Anesthetic techniques for neutering 6- to 14-week-old kittens

Abstract

Forty-eight male and 48 female 6- to 14-week-old kittens were neutered by use of 4 anesthetic protocols. Preanesthetic disposition, depth of sedation, loss of resistance to handling, induction quality, induction time, sternal and stand times, and recovery quality were evaluated. Analgesia and muscle relaxation without supplemental inhalational anesthetics were evaluated in male kittens, and the time until extuation was recorded in female kittens. Intramuscular administration of tiletamine/zolazepam (TZ), midazolam/ketamine, atropine/midazolam/ketamine/butorphanol (AMKB), and atropine/midazolam/ketamine/oxymorphone (AMKO) produced rapid sedation and smooth induction into anesthesia. In male kittens, there were no significant differences in sedation, relaxation, induction time, or quality. Tiletamine/zolazepam administration induced the best analgesia, and midazolam/ketamine administration induced the least analgesia for castration. The recovery time in male kittens was longest with TZ and shortest with the opioid groups (AMKB, AMKO). In females, TZ produced significantly faster induction times, but the degree of sedation and relaxation after administration of injectable agents was not significantly different among the groups. More females given TZ could be intubated without supplemental inhalational agents than females in other groups. Extubation time was rapid in all groups, but the times until sternal and standing were significantly longer, and recovery quality was significantly poorer in females given TZ. In kittens given opioids, reversal of the opioid did not shorten recovery time or improve recovery quality. Because TZ administration provided the best and most consistent analgesia in males and longer recovery times did not have any adverse effects on male kittens, IM administration of 11 mg of TZ/kg of body weight, was the most effective anesthetic combination for neutering 6- to 14-week-old male kittens. None of the injectable techniques provided sufficient analgesia for ovariohysterectomy in females. Because of its ease of administration, rapid extubation time, and recoveries that were rapid and generally excitement free, IM administration of 0.22 mg of midazolam/kg and 11 mg of ketamine/kg, followed by inhalational anesthesia, was the most effective anesthetic combination for neutering 6- to 14-week-old female kittens.