I'd ask if the pup has been to the vet, and if it's a congenital defect - one she was born with, I'd not hesitate. Likely she doesn't know she's "different" and if she's healthy, go for it! I don't know if Cairns are prone to eye problems, that's something you can research on the web. As long as she is to be a pet, and get spayed when she's old enough, there's no reason not to take her and love her!