Mycoplasma gallisepticum as a model to assess efficacy of inhalant therapy in budgerigars (Melopsittacus undulatus).

One hundred budgerigars (Melopsittacus undulatus) were infected in the nares (0.02 ml/naris), eye (0.02 ml/eye), and throat (0.2 ml) with Mycoplasma gallisepticum (MG) R strain (3.175 x 10(7) colony-forming units/ml). Fifty birds were treated with sterile broth and served as the controls; 25 of those were exposed to an inhalant, and the others were not treated. Infected birds were divided into four groups; 1) no treatment, 2) penicillin in drinking water, 3) inhalant, 4) both penicillin and inhalant. At days 3, 7, 10, 14, and 21 postinfection (PI), birds were assessed for clinical signs of disease. Five birds in each group were euthanatized at each interval PI; quantitative cultures were performed on lavages from the nares and trachea and on throat swabs; tracheas and air sacs were examined histopathologically. No clinical signs, lesions, or cultural isolations occurred in any control birds. All infected birds developed clinical signs and lesions of the trachea and air sac, but none died. The most severe clinical signs were seen in birds that were infected with MG and received no other intervention or birds that received penicillin in conjunction with infection. Increased respiratory tract lesions were associated with penicillin treatment; aerosol therapy resulted in fewer lesions.