Prevalence and characteristics of ventricular septal defects in a non-racehorse equine population (2008-2019).
Authors: De Lange Lisa, Vera Lisse, Decloedt Annelies, Van Steenkiste Glenn, Vernemmen Ingrid, van Loon Gunther
Journal: Journal of veterinary internal medicine
Summary
# Ventricular Septal Defects in Non-Racehorse Populations: Prevalence and Clinical Significance Ventricular septal defects (VSDs) represent the most common congenital cardiac anomaly in horses, yet their prevalence in non-racing populations and true clinical burden remain poorly characterised. Between 2008 and 2019, researchers reviewed echocardiographic records from 1,894 horses at a large equine teaching hospital, identifying 54 cases with confirmed VSDs (42 isolated lesions and 12 as part of complex congenital heart disease) and stratifying findings by age, breed, sex, and cardiac dimensions. Perimembranous VSDs dominated the isolated group (86%), with surprisingly few horses (15%) exhibiting associated clinical signs; however, symptomatic animals demonstrated significantly reduced shunt velocity (3.77 versus 5.20 m/s), larger defects relative to aortic root diameter, and marked left atrial and pulmonary artery enlargement compared to asymptomatic counterparts. Notably, Warmbloods and males were overrepresented, and whilst most isolated VSDs were diagnosed at a median age of 5 years, animals with complex congenital heart disease presented earlier with clinical manifestations and abnormal cardiac remodelling. These findings suggest that many isolated VSDs remain haemodynamically inconsequential throughout the horse's life, yet practitioners should monitor cardiac dimensions and shunt velocity patterns to identify the minority of cases likely to progress, particularly in young Warmblood stallions and those with complex lesions.
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Practical Takeaways
- •Most isolated VSDs are clinically silent and diagnosed incidentally in older horses; their presence alone does not predict exercise intolerance or poor prognosis
- •Echocardiographic findings of lower shunt velocity, larger VSD size relative to aortic root, and chamber enlargement correlate with clinical signs and should prompt closer monitoring or restrict athletic use
- •Complex congenital heart disease presents differently than isolated VSD: affected horses develop clinical signs earlier and at younger ages, requiring careful case management
Key Findings
- •Among 1,894 horses undergoing echocardiography, 54 had VSD (2.9%): 42 isolated and 12 as part of complex congenital heart disease
- •Only 15% of horses with isolated VSD showed associated clinical signs; most had perimembranous VSD (86%)
- •Warmbloods and males were overrepresented in the VSD population
- •Horses with clinical signs showed lower maximal shunt velocity (3.77 vs 5.20 m/s), larger VSD/aortic root ratio, and increased cardiac chamber dimensions compared to asymptomatic horses