Cattle Health: Mycoplasma – Signs, Treatment & Prevention

Arthritis

Some calves with pneumonia due to M. bovis will develop a severe arthritis two to four weeks later. Different strains of M. bovis have different likelihoods of causing joint problems so some outbreaks have many lame calves while others have none. Affected calves will have swollen joints that are so painful that they will be reluctant to walk to the feed and water bunks. By the time the infection reaches the calf’s joints, severe lung damage has probably occurred. In rare cases, calves can have joint involvement without any signs of pneumonia.

The carpus (knee) and stifle are the most commonly affected joints, but any joint can be involved. Calves can be lame in one or more joints.

The joint swelling primarily comes from inflammation of the joint capsule and the tissues surrounding the joint. The cartilage-covered bone surfaces in the joint, which heal poorly, are minimally affected. This is very important for the prognosis of affected calves, as even joints that are severely affected often recover.

Other Clinical Signs

A small percentage of beef cattle that have Mycoplasma pneumonia will develop ear infections, or otitis. Affected calves will have drooped ear(s) with yellow pus draining from one or both ears. In rare cases, Mycoplasma invades into the inner ear causing a head tilt, circling or falling to one side, or the inability to rise with the affected side toward the ground (Smith, 2002, p 951).

Mycoplasma can also cause abortions, infertility, mastitis, and inflammation of the eyes in beef cattle, but cases are rare.

Diagnosis

A definitive diagnosis of Mycoplasma pneumonia is difficult because M. bovis can be cultured from the nasal secretions and upper airways of normal calves. In order to be sure that M. bovis is contributing to the pneumonia, it needs to be recovered from the lungs of calves. As mentioned before, this requires a special culture medium. M. bovis should be suspected when joint swelling or single drooped ears are noted in a group of calves that have had pneumonia, or when the pneumonia is unresponsive to treatment. It is important to remember that some strains of M. bovis may not cause lameness or drooped ears, so it is very possible to have Mycoplasmosis without these additional signs. In the U.S., M. bovis has become the most common respiratory pathogen of cattle that do not respond well to treatment.

Treatment

Mycoplasma is very difficult to treat because many commonly used antibiotics do not work well. Penicillin kills bacteria by destroying the cell wall. Since Mycolplasma does not have a normal cell wall, these antibiotics are ineffective in treating it.

Oxytetracycline has produced mixed results in treating Mycoplasma. In one study 50 percent of M. bovis isolates were resistant to oxytetracycline. Tulathromycin is the only drug approved for Mycoplasma, and in one study, was the drug most likely to be effective (Godinho, et al., 2005).

The two most important factors in the treatment of Mycoplasma are early recognition and prolonged treatment. Calves treated early in the course of the disease respond fairly well. The need for longer treatment than usual for BRDC is underscored by the fact that without extended therapy, 30 percent to 70 percentof the calves can relapse and require treatment again. Each time a calf relapses it will have more lung damage and be less likely to recover. Current recommendations are to provide continuous therapeutic levels of antibiotics to calves with Mycoplasma pneumonia for 10 to 14 days.

Chlortetracycline at a rate of 0.25 to 1.0 grams per 100 pounds of body weight per day can be added to the feed to extend the therapy protocol to the recommended 10 to 14 days. If a Mycoplasma infection is suspected, a veterinarian should be consulted in developing a treatment protocol that will fit these guidelines and best meet the needs of the operation. Using antibiotics to treat swollen joints is usually unrewarding once the pneumonia has been controlled. The most effective treatment for arthritic calves is to provide easy access to feed and water to prevent starvation and dehydration. It may also be necessary to run these animals to feed and water several times daily until they have begun to recover. The most fortunate aspect of this disease is that it appears, given enough time, a large number of calves will recover. It can take weeks to months for the joints to fully recover and the cattle to start gaining weight.

Prevention

Because a large percentage of normal cattle have M. bovis in their upper respiratory tract, it is next to impossible for stocker operations, which obtain all their cattle from outside sources, to implement biosecurity measures to prevent Mycoplasma from entering their farms. However, cow-calf producers should observe a strict biosecurity protocol when bringing in new additions to the herd.

Since Mycoplasmosis often occurs after BRDC, the most important aspect of prevention of Mycoplasma pneumonia is to reduce the stressors to which cattle are exposed. The same practices that lower the risk of BRDC work best to decrease the risk of Mycoplasmosis. Good vaccination, nutrition, and mineral programs strengthen the immune system of calves making them less likely to develop BRDC and Mycoplasmosis. The number of cattle purchased at any one time should not exceed the capacity of the facilities. Poor-quality or high-risk calves should not be acquired unless they can be watched closely and easily handled for treatment. Also, drenching and balling guns should be disinfected between each use when dosing several calves in a row. Recognizing and treating sick animals early not only decreases the number of “chronics” and calf deaths, but also decreases the spread among populations of cattle.

The vaccines currently available against M. bovis have not been shown to be effective in beef cattle.

Summary

Mycoplasma is a major cause of pneumonia and associated lameness in beef cattle. The frequency and severity of disease has been growing rapidly over the last decade. Early recognition and treatment of sick animals, as well as good overall management programs will decrease the incidence and severity of disease. If a Mycoplasma problem is suspected, work closely with your veterinarian. This is a disease that can have disastrous economic and management effects on a farm if not addressed quickly and aggressively.