If a bird is severely injured, will it sit up?

My sister has a parakeet, who somehow got out of her cage today. My parents have a big dog, and it seems like the bird is missing a lot of feathers. They found the bird, hiding in a corner where the dog couldn't reach her. The bird acknowledges a touch, and can sit, but when put back in her cage, she sits up on the floor, cowering under her food dish. If this bird was severely injured, would she be able to sit up? Or would she be laying on the floor? They see no injuries on the bird, so we're hoping the little thing is just in shock.

Birds are really good at hiding illness and injury. It may have internal injuries that you can't see. If it was bitten by a dog it should be checked out by a vet b/c the bacteria from the dog's mouth can cause sever infection, even if the bites were minor. you should get the bird to a vet asap. I have a budgie that survived a dog bite. Even with vet care it has one leg and one wing that are permanently paralyzed.