The incident happened Tuesday afternoon at the park in northeast Bend.
An American Bull Dog killed a Papillon -- both were off leash in the park.
Vance Lawrence is a patrol sergeant with the Deschutes County Sheiff's Office and says this is the first dog death he's heard of at a park.
"I'm not aware of any incident of this level. We do hear about people having aggressive dogs and the Parks and Rec controls the dog park. They handle most of the issues and patrol issues."
The Sheriff's Office was called in because of the severity of the incident.
"I wasn't there, but after talking with the technician, they both seemed appropriately traumatized by this and the suspect's dog owner was unaware their dog had this kind of aggression in it."
The owner of the bull dog was ticketed for animal nuisance, but that is as far as law enforcement can go, unless the Papillon owner pursues civil action.