Cardiovascular system Cardiovascular system

Subclinical and clinical cardiac disease is common in older dogs, and impaired cardiovascular function should be expected in elderly patients.

Baroreceptor function may be impaired, particularly in patients with chronic congestive heart failure, and the cardiovascular system's ability to compensate for surgical haemorrhage, or for the vasodilatory effects of anaesthetic agents may be inadequate resulting in severe hypotension.

Existing cardiovascular conditions such as congestive heart failure, cor pulmonale, sick sinus syndrome and the cardiac signs associated with hyperthyroidism in cats should be stabilised before general anaesthesia.

Anaesthetic agents depress cardiac function and cardiac arrest can be precipitated if cardiac arrhythmias are present, particularly ventricular arrhythmias that are refractory to therapy, right bundle branch block and bradycardia (heart rate below 60 in dogs; below 80 in cats).

Monitoring heart rate and systolic and diastolic blood pressures by direct or indirect methods is desirable throughout anaesthesia as is ECG recording, monitoring pulse character and regular examination of visible mucous membranes for capillary refill time.