Friesian horses could provide useful insights into a rare condition in humans known as acquired aortopulmonary fistulation, according to researchers in the Netherlands.
The condition is an abnormal connection – a fistula – between two major blood vessels – the thoracic aorta and pulmonary artery.
It usually results as a late complication in the thoracic aorta of an aneurysm or pseudoaneurysm (a hematoma that forms as the result of a leaking hole in an artery). It is most commonly associated with trauma or surgery, less commonly with atherosclerosis, inflammation, hypertension, or Marfan’s syndrome.
On rare occasions it is reported in older patients without any of the above-mentioned triggering factors.
Veronique Saey and her colleagues, writing in the journal BMC Research Notes, said the manner in which the disease developed was not yet completely understood.
Aortic rupture is extremely rare in the general horse population, but can occasionally be seen in older breeding stallions and sports horses in full exercise.
Friesian horses, they said, were highly inbred and were affected by several genetic conditions. Rupture of the thoracic aorta had a relatively high prevalence in Friesians and was often characterized by the formation of a pseudoaneurysm with subsequent fistulation into the pulmonary artery.
Affected animals may survive for several weeks to months.
The researchers, from Grent University and Utrecht University, carried out an investigation of the condition in three affected Friesians. They took post mortem casts of the involved blood vessels using silicone in two cases and a propriety preparation for the third.
In all three cases, a rupture at the caudoventral side (the underside, toward the tail) of the aorta was connected with a rupture of the main pulmonary artery near where it split into two branches.
“Affected Friesians show a consistent location and configuration of the aortic rupture site, very similar to the human condition,” the study team wrote.
“In summary,” they continued, “the aortic rupture and aortopulmonary fistulation formation in Friesian horses occurs without any history of trauma or signs of inflammation.
“Considering the similar location of the lesions in Friesian horses and humans, the chronic aspect of this disease, the fatal outcome and the possibility to obtain vascular casts, the Friesian horse could be a valuable spontaneous model for this condition in humans.”
Friesian horses as a possible model for human acquired aortopulmonary fistulation.
V. Saey, T. Vandecasteele, G. van Loon, P. Cornillie, M. Ploeg, C. Delesalle, A. Gröne, I. Gielen, R. Ducatelle and K. Chiers
BMC Research Notes 2016 9:405 DOI: 10.1186/s13104-016-2201-5