Rabbits provide a viable model for preclinical penile implant studies

Abstract Introduction Inflatable penile implants (IPP) are the mainstay treatment for refractory erectile dysfunction (ED), but device infection is common and confers significant morbidity. Besides the addition of antibiotic and hydrophilic coatings, improvements targeting this complication are lacking. Preclinical in vivo studies to study methods of decreasing biofilm and mitigating infection sequelae are hindered by the lack of animal models containing functional IPPs. Previously, IPP fragments have been subcutaneously placed to study antimicrobial strategies, but the placement of complete, functioning IPP cylinders has not been demonstrated. Objective This biocompatibility study aimed to demonstrate the feasibility of placing and inflating IPPs in rabbits, with the goal of developing a viable model to study penile implant infections. Methods This study utilized 2 cadaveric and 2 live male New Zealand White rabbits. Experimental protocols were approved by IACUC (21-08-418). Cadaveric rabbits were utilized to evaluate surgical technique and ultrasound parameters prior to in vivo study. Following anesthesia and surgical site preparation, functioning IPPs were placed into the rabbits’ flanks. Upon dissection down to the plane between the panniculus carnosus and underlying muscle fascia, a subcutaneous pouch was developed to accommodate the implant. Following implantation, unrestricted ambulation was permitted, and the rabbits were observed daily for activity and recovery. Wounds were inspected daily for drainage, erythema, warmth, and swelling. Inflation-deflation cycling was performed following a 3-day post-implantation recovery period and evaluated via ultrasound. Surveillance was conducted for 14 days, after which the animals were euthanized. Results A single cylinder 14 cm implant without rear tip extender was successfully placed into each rabbit. IPP cycling mimicking the inflation protocol was successfully completed without tissue damage or harm to the animals. All IPP components were successfully visualized via ultrasound, which demonstrated the superficial position of the implant (Figure 1). Over a 14-day observation period, no concerns were identified, and signals of pain or distress, including gait disturbance, hypoactivity, restlessness, weight loss, dehydration, or reduced eating/drinking, were not observed, indicating the biocompatibility of functioning penile implants in the back of rabbits. Conclusions Preclinical in vivo models are the primary representative way to investigate IPP infection. This rabbit model may serve as an effective tool for the evaluation of novel infection prevention strategies following penile prosthesis implantation for ED. Disclosure Any of the authors act as a consultant, employee or shareholder of an industry for: PHC: Boston Scientific and Coloplast.