Information about animal research in Sweden

Pain reflex

Pain withdrawal reflex is an involuntary reaction to harmful stimuli. If, for example, we touch a hot stove our reflex is to pull back our hand, even before we are aware of any pain. Animals have a similar reflex. This occurs at the spinal cord level without involving the brain. Pain reflex is the first level of pain reaction in the nervous system.
The reflexes are used in research, e.g. to assess analgesics. One such method is called the tail-flick method, where researchers aim a warm ray of light at a rat´s tail and measure the time it takes for the rat to move its tail. If the animal were given a drug that enables it to keep its tail in the light longer, this would suggest that the drug has an analgesic effect.

Text: Karin Nordin


  • Michael Axelsson, professor in zoology, Göteborgs university.
  • Patricia Hedenqvist, veterinarian, Biovitrum AB
  • Klas Abelson, research assistant, Uppsala university.
Published: 2009-04-15
Last updated: 2009-04-06
Responsible for content: Mats Ulfendahl, Secretary General of Medicine and health, Swedish Research Council.
Editor: Anna Sandström, Swedish Research Council. Contact: Send email to the editorial staff.