Routine Cardiovascular Monitoring

Heart sounds are best auscultated over the left lower lateral thoracic wall between the 4th and 5th intercostal spaces, typically where the elbow crosses the chest wall when the forelimb is pulled caudally.

The arterial pulse is best palpated at the femoral artery on the medial aspect of the proximal thigh in the inguinal area (Figure 17 and 18). The arterial pulse can also be palpated at the dorsal metatarsal artery on the dorso-medial aspect of the proximal hind paw, distal to the hock (ankle).

Figure 17. Location for palpation of the femoral arterial pulse while dog is standing.
Figure 18. Location for palpation of the femoral arterial pulse from medial view of the hind limb.

ELECTROCARDIOGRAMS

Electrocardiogram (ECG) electrodes should be taped to the pads of the paws (Figure 19 below) on the left forelimb (black lead), right forelimb (white lead), and left hind limb (red lead). Three-lead ECGs are sufficient. Canine ECG complexes resemble human complexes, with minor variations in key ECG intervals and possible inverted T-waves. Electrode or ultrasound gel may be required between the electrode and footpads to improve contact.

Figure 19. Placement of ECG electrode pads.

PULSE OXIMETRY

Human pulse oximetry probes (typically finger probes) are best placed on the tongue for optimal reliability in unconscious, sedated or anesthetized MWDs (Figure 20) but can also be placed on the prepuce or vulva. In conscious dogs, use the ear pinna, lip fold, or flank skin fold. Although these are not optimal for pulse oximetry, these alternate sites generally yield reliable results. Normal pulse oximetry for an MWD is greater than 95%.

Figure 20. Placement of human pulse oximeter finger probe on tongue.

NON-INVASIVE BLOOD PRESSURE MONITORING

Non-invasive blood pressure (NIBP) monitoring is accomplished with doppler or oscillometric techniques. Cuff size and patient positioning are critical to obtain accurate readings. The width of the cuff should be 30 - 40% of the limb circumference at the site of cuff placement.4 Human pediatric cuffs (size 6 to 8) fit most MWDs.

Common locations for doppler probe placement include the dorsal pedal artery, digital artery, and coccygeal artery (Figure 21 below). Patients should lie in lateral recumbency with the cuff positioned on the limb at the level of the right atrium.

Common locations for cuff placement for oscillometric measurements are over the dorsal metatarsal artery, lower forearm, and tail base.

Figure 21. Placement of doppler probe on digital artery with accompanying cuff placement.