Like all terriers, they are frisky, independent bundles of energy. They are long lived dogs, with few health problems, and many live well into their late teens. They are also quite sturdy, and are much tougher than their small size suggests. The most famous example of a Cairn is Toto from the Wizard of Oz. However, there are some Cairns out there weighing up to eighteen lbs., due to the influence of British breeding stock.
Cairns also have large teeth for their size, large feet and strong nails.
They have muscular shoulders, and very strong legs for digging. Cairns are short, shaggy dogs, fairly long for their height, with large heads and pricked up ears. They have a waterproof, rough coat, and do not shed. They come in a variety of colors, with brindle shades predominating. A Cairn can be any color but white.