For six years Bianca Dunnet and Bow played together in their backyard after school. But when Bow disappeared in the early hours of Sunday morning in the midst of a raging storm, Bianca lost the best friend she ever had and the only one who really understood her.

"Bianca's autistic and the only way she can really communicate is through Bow," Bianca's guardian Jamie Lawton said.

"We'd do anything to get her back; we'll give anything, any reward. We just have to get her back for Bianca."

"Bianca's whole life is about routine," Bianca's mum Lindsay Wickey said.

"Everything has to be done the same and Bow used to always be waiting outside for her when she came home from school.

"We've been able to keep her distracted so far so she hasn't realised yet but her school work's already been affected and when she does realise Bow's not coming back she'll stop eating."

The six-year-old Labrador cross Bullmastiff is a very distinctive dog with an amazing affinity with children her owners said and because of this they are worried that whoever might have found her might not give her back.

"We're just hoping that whoever picked her up has a heart and will give her back," Ms Wickey said.

"Bianca really needs her, they're best friends. They did everything together; you'd never see one without the other."

The dog's owners are also concerned about Bow's health as she is on medication and needs to visit the vet regularly.

Bow would have last been seen walking or running down Kidman Way near Nugan Estate Wines. Anyone with any information about Bow is urged to contact Lindsay Wickey on 0458 090 165.