
Gosh I'm sorry to hear about your pup.
> that surgery on the digital flexor tendons is rarely successful
wish someone had told me that. My collie dislocated her superficial digital flexor tendon several years ago, my vets told me it had to be repaired, this involved a long journey to an orthopaedic specialist, an overnight stay for her, a huge bill for me, 6 weeks strict rest and the tendon dislocated again soon after.
She damaged hers running and twisting to fetch her ball, so don't blame your daughter, sometimes these things just happen and we can't plan for it or guard against it. My girl is now 7 and very active but she does occasionally limp on that leg - just a slight limp not the complete holding the leg up she did when it happened.