I called the El Cajon Animal Shelter today to see if I could find out anything about the elderly golden retriever that I took in last Thursday. http://www.adoptapet.com/adoption_rescue/69341.html
The dog is still at the shelter and is up for adoption. Although he had a microchip, the people at the shelter were unable to find his owner. They thought the owner information had probably not been updated if the original owner had moved or the dog now belonged to somebody else.
Since Rob and I are unable to adopt him, we are really hoping that someone at the dog park may be interested in having him.