Anesthesia: Anesthesia is the act of rendering the patient senseless to pain or discomfort.

Monitoring Anesthesia: All anesthetized animals must be constantly attended and monitored continually to assess adequate level of anesthesia. There are as many acceptable methods to monitor anesthesia as there are species of animals. Certain methods are fairly common between species. These include:

• Toe pinch: Effective if the animal has a toe large enough to pinch.  A gentle pinch, which does not break the skin or cause any deep tissue damage, is sufficient to show if the animals is too light.  Any observed movement (withdrawing the paw) indicates that the animal is not sufficiently anesthetized to do surgery.

• Skin pinch: More sensitive areas of skin work best.   A gentle pinch of a small fold of skin, which does not break the skin or cause any deep tissue damage, is sufficient to show if the animals is too light.  Any observed movement (twitching of the skin) indicates that the animal is not sufficiently anesthetized to do surgery.

• Jaw "tone": Generally a good indicator of muscle relaxation.  The lower jaw is gently opened to its maximum extent.  Any observed closing of the mouth is an indicator that the animal is too light to do surgery.

• Respiratory rate: Good indicator of depth of anesthesia. Rapid, shallow respirations usually indicate the animal is too "light".  Normal respiration rate varies among animals, consult veterinary text for normal values, or Email our clinical veterinarian.

• Heart rate: An increase in heart rate and/or blood pressure usually indicates a decrease in anesthetic depth.  Normal heart rates vary greatly among species, consult veterinary text for normal values, or Email our clinical veterinarian.

• Palpebral: The blink reflex is quite variable, depending on the anesthetic agent used, and difficult to assess in small animals (i.e. mice and rats).  DO NOT USE FOR RODENT ANESTHESIA!

• Corneal: The cornea can be damaged, if not protected, but when used carefully, it is a good reflex. Touch the edge of the cornea with a gauge sponge or cotton q-tip.  Movement of the eyelids are an indication that the depth of anesthesia is not sufficient to do surgery.

• Body Temp: Most anesthetic agents depress body temperature to a significant degree. Therefore, it is important that anesthetized animals be maintained on some type of material which shields them from contact with cold surfaces and reduces heat loss.  The use of a supplemental heat source is a good idea, but must be used with caution, since burns can occur from electric blankets or water bottles that are too hot.

Anesthesia Recovery: All animals recovering from anesthesia must be constantly attended until they have recovered their swallowing reflexes. In the case of rodents and other small species, this is usually indicated by the animal starting to move around. All animals should be kept warm during the recovery period. In rodents this can be accomplished by placing the animal under a heat lamp or on a heating pad, placing the animals in a cage warmed on a heating pad, or wrapping the animal in a small towel. Care must be taken to avoid overheating when a heating lamp or heating pad is used. Whenever a heat source is used, a thermometer should be placed at the animal's level to monitor actual heat. Animals will overheat and can "sun burn". Animals which have had any significant blood/fluid loss during surgery should be provided with fluid or blood replacement during surgery and/or the anesthesia recovery period. In small rodents, this is best accomplished via the intraperitoneal or subcutaneous route.