Evaluation of anesthetic protocols for neutering 6- to 14-week-old pups

Ninety-nine 6- to 14-week-old pups were given anesthetic agents according to 10 anesthetic protocols. Mean quality rating scores were determined to compare anesthetic protocols. In male pups, IV administration of propofol (6.5 mg/kg of body weight) 15 minutes after IM administration of atropine (0.04 mg/kg) and oxymorphone (0.22 mg/kg) provided the best quality anesthesia. Intramuscular administration of midazolam (0.22 mg/kg) and butorphanol (0.44 mg/kg) instead of oxymorphone provided little sedation, but induced good analgesia. Atropine/oxymorphone/midazolam/xylazine, atropine/butorphanol/midazolam/xylazine, and tiletamine/zolazepam were unsatisfactory combinations for use in castration of 6- to 14-week-old male pups. In female pups, IV administration of propofol (3.4 mg/kg) 15 minutes after IM administration of atropine (0.04 mg/kg) and oxymorphone (0.11 mg/kg) was the most effective anesthetic protocol. Administration of the drugs according to this protocol enabled a pup to be intubated. Anesthesia was maintained with isoflurane in oxygen. If inhalational induction was preferred, IM administration of 13.2 mg of tiletamine/zolazepam/kg, 0.04 mg of atropine/kg and 0.11 mg of oxymorphone/kg, or 0.22 mg of midazolam/kg and 0.44 mg of butorphanol/kg may be used prior to mask delivery of inhalational anesthetics. In female pups, it was not advantageous to combine midazolam with oxymorphone, and use of high dosages of oxymorphone (0.22 mg/kg) or midazolam/butorphanol provided little sedation. Time of recovery after use of tiletamine/zolazepam was the longest for the combinations used, but did not adversely affect pups. Male pups were castrated via scrotal incisions, using hemostatic clips. Ovariohysterectomies were performed via a ventral abdominal midline approach, using hemostatic clips for ligation, five females developed signs of inflammation at the surgical site within 1 to 2 weeks after surgical, and were treated conservatively with warm compresses.