Xena, a Coonhound-Rhodesian Ridgeback mix, went missing January 4 in north suburban Barrington. On Friday, Jack Martin underwent surgery as part of his treatment for Ewing's sarcoma, a rare bone cancer.
While he's headed home to recover, his parents say it would all be better if Xena was also there.
"He hasn't left his side, that's his buddy," said Jason Martin, his father. "So we're trying to get her back and she'll help him mend.
Cubs first baseman Anthony Rizzo tweeted out support of the search.
The Martins say Xena might be scared, so if anyone sees her, they probably shouldn't chase her.