Sedative and cardiopulmonary effects of medetomidine and butorphanol, with or without vatinoxan, in puppies - randomised, blinded clinical trial.

Medetomidine-butorphanol effectively sedates puppies; adding vatinoxan reduces bradycardia, and supplemental oxygen is recommended.

This randomised, blinded clinical trial evaluated the sedative and cardiopulmonary effects of medetomidine-butorphanol (MB) versus medetomidine-vatinoxan-butorphanol (MVB) in 32 healthy client-owned puppies aged 42–51 days undergoing elective brainstem auditory-evoked response (BAER) testing. Puppies were randomised within litters to receive either MB (medetomidine 10 μg/kg + butorphanol 0.2 mg/kg) or MVB (medetomidine 10 μg/kg + vatinoxan 0.2 mg/kg + butorphanol 0.2 mg/kg) intramuscularly. Both protocols achieved adequate sedation within 5 minutes. Vatinoxan, a peripherally acting alpha-2 adrenoceptor antagonist, significantly attenuated the bradycardia associated with medetomidine; pulse rate nadir at 5 minutes was 109 ± 15 bpm (MB) versus 142 ± 28 bpm (MVB). Mean arterial pressure was significantly higher in the MB group during the first 15 minutes, though no animal developed clinically significant hypotension (MAP < 60 mmHg). Hypoxaemia (SpO2 < 95%) was the most frequent complication, occurring in 56% of puppies (18/32) breathing room air, but resolved promptly with supplemental oxygen. Sedation was reversed with atipamezole 25 μg/kg IM, and all recoveries were uneventful. Sedation scores did not differ significantly between groups, indicating vatinoxan did not compromise sedation quality. The study highlights that medetomidine-butorphanol is a clinically effective sedation protocol for young puppies, and that vatinoxan addition mitigates alpha-2-mediated cardiovascular depression. Supplemental oxygen is strongly recommended regardless of protocol used.

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