Why is my dog scratching her back on the couch? Anxiety? Dry skin?

She doesn't have fleas. Hair in straight line falling out across her back.

Why is my dog scratching her back on the couch? Anxiety? Dry skin?

Poor puppy. Some dogs suffer from hot spots, depending on the breed but if her hair is falling out sounds like the vet needs to be involved. It must really Itch if shes is rubbing it so hard and so much for the hair to fall out. Are you sure she is rubbing it out on the couch or is it falling out? She might have a type of mange, its very curable but the vet needs to take a sample. I know its expensive but if her hair is falling out on her back it might keep on until it covers her entire body, my dog did that. Good luck and give puppy a hug from me, and an Itch. :^)

Why is my dog scratching her back on the couch? Anxiety? Dry skin?

maybe she is allergic to something, have you changed anything around lately ?

Why is my dog scratching her back on the couch? Anxiety? Dry skin?

Vets - quick!

Why is my dog scratching her back on the couch? Anxiety? Dry skin?

Fleas.

Why is my dog scratching her back on the couch? Anxiety? Dry skin?

Sounds like either an allergy (either food or something that got on her skin) or eczema. Take her to the vet. He can prescribe a cream that should help.