If a puppy hasn't been wormed its will become enlarged.. But once you worm it should go down ,then you need to put your puppy on a timed based died with lots of nutrition.. Make sure you make regular vet visit and make sure your pup is updated on its shot ,, thats very important... The reason I say this is because I use to work in a kennel
When you get a puppy it will have worms unless you deworm it. It will get them from the mother..you should always take a new puppy to the vet to have it checked and shots are needed at 6wks also will check for other things. If you can't get it there right away then you can buy worming pills at the pet shop and follow directions very good..But their immune system is only good for a little while (from mothers milk) and then they could catch something and you will have a sick puppy. You should research this!