From Seattle City Light Superintendent Jorge Carrasco:

On Thanksgiving, a dog was electrocuted on Queen Anne Avenue when it came into contact with a metal plate covering some electrical wires for four streetlights. This was a tragic incident and devastating for the family that owned the dog. We are truly sorry for their loss of a beloved family member. I want to assure the public that as soon as City Light was made aware of the situation, we responded by de-energizing the electrical service.

An explanation about how the lights had no grounding and the assurance this was a freak accident are here.