Which species is associated with a bradycardia rate as low as 25 bpm during stage III anesthesia?

Which species is associated with a bradycardia rate as low as 25 bpm during stage III anesthesia?

• A. Dog 60-70 bpm
• B. Cat 100 bpm
• C. Horse 25 bpm
• D. Cow 40 bpm

Answer: (C)

During stage III anesthesia, heart rate response varies by species, and horses show the strongest tendency toward profound bradycardia. Their autonomic balance under anesthesia—marked vagal influence and sensitivity to inhaled anesthetics—can push the heart rate down very low, sometimes around 25 beats per minute. This level of bradycardia is much less typical in dogs or cats, whose heart rates under similar anesthesia tend to be higher (dogs often around 60–70 bpm, cats around 100 bpm). Cattle can experience bradycardia as well, but it generally isn’t as deep as what’s seen in horses. So, a 25 bpm rate during stage III anesthesia is characteristic of horses, reflecting their unique autonomic and anesthetic responsiveness. Clinically, such bradycardia signals the need to reassess anesthetic depth and consider interventions to support heart rate if needed.

During stage III anesthesia, heart rate response varies by species, and horses show the strongest tendency toward profound bradycardia. Their autonomic balance under anesthesia—marked vagal influence and sensitivity to inhaled anesthetics—can push the heart rate down very low, sometimes around 25 beats per minute. This level of bradycardia is much less typical in dogs or cats, whose heart rates under similar anesthesia tend to be higher (dogs often around 60–70 bpm, cats around 100 bpm). Cattle can experience bradycardia as well, but it generally isn’t as deep as what’s seen in horses. So, a 25 bpm rate during stage III anesthesia is characteristic of horses, reflecting their unique autonomic and anesthetic responsiveness. Clinically, such bradycardia signals the need to reassess anesthetic depth and consider interventions to support heart rate if needed.