The Humane Society of Durham Region has offered a reward to help find a man who beat a puppy so badly the dog had to be put down.

The Rottweiler was allegedly beaten in Ajax on Jan. 30, behind the McLean Community Centre on Magill Drive, near Westney Road North.

The eight-month-old dog was euthanized at 4 p.m. Friday, CityNews has learned. The dog had other underlying issues, including an aggressive form of cancer. Tests showed he was permanently blind and had swelling in his brain.

"As much pain as he's been in, he's just been a gentle, sweet, dog," Brenda Cameron, shelter manager at the Humane Society, said.

Authorities say that on Jan. 30, two people heard what sounded like a person crying and ran to help. They say they saw a white man in his 20s violently beating a whining Rottweiler puppy.

The witnesses yelled at the man, and he fled the scene.

Veterinarians first thought the dog — whom they called Geoffrey — had recovered, but later said there appeared to be swelling in the brain or eye area.

The Humane Society is offering a $1,000 reward for information leading to a charge and conviction.

If you can help, call the Humane Society at 905-242-8461 or 905-665-7430 ext. 225.