Table 13.

Methods for monitoring heart rate during anesthesia

Modality	Reliability in cats	Comments
Manual palpation	++	Small patient size makes palpation challenging
Auscultation with external stethoscope	+++	Placement of an external stethoscope can be challenging when cat is covered by surgical drapes
Auscultation with esophageal stethoscope	++++	Tip of esophageal stethoscope is positioned directly over the heart; easy access throughout surgery
Doppler ultrasonography	+++	Audible signal of pulse rate and rhythm
Pulse oximeter	++	When signal quality is good, pulse rate is accurate; many factors decrease signal quality (see later section on oxygenation)
ECG	+	Small patient size often associated with poor ECG signal; ECG rate (electrical activity) is not the same as heart rate (physical contraction/pulse)

+ = Poor reliability; ++++ = very reliable; ECG = electrocardiography