Foal Heart Murmurs Could Signal Other Problems

Any foal with an abnormally high respiration rate, heart rate, blue gums, or exercise intolerance should be evaluated for heart defects. If one is found, it's a good idea to look for other congenital problems.

K. Gary Magdesian, DVM, Dipl. ACVIM, ACVECC, ACVCP, and his colleagues at the University of California, Davis reviewed the medical records of 18 foals that were born with one or more cardiac defects. Just as in people, the most common congenital heart defect was ventricular septal defect (VSD)--a hole in the wall that separates the right and left ventricles. Other common problems were tetralogy of Fallot, a set of four defects that lowers the amount of oxygen in the blood, and tricuspid valve atresia, where the heart valve that prevents the backflow of blood between the right atrium and right ventricle is missing or malformed.

Half of the foals also had a congenital defect that affected another organ. "Foals should be evaluated for loud murmurs as part of a healthy foal examination during the first one to two days of life," said Magdesian. "If a loud murmur is heard, and the foal exhibits high heart or respiratory rate, blue tinged gums, or exercise intolerance, it should be evaluated with an echocardiogram [an ultrasound examination of the heart] for a heart defect. If none of these signs are present, the murmur should be evaluated in a few days. If the intensity does not decrease, then an echocardiogram would be indicated.

"In addition, half of the foals in our study had concurrent defects in other organ systems, so affected foals should be evaluated for other defects, including kidney, neurologic, and musculoskeletal abnormalities."

In his study, Arabian horses were over-represented: 39% of the foals were Arabians.

The heart defects in this study were so severe that most foals did not survive beyond the first few days of life, Magdesian said, but two foals survived for more than eight years and one was a successful performance horse.

"Not all murmurs are life threatening or serious," he reminded, and horses with minor defects can lead normal lives. The study, "Congenital cardiac defects in neonatal foals: 18 cases (1992-2007)," was published in the January-February issue of the Journal of Veterinary Internal Medicine.

The abstract is available on PubMed.

About the Author

Marie Rosenthal, MS

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