Sedation Quality and Cardiorespiratory, Echocardiographic, Radiographic and Electrocardiographic Effects of Intramuscular Alfaxalone and Butorphanol in Spanish Greyhound Dogs

SIMPLE SUMMARY: Sedation is sometimes necessary in veterinary practice to perform different medical procedures, such as echocardiography or radiography, due to uncooperative or aggressive patients. In patients with cardiovascular disease, anxiety needs to be reduced; however, hemodynamic conditions have to be preserved, so it is advisable to avoid sedatives such as alpha-2 agonists or phenothiazine, due to their cardiovascular side effects. Many studies support the cardiovascular stability obtained by the administration of alfaxalone, alone or in combination, in dogs. Butorphanol is a synthetic opioid characterized by minimal cardiovascular effects, making it an ideal drug for sedation protocols. We aimed to evaluate the hemodynamic impact of the administration of intramuscular alfaxalone and butorphanol in healthy dogs. The evaluation involved assessing the degree of sedation and the effects of the sedation on cardiorespiratory, echocardiographic, radiographic and electrocardiographic parameters at baseline and 30 min after the administration of sedation. Although statistically significant changes were observed in some of the studied parameters, no clinical alterations were found 30 min after drug administration. The results showed that alfaxalone and butorphanol at the doses used in this study provided moderate sedation for performing diagnostic procedures, and they caused mild hemodynamic and respiratory changes. ABSTRACT: The quality of sedation and changes in cardiorespiratory variables after the intramuscular administration of alfaxalone and butorphanol in Spanish greyhound dogs were evaluated. Twenty-one adult dogs were included. The dogs received alfaxalone (2 mg/kg) and butorphanol (0.2 mg/kg) intramuscularly. Sedation scoring, cardiorespiratory parameters (including blood gas analysis), echocardiography, thoracic radiography and electrocardiography were performed before sedation and 30 min after drug administration. Moderate sedation was observed, and side effects, such as tremors, nystagmus and auditory hyperesthesia, were noticed. Statistically significant changes in heart rate, invasive blood pressure, pH, arterial saturation of O(2) and partial pressure of O(2) and CO(2) were found. Echocardiographic variables, including end-diastolic volume, left ventricular diameter in diastole, aortic and pulmonic flow, diastolic transmitral flow and left atrial/aortic ratio, and electrocardiography parameters, including PQ interval and QT interval, showed statistically significant changes. In conclusion, the intramuscular administration of alfaxalone and butorphanol to healthy dogs produced moderate sedation with mild cardiorespiratory, echocardiographic and electrocardiographic changes, without alterations in cardiac size on radiographic images.