Uso De Sulfato De Morfina Em Equinos Para Controle Da Dor E Seus Efeitos Adversos

Abstract

Morphine has marked clinical and analgesic effects in horses, however clarifications about its adverse effects require research, especially in relation to clinical effects such as: gastrointestinal depression, gastric distension, hyperphagia and intestinal colic. Ultrasonography is a non-invasive tool that allows the evaluation and characterization of physiological and pathological processes that may involve organs of the abdominal cavity. Being an important tool in the diagnosis of horses with acute abdomen, providing valuable information and helping to choose appropriate therapies. In order to grade pain, the use of the EQUUS-FAP system has been proposed. It is widely used in the evaluation of animals with acute colic and for objective monitoring of pain through facial expressions. However, studies evaluating the clinical effects of morphine on gastric distension and intestinal motility in horses with painful stimuli had not yet been performed. Thus, the objective of this study was to evaluate the side effects and analgesics of the systematic administration of morphine in a single dose, using clinical and ultrasonographic parameters and the use of the EQUUS-FAP scale in horses undergoing elective orchiectomy surgery using the open technique. Twenty-nine healthy, non-castrated male horses of different breeds, aged between three and nine years old, were equally distributed into three groups: the control group (G1), the morphine group with surgery (G2) and the morphine group without surgery ( G3). The anesthetic protocol included tranquilization with 1% acepromazine (0.05mg/kg intravenously/IV) and after five minutes, sedation with 1% detomidine (10µg/kg IV). Five minutes after sedation, morphine sulfate 10mg/ml (0.05 mg/kg slow IV) was administered to animals in G2 or the same volume of saline solution for a blind study in G1. Additionally, 10 to 15 ml of 2% lidocaine without vasoconstrictor were administered intratesticularly, in each testicle, and 5 ml were deposited along the incision line, parallel to the raphe. The EQUUS-FAP scale was used to assess pain. The evaluations were performed at the following times: M1 - day before, M2 - immediately before the surgical procedure, M3 - one hour, M4 - two hours, M5 - four hours, M6 - six hours and M7 - eight hours after administration of saline solution or morphine. Results The number of contractions of the duodenum, cecum, left and right ventral colon decreased in the moments after morphine administration. Stomach size increased significantly in group 3 (G3) compared to the other two groups (G1-G2). Group 2 (G2) showed higher values one hour after morphine administration. Conclusions: The administration of morphine in a single clinical dose in horses undergoing elective orchiectomy surgery produced better sedative effects, without major adverse effects, minimal decrease in intestinal motility and without producing gastric dilatation. The use of morphine associated with detomidine resulted in calm cavities with effective pain control during the period evaluated without alterations in cardiorespiratory parameters.