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Across the Americas, great horned owls ( Bubo virginianus ) are often presented to veterinarians for conditions requiring pain management. Although recent studies have evaluated opioid drugs in raptor species, information in Strigiformes is lacking. The objective of this study was to evaluate the analgesic effect and duration of action of hydromorphone hydrochloride, a full µ-opioid receptor agonist, in great horned owls. In a randomized, blinded, balanced crossover study, 6 adult birds (5 females and 1 male) received hydromorphone (0.3 and 0.6 mg/kg) or saline (0.9% NaCl) solution (0.03 mL/kg; control) in the left pectoral muscle, with a 7-day washout interval between treatments. Each bird was assigned an agitation-sedation score, and the thermal foot withdrawal threshold (TFWT) was measured at predetermined times before ( t = 0 hours) and after treatment administration ( t = 0.5, 1.5, 3, and 6 hours). Measurements of the TFWT were obtained with a test box equipped with a thermal perch, which delivered a gradually increasing temperature 40-62°C (104-143.6°F) to the right plantar surface of the owl's foot. Compared with controls, hydromorphone at 0.3 mg/kg dose resulted in significantly higher mean TFWT at 0.5 hours ( P < 0.001), 1.5 hours ( P = 0.003), and 3 hours ( P = 0.005), whereas the 0.6 mg/kg dose resulted in significantly higher mean TFWT from 0.5 hours ( P = 0.035) to 1.5 hours ( P = 0.001). Both hydromorphone doses were associated with a significant change in the agitation-sedation score ( P = 0.001), consistent with mild to moderate sedation. Two owls were observed tremoring after administration of the 0.6 mg/kg dose, which was not noted after the 0.5-hour timepoint; no other adverse effects were identified. This study offers scientific evidence to support the use of a µ-opioid agonist in great horned owls for pain management. Pharmacokinetics and other pharmacodynamic studies of other pain models evaluating hydromorphone and other opioid drugs in this species are still needed.

Distraction osteogenesis was used in 2 wild raptor patients for the repair of tibiotarsal fractures. The first case was a hatching year female peregrine falcon ( Falco peregrinus ) admitted with an open oblique right distal tibiotarsal fracture. The fracture was surgically managed with the external skeletal fixator intramedullary pin tie-in technique (ESF-IM pin tie-in). Appropriate healing of the fracture site occurred with the ESF-IM pin tie-in. However, there was significant pelvic limb shortening of the affected leg, and the bird consequently developed pododermatitis on the contralateral foot. The second case was an adult female great horned owl ( Bubo virginianus ) that was admitted with a closed, partially healed, overriding right tibiotarsal fracture. Because of the advanced stage of this fracture, which presented with a fibrous callus, and the already apparent pelvic limb shortening, the ESF-IM pin tie-in was not used. Both patients were fitted with a circular external skeletal fixator (CESF), and distraction osteogenesis was performed until the length of the pelvic limb was deemed anatomically adequate. It is critical that rehabilitated raptors be released without any physical conditions that may reduce their ability to survive and reproduce in the wild. Pelvic limb shortening can potentially predispose a raptor patient to pododermatitis, even with fatal consequences, in both captive and wild environments. The orthopedic technique used here proved useful to repair the limb shortening in both raptor cases, and each bird fully recovered and was released.