A baby bison that died Wednesday after apparently running into a fence in fright while being chased by a small dog showed signs of blunt force trauma, according to San Francisco Zoo officials.

The zoo released the results of a post-mortem exam Thursday that showed the bison suffered three broken ribs, extensive bruising on its left chest wall and sternum and blood within the left chest cavity. In addition, it suffered lacerations to its skin and muscles.

The bison was in good condition outwardly aside from its injuries, zoo officials said.

The bison’s injuries occurred around 9 a.m. Wednesday, when Recreation and Park rangers responded to the bison paddock in Golden Gate Park.

They found a small dog running around a part of the enclosure where seven recently arrived young bison were being quarantined as they adapted to their new surroundings, zoo spokeswoman Lora LaMarca said.

The dog eventually burrowed under a fence and exited the paddock, likely at the same spot where it came in, park officials said.

Park officials notified the zoo, which is responsible for the bison in partnership with the Recreation and Park Department. The seven young calves were added to the paddock in November.

Zookeepers responded and found that one of the small bison had suffered the laceration to its left side and three broken ribs, LaMarca said.

She said the bison apparently ran into a fence in the enclosure because it was “really upset about the dog that had gotten in there.”

The young animal was briefly taken out of the enclosure but was later returned to the herd, LaMarca said.

But at about 5:20 p.m. Wednesday, officials learned that the bison had died.

The dog handler was found to have five dogs without a leash. The handler, who has not been identified, was cited for animal disturbance and failure to use a leash in a designated on-leash area, park officials said.

There has been a bison herd in Golden Gate Park since 1877, and the herd has been at its current location since 1899. The paddock fencing was upgraded in 2007 and the paddock service area was renovated last fall in preparation for the arrival of the new calves.

Park officials said they plan to investigate how the dog got into the enclosure.

Want more news, sent to your inbox every day? Then how about subscribing to our email newsletter? Here’s why we think you should. Come on, give it a try.

Please make sure your comment adheres to our comment policy. If it doesn't, it may be deleted. Repeat violations may cause us to revoke your commenting privileges. No one wants that!