Heart Defects in Foals

Newborn foals that show rapid heartbeat and respiration rate, have a heart murmur that is easily heard, and exhibit a bluish appearance to the gums may have a congenital heart defect such as a hole in the wall that separates the two lower chambers of the heart.

This cardiac abnormality can allow some blood to move between the ventricles instead of being circulated to the lungs and the rest of the horse’s body. While small holes may not cause a problem, larger openings generally keep the affected animal from being able to exercise normally and are likely to play a role in shortening the horse’s life.

A review of the records at the University of California-Davis veterinary clinic during a 15-year period showed that 18 foals were diagnosed with cardiac defects. The foals were a few weeks old when the diagnosis was made. Fourteen of the foals had the ventricular defect described above, and six of the foals had more than one defect. Only two of the 18 foals lived longer than eight years; one of these was healthy enough to train and compete at the third level of dressage.

The foals represented a number of different horse and pony breeds. Seven of the foals, or 39% of the total, were of Arabian breeding. This suggests, but does not prove, that cardiac defects may be more common in Arabian horses. Research with a larger sample of horses might clarify this question.

Owners or managers should watch newborn and very young foals for signs that could indicate a heart problem and should get a veterinarian to examine any foal that appears weak, has an elevated respiration or heart rate, and shows blue mucous membranes.