VN April 2023

Vetnuus | April 2023 10 Heart rate and rhythm can be monitored by an infant or pediatric stethoscope, an esophageal stethoscope, electrocardiogram (ECG), or a Doppler ultrasonic flow probe. The peripheral pulse rate can be palpated in birds and mammals, and an apex beat or pulse can sometimes be visualized in the reptile patient. EXOTIC COMPANION MAMMALS Assess the rate, rhythm, and quality of the peripheral pulse in larger species like the rabbit ( Oryctolagus cuniculus ). The femoral artery is most easily palpated. 6 The peripheral pulse rate can also be palpated at the dorsal pedal artery, axillary artery, auricular artery, and the caudal (tail) artery. Heart rate can also be palpated directly over the thoracic cavity. Similarly, the transducer of the Doppler monitor can be placed directly over the heart or a superficial artery, like the carotid, carpal, or femoral artery, to generate real-time, continuous monitoring of heart rate. 23 Use of the Doppler probe is particularly useful in tiny patients since changes can occur rapidly (Fig 3). 20,31 An esophageal stethoscope can be used to monitor heart rate in larger animals, like the rabbit and ferret ( Mustela putorius furo ), but can induce regurgitation in guinea pigs ( Cavia porcellus ). 14 Leading Article Bradycardia Tachycardia • Anesthetic agents • Increased vagal tone • Drugs: mµ opioid agents, beta blocking agents • Metabolic: hypothermia, end-stage hypoxemia, hyperkalemia • Heart disease (sick sinus syndrome, AV conduction disturbance) • Sepsis • Shock • Dive response • Light level of anesthesia: arousal to sensory input, pain response • Drugs: ketamine, parasympatholytics, sympathomimetics • Metabolic: hypovolemia, hypoxemia, hypercapnia, hyperthermia • Post-operative pain • Heart disease (supraventricular tachycardia, ventricular tachycardia) • Disease (pheochromocytoma, hyperthyroidism in small animals) Table 4. Potential causes of bradycardia and tachycardia 9 Figure 3: A Doppler ultrasound probe placed directly over the thoracic cavity of a rat (Rattus norvegicus). Photo credit: Katrina Lafferty, CVT, VTS.