Cardiac findings in Quarter Horses with heritable equine regional dermal asthenia.

This research investigated and compared the structural and functional characteristics of heart valves in Quarter Horses affected by heritable equine regional dermal asthenia (HERDA) and those without the disease. The findings showed that heart valves in HERDA-affected horses were weaker, supporting the theory that not just skin, but other tissues rich in collagen are abnormal in horses with HERDA. Though most echocardiographic findings were similar in both groups, further research is needed to confirm these results.

Methods and Procedures

• The study was designed as a prospective case-control study, involving 41 Quarter Horses.
• A combination of biomechanical testing, histologic evaluation, and echocardiography was used to assess the horses.
• The biomechanical strength of aortic and mitral valve leaflets was gauged in 5 horses affected with HERDA and 5 without it (controls).
• The histological analysis of aortic and mitral valves was done for 6 HERDA-affected and 3 control horses.
• Echocardiography was conducted in 14 HERDA-affected and 11 control horses.

Results

• The mean and maximum strength of heart valves (UTS) was significantly lower in HERDA-affected horses than in controls.
• Unusually, blood vessels were identified in the aortic valve leaflets of HERDA-affected horses but not in the control group.
• When body weight was accounted for, the mean and maximum height and width of the aorta at the valve annulus in short-axis images were considerably related to HERDA status and were smaller for affected horses.
• However, most echocardiographic data did not vary significantly between the two groups.

Conclusions and Clinical Relevance

• The lower tensile strength of heart valves in HERDA-affected horses confirms that tissues with high amounts of fibrillar collagen, not just skin, are abnormal in horses affected by HERDA.
• Due to the lack of significant differences in most echocardiographic variables between affected and control horses, it was suggested that echocardiography may not be sufficient to pinpoint considerable loss of heart valve tensile strength.
• This study puts forward that there might be a need for further research to solidify these findings.
• Studies of this kind, examining horses with HERDA, could potentially provide chances to understand better cardiac abnormalities in humans suffering from collagen disorders.