In a case study from Ghent University, a 16-year Friesian gelding was admitted with complaints of exercise intolerance, pale mucous membranes, tachycardia (increased heart rate) and an irregular heart rate. Further examination revealed decreased heart sounds and a low hematocrit (measure of red blood cells in a blood sample), which led to a suspicion of hemothorax. This was confirmed when the chest was ultrasounded.
Because this was a Friesian, it was thought that it was due to aorto-pulmonary fistulation, but that was ruled out by an echocardiogram. It was determined that the irregular heart rate was caused by atrial premature contractions (premature heartbeats that originate from the atria). The horse was hospitalized and treated conservatively with antibiotics. A repeat of the ultrasound and the hematocrit showed improvement and the horse was released from the hospital after 15 days. A follow up at 6 weeks showed no abnormalities.
Relevance: With aortic fistulation/rupture a very real concern in this breed, it can be difficult to keep an “open mind” when a Friesian horse shows symptoms consistent with those seen with aortic fistulation/rupture. This case study points out the need to be thorough when examining these horses in the event that an entirely different problem may indeed be masquerading as an aortic issue.
Scientific Article: Vera L, DeClercq D, Decloedt A, VanLoon G. Hemothorax in a Friesian horse: Not always an aortic rupture! Vilaams Diergeneeskundig Tijdschrift 84(3): 142-146 April 2015.