KETAMINE, MEDETOMIDINE, AND MIDAZOLAM ANESTHESIA WITH AND WITHOUT BUTORPHANOL IN SLOW LORISES (NYCTICEBUS BENGALENSIS...

Slow lorises (Nycticebus bengalensis and Xanthonycticebus spp.) are endangered small nocturnal prosimians that are frequently rescued from the illegal wildlife trade in Southeast Asia. Routine health examinations under anesthesia are essential for their care but anesthetic protocols are based largely on protocols established for other prosimians, with limited species-specific data. This study evaluated the efficacy and safety of adding butorphanol to a ketamine (6 mg/kg IM)-medetomidine (0.05 mg/kg IM)-midazolam (0.15 mg/kg IM) (KMM) anesthetic combination (KMMB) during health examinations of two loris species: Bengal slow loris (N. bengalensis) and pygmy slow loris (Xanthonycticebus spp.). Anesthesia was induced in 27 lorises (12 N. bengalensis, 15 Xanthonycticebus spp.), using either KMM (5 N. bengalensis and 4 Xanthonycticebus spp.) or KMMB (7 N. bengalensis and 11 Xanthonycticebus spp.). At the end of procedures, atipamezole (0.2 mg/kg IM) was administered to antagonize medetomidine. Induction and recovery times, vital parameters, and isoflurane supplementation requirements were recorded. In N. bengalensis, the addition of butorphanol (0.05 mg/kg IM) significantly shortened induction and recovery times without significantly influencing heart rate or oxygen saturation. In Xanthonycticebus spp., a higher butorphanol dose (0.1 mg/kg) was necessary to reach an adequate anesthetic plane. This species exhibited decreased heart rate, increased oxygen saturation, and shorter recovery times with the use of KMMB compared to KMM alone. Both species maintained spontaneous respirations without respiratory depression or apnea. Supplementation with isoflurane for the maintenance of anesthesia did not affect vital parameters but lengthened recovery times in both species. Although the need for isoflurane supplementation could not be completely prevented, KMMB reduced its requirement, potentially reducing adverse effects associated with inhalant anesthetics. These findings support the use of a species-adapted KMMB protocol, supplemented with isoflurane for maintenance of anesthesia as a safe and effective anesthetic option for health evaluations in rescued slow lorises.