The dog, a black Labrador cross, was found near Jane Street and Finch Avenue with broken ribs, an elastic around its jaw and what appeared to be chemical burns on his body.
The dog was found eight days ago on Firgrove Crescent with no name tag and few clues about what happened. It was put to sleep Thursday because its injuries were too severe.
"I'm so glad that we could keep him out of pain as much as possible," said Dr. Stephanie Sparling of Toronto Animal Service.
"I'm so glad that we could make the responsible decision to end his life humanely … but I don't want us to have to provide that service to these animals. I don't want it to happen, it's upsetting."
Toronto police say they are aware of the case but they have little information to go on. Anyone with information can call 31 Division at 416-808-3100 or Crime Stoppers at (416) 222-TIPS.