Use of Transoesophageal Ultrasound to Visualise the Aortopulmonary Region in Two Normal Friesian Horses and Three Friesians With Aortic Rupture or Aortopulmonary Fistulation

Aims: Aortic rupture and aortopulmonary fistulation are reported with increased incidence in the Friesian breed. In contrast to Warmblood horses, the aorta in Friesian horses typically ruptures at the level of the ligamentum arteriosum (Ploeg et al. 2013). This remote location often creates difficulties in identifying the rupture with transthoracic ultrasound. The aim of this study was to evaluate the usefulness of transoesophageal visualisation of the aortopulmonary region with a linear probe in both standing unsedated horses and horses suffering from aortic rupture.

Methods: Five Friesian horses, 2 healthy and 3 affected, were subjected to transthoracic ultrasound (2.5 MHz sectorial probe GE) followed by transoesophageal ultrasound (7.5 or 10 MHz linear probe). Correct oesophageal introduction of the probe was guided by means of endoscopy. After visualisation of the aortopulmonary region, horses were anaesthetised, and the transoesophageal ultrasound was repeated. In 4 horses, simultaneous carotid artery catheterisation was performed, to visualise the catheter at the zone of interest. After obtaining a diagnosis, all affected horses were subjected to euthanasia and autopsies were performed. [...]