Should laboratory mice be anaesthetized for tail biopsy?

Area of Science:

• Animal Welfare Science
• Laboratory Animal Science
• Genetically Modified Organisms

Background:

• Tail biopsies are standard for genotyping genetically modified mice.
• The impact of tail biopsy on mouse wellbeing is poorly understood.
• Investigating the duration and severity of pain and distress is crucial.

Purpose of the Study:

• To assess the physiological and behavioral effects of a single tail biopsy in adult mice.
• To determine if anesthesia improves mouse wellbeing post-biopsy.
• To characterize the effects of methoxyflurane and diethyl ether anesthesia alone.

Main Methods:

• Recording body weight, food/water intake, heart rate, body core temperature, and locomotor activity for three days post-biopsy.
• Comparing outcomes with and without anesthesia (methoxyflurane or diethyl ether).
• Assessing anesthesia effects independently.

Main Results:

• Tail biopsy alone caused transient increases in heart rate and activity (1h) and elevated body temperature (2h).
• Anesthesia prolonged heart rate increases (4h) and significantly altered body temperature for extended periods (20-44h).
• Methoxyflurane slightly reduced body weight; diethyl ether caused a 7% mortality rate.

Conclusions:

• Tail biopsy has a short-term impact on mouse physiology and behavior.
• Methoxyflurane and diethyl ether anesthesia do not enhance mouse wellbeing after tail biopsy.
• Anesthesia itself induces significant physiological disturbances, outweighing potential benefits for this procedure.