SAN DIEGO — Investigators with the San Diego Humane Society are looking for the person who abandoned a “severely emaciated” dog in Pacific Beach last week that had to be euthanized. The dog, a male shepherd mix thought to be around 3 years old, was found near the Kendall-Frost Marsh Reserve by Pacific Beach Drive and Olney Street last Tuesday, the Humane Society said. The person who found the dog immediately took it to a veterinarian, and it was transferred to the Humane Society to be treated. Veterinarians there determined the abandoned dog was in such a deteriorated state that it needed to be euthanized. It was put down that same day, a spokeswoman said.