Transient millwheel heart murmur and cardiorespiratory alterations in a dachshund during hemilaminectomy

Abstract

A four‐year‐old dachshund was admitted for progressive para‐paresis. The dog had no signs of cardiovascular disease, and cardiac auscultation was unremarkable. The dog was anaesthetised for MRI and subsequently hemilaminectomy. During surgery, drops in blood pressure and end‐tidal carbon dioxide were observed concurrent to surgical site haemorrhage. At this time, a rumbling/churning ‘millwheel’‐type cardiac murmur was detected via an oesophageal stethoscope. Other anomalies, such as arrhythmias and tachypnoea, were also observed. The planned surgery was shortened and the dog made a full uneventful recovery. The heart murmur audible externally immediately after recovery, disappeared over the following 12 hours. The events reported are compatible with the occurrence of a venous air embolism (VAE). Review of the literature indicates that subclinical VAE might be more frequent than usually believed, as precursor signs might be tenuous and non‐evocative of VAE. Awareness of this potentially life‐threatening complication should be raised.