Firstly, have you had your puppy checked over by a vet. It is advisable to get a vet check once your puppy is home with you. A responsible breeder will provide you with a vet check letter and ask you follow this up with your own vet check. A vet check is totally different to health testing results. A vet check is a basic examination carried out by any vet. Health testing is specific tests or xrays for a particular breed, some need to be carried out by specialists. Health tests are highly recommended as you can avoid so many heart breaking and expensive issues by knowing they exist and avoiding them. The Kennel Club will provide a list of tests that each responsible breeder should carry out on parents and offspring and Most breed clubs will have an extra list of other recommended tests.
Secondly if you are worried that your puppy is not eating because he/she is sick it is advisable to get him/her checked over by a vet.
Once we have established that puppy is not sick we need to remember that puppy has just experienced a huge change in their life.
Stress causes the release of Adrenaline and hormones, including Cortisol, this slows the appetite right down and conserves energy for the fight or flight response. Stress factors can include being taken away from mum and litter brothers & sisters, new noises, loud noises, new places, new people, new routine, confusion. All things taken into account it is not surprising that new puppy has no appetite.
Lots of people presume that new puppy does not like the food they are feeding and they change his food, they may even change it again and again. This is not a good idea and can result in puppy getting diarrhea from being switched on to new food too quickly, this plus stress and lack of nutrition can affect your puppies immunity and at this stage we would definitely not want them to come into contact with any virus or bacterial infection.
It takes any puppy time to adjust, you just have to be patient and if they need a few added healthy extras while they are settling in then so be it. Tinned Sardines, Tuna, Roast Chicken, sometimes we do have to try anything. Most importantly once they are through this natural stage of transition into their new home (which can take weeks), we should feed puppy a high quality, nutritious, balanced kibble or raw diet to provide them with all the vitamins, proteins and fats they need to develop into healthy adults.