Evaluation of a Multimodal Anesthetic Protocol for Immobilization in Black Vultures (Coragyps atratus) and Turkey Vultures (Cathartes aura)

Anesthetic protocols for non-invasive immobilization of Black Vultures (<i>Coragyps atratus</i>) and Turkey Vultures (<i>Cathartes aura</i>) for procedures lasting up to two hours are lacking. This study directly evaluated the safety and efficacy of a multimodal anesthetic protocol in 11 Black Vultures and 4 Turkey Vultures undergoing electroretinography (ERG). Vultures were anesthetized with intramuscular dexmedetomidine (5 μg/kg), midazolam (0.2 mg/kg), butorphanol (0.2 mg/kg), and ketamine (5 mg/kg) (DMBK), followed by isoflurane induction and maintenance. All vultures were mechanically ventilated to maintain consistent end-tidal CO₂. Monitored parameters included sedation and recovery quality, heart and respiratory rates, hemoglobin oxygen saturation, non-invasive blood pressure, body temperature, and end-tidal concentrations of CO₂, isoflurane, and oxygen. All vultures achieved profound sedation with smooth induction and a median isoflurane maintenance concentration of 1.4% for approximately two hours. Recovery was rapid and uneventful. Heart rates ranged from 60 to 119 beats/min. Mean arterial blood pressure averaged 149 mmHg in Black Vultures and 158 mmHg in Turkey Vultures, with Turkey Vultures showing significantly higher diastolic pressure. A second-degree heart block was detected in one Black Vulture but required no treatment. All ERG procedures were completed successfully. The DMBK protocol provided profound sedation in both species, maintained key cardiorespiratory parameters, including heart rate and arterial blood pressure, within a clinically acceptable range throughout isoflurane maintenance, and enabled uneventful rapid recovery. These findings support DMBK with the cardiorespiratory monitoring system as a safe and effective regimen for anesthetizing vultures and likely other similarly sized raptors requiring non-invasive immobilization.