Puppies are not miniature dogs with cute faces

Cairn Terriers under 3 months of age should be considered infants. They need a  tremendous amount of care and attention.   

Never, EVER, acquire a puppy that has been separated from its mother before 7 weeks of age.  

Puppies who are 6 to 20 weeks old are in a sensitive developmental stage. This period of socialization is critical in the formation of the pup's personality. Some things, like bite inhibition, can only be taught by the mother and only before the eight week of age.  It is imperative that the pup not be left for long periods of time and isolated from the family (stuck down in the basement or behind closed doors). During this stage of development puppies must be exposed to as many new places, people and experiences as possible.  If a puppy has the constant companionship of another dog during this stage, he may become dog-oriented rather than people-centered. If you are raising two puppies, it is important to spend one-on-one time each day with each puppy.   

Puppies under 7 weeks of age are unable to learn. They cannot carry memory from one day to the next. New owners should be aware of this fact and not attempt to teach a puppy specific tasks and then discipline him when he fails.   

Dogs between 3 and 6 months of age are juveniles who need constant supervision. Left to themselves, dogs will be dogs, and in most instances this is less than desirable (house soiling, destructive chewing, excessive barking and biting) when the dog is living in close quarters with humans in an urban environment  

Puppies must be fed often:

8 to 12 weeks - four times a day

3 to 6 months - three times a day

6 to 12 months - two times a day  

Puppies need to eliminate (go to the bathroom) after each meal. They should be taught where to go (on paper, in the backyard, etc.). They should be brought there on a leash or carried so they get there quickly. No side trips should be made en route. Puppies should get praise each and every time they go to the bathroom in the right place. 

When a dog under 6 months of age is left alone for long periods of time (more than five hours) with a bowl of food and water, chances are good that he will have to go to the eliminate. Unless the pup is housed in such a way so that he cannot make a mistake, he will "go" wherever he pleases and get neither praise or a reprimand when he does go. Isolation in a unresponsive environment (no immediate feedback) makes it difficult for a pup to learn right from wrong, prolongs house soiling and promotes destructive chewing.   Extreme care and diligence must be used  in training the puppy during the hours he is with humans to achieve optimum results.