The Triad of Anaesthesia
Due to the benefits of producing loss of consciousness (avoiding stress associated with restraint, and immobilising the animal to make procedures easier to undertake), most laboratory animals are anaesthetised using a general anaesthetic.
General anaesthesia is considered to have three components:
- Loss of sensation
- Loss of consciousness
- Production of muscle relaxation.
This is sometimes known as the Triad of Anaesthesia. These components can be provided by administration of several different agents in combination, or use of a single anaesthetic agent that produces all of these effects. The anaesthetic agents used can be given either by injection, or by inhalation. Although an animal that is not conscious cannot experience pain, it is often considered advantageous to include a specific analgesic in anaesthetic protocols.
General anaesthesia can be produced using either inhalational anaesthetics, injectable anaesthetics, or a combination of agents. This may also include local anaesthetics. In some circumstances, it may be useful to administer some components of the anaesthetic regimen as pre-anaesthetic medication.