Anesthesia

• Part of the physical exam

• Diagnostic sampling, procedures

• Gloves

• Forceps

• Transparent plastic box (tupperware)

• Anesthesia setup (e.g., isoflurane vaporizer)

• Enclose the patient in a gas delivery chamber, and deliver the agent by a direct method or, preferably, with a vaporizer.

• In the tarantula, recommended anesthetic protocols include carbon dioxide at 10% to 20% for 3 to 5 minutes, halothane at 4% for 5 to 10 minutes, methoxyflurane at 4% for 10 to 30 minutes, and isoflurane at 3% to 4% for 10 to 15 minutes.

• For direct delivery, a cotton ball or sponge may be soaked in anesthetic agent and placed in the chamber.

• To ensure that the patient cannot come into contact with the anesthetic agent, a specially built induction chamber is required for the direct method.

• For aquatic species: MS-222 is commonly added to water in a concentration of 100 mg/1 L of water.

• Benzocaine is probably the best choice of available anesthetics, but it must be made as a stock solution in ethanol and stored away from light.

• Commonly used inhalant anesthetics, such as isoflurane, may be used in aquatic invertebrates by bubbling them through water.

• Immerse the entire patient (or just the foot of gastropods) in the anesthetic solution until it is immobile, then remove it.

• To keep the patient moist and sedate, a misting of anesthetic solution may be applied periodically; by varying this solution’s concentration, one can control anesthetic depth.

• Determination of depth of anesthesia in invertebrates may be challenging.

• In terrestrial invertebrates, the righting reflex, immobility, and response or lack thereof to gentle prodding or other aversive stimuli are generally used to determine the depth of anesthesia.

• In leeches, attachment to the surface, swimming motion, muscle tone, sucker function, and response to stimulation were assessed for determination of anesthetic depth.

• Reversal of anesthesia in aquatic species is simple and rapid when they are returned to normal water.

• Oxygen supplementation of both terrestrial and aquatic species is recommended for anesthetic recovery or in the event of anesthetic complications.