Banca de DEFESA: ROGÉRIO JOSÉ BARBOSA ROCHA FILHO

Evaluation of different administration rates of propofol for anesthetic induction in goats.

General anesthesia; Intravenous hypnotics; Ruminants.

General anesthesia in goats presents specific challenges due to the physiological particularities of ruminants and the scarcity of anesthetic protocols validated for this species, especially with regard to the critical moment of anesthetic induction. Propofol is widely used in veterinary medicine because of its rapid onset of action, short duration, and smooth anesthetic recovery; however, its administration may cause significant cardiorespiratory depression, particularly when administered as a bolus or at high infusion rates. Therefore, the present study aimed to evaluate the effects of different propofol administration rates during anesthetic induction in goats, determining the dose required for induction, the incidence of post-induction apnea, and changes in cardiorespiratory physiological parameters, in order to identify the safest and most effective infusion rate for the species. Six healthy male Boer goats, aged between 11 and 12 months, were used. Each animal received four different propofol infusion rates—0.5, 1.0, 1.5, and 2.0 mg/kg/min—with a one-week interval between procedures. The animals were premedicated with xylazine (0.1 mg/kg), and anesthetic induction was performed using an infusion pump until an anesthetic plane compatible with orotracheal intubation was achieved. The total dose of propofol administered, time to anesthetic induction, occurrence and duration of post-induction apnea, as well as heart rate, respiratory rate, peripheral oxygen saturation, arterial blood pressure, and end-tidal carbon dioxide were evaluated. The results demonstrated that the rate of propofol administration directly influences induction time, total dose requirement, and cardiorespiratory stability in goats, with a higher incidence of apnea and respiratory instability observed at higher infusion rates. In contrast, intermediate infusion rates provided effective anesthetic induction, with a lower incidence of apnea and greater physiological stability. It is concluded that propofol administration at infusion rates of 1.0 and 1.5 mg/kg/min represents a safer strategy for anesthetic induction in goats, providing the best balance between anesthetic efficacy and cardiorespiratory safety.