Gaseous anesthetics provide the best means for long periods of anesthesia due to the continuous administration via inhalation. Since methoxyflurane is no longer available, and the use of ether is not recommended, researchers have access only to those agents that are best administered via a vaporizer. Recommended agents: isoflurane and halothane.
Injectable anesthetics are generally used in a cocktail mixed with one or more sedatives and analgesics. The anesthetic cocktails most commonly used on mice in the USA contain ketamine or tiletamine as the anesthetic agent. Bolus injections of anesthetic cocktail may produce a surgical level of anesthesia for periods ranging from 20 to 45 minutes, which is ideal for many surgical procedures commonly performed in mice, such as embryo implantation. The duration of surgical anesthesia depends on the drug agents used as well as the strain/stock of mouse. Repeated dosage of injectable agents to provide a long term anesthesia is not recommended because of the resulting fluctuations in systemic blood concentration and therefore in anesthetic effect. In such situations, the repeat doses of anesthetic cocktail are administered only when the animal begins to show evidence of pain. This is a poor practice of anesthesia because a surgical plane of anesthesia is not continuous throughout the procedure. Animal welfare mandates require an avoidance of such unnecessary animal pain and distress.
Examples (administered IP):