Inefficacy of Dilute Epinephrine in Preventing Feline Scrotal Hematomas: Results From a Randomized Control Trial

Abstract

Introduction: The authors previously investigated the use of epinephrine at 1:400,000 dilution to prevent scrotal hematoma but found no significant reduction in hematomas. We hypothesized that higher concentrations of epinephrine would reduce the incidence of hematomas. Methods: Male cats trapped for Midwestern University College of Veterinary Medicine’s Trap-Neuter-Return program were assigned to one of three treatment groups in this randomized control trial: LRS control (A), 1:40,000 epinephrine (B), or 1:120,000 epinephrine (C). Each patient received 0.2 mL of treatment as a topical wash within the scrotum. Veterinarians blinded to the treatment group assessed for the presence and severity of hematoma at three stages. Results: 398 cats were enrolled into groups A (n = 136), B (n = 133), and C (n = 129). Number of hematomas occurring in each group were 15 (11%, 95% confidence interval [CI]: 6–18%), 12 (9%, 95% CI: 5–15%), and 8 (6%, 95% CI: 3–12%), respectively. There was no difference in the incidence of scrotal hematoma (P = 0.397) or scrotal hematoma requiring treatment (P = 1.0). Weight was the only variable associated with the risk of hematoma (odds ratio [OR]: 1.7; 95% CI: 1.3–2.3; P < 0.0001). Conclusion: Despite its vasoconstrictive effects, dilute epinephrine as a topical wash was not effective in preventing feline scrotal hematomas.