This is a retrospective case series of 27 dogs with emphysematous cystitis. Medical records from two veterinary teaching hospitals from 1992 to 2014 were reviewed. The aims of the study were to determine imaging findings, common underlying disease processes, and prevalent bacterial species and their antimicrobial susceptibility patterns in dogs with emphysematous cystitis. The most common lower urinary tract sign was hematuria. Gas was detected in the wall and lumen of the urinary bladder in 14 of 27 dogs (51.9%), in only the wall of the bladder in 9 of 27 dogs (33%), and in only the lumen of the bladder in 4 of 27 dogs (14.8%). Comorbid diseases were identified in all but one case. The most common comorbid disease processes were diabetes mellitus in 33% of dogs, neurologic disease in 26% of dogs, and adrenal disease in 19% of dogs. Bacterial isolates included Escherichia coli, Enterococcus spp., Klebsiella pneumoniae, Proteus mirabilis, Streptococcus spp., and Actinomyces spp. Enterococcus spp. were always isolated in mixed infections with gas-producing bacterial species. During the period of study, most isolates were predicted to be susceptible to beta-lactam drugs, but updated veterinary breakpoints suggest that fluoroquinolones or trimethoprim-sulfamethoxazole would be more appropriate choices for empiric therapy.