Recent news out of Chicago shows a dog playing in the backyard when it was attacked by a coyote. Thankfully, the dog was not killed; but was severely injured. The coyote was chased away by the homeowner.
Homeowners are encouraged to install an outdoor dog enclosure in the backyard to avoid wildlife encounters. Coyotes and wolves will harm dogs, cats and livestock animals including backyard chickens, if given the opportunity.
This is why homeowners should install dog fence to keep coyotes, wolves, and other wild animals away from yards. In addition to wildlife exclusion, there are animal wellness reasons for why a fence is beneficial to dogs such as for: dog exercise; socialization and happiness.