updated 01/18/2012 AT 12:50 PM ET
•originally published 01/18/2012 AT 2:15 PM ET
When the staff at the Fredericton SPCA in New Brunswick, Canada, received a box on Dec. 30, they thought it would contain donated materials – but they were in for a big surprise.
“We kind of assumed it was a box of newspapers because we use them for the dog kennels,” education coordinator LeeAnn Haggerty tells PEOPLE. “And then the box meowed.”
Inside the box were two cats – and the biggest surprise? One of them weighed 30.2 lbs. The massive feline’s body covered the other cat, who looked like a kitten at first, but turned out to be a full-grown female.
“We were pretty shocked and concerned about his health,” Haggerty says of the cat that the SPCA named Tiny. A vet determined both felines were in fine condition, but Tiny was morbidly obese and in need of a serious slim-down.
In his first few days at the shelter, Tiny actually shed 3 lbs., but cats that rapidly lose weight are in danger of liver failure, so he has been closely monitored since.
“We try to do everything we can to make it less stressful for the animals, to make them happy and comfortable, but it’s still a big change for them,” says Haggerty. “And a lot of cats don’t adapt well to change.”
“We want to make sure that his weight loss is slow and healthy,” Haggerty says. “He has a target of about three-quarters of a pound a month.”
All that’s known about Tiny’s history is that a man dropped the box off, according to KCTV News, which first reported the story. No matter. The shelter is determined to help Tiny keep a New Year’s resolution of losing weight so he can eventually be adopted (the other cat, Rapunzel, will be available for adoption in a few days).
Tiny is a “social” kitty, who has found a friend in foster mom Nancy Garon’s bulldog, and he may not have to look very far for a forever home. Says Haggerty, “She is falling for him quite a bit, so we’ll see.”
Though he tires easily and needs help getting onto the human bed where he sleeps, Tiny is motivated to get in shape – thanks in part to a Weight Loss Challenge donation page set up by the shelter which chronicles his weight loss and is raising funds for other special needs animals.
[RELATED_TEXT “Can’t get enough pet news? See more on PEOPLE Pets