In 2016, a case report of a 24-day-old Friesian colt who died suddenly was published by a group of veterinarians from the Western College of Veterinary Medicine in Saskatoon, Canada. This very young colt had an uneventful delivery and nursed well at birth, had a normal IgG and physical examination findings. He was found dead in the afternoon following a thunderstorm, lying on his left side with no signs of a struggle.
Physical examination of the foal showed no abnormalities, and the body of the foal was transported quickly such that a necropsy was performed very shortly after death. Findings included blood in the chest cavity with a rupture of the aorta at the aortic root. Histopathology also showed the presence of two bacteria in the large colon, but this was considered to be an incidental finding, although of interest due to the type and location of these two bacteria.
The authors found this case to be unique for a number of reasons:
The very young age of this foal.
The rupture was at the aortic root rather than at the ligamentum arteriosum (the more consistent and described location in the Friesian).
The fact that this colt was an asymptomatic carrier of two bacteria not usually found in the large colon in equids in North America.
This case study and the accompanying clinical commentary help to bring to the forefront the issue of aortic rupture in the Friesian horse.
Scientific Article: Diel de Amorim, M, Nielsen, K, McKell, B, Huang, Y., and Card, C. Aortic rupture causing cardiac tamponade in a 24-day-old Friesian colt with concurrent colonic Chlamydiosis and Balantidiosis. EVE American Edition, Feb. 2016, pp. 68-72