Diego Sarotti ^1* Elena Lardone ² Paolo Franci ² Stefano Oricco ³ Roberto Rabozzi ⁴

• ¹ Fossanese Veterinary Center, Fossano, Italy
• ² Department of Veterinary Science – University of Turin, Grugliasco, Italy, Turin, Italy
• ³ Clinica veterinaria imperiese, Imperia, Italy
• ⁴ Veterinary Clinic Roma Sud, Rome, Sicily, Italy

This randomized prospective clinical study aimed to compare the hemodynamic effects of propofol and alfaxalone for the induction of anaesthesia in dogs. Thirty-one healthy dogs undergoing various procedures in a private referral centre were premedicated with intramuscular acepromazine (0.015 mg/kg) and methadone (0.15 mg/kg). They then received 5 mg/kg of propofol over 30 seconds for induction, followed by a maintenance dose of 25 mg/kg/h (Group P), or 2 mg/kg of alfaxalone over 30 seconds for induction, followed by a continuous rate infusion of 10 mg/kg/h (Group A). Heart rate (HR), mean arterial pressure (MAP), and the velocity time integral (VTI) of the aortic blood flow using transthoracic echocardiography were measured before anaesthetic induction and every 15 seconds for 180 seconds. Dogs not adequately anaesthetized for intubation were excluded from the hemodynamic evaluation. Events of bradycardia (HR < 60 beats/min) and hypotension (any MAP value lower than 60 mmHg) were also recorded. Statistical analyses utilized ANOVA for repeated measures, two-way repeated measures ANOVA, paired t-tests, or Wilcoxon signed rank-test as appropriate. Significance was set at p< 0.05. Two dogs in Group P (2/14) and 3 in Group A (3/17) were excluded from the study because the anaesthesia plane was too light to allow intubation. Treatment P resulted in a significant decrease in MAP between 45-75 seconds during the induction period, with no significant variation in HR, VTI, and VTI*HR. In treatment A, HR increases between 60-105 seconds, VTI decreases at 150-180 seconds. Analysis between groups didn’t show any difference in MAP (p=0.12), HR (p=0.10), VTI (p=0.22) and VTI*HR (p=0.74). During induction, hypotension was detected in 3/12 (25%) dogs in Group P and 1/14 (8%) in Group A. In healthy premedicated dogs, propofol and alfaxalone induction produce similar hemodynamic variations. Propofol induction results in a short-term reduction in MAP, whereas alfaxalone induction preserves MAP and cardiac output by significantly increasing heart rate.