Cairn Terriers exist happily in an apartment when sufficiently exercised. They are very active indoors and suffice even without a yard. Daily walks help keep Cairn terriers happy and healthy. Fenced-in yards are strongly recommended for safety and well-being as well as being kept on leash when not in the yard. Cairn Terriers are particularly easily trained; ethical breeders strongly suggest obedience school or some other type of training to direct Cairn Terriers's focus on the owner as the one in command if they are going to be used for hunting. If allowed to take control of the household, behavior problems may develop that only can be resolved by hiring a professional dog trainer. Many breeders only sell puppies to dedicated dog owners who agree to basic obedience school.