Spinal anesthesia - this technique involves an intrathecal or epidural injection of the drug to block sensation from a large part of the body. Xylazine has been used for this purpose, as well as the more traditional local anesthetics. This technique is very useful for caudal abdominal, perineal or hind limb surgical procedures. The amount of anesthetic injected can be increased to increase the area that is anesthetized. Overdosing using this method can result in paralysis of the respiratory muscles, requiring mechanical ventilation until the drugs have worn off.
Considerable training is necessary for proper needle placement and drug dose calculations.
This allows for very precise anesthesia localization, retaining function in adjacent areas. A good knowledge of nerve locations is necessary to make this technique work. General anesthesia - these drugs cause generalized depression of the central nervous system, resulting in loss of consciousness, loss of pain perception, immobilization, amnesia, as well as side effects such as cardiopulmonary depression and loss of thermoregulation. Inhalant Anesthetics - include low vapor pressure drugs such as ether and methoxyflurane that may be used in a bell jar or with a drop system, or the high vapor pressure drugs such as halothane or isoflurane which require a precision vaporizer or vernitrol delivery system. These can be used as sole agents for surgery.