Potencial Antinocipcetivo Mecânico E Efeitos Sobre A Hiperalgesia Pós-Incisional Do Tramadol Em Equinos
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2011-03-25
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Universidade Federal de Goiás
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Tramadol is an analgesic with action of opioids and non-opioid receptors, which acts by promoting activation of central inhibitory mechanisms of pain. In the last decade, there was a significant advance in research related to the use of tramadol in horses. There is evidence that the drug has significant analgesic effect in horses through mechanisms unclear. The aim of this study was to evaluate clinical and cardiorrespiratory effects and mechanical nociceptive threshold of tramadol, administered intravenously in horses. Moreover, we assessed also the effects of preemptive administration of tramadol on the clinical effects and post-incisional mechanical hyperalgesia. In the first study, seven adult horses were used in a three-way crossover study design in which tramadol was intravenous administered at 1mg kg-1, 2mg kg-1 e 3mg kg-1. Heart rate, respiratory rate, rectal temperature, systolic arterial pressure, diastolic arterial pressure, mean arterial pressure, intestinal motility, head height and behavioral change were recorded before and during 180 minutes after treatment. Mechanical nociceptive threshold from these points were averaged to obtain mean values at each time with von Frey electronic analgesiometer, applying a force in a hoof. Compared to others treatments, the horses that received 3mg kg-1 showed significant increases in respiratory rate and more pronounced behavioral changes. In horses treated with 1mg kg-1, there was a significant decrease in respiratory rate and more pronounced behavioral changes. Motility scores showed transitory decreased in horses treated with 2 mg kg-1. The tramadol did not caused changes in mechanical nociceptive threshold regardless of treatment. In conclusion, the tramadol at doses evaluated produced minimal transient side effects or clinical changes. However has no antinociceptive effect in a model of mechanical stimulus. In a second study, ten horses were divided in two groups. The horses were treated IV with a single dose of 2 mg kg-1 of tramadol (TG) or with a similar volume of sterile water (SG). Heart rate, respiratory rate, rectal temperature, systolic arterial pressure, diastolic arterial pressure, mean arterial pressure, intestinal motility, and behavioral change were recorded before and during 48 hours after treatment. Mechanical nociceptive threshold was measured by von Frey electronic analgesiometer in post-incisional model. To study, a skin incision was made over the thigh region. Compare to saline, tramadol caused transitory increased in mean and diastolic arterial pressure in first hour after treatment. The tramadol was able to decrease a remained time of primary hyperalgesia, but not prevented its appearance in compared to SG. In the global range score no changes were observed between groups along the moments.
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FRANCO, Leandro Guimarães. Mechanical antinociceptive potential and effects in the post incisonal iperalgesia of tramadol in horses. 2011. 121 f. Tese (Doutorado em Ciências Agrárias) - Universidade Federal de Goiás, Goiânia, 2011.