Teeth should be white except in some breeds where yellow teeth is good and white teeth signifies a lack of calcium. A smelly mouth is a sign of disease. The ears should be clean. Massage the ear lobe's base and watch for any reaction of pain. Rub your hands over the pup's body, parting the hair to look at the skin.
Rashes are indications of skin disease.
Look at the chest and the pup's breathing rhythm. Listen for any abnormal sound in breathing. Feel the pup's abdomen for any abnormal lumps. A swollen tummy is a clinical sign of illness. For a male pup, check that its genitalia are well formed.