Assessment of Dilute Epinephrine and Mechanical Pressure for Prevention of Feline Postoperative Scrotal Hematoma: A Randomized Controlled Trial

Abstract

To determine whether two immediately postoperative preventive procedures, dilute epinephrine (1:400,000) as a scrotal wash or application of controlled mechanical pressure to the scrotum, reduce the risk or severity of scrotal hematoma following routine castration. Male cats with two descended testicles presenting to Midwestern University's Trap Neuter Return program were eligible for inclusion. Cats were assigned via block randomization to control, dilute epinephrine wash, or controlled mechanical pressure groups. For the epinephrine group, 0.2 ml (0.008 mg) of epinephrine diluted with sterile saline was instilled inside the scrotum. In the case of mechanical pressure, a broad-based clip generating less than 0.5 kg of pressure was applied for 10 minutes. Cats were evaluated for scrotal hematoma and the need for treatment by a veterinarian blinded to treatment group. Multivariable logistic regression was used to determine if the incidence of scrotal hematoma or scrotal hematoma requiring treatment was different between groups while controlling for other variables. There were 276 cats with a median age of 30 months (IQR 12,48) and a mean weight of 3.5 kg (SD 1.2). Scrotal hematomas were noted in 15 of the 92 (16%) control cats, as compared with 12 of the 92 (13%) epinephrine and nine of the 92 (10%) pressure cats. Treatment was required for 10 (67%) control, six (50%) epinephrine, and three (33%) pressure hematomas. Regression demonstrated a decreased risk of scrotal hematoma requiring treatment for cats in the pressure group (OR = 0.2, P = .044) controlling for weight (OR = 2.2, P = .006) and surgical duration (OR = 1.1, P = .026). Weight was the only significant variable for the presence of scrotal hematoma (OR = 2.2, P < .0001). Controlled mechanical pressure applied immediately after routine castration can help decrease the proportion of scrotal hematomas that require treatment.