Low-dose anesthesia for corneal transplantation in mice.

BACKGROUND: Despite technical difficulties caused by the small dimensions, scientific and economic considerations stimulated activities in the murine keratoplasty model. Delicate surgery requires stable anesthesia with rapid postoperative waking.

METHODS: For corneal transplantation, all animals were intraperitoneally injected with 0.08 ml of a 1:8 mixture of 2% xylazine and 2.5% esketamine hydrochloride. Thus they all received 0.18 mg of xylazine and 1.8 mg of ketamine. In other words, 4.5 mg/kg BW of xylazine and 45 mg/kg BW of ketamine were injected in a mouse weighing 25 g. The inhalation anesthetic isoflurane was used for short interventions like removing lid sutures or in the case of an animal awaking before the end of the operation. A small but effective set of apparatus comprising a glass bottle, a test tube and several interconnected syringes was developed to create a closed system and visualize the amount of isoflurane used in the animal. Air bubbles showed the amount of isoflurane escaping from the opened respiratory mask.

RESULTS: The dose reduction of systemic anesthesia requires additional inhalation anesthesia with isoflurane in nearly all cases. The equipment developed is easy to handle and allows systemic anesthesia with a very low dose.

CONCLUSION: This murine anesthesia model may be expected to help other surgeons performing corneal transplantations in mice.