Effects of dissociative anesthesia opioid-free protocols combined with local anesthesia, with or without flumazenil or atipamezole postoperatively, for orchiectomy in cats

Published:September 21, 2021DOI:



      To evaluate the anesthetic effects of two drug combinations with local anesthesia, with or without postoperative antagonists, for orchiectomy in cats.

      Study design

      Prospective, randomized blinded clinical study.


      A total of 64 healthy cats.


      Cats were assigned to four equal groups: ketamine (5 mg kg–1) and dexmedetomidine (10 μg kg–1) were administered intramuscularly (IM), followed postoperatively with intravenous (IV) saline (5 mL; group KDS) or atipamezole (50 μg kg–1; group KDA); and ketamine (14 mg kg–1) with midazolam (0.5 mg kg–1) and acepromazine (0.1 mg kg–1) IM, with postoperative IV saline (5 mL; group KMAS) or flumazenil (0.1 mg kg–1; group KMAF). Lidocaine (2 mg kg–1) was divided between subcutaneous and intratesticular injection. Physiologic variables were recorded at time points during anesthesia. Ketamine rescue dose was recorded. The degree of sedation and the quality of recovery were evaluated postoperatively.


      Time to loss of pedal reflex was longer in groups KMAS and KMAF than in groups KDS and KDA (p = 0.010). Total rescue dose of ketamine was higher in KMAS and KMAF than in KDS and KDA (p = 0.003). Heart rate (HR) during anesthesia was higher in KMAS and KMAF than in KDS and KDA (p = 0.001). Times to head up (p = 0.0005) and to sternal recumbency (p = 0.0003) were shorter in KDA than in KDS, KMAS and KMAF. Lower sedation scores were assigned sooner to KDA than KDS, KMAS and KMAF (p < 0.001). Recovery quality scores were good in all groups.

      Conclusions and clinical relevance

      Both anesthetic protocols allowed the performance of orchiectomy. Groups KMAS and KMAF required higher rescue doses of ketamine before injecting lidocaine. HR and oscillometric systolic pressure were minimally changed in groups KD and tachycardia was recorded in groups KMA. Only atipamezole shortened the anesthetic recovery.


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