Effects of atipamezole and flumazenil on stress-related hormonal and metabolic responses in cats anesthetized with medetomidine, midazolam, ketamine and isoflurane undergoing ovariohysterectomy and castration

Abstract

This study examined the post-operative effects of atipamezole (Ati) and flumazenil (Flu) on stress-related neurohormonal and metabolic responses in isoflurane-anesthetized cats premedicated with medetomidine, midazolam and ketamine and undergoing ovariohysterectomy or castration. Client-owned mixed-breed cats (n = 108) were treated with 50-μg/kg medetomidine and 0.5-mg/kg midazolam, followed by 5-mg/kg ketamine (MMK) intramuscularly (IM) and maintained under isoflurane anesthesia. The cats were divided into nine groups (six cats/group): control (saline IM), 50-μg/kg Flu IM or intravenously (IV), 100-μg/kg Ati IM or IV, 200-μg/kg Ati IM, 100-μg/kg Ati + 50-μg/kg Flu IM or IV and 200-μg/kg Ati + 50-μg/kg Flu IM. Five blood samples were taken: before pretreatment, post-operatively during anesthesia and 10, 60, and 120 mins after antagonist administration. MMK-isoflurane anesthesia decreased adrenaline, noradrenaline, cortisol and non-esterified fatty acid (NEFA) levels. It also caused hyperglycemia. Compared to the controls, Ati IV rapidly reversed the decreased catecholamine and cortisol concentrations in ovariohysterectomized cats. Ati IV and/or Ati + Flu IV tended to induce rapid recovery from hyperglycemia and reverse the NEFA decreases. Compared to IM, the IV administration of Ati, alone and in combination with Flu, induced a more rapid recovery from anesthesia. Compared to Ati alone, the Ati–Flu combination improved the quality of recovery. Thus, Ati IV is effective for rapidly reversing stress-related neurohormonal and metabolic effects in MMK-isoflurane anesthetized cats. Ati–Flu IM aids in rapid recovery without altering post-operative neurohormonal and metabolic changes.