If you suspect that your puppy has ingested something that is harmful, seek veterinary advice. Otherwise, you can put a small amount of warm milk, bran or oil in food.
If your dogs constipation is accompanied with vomiting, loss of appetite or lethargy than you should call your veterinarian. Otherwise, try adding a little extra fiber to your dogs diet.
You need to make sure that your puppy has plenty of water to drink. You can try adding veggies to her diet. A teaspoon of salmon oil may loosen up her bowels so she can defecate.
First make sure he gets plenty of water and lots of exercise. Cooked or canned pumpkin can sometimes help move things along. You can also us baby suppositories with puppies. If this is a continuing problem - you need to see your vet.