"Jolie Rose" was dropped off Saturday night at the Newport Beach police station.
The owner says the 1-year-old dog was shaking and nervous, and apparently had not eaten since being stolen around 4 p.m. last Sunday.
Police have made no arrests and say their investigation is ongoing.
It is not clear whether the $5,000 reward offer has been claimed.
Her owners believe "Jolie Rose" was taken from their porch on the Newport Beach peninsula near 6th Street and Balboa Boulevard.
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Due to a recent power outage on the peninsula, the dog's owners said surveillance camera systems in the area were shut down.
A technician recently told them there was no footage showing who may have taken "Jolie Rose."