It’s fitting that when a rotund cocker spaniel came to Muttville Senior Dog Rescue in San Francisco last year, her name was “Cocoa Puff.” The 9-year-old dog weighed 40 pounds, a whopping 15 pounds above her ideal weight.

To make matters worse, Cocoa Puff couldn’t really exercise because she had kennel cough and needed to be isolated from other dogs.

Still, her smile and wagging tail made her zest for life obvious.

Cocoa Puff weighed 40 pounds when she arrived at Muttville Senior Dog Rescue in San Francisco. Courtesy of Muttville Senior Dog Rescue

Muttville volunteer Christine Falletti, 42, fell in love with the dog the first day they met.

“There was this really, really overweight, really happy, ungroomed cocker spaniel,” she told TODAY. “We were not looking into adopting a dog but I really felt she was meant to be with us.”

Sure enough, Falletti and her husband, Dominic, brought Cocoa Puff home on her 10th birthday, June 15, 2018. They renamed her Penelope and vowed to help her lose weight.

“You could tell when we first got her that she wanted to play and walk a lot, but she just couldn’t do as much,” she said. “She was happy, but she wasn’t healthy. She was so overweight I knew it would shorten her lifespan.”

So within a week of adopting Penelope, they visited their veterinarian to develop a plan. (The couple has three other dogs.) First, the veterinary team tested her thyroid to see if a medical issue was causing her weight issues, but it was normal. They recommended a high-quality kibble and how much of it to feed to Penelope each day.

She quickly lost 7 pounds but then hit a plateau.

Undeterred, the Fallettis took Penelope to a canine rehabilitation center to work out on an underwater treadmill once a week for months. The water helped provide buoyancy to relieve pressure on her joints. They continued reducing her food intake and supplemented meals with slices of apple.

In less than a year, Penelope reached her ideal weight of 25 pounds.