The purpose of anaesthetizing a laboratory animal is to enable performing a procedure without causing pain, stress or other suffering to the animal. Sufficient pain relief during the procedure helps to minimise the pain also afterwards together with the post-operative pain medication. The procedure must not leave unpleasant memories to the animal.

Components of surgical general anaesthesia

  • Unconsciousness
  • Painlessness
  • Immobility
  • Relaxation

In order for all the components to be fulfilled, a combination of several different substances may be required.

Anaesthesia and anaesthetics must have as little impact as possible on the research goals. The impact of surgical stress on animal physiology may, however, be much greater than the impacts of the medication on the research, and therefore there are usually no scientifically based reasons that would justify lowering the level of the anaesthesia and analgesia – or the laboratory animal’s wellbeing. Often there are multiple acceptable options for anaesthesia, and the impacts of different options in terms of the research must be weighed in advance.

There are many factors that influence the functionality and dosage of the anaesthetics, and for this reason the normal administration guidelines or the anaesthesia protocol for a previous experiment may not be appropriate for a new experiment.

Biological factors to be taken into account in anaesthesia

  • Animal species, breed and strain
  • Age
  • Sex
  • Pregnancy
  • Body weight and nutritional status (thin – fat)
  • Research (disease) model
  • Biological rhythms (e.g. circadian rhythm, estrous cycle)

The administration route may affect the dosage significantly. If there is any uncertainty about the functionality of the anaesthesia protocol, a pilot experiment is advisable.

Last updated: 5.1.2017