Pain is subjective and is defined as an unpleasant sensory or emotional experience associated with actual or potential tissue damage.1 Animals greatly vary in their behavioral responses to pain. Immediate responses include vocalization and attempts to escape, whereas longer term responses also include loss of appetite or lack of grooming.1 Most of these responses are very difficult to assess in ectothermic vertebrates, which often remain motionless and have a behavioral repertoire that is considerably more difficult to interpret than that of mammals. In mammals, pain also elicits consistent physiologic responses, including increased heart rate and blood pressure,2 altered breathing patterns,2 and increased plasma concentrations of epinephrine3 and cortisol.3,4 Administration of analgesics consistently reduces these behavioral and physiologic responses in mammals.2,5 It follows that such physiologic responses would provide a useful means of assessing the sensation of pain in amphibians and reptiles.
Pain and pain management in nonmammalian vertebrates remain poorly understood. Results of several studies indicate that reptiles,6–8 fish,9 and birds10 react to painful stimuli and that analgesia relieves pain, yet the basic physiologic response to painful stimuli has not been described to our knowledge. In a survey,11 98.4% of 367 members of the Association of Reptile and Amphibian Veterinarians stated that they believe reptiles can feel pain. Nonetheless, only 39% of those veterinarians reported using analgesics during surgical procedures in reptiles. According to results of the same survey, butorphanol (a mixed opioid receptor agonistantagonist) and NSAIDs are the most commonly used analgesics for reptiles,11 even though their effects on reptiles are largely unknown.
The aim of the study reported here was to characterize the physiologic responses of ball pythons (Python regius) following a minor surgical procedure, to assess whether physiologic variables can be used as a measurable indicator of pain, and to assess whether preoperative administration of butorphanol and the NSAID meloxicam affects postoperative physiologic responses.
HI 665 ventilator (tidal volume of 50 mL/kg [22.7 mL/lb] at 10 breaths/min), Harvard Apparatus, Holliston, Mass.
Fluotec, Cyprane Ltd, Keighley, England.
PE50, SIMS Portex Ltd, Hythe, England.
PH radiometer (PHM73) connected to Blood Micro System (BMS2), Radiometer, Copenhagen, Denmark.
Oxygen radiometer connected to Blood Micro System (BMS2), Radiometer, Copenhagen, Denmark.
Haemofuge, Heraeus Sepatech GmbH, Osterode/Harz, Germany.
Delfia Cortisol 1244-060, PerkinElmer Life and Analytical Sciences, Turku, Finland.
Victor3 1420 multilabel counter, PerkinElmer Life and Analytical Sciences, Hvidovre, Denmark.
Workout, version 1.0, PerkinElmer Life and Analytical Sciences, Hvidovre, Denmark.
Model Px600, Baxter-Edward, Irvine, Calif.
AcqKnowledge MP 100, BioPac Systems, Santa Barbara, Calif.
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