Preferred Inhalation Anaesthetic for Laboratory Animals: Isoflurane

In laboratory animal research, anaesthesia plays a crucial role in facilitating procedures that require animals to be immobilized or insensible to pain. The choice of anaesthetic is essential not only for ensuring animal welfare but also for the success of the experiment. Among the various inhalation anaesthetics available, Isoflurane is widely regarded as the preferred choice for laboratory animals.

Why is Isoflurane Preferred?

Isoflurane is a volatile inhalation anaesthetic that is commonly used in both small and large animals in laboratory settings. It has become the preferred choice due to several key factors:

1. Rapid Onset and Recovery: Isoflurane induces anaesthesia quickly and allows for fast recovery once the administration is stopped. This feature is crucial in laboratory settings where minimal downtime is desired between experiments.

2. Safety Profile: Isoflurane has a high therapeutic index, meaning it can be used safely at relatively low concentrations, minimizing the risk of overdose. It also has minimal effects on the cardiovascular system compared to other anaesthetics.

3. Minimal Metabolism: Isoflurane is minimally metabolized in the liver, reducing the burden on the animal’s body and making it a safer option for prolonged use.

4. Wide Range of Applications: It is suitable for a variety of species, including rats, mice, rabbits, and larger animals such as dogs and non-human primates.

5. Low Solubility: Isoflurane has a low blood-gas solubility coefficient, which means that its effects can be rapidly adjusted by changing the concentration of the anaesthetic in the inhaled gas mixture.

Comparison to Other Anaesthetics

While Isoflurane is widely preferred, other inhalation anaesthetics also have their roles in laboratory settings.

• Nitrous Oxide: Although commonly used in conjunction with other anaesthetics, Nitrous oxide is not typically used as the sole anaesthetic in laboratory animals. It is often used to supplement other anaesthetics, as it has a mild anaesthetic effect but does not produce sufficient depth of anaesthesia alone.

• Anaesthetic Ether: Once a popular choice, ether has fallen out of favor due to its flammability, irritant properties, and slower induction and recovery times compared to modern alternatives like Isoflurane.

• Methoxyflurane: While Methoxyflurane is a potent anaesthetic, it is less commonly used in laboratory animals due to concerns about nephrotoxicity (kidney damage) at higher concentrations.

Conclusion

Isoflurane stands out as the preferred inhalation anaesthetic for laboratory animals, thanks to its fast onset and recovery, excellent safety profile, and suitability for a variety of species. While other anaesthetics like Nitrous oxide and Methoxyflurane may have their uses, Isoflurane remains the most reliable and commonly used choice in animal research.

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