension Veterinarian at the University of California-Davis, says such infections can occur as early as four days and up to 10 weeks of age in pre-weaned calves. They also have been reported in post-weaned calves up to 18 months of age.
Herds with clinical outbreaks of Mycoplasma ear infections have reported infection incidence up to 40 percent, and mortality incidence as high as 100 percent.
Clinical signs of the infection include weakness and unsteadiness when walking; head tilt; purulent discharge from ears; excessive eye discharge and tearing; coughing; nasal discharge; and drooping of one or both ears.
The infections sometimes are complicated by joint infections, pneumonia, genital infections and abortions. Mycoplasma mastitis commonly is present in herds with a high incidence of Mycoplasma ear infections, and colostrum and/or waste milk serve as vectors to transfer the disease from adult animals to calves.
Kirk says some clinical cases respond to tetracyclines, but that treatment always should be discussed with the herd veterinarian. Early detection can be expected to increase the effectiveness of treatment.
To prevent the disease and interrupt the infection cycle in clinical outbreaks, he recommends pasteurization of waste milk at 158' F for one minute or 148' F for two minutes.
Read more of Kirk's observations.