Of all the causes of pneumonia in beef cattle, Mycoplasma bovis ranks up there as one of the most frustrating. It is hard to identify in the early stages, hard to treat and causes irreversible lung damage. If mycoplasma pneumonia were a song, it would be the annoying little ditties that blare from the speakers of battery powered toys for toddlers — incredibly annoying and hard to ignore.

Mycoplasma bovis is a bacteria without a cell wall. It can reside in the nasal passage of cattle without showing any issues. From there, it can be secreted from the nose and spread to other cattle. If it stays in the nose, then there’s no huge issues.

The trouble is that it won’t stay there. When a calf has a stressful life event or comes down with another cause of pneumonia, mycoplasma migrates from the nose to the lungs. There, it slowly grows, leading to creeping inflammation and permanent damage to lung tissue. While it doesn’t show signs that are obviously different from other pneumonias, mycoplasma pneumonias produce a low-grade fever, a dry cough and make the animal lethargic. If allowed to progress, the disease can spread through the animal’s body, leading to arthritis in joints in the limbs and ear infections.

Its slow growth sets up the mycoplasma catch-22. Because it grows slowly, it isn’t always easy to notice during the early part of the infection. Since it sets up pneumonia during a stressful event, such as a nasty spring blizzard, our normal ways of identifying sick cattle are compromised because all the cattle look a little off. Yet, if mycoplasma is allowed to gain a good foothold in the lungs, antibiotic therapy is often unrewarding. It’s easy to say that early detection and treatment is the key to overcoming this disease, but in practice that’s not always feasible.

In regard to treatment, due to its lack of a cell wall, mycoplasma is not susceptible to antibiotics that function by attacking that structure. Of the products available, tulathromycin, gamithromycin, and enrofloxacin are the only ones that have a label for this disease. My opinion it is better to use the first two, as they have a longer duration of efficacy than enrofloxacin.