Congenital heart defects are problems with the heart's structure that are present at birth. These defects can involve the interior walls of the heart, the valves inside the heart, or the arteries and veins that carry blood to the heart or the body. Congenital heart defects change the normal flow of blood through the heart.
Approximately 3% of all horses presented for a cardiovascular workup are diagnosed with congenital heart disease. In addition, 90% of newborn foals have been reported to have audible murmurs and 96% to have various cardiac arrhythmias which normally disappear by 15 minutes post-partum.
It is important to detect a congenital heart defect as early as possible. Certain defects can be corrected with surgery, and treatment should be performed before the defect leads to congestive heart failure or irreversible heart damage. If the defect is discovered in a recently purchased horse, you may be able to return it for a refund. Horses with congenital heart defects are likely to die prematurely, causing emotional distress. Animals purchased for performance have limited potential and will likely be unsatisfactory. Early detection also prevents continuing genetic defects into breeding lines.
The most frequent congenital heart defects found in horses are ventricular septal defects (VSD)
, followed by patent ductus arteriosus (PDA), atrial septal defect, patent foramen ovale, valvular dysplasia and atresia.