In an update Saturday afternoon, they said the dog has now been located safely.
The department said Vesuc, a German Shepherd, went missing around 1 a.m. Saturday in the area of West Graham Street in Dixon, Illinois. Vesuc is 80 pounds and was wearing a black collar when he went missing.
Dixon Police Chief Ryan Bivins issued a statement, saying, "K-9 Vesuc is not just a highly trained police service dog, he's a beloved member of our department and our community. Our officers are working around the clock to bring him home safely, and we're asking for the public's help in this effort. We are deeply grateful for your support."
The Dixon Police Department said it had launched a full-scale search.
K-9 Vesuc has now been returned to his handler, police said.