Analgesic efficacy and respiratory effects of butorphanol and morphine in turtles.
OBJECTIVE
To test the hypothesis that butorphanol or morphine induces antinociception with minimal respiratory depression in conscious red-eared slider turtles.


METHODS
Prospective crossover study.


METHODS
37 adult male and female red-eared slider turtles (Trachemys scripta).


METHODS
Antinociception (n = 27 turtles) and respiratory (10 turtles) experiments were performed. Infrared heat stimuli were applied to the plantar surface of turtle limbs. Thermal withdrawal latencies were measured before and at intervals after SC administration of physiologic saline (0.9% NaCl) solution, butorphanol tartrate (2.8 or 28 mg/kg [1.27 or 12.7 mg/lb]), or morphine sulfate (1.5 or 6.5 mg/kg [0.68 or 2.95 mg/lb]). Ventilation was assessed in freely swimming turtles before and after SC administration of saline solution, butorphanol (28 mg/kg), or morphine (1.5 mg/kg).


RESULTS
For as long as 24 hours after injection of saline solution or either dose of butorphanol, thermal withdrawal latencies among turtles did not differ. Low- and high-dose morphine injections increased latencies significantly by 8 hours. Ventilation was not altered by saline solution administration, was temporarily depressed by 56% to 60% for 1 to 2 hours by butorphanol (28 mg/kg) administration, and was significantly depressed by a maximum of 83 +/- 9% at 3 hours after morphine (1.5 mg/kg) injection. Butorphanol and morphine depressed ventilation by decreasing breathing frequency.


CONCLUSIONS
Although widely used in reptile species, butorphanol may not provide adequate antinociception for invasive procedures and caused short-term respiratory depression in red-eared slider turtles. In contrast, morphine apparently provided antinociception but caused long-lasting respiratory depression.
Sladky
Kurt K
KK
Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706, USA.
Miletic
Vjekoslav
V
Paul-Murphy
Joanne
J
Kinney
Matthew E
ME
Dallwig
Rebecca K
RK
Johnson
Stephen M
SM
D000701:Analgesics, Opioid / Q000009:adverse effects / Q000494:pharmacology*; D000818:Animals; D002077:Butorphanol / Q000009:adverse effects / Q000494:pharmacology*; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D005260:Female; D008297:Male; D009020:Morphine / Q000009:adverse effects / Q000494:pharmacology*; D010146:Pain / Q000517:prevention & control / Q000662:veterinary; D010147:Pain Measurement / Q000662:veterinary; D011446:Prospective Studies; D012119:Respiration / Q000187:drug effects; D013997:Time Factors; D014426:Turtles / Q000502:physiology*
D000701:Analgesics, Opioid; D009020:Morphine; D002077:Butorphanol