New applications of alpha2-agonists in veterinary medicine

Alpha2-agonists are a class of drugs widely used in veterinary anaesthesia; moreover by means of their action on adrenoceptors that are widespread distributed in several tissues, they can be beneficial for different clinical applications. The aim of this work was to describe new applications of alpha2-agonists in veterinary medicine. In cats, high dose medetomidine is administered to perform semen collection by urethral catheterization. We have investigated the haemodynamic effects of high dose medetomidine (0.13 mg kg-1) administered to healthy male cats. Haemodynamic evaluations were performed before and after medetomidine administration and consisted of: clinical examination, blood pressure evaluation and transthoracic echocardiography. Significant hemodynamic alterations were observed, even if they were similar to that provided by lower dosages. The cats recovered without clinical alterations. Despite their cardiovascular side effects, low doses of alpha2-agonists can be beneficial for the maintenance of a good cardiovascular stability for specific conditions. In humans, dexmedetomidine helps in maintaining a good hemodynamic stability if administered for pheochromocytoma ablation. We have described the administration of dexmedetomidine for the anesthetic management of two dogs with a suspicion of pheochromocytoma undergoing adrenalectomy. Dogs received dexmedetomidine intramuscularly (0.001 mg kg-1) and dexmedetomidine and remifentanil were administered (0.0005 mg kg-1h-1 and 0.0003 mg kg-1min-1, respectively) throughout the surgery. In this study dexmedetomidine infusion together with remifentanil provided satisfactory intraoperative anesthetic and hemodynamic control in two dogs with a suspicion of pheochromocytoma. In patients undergoing craniotomy, dexmedetomidine, increasing the cerebral vascular resistance, prevents alteration of the cerebral blood flow. We have described the administration of dexmedetomidine in five Macaca fascicularis undergoing craniotomy for physiologic research. The Macaca were sedated with ketamine (8 mg kg-1) and dexmedetomidine (0.02 mg kg-1) intramuscularly. Dexmedetomidine was administered by infusion (0.012 mg kg-1h-1) throughout the procedure and provided adequate analgesia and a stable hemodynamic control in healthy Macaca.