I think my Sadie is a lab/whippet mix. She has the same slender back end you're talking about with Toby. She also looks the same laying down - same position - and her paws look the same. I did some reading on whippets and her personality matches - loves to run and chase squirrels/cats/moving objects outside but inside sleeps on the softest cushions and under the covers. She is quiet, gentle, and a bit neurotic.

How much does Toby weigh? (Sadie's about 35lbs)

Sadie: