Comparison of intramuscular alfaxalone and ketamine combined with dexmedetomidine and butorphanol for castration in cats.

Objectives Cardiorespiratory parameters and anaesthesia quality in cats anaesthetised with either intramuscular (IM) alfaxalone or ketamine both combined with dexmedetomidine and butorphanol for castration were evaluated. Methods Thirty-two client-owned cats were randomly assigned to receive either alfaxalone (A; 3 mg/kg IM) or ketamine (K; 5 mg/kg IM), combined with dexmedetomidine (10 µg/kg) and butorphanol (0.2 mg/kg). Heart rate (HR), respiratory rate (RR) and rectal temperature (T°) were recorded prior to drug administration. Pulse rate (PR) and RR were recorded 10 (T10) and 15 (T15) mins after injection (T0). Cardiorespiratory values (PR, RR, SPO2, blood pressure, PE'CO2) were recorded every 5 mins for the duration of the procedure. Pain at injection, intubation and recovery were evaluated with simple descriptive scores. Feasibility of anaesthesia was evaluated by the number of top-ups of anaesthetic needed. Cat attitude, ability to walk and presence of ataxia were assessed several times after extubation (Texmin) and the time between injection and extubation recorded. Pain was assessed at Tex120 and Tex240 with the 4Avet-pain score. Results The RR was significantly lower in group K at T10 (RRK = 28 ±13.35 breaths per minute [brpm], RRA= 43.24 ±7.04 brpm) and T15 (RRK = 28 ±11.53 brpm vs RRA = 43 ±12.18 brpm). Time to extubation was significantly longer in group A (TA = 62 ±14.6 mins, TK = 45.13 ± 7.38 mins). Cats in group K needed more top-ups, were more ataxic at Tex120, had a worse recovery score at Tex60 and were less willing to walk at Tex30. Conclusions and relevance Cats receiving alfaxalone had a longer but better quality recovery. Cardiorespiratory parameters were stable and within clinically acceptable values following IM injection of either alfaxalone or ketamine in healthy cats. Intramuscular alfaxalone is a suitable alternative to ketamine for short procedures requiring anaesthesia when used in combination with dexmedetomidine and butorphanol.