A six-month-old, male Przewalski’s horse died at the National Zoo’s Conservation and Research Center in Front Royal, Va. Friday, Jan. 30 due to a fractured neck. The cause of injury remains undetermined-staff closely observing the horse in the moments preceding its death did not notice any unusual behavior that would have caused the injury.

Staff directed the colt into a chute system leading into a trailer which would transport him and a six-month-old filly to a new pasture on Friday afternoon. The animal walked onto the trailer-as it had many times previously-without exhibiting any signs of stress or injury. Following protocol, staff checked on the animals a few minutes after they entered the trailer. Staff found the colt unconscious, but it was still breathing. The horse was quickly transported to the Center’s veterinary hospital where veterinarians attempted to resuscitate him, but he died a short while later. A subsequent necropsy report showed that the horse had sustained a fracture of the fourth cervical vertebrate in his neck.

The colt was born in July, sired by a 9-year-old stallion named Frog, the most genetically valuable Przewalski’s horse in the North American breeding program. Its mother came from Europe to breed with Frog in order to boost the breeding program. The Przewalski’s horse is a horse species native to China and Mongolia that was declared extinct in the wild in 1970. Currently, there are approximately 1,500 of these animals maintained in zoological institutions throughout the world and in several small reintroduced populations in Asia.

The filly that was also being transported sustained no injury and is in good health.

From a release.