Tramadol Analgesic and Respiratory Effects in Red-Eared Slider Turtles (Trachemys scripta)
American Association of Zoo Veterinarians Conference 2009
Bridget B. Cummings1, MS; Kurt K. Sladky2, MS, DVM, DACZM; Stephen M. Johnson1, MD, PhD
1Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI, USA; 2Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI, USA


Tramadol (Ultram®, PCCA, Houston, TX) is a non-controlled opioid drug with a dual mechanism of action as a µ-opioid agonist and serotonin/norepinephrine reuptake inhibitor, both of which contribute to analgesia in mammals.1-4,6,7 Respiratory depression is less severe with tramadol compared to morphine in dogs and cats.5,9 Based on these findings, we hypothesized that tramadol would also produce analgesia in reptiles with less respiratory depression than morphine. Thus, we studied the dose- and time-dependent changes in analgesia and respiration caused by tramadol in red-eared slider turtles.

Using a crossover design, oral tramadol (1, 5, 10, and 25 mg/kg), injectable tramadol (10 and 25 mg/kg), and controls were administered to adult, red-eared slider turtles. Analgesia was measured with hindlimb withdrawal latencies to noxious thermal stimuli at 0, 3, 6, 12, 24, 48, 72, and 96 hours post-drug administration. Respiration was measured in freely swimming turtles in individual tanks with access to a small breathing hole. Tramadol (10 mg/kg PO) increased thermal withdrawal latencies for 6–96 hours post-drug compared to controls. In contrast, tramadol (10 mg/kg SC) only increased latencies between 12–48 hours post-drug. Tramadol (25 mg/kg PO or SC) increased latencies for 6–96 hours post-drug, but this dosage was associated with mouth gaping and flaccid limbs and necks. Respiratory depression was observed in all turtles given tramadol (5, 10, 25 mg/kg PO), but, unlike morphine,8 breathing continued at all dosages. Thus, tramadol (10 mg/kg PO) is an effective, long-lasting analgesic drug that may be safer than morphine.


This work was supported by the National Institutes of Health [T32 RR17503-01A1 (BBC)] and the National Science Foundation (IOB 0517302).

Literature Cited

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Speaker Information
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Bridget B. Cummings, MS
Department of Comparative Biosciences
School of Veterinary Medicine
University of Wisconsin
Madison, WI, USA

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