Estudo da dor e avaliação de toxicidade da dipirona por via epidural em coelhos.

Abstract

Understanding the sensitivity of animals to pain makes us to seek ways to treat them, always choosing the most accessible, fast and least invasive means. In this sense, this thesis consists of three chapters that approach the subject of analgesia and animal welfare linked to the use of dipyrone, also called metamizole. The first chapter consists of a review of the literature on pain and use of dipyrone in rabbits, emphasizing the mechanisms of nociception, pain, neurotransmitters of excitatory and inhibitory action, clinical signs and the recognition of this through scales. The second chapter contains a scientific paper, where the dose of 1 mg/kg were administered in the epidural route and clinical, neurological and histopathological evaluations were performed, demonstrating that dipyrone at the proposed dose was safe from the neurological and systemic point of view in leporidae. The third chapter report a case on acute epidural dipyrone intoxication in three rabbits at doses of 50, 20 and 5 mg/kg. After the application of the drug two animals that were submitted to the highest doses had clinical reactions that culminated in death in up to 50 minutes, and necropsy was performed immediately after confirmation of death. The third animal submitted to the dose of 5 mg/kg initially presented pruritus, limited movement of pelvic limbs without alteration of pain sensitivity, abdominal contractions and defecation. After an hour of application of the dipyrone the animal obtained recovery of pain sensitivity, however the same demonstrated permanent paralysis of the pelvic limbs. It is suggested that dipyrone at epidural doses above 5 mg / kg causes neurotoxicity and is contraindicated in rabbits. In this way, we conclude that the use of analgesics in experimental animals provides animal welfare, as well as, more reliable results to the researches carried out, being dipyrone a widely used drug for the treatment of pain in laboratory animals, having pharmacological safety in the doses of 20 to 50 mg/kg when applied by the oral or intravenous routes. At the dose of 1 mg / kg of dipyrone via epidural, clinical and histopathological changes were not observed, and this dose was proposed for new studies of analgesic action of the drug.