It's hard out there for a bovine.

One of seven new baby bison introduced to the Bison Paddock in Golden Gate Park has died after sustaining injuries from an incident with a small dog Wednesday afternoon, according to the San Francisco Zoo.

Witnesses saw a "toy breed" dog running around the rear of the paddock around 9 a.m. The dog was seen burrowing under a fence to exit the animal enclosure, and it is suspected that it entered in the same manner as well. An investigation into how the dog was able to breach the paddock is ongoing.

Park Patrol identified the dog handler who was trying to coax the dog from the area. The handler was found to have five dogs off leash and was cited for failure to use a leash in a designated on-leash area as well as for animal disturbance.

The SF Zoo was immediately notified and zookeepers were dispatched to examine the herd. A laceration on the left side of one of the smallest, young bison was found.

Further examination by a veterinarian uncovered three broken ribs. The injuries were treated and the animal was allowed to rejoin its herd.

At approximately 5:20 p.m. Wednesday evening,  the Zoo received notification that the bison was found dead.  The cause of death is under investigation.  A necropsy is scheduled for later today at SF Zoo.

The dead bison is one of seven that arrived at in Golden Gate Park on Dec. 6.

The new baby bison were purchased after state Assemblywoman Fiona Ma helped arrange the funding and Richard Blum, the husband of Sen. Dianne Fienstein, chipped in with help.