During the age of 3 to 6 months, it’s expected for your puppy's teeth to start shedding. Your puppy might experience pain during this stage, since their gums become very sensitive and can possibly lead to poor appetite.
Here are some tips to help your puppy eat while teething:
Mix canned food with dry food
Make chicken broth ice cubes - give when your puppy needs something to chew on
Freeze fruits like strawberries or bananas
Soak dry food in warm water for 10-15 mins before serving