Buffering mepivacaine with sodium bicarbonate speeds and potentiates analgesia of median and ulnar nerve blocks performed on horses

Castration of Dogs Using Local Anesthesia After Sedating With Xylazine and Subanesthetic Doses of Ketamine

Orchiectomy is performed in some species using only sedation and local anesthesia to decrease the expense of performing the procedure using general anesthesia. The objective of this study was to determine if dogs can be castrated safely and painlessly by using only sedation and local anesthesia. After dogs were sedated with intramuscularly administered xylazine (1 mg/kg) and subanesthetic ketamine (1 mg/kg), testes and skin were anesthetized with 2% lidocaine (6 mg/kg, total dose) buffered with sodium bicarbonate. Systolic, diastolic, and mean blood pressures; heart and respiratory rates; and movement scores were determined before and during surgery when manipulations were most likely to cause pain. No dog reacted substantially to injection of the combination of sedatives, and no dog reacted noticeably to injection of lidocaine. During surgery, the average heart rate was reduced from baseline by 40–60 beats per minute, and the average respiratory rate was reduced by ~10 breaths per minute. An overall reduction of arterial blood pressures was observed. All but one dog moved purposely in response to a toe pinch at the end of surgery. We found that sedating dogs intramuscularly with xylazine and a sub-anesthetic dose of ketamine and administering lidocaine at the incision site and intratesticularly allowed dogs to be castrated humanely and avoided the expense of general anesthesia and the need for hospitalization.