The fire on Sunday night completely destroyed the barn in Yorklyn.
Firefighters took an hour to get the blaze under control, with tankers needed to get water to the scene.
One horse managed to escape the blaze.
The property owners are understood to be breeders of Egyptian Arabians, and The Pyramid Society in the US is rallying its members to help in recovery efforts. “We are united with the Egyptian Arabian horse community in our sympathy and heartbreak for the loss of so many horses treasured by Jeannette, Nadia and the Amer family,” said society president Bob Miars.
Fire investigators are working to establish the cause of the fire.