That pup has got the look for sure. Not to step on anyones toes here. I think a pup is a pup. I keep em fat and only let them play and have fun until around 10 months. Imo that puppy is way to skinny for a 4 month old. But I'm sure you know what you do. And again not trying to step on your toes. We all have different views. I live in a colder country and if the general population saw a pup like that at my place I would have the animal cops here the next day. I also know that some pups are impossible to gain fat, if that's the case I apologies. Good luck with him tough.