A dog has overcome a lifelong fear of cats and is now the perfect stand-in mother - to foster kittens.

Border collie Phoebe was terrified of cats when owner Aki Yamaguchi adopted her from a foster service.

Aki, a photographer, said: "One day we were walking down our street and there was a stray cat standing there. She just freaked out, barking, lunging and running around."

To help Phoebe get over her fear, Aki decided to foster kittens and eased her into living with them.

Initially Phoebe was scared - but within a week-and-a-half, she warmed up and now dotes on the little bundles of fluff.

"At first, she was growling and hiding. I waited five days to introduce them through the puppy gate but within a week and a half they were inseparable.

"It turned out that she loves kittens a lot. I think it's her calling.

"She's completely crazy. She's wild sunny and playful, but when the kittens are little she immediately changes, she slows down and gets eye to eye to not scare them.

"She understands size and how vulnerable they are."

Phoebe, who is three, now acts as a surrogate mother and pampers the kittens when they are young.

She plays with the kittens, cuddles them, lets them sleep on her stomach, and moves around on their eye level so as to not scare them.

Aki, from Houston, Texas, USA, regularly fosters kittens before they are placed with permanent owners.

She added: "I think Phoebe plays different roles When they're young she's a mama, and helps them go potty and lets them hide under her tummy.

"Once they get older, she's like a sibling and plays with them. I call her a grandma dog, because she plays with them but never gets mad."