The formalin test: an evaluation of the method.

The formalin test for nociception, which is predominantly used with rats and mice, involves moderate, continuous pain generated by injured tissue. In this way it differs from most traditional tests of nociception which rely upon brief stimuli of threshold intensity. In this article we describe the main features of the formalin test, including the characteristics of the stimulus and how changes in nociceptive behaviour may be measured and interpreted. The response to formalin shows an early and a late phase. The early phase seems to be caused predominantly by C-fibre activation due to the peripheral stimulus, while the late phase appears to be dependent on the combination of an inflammatory reaction in the peripheral tissue and functional changes in the dorsal horn of the spinal cord. These functional changes seem to be initiated by the C-fibre barrage during the early phase. In mice, the behavioural response in the late phase depends on the ambient temperature. We argue that the peripheral tissue temperature as well as other factors influencing the peripheral inflammation may affect the response, possibly confounding the results obtained with the test. Furthermore, we discuss the methods of recording the response and the value of observing more than one aspect of behaviour. Scoring of several behavioural variables provides a means of assessing motor or sensorimotor function as possible causes for changes in behaviour. In conclusion, the formalin test is a valuable addition to the battery of methods available to study nociception.

Spatial and temporal aspects of spinal cord and brainstem activation in the formalin pain model

Measurement of pain and analgesia in animals poses a variety of problems. In addition to the fact that pain itself constitutes a multiplicity of sensory entities, the term pain is poorly defined in relationship to animals and animal behaviour.

Animal Models of Analgesia

Objective—To determine anesthetic techniques and the drugs used to provide anesthesia and analgesia to reptiles. Design—Mail-out questionnaire. Sample Population—367 members of the Association of Reptile and Amphibian Veterinarians. Procedure—1,091 members listed in the 2002 directory of the Association of Reptile and Amphibian Veterinarians were asked to complete a questionnaire regarding anesthesia and analgesia. Results—367 of 1,091 (33.6%) individuals completed the questionnaire; 88.8% used inhalants (particularly isoflurane) for anesthesia, and ketamine, propofol, and butorphanol were the most commonly used injectable agents. Intubation, fluids, and having a dedicated anesthetist were most commonly used for patient support, and pulse oximetry and Doppler ultrasonography were most commonly used for monitoring. Respiratory depression, difficulty monitoring anesthetic depth, prolonged recovery, and hypothermia were the most frequent complications. Nearly all respondents believed that reptiles feel pain,...

Evaluation of the use of anesthesia and analgesia in reptiles

Analyse de l'existence et de la sensibilite d'un systeme nociceptif chez C.n. africana par l'utilisation de 3 tests experimentaux

Titus I. Kanui

Papers

Nociception in Crocodiles: Capsaicin Instillation, Formalin and Hot Plate Tests: COMMUNICATION: Physiology