A crow is suspected of snatching a tiny puppy from a backyard in Melbourne's east, breaking its owner's heart.

Fudge, a four-month-old miniature chihuahua, disappeared from her owner's home in Kilsyth on Wednesday morning and has not been seen since.

The pup was bought for Melinda Pride's mother as a companion while she underwent treatment for lung cancer, following her diagnosis just before Christmas.

"It was only last week Mum said 'if anything happened to Fudgey I don't know what I'd do; she's just my saviour'," Ms Pride said.