In one study researchers examined the effect of tiamulin, lycomy- cin, and a combination of chlortetracycline and tiamulin on the development of pneumonia and growth performance in naturally exposed pigs and the results indicate that the antibiotics used had little influence on the development of lesions of enzootic pneumonia. Although these antibodies enhanced growth performance, their use was not cost effective. In other studies, kitasomycin, tiamulin, and lincomycin, used either before or after M. hyop- neumoniae challenge, did not reduce the clinical signs or lesions of mycoplasmal pneumonia. The newer quinolone antibiotics appear to be effective against mycoplasmal pneumonia, but none of these antibiotics are commercially available in the United States. The fact that pigs that recovered from mycoplasmal pneumonia were refractory to subsequent challenge led researchers to investigate the possibilities of preparing an immunizing agent.
Commercial vaccines are available for the prevention of mycoplasmal pneumonia in pigs.
Other studies confirmed the improvement in lung lesions, but have not always demonstrated an advantage in growth rate. The value of vaccination in relation to the cost of the pro- cedure should be examined in each herd before initiating an immunization program. Whenever possible, the farm manager should attempt to incorporate sound management procedures into the pro- duction system. Special attention should be given to the factors listed in Table 1 especially the major influences designated with 3 pluses. These programs used alone or in combination have been shown to allow pigs to attain a growth rate near their genetic potential if all other inputs are correctly managed.