Zoey had been dumped from a vehicle at a rural property near Stockton and was found by someone who called police, saying she seemed old and ill.
An animal services officer scanned the dog's microchip and discovered she had been missing since 2010.
"I definitely didn't expect this to ever happen so I'm really excited," said Zoey's owner Michelle.
Zoey had been missing for so long the microchip company had listed her as dead since 2015, San Joaquin County Sheriff's Office said.
Officer Brandon Levin, who scanned Zoey, got her owner's contact details from the chip firm, and found she still had the same mobile number. He said: "She was in complete shock."
The dog was found about 60 miles from where she had gone missing in 2010, her family home in Lafayette.
Michelle said: "We got her and her twin sister from the pound when they were six months old, she was with us for about six months.
"We went to the store for about 20 minutes and came back and she was missing.
"I'm excited to hopefully bring her back, get her healthy and let her live the rest of her life."