Is it dogs hip dysplacia?

I tole my parents about this and my father told me she could have hip dysplacia.

Hip dysplatia is supposedly hereditary, which causes a problem. We have no clue who her parents are (she’s a pet shop dog. shame on me, I know, I know.) She’s a Pembroke Welsh Corgi, 4 years old. The leg she has been trying to comfort is her back right leg. When she walks, she puts her leg up. We have many flights of stairs, (condominium living. =/ ) so at first I though she may have a sprain. Later I realized that there was no swelling.

I have another corgi and I took into consideration that maybe he was playing with her and went a bit too far. No blood was drawn, no skin was ripped. (He is a very calm dog, loves her, and would NEVER hurt her.)

If any of you have/had or know something that might be the reason for my baby’s pain.. Tell, tell!
(Going to the vet in a few days, but I would like to know just in case so I’m not spending $400 for nothing, thanks.)

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