How can a rat be put to sleep? - briefly
Commonly, rodents are euthanized with an inhalant anesthetic (e.g., isoflurane) followed by a barbiturate injection such as sodium pentobarbital to achieve rapid unconsciousness and death. Controlled CO₂ exposure is also accepted for large‑scale procedures.
How can a rat be put to sleep? - in detail
Inducing unconsciousness in a rodent requires a method that produces rapid loss of sensation and minimizes pain. The most widely accepted techniques are chemical and physical, each with specific protocols.
Chemical agents
- Carbon dioxide (CO₂): Fill a sealed chamber with 100 % CO₂ at a flow rate of 20 % of the chamber volume per minute. Monitor the animal until breathing ceases, typically within 2–3 minutes. Ensure proper ventilation after the procedure.
- Inhalant anesthetics: Isoflurane or sevoflurane delivered via a calibrated vaporizer at 5–7 % concentration in oxygen will induce deep anesthesia within 30–60 seconds. Confirm lack of reflexes before proceeding to euthanasia.
- Injectable barbiturates: Sodium pentobarbital at 150 mg kg⁻¹ administered intraperitoneally provides rapid unconsciousness followed by cardiac arrest. Verify injection site and observe for cessation of respiratory movements.
Physical methods
- Cervical dislocation: Grasp the animal’s neck with thumb and forefinger, apply a swift, downward force to separate the vertebrae. Requires training to avoid incomplete severance.
- Decapitation: Use a sharp guillotine or scissors designed for laboratory rodents. Perform immediately after confirming deep anesthesia to prevent distress.
- Blunt force trauma: Deliver a single, forceful strike to the skull with a calibrated device. This method is less favored due to variability in effectiveness.
Procedural considerations
- Confirm absence of corneal reflex, pedal withdrawal, and respiratory effort before declaring death.
- Use personal protective equipment to avoid exposure to gases or chemicals.
- Document the method, dosage, and time of completion for compliance with institutional animal care protocols.
- Dispose of carcasses according to biohazard regulations.
Selecting the appropriate approach depends on the experimental context, available equipment, and ethical guidelines governing animal research.