Vinny was rescued on February 20, and found extremely undernourished and with kidney problems. He's been in the care of the South Suburban Humane Society since.
"If he wasn't found in the time frame that he was found, he wouldn't be with us," said Emily Klehm, CEO of the South Suburban Humane Society.
In an update posted to their Facebook page Sunday, the rescuers said Vinny "loves squeaky toys and butt rubs and now freely comes to us for pets!" The dog was very shy towards humans when he was first rescued.
The group also said he's eating well and putting on weight, and they're expecting to see great improvement in blood test results.
They posted photos of him wearing a new coat and playing with a toy, both provided by "generous donors."
"We love you all and we're so grateful for all of your support the past few weeks," the group wrote.
The Cook County Animal and Rabies Control turned over the case of Vinny's abandonment to the Cook County Sheriff's Office.
Anyone with information is asked to contact the sheriff's office.