Immobilization, cardiopulmonary and blood gas effects of ketamine–butorphanol–medetomidine versus butorphanol–midazolam–medetomidine in free-ranging serval (Leptailurus serval)

To compare ketamine–butorphanol–medetomidine (KBM) with butorphanol–midazolam–medetomidine (BMM) immobilization of serval.Blinded, randomized trial.A total of 23 captures [KBM: five females, six males; 10.7 kg (mean); BMM: 10 females, two males; 9.6 kg].Serval were cage trapped and immobilized using the assigned drug combination delivered via a blow dart into gluteal muscles. Prior to darting, a stress score was assigned (0: calm; to 3: markedly stressed). Drug combinations were dosed based on estimated body weights: 8.0, 0.4 and 0.08 mg kg–¹ for KBM and 0.4, 0.3 and 0.08 mg kg–¹ for BMM, respectively. Time to first handling, duration of anaesthesia and recovery times were recorded. Physiological variables including blood glucose and body temperature were recorded at 5 minute intervals. Atipamezole (5 mg mg–¹ medetomidine) and naltrexone (2 mg mg–¹ butorphanol) were administered intramuscularly prior to recovery. Data, presented as mean values, were analysed using general linear mixed model and Spearman’s correlation (stress score, glucose, temperature); significance was p < 0.05.Doses based on actual body weights were 8.7, 0.4 and 0.09 mg kg–¹ for KBM and 0.5, 0.4 and 0.09 mg kg–¹ for BMM, respectively. Time to first handling was 10.2 and 13.3 minutes for KBM and BMM, respectively (p = 0.033). Both combinations provided cardiovascular stability during anaesthesia that lasted a minimum of 35 minutes. Recovery was rapid and calm overall, but ataxia was noted in KBM. Stress score was strongly correlated to blood glucose (r² = 0.788; p = 0.001) and temperature (r² = 0.634; p = 0.015).Both combinations produced similar effective immobilization that was cardiovascularly stable in serval. Overall, BMM is recommended because it is fully antagonizable. A calm, quiet environment before drug administration is essential to avoid capture-induced hyperglycaemia and hyperthermia.