A 6-year-old, spayed female Labrador retriever was presented with clinical signs of stranguria, pollakiuria, and hematuria of 12 weeks' duration. A bacterial urinary tract infection, diffuse polypoid cystitis, and emphysematous cystitis were diagnosed. Antibiotic therapy combined with extensive resection of the mucosa and submucosa associated with polypoid lesions resulted in complete resolution of clinical signs and resolution of the remaining polypoid lesions. Polypoid cystitis is an uncommon but clinically relevant and reversible condition of the urinary bladder. Resection of mucosa and submucosa of the urinary bladder in dogs with polypoid cystitis may be a useful surgical treatment and can be considered as an alternative to partial cystectomy or mucosal resection.