103 Myth or Real? There may be more to aortic rupture in the Friesian horse than can be explained by the current knowledge regarding collagen and elastin.

Answer – Real

A recent literature search turned up an article entitled “Friesian horses show higher arterial blood pressure compared to Warmbloods” which immediately caught my attention. A group of researchers at the University of Gent explored the idea that hypertension could be a possible risk factor for aortic rupture in Friesian horses and, because there has been little research done on this topic, set out to compare blood pressure values between the two breeds of horse. 82 healthy Friesian horses and 72 healthy Warmblood horses were evaluated for systolic (SAP), diastolic (DAP) and mean (MAP) arterial blood pressure using a tail blood pressure cuff. SAP is the pressure in the arteries during the contraction of the heart muscle. DAP is the pressure in the arteries when the heart muscle is between beat. Pulse pressure (PP) was also calculated (PP = SAP – DAP) and represents the force that the heart generates each time that the heart muscle contracts. These horses were standing, non-sedated and corrections were made for the height difference between the level of the heart base and the tail cuff. Each measurement was repeated 5 times on each horse with the mean value used for comparison. The results showed that Friesian horses had a statistically higher SAP and MAP as compared to the Warmblood horses. There was no statistical difference in the DAP values between the two breeds. Because the SAP values were statistically higher in the Friesian breed, this also means that the PP was also statistically higher as compared to the Warmbloods. These results led the researchers to suggest that there are different cardiovascular characteristics between the two breeds. They also went on to suggest that a higher SAP and PP might be the result of a less “compliant” vascular system (an inherent stiffness of the blood vessels, including the aorta). How might these findings play into aortic
rupture in the Friesian horse? Further research would be needed to determine that answer. In human medicine, the most important cause of elevated PP is stiffness of the aorta (due to high blood pressure or fatty deposits that damage the arterial walls), which leaves the aorta less elastic. The greater the PP in humans, the stiffer and more damaged the vessels are thought to be. Does this apply at all to the Friesian horse? Again, one might hope that further research would help to answer that question.

Scientific Article: Usse, V, et al. Friesian horses show a higher arterial blood pressure compared to Warmbloods.

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