Evaluation of a method using Proteus mirabilis and Pseudomonas aeruginosa to experimentally induce dual infection of the urinary bladder in dogs

OBJECTIVE: To evaluate a method using Proteus mirabilis and Pseudomonas aeruginosa to experimentally induce dual infection of the urinary bladder in dogs. ANIMALS: 6 healthy mixed-breed dogs. PROCEDURE: Dogs were anesthetized, and cystitis was induced by infusing a solution of salicylic acid in ethanol into the bladder, followed by an inoculum containing field isolates of P. mirabilis and P. aeruginosa. Dogs were examined daily for 21 days after induction of cystitis. On day 21, dogs were euthanatized, and urinary bladder, renal pelvis, and prostate specimens were submitted for bacterial culture. RESULTS: After induction of cystitis, all dogs had evidence of thickening of the bladder wall, dysuria, tenesmus, and hematuria. Urinalysis revealed proteinuria, hematuria, and pyuria. All urine samples obtained on day 21 yielded growth of P. mirabilis, but P. aeruginosa was not cultured from any of these samples. Proteus mirabilis was isolated from bladder, renal pelvis, or prostate specimens from 4 dogs; P. aeruginosa was not isolated from any of the tissue specimens. CONCLUSION: Results suggest that the method used in the present study fails to induce dual infection of the urinary bladder with P. mirabilis and P. aeruginosa. The inability to establish a persistent dual infection with this method may have been a result of insufficient pathogenicity of the Pseudomonas isolate or an inadequacy of the experimental design.