Typically (but not always) the dog will be have no appetite or would be unable to eat- food comes back up. He won't be able to defecate or will be straining without producing anything. He'd have a hunched back posture and might be drooling more than usual. The signs would be obvious with a blockage, if you're looking for it. If you don't see any of that, chances are there is no blockage & no need for x-rays.
All you can do is keep everything as puppy proofed as you can, and keep an eye on him. Good luck.
All you can do is keep everything as puppy proofed as you can, and keep an eye on him. Good luck.