Cairn Terriers used to be hard working dogs that thrived on hunting and expedition. In the Scottish Highlands, these dogs were used as vermin exterminators, small game hunters and loyal home companions. Today, the modern Cairn Terriers enjoy a much more sedentary existence as household pets. Unfortunately, this breed of dog may be too much to handle. They were simply never bred to be docile animals. They make miserable lapdogs and should never be treated as such.
Perhaps the best way to start off your Cairn Terrier puppy is to make it undergo basic respect and obedience training. The younger the puppy when you begin this, the greater rewards you will get out of it in the end. Left in their natural state, Cairn Terriers are quick to react, quick to bark and quick to chase after anything that moves. They can be very lively and energetic the whole day so much so that they can literally wear you down. They are known to become bossy, feisty and stubborn (and those were the good points too). They can also become very persistent, impulsive and independent on such intense levels that you don't know who is training whom. Of course, if there is one word to really describe a Cairn Terrier, then it would have to be "scrappy" - adorably and endearingly scrappy.
If you really want to keep a Cairn Terrier as a pet, you must be able to curb some of its "undesirable" traits through constant training and vigilant guidance. If you tend to count 1 to 10 every time something upsets you, your Cairn Terrier pet just may make you count all the way to 100! Be patient, and understand that your dog is exuberant to a fault, and will try to outwit you anytime it spies a chance. This doesn't mean that it is being disrespectful to you or your authority. It just means that it wants to dole out some of its pent-up energy.
Try to create games that both of you will enjoy while at the same time incorporating some of the most fundamental lessons in obedience. And yes, you can try to and you should Cairn Terrier proof your home and your yard. Cairn Terriers are excellent diggers and are intelligent enough to worm their way out of fences and barred entrances/exits. If you don't find a way to make your pet stay in one place with you during training, you may as well teach your cat how to bark. A leash will do fine. Do not go for the choke-hold leashes because your dog has a very short neck. In addition to that, a Cairn Terrier's high spirited flights of fancy just may lead it to pull on the leash so forcefully that its windpipe be crushed.
Another thing that your should remember about your Cairn Terrier is that it can never be trusted off-leash. As earlier stated, it is an escape artist and it will move independent of your instructions. It is best if your training begins and ends at a specific time. This will teach your pet the rules of routine. Pretty soon, it will learn that after your training routine, it can go about and play.