BERLIN, Md. — Officials say a wild horse had been found dead after eating dog food that someone improperly stored at Assateague Island National Seashore.

The National Park Service said in a statement that the body of the 7-year-old mare called Chama Wingapo was found dead in a campground on Thursday.

The statement says an investigation found the horse had ingested a “large quantity” of dog food days earlier on July 17. A necropsy determined the dog food caused a blockage and resulted in a ruptured intestine, causing death.

While the food may not have been given directly to the horse, officials say the dog food wasn’t properly stored away from the horses. The statement says visitors must make sure all food, including pet food, is properly stored.