Researchers in the Netherlands have developed a diagnostic technique for the visualization and diagnosis of Friesian horses suspected of having an issue with their aorta (rupture or aortopulmonary fistulation). It has been shown that Friesian horses have an issue with a specific location of the aorta (at the level of the ligamentum arteriosum) that is different from what is observed in other breeds. This area is located further away in a more remote location on the aorta and is very difficult to identify when an attempt is made to see it via a thoracic (chest) ultrasound. In this project, the goal was to evaluate the usefulness of a transesophageal ultrasound method (visualization of the aorta through the esophagus) that could be performed in a standing unsedated horse.
For this study, 5 Friesian horses, two healthy and three affected, were first ultrasounded by the standard method through the chest wall. They were next ultrasounded through the esophagus by passing the ultrasound probe through a clear nasogastric tube and using an endoscope to visually guide the probe/tube down into the esophagus. The region of the aorta was then visualized and recorded, the horses were put under anesthesia, and the transesophageal ultrasound was repeated.
The researchers found that the region of interest on the aorta was easily visualized on all of the horses. With the three affected horses, “the presence or absence of a periaortic blood cuff, aortic rupture and/or aortopulmonary fistulation could be clearly identified.” It was concluded that this method provided good visualization of the aortopulmonary region and for diagnosing aortic rupture in Friesian horses. It is hoped that this technique could also “be further developed as an elegant noninvasive way to screen Friesian horses for this pathology, even in the standing, nonsedated animal.”
Bruijn, M. et al. “Use of transoesophageal ultrasound to visualize the aortopulmonary region in two normal Friesian horses and three Friesians with aortic rupture or aortopulmonary fistulation”, Equine Veterinary Journal, 2013, EVJ Ltd.