Carolyn, I should know about Sammy, but I don't. He is due for his yearly vet check so I'll weigh him when I take him in. When he came to us he'd been nearly starved to death and he was 68#. I know that he was still a bit thin last Aug when he weighed in the 90's, but Sam's probably around 6 or 7 y/o.
Marley is just 2 now, right? If so, he's still in the teenage pyr stage, and all of mine have been thin & lanky still at that age. I would hesitate to give him puppy food though if I were you. The protein levels can be a real issue for the giant breeds. As long as his energy is good & he's well in all other ways, I probably wouldn't worry. Vets often think that dogs should be fully grown by 2, but that's not been my experience with Pyrs. So if Marley's anything like my Pyr girls have been, he'll come into his full size around 3 to 3 1/2 years. (Besides all of that digging & fence eating has got to use up extra calories, right? LOL

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Modified to add: I didn't see the pics when I first posted. Ohhhh my, are you sure that Berner baby doesn't have fluffy stuffing inside?? Honestly, that baby is so cute that I'd swear that she (I think?) is a stuffy.

Also, looking at the pic of Marley, he does look pretty thin stretched out like that. What food is he eating right now & about how much daily? I really, really like Innova Adult for putting on weight, at least it sure did it for Cassifras. We've actually had to mix her Innova with Wellness Weight Management to help her slim down a touch. If you haven't tried Innova yet, it's great food & it might be worth a try.