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Table 1 Properties of main anaesthetic agents used in preclinical research: halothane and isoflurane

From: Anaesthesia and physiological monitoring during in vivo imaging of laboratory rodents: considerations on experimental outcomes and animal welfare

Agents Advantages Disadvantages Dosing
Halothane Potent anaesthetic Highly metabolised (hepatotoxic) Induction 3% to 4% Maintenance 1% to 2% (rats and mice)
  High therapeutic index Cardiovascular depressant  
  Rapid induction and recovery (1 to 3 min) Moderate hypotension: reduction in cardiac output and peripheral vasodilatation)  
  Adequate muscle relaxation Respiratory depressant  
  Non-irritant, non-flammable nor explosive Halothane sensitises the heart to catecholamines (sympathetic stimulation)  
  Easy to vaporise   
Isoflurane Similar physical properties to halothane Decreases arterial blood pressure (vasodilatation) Induction 3% to 4% (rats and mice) Maintenance: 1.5% to 2% (mice)1.5% to 2.5% (rats)
  Rapid induction and recovery More expensive than halothane  
  Low toxicity and metabolic activity: highly safe Strong smell: aversive  
  Suitable for high frequency and long-term anaesthesia More potent respiratory depressant than halothane  
  Minimal cardiovascular depression   
  Moderate respiratory depression   
  Good muscle relaxation