Evaluation of a chemical immobilization protocol in Cape porcupine (Hystrix africaeustralis) undergoing surgical gonadectomy

Chemical immobilization of porcupine is often required for wildlife studies or specific clinical needs, but details and clinical effect of general anaesthesia for surgical procedures in this specie is not reported in literature. The aim of this preliminary study was to investigate the use of a novel balanced anaesthesia protocol in Cape porcupines (Hystrix africaeustralis). The primary objectives were to evaluate the quality of sedation, intubation, maintenance and recovery from anaesthesia and the impact of the combination of drugs used on the physiological parameters. The secondary objective was to assess the ease of orotracheal intubation using a traditional laryngoscope versus video-assisted intubation by means of a smartphone otoscope. The study was conducted at the Valcorba Zoological Park, following approval from the Institutional Ethical Committee of the University of Padova. Six porcupines received a combination of dexmedetomidine (0.008 mg/kg), butorphanol (0.3 mg/kg), ketamine (5 mg/kg) and midazolam (0.2 mg/kg) intramuscularly. All the animals achieved recumbency within 5 minutes of injection and lost palpebral reflex within 10 minutes. Intubation was firstly attempted using a video-otoscope and then achieved within 12 minutes from injection in all porcupines after 1 to 4 attempts using a laryngoscope with a Miller blade and a urinary catheter as guidewire inserted into the endotracheal uncuffed tube. All animals underwent volatile anaesthesia with isoflurane in oxygen by spontaneous ventilation. Echocardiography and abdominal ultrasound were performed on all porcupines, surgical orchiectomy on 5 subjects. Physiological parameters such as heart rate, respiratory rate, pulse-oximetry, arterial blood pressure, end-tidal CO2 and temperature were stable in all animals during the procedures. Intratesticular administration of lidocaine 2 mg/kg contributed to preventing any pain-response to surgical stimuli. Extubation was feasible in less than a minute after the isoflurane was turned off and all porcupines were able to walk within 12 minutes of intramuscular administration of atipamezole (0.08 mg/kg). Sedation, intubation, maintenance, and recovery quality were assessed as good in all animals, ensuring safe and effective immobilization during procedures. Moreover, recovery was predictable, and smooth in all animals. No complications occurred during the procedure nor in the follow-up. The studied drug combination might be a valid alternative in porcupine chemical immobilization and offers the possibility to perform a safe and stable anaesthesia allowing surgical orchiectomy. Moreover, the drug combination used allowed intubation, nevertheless some technical difficulties were encountered. Larynx visualization was challenging due to the anatomical features of porcupines and laryngoscope provided acceptable larynx visualization, but many attempts were often required to perform intubation. In contrast, otoscope laryngoscopy was unsuccessful in this study, although it has been reported as a simple and effective in small laboratory rodents. Other investigations are needed to optimize intubation technique, as correct airway management is fundamental to safe anaesthetic practice.