It's hard to tell but it looks like pup (JRT x Whippet) is going to be quite a whippety shape, with his head smaller than his neck. He is also quite bouncy so I'm concerned about him getting out of his collar.
Does this mean he will need a martingale? Are harnesses a good option for whippety looking things? I'm learning but not very hound savvy. So far he seems to be terrier temperament in a whippety body, which is somewhat frightening in terms of his ability to leg it away from me at high speed!