Comparison of clinical signs, diagnostic findings, organisms isolated, and clinical outcome in dogs with bacterial pneumonia: 93 cases (1986-1991).

Medical records were reviewed for 93 dogs with bacterial pneumonia from which transtracheal aspiration samples were obtained for culturing of Mycoplasma spp and aerobic bacteria. On the basis of culture results, there were 65 Mycoplasma-positive dogs, including 7 dogs for which only Mycoplasma spp were isolated, and 28 Mycoplasma-negative dogs. Most dogs were > 5 years old, and differences in breed or gender distribution among the 3 groups of dogs were not detected. Hematologic and serum biochemical analysis results did not differ significantly between Mycoplasma-positive and Mycoplasma-negative dogs. Fifty-three of 93 (57%) dogs had a concurrent medical problem that may have predisposed them to developing bacterial pneumonia as a sequelae to aspiration or immunosuppression. Mycoplasma-positive dogs were significantly (P < 0.005) more likely to have > 1 species of bacteria isolated from their transtracheal aspiration samples. Clinical outcome was favorable when antimicrobials were selected on the basis of antimicrobial susceptibility results for the other bacterial isolates and not on results of the antimicrobial activity against Mycoplasma spp. It could not be determined whether Mycoplasma spp were primary pathogens or only opportunists.