Case Report Penile Prolapse (Paraphimosis) Following Acepromazine Administration in a Laboratory Rabbit

Background: Penile Prolapse (Paraphimosis), defined as the persistent extrusion of the penis from the preputial sheath without erection, is a rare condition in rabbits. It may result from trauma, neurological dysfunction, infection, or drug-induced relaxation of the preputial muscles like administration of phenothiazine in horses. Acepromazine, a phenothiazine tranquilizer commonly used for sedation, exerts α-adrenergic blockade and peripheral vasodilation, which may predispose to penile protrusion or prolapse. However, this reaction has rarely been reported in rabbits. Methods: ۱۰ male laboratory rabbit intended for use in orthopedic surgical project, were administrated with acepromazine (۱mg/kg) + ketamine (۳۵mg/kg) +xylazine (۵mg/kg). Next day, each rabbit received acepromazine (۱mg/kg) for sedation purposes in order to clean surgery wound. no surgical or medical intervention was performed afterwards. Results: On each administration of acepromazine, one of the rabbits (same each time) exhibited paraphimosis that lasted for approximately three hours. The penis appeared swollen, exposed and out of sheath but showed no signs of necrosis or trauma. No other clinical abnormalities were observed. The condition resolved spontaneously without surgical or medical intervention, and no recurrence was reported afterward. Conclusion: This case suggests that acepromazine can induce transient penile prolapse (Paraphimosis) in some rabbits, likely due to smooth muscle relaxation and α-adrenergic blockage. Even though paraphimosis caused by acepromazine is uncommon, it has been mostly reported in horses and only rarely in other species, likely due to individual variability. In rabbits, potential complications following paraphimosis may include penile edema, impaired drainage, pain, secondary infection, and, in prolonged cases, ischemia or necrosis. Therefore, veterinarians and laboratory animal researchers should be aware of this possible adverse effect, especially during pre-anesthetic or sedative use of acepromazine

کلیدواژه ها:

Rabbit ، Penile prolapse ، acepromazine ، Adverse drug effect ، laboratory animal