These rugged little terriers are named after the piles of stones, or cairns, used to mark memorials and pathways. The Cairn Terrier was used to go into these stacked stone formations to catch mice, rats, and other critters.
While no dog is truly allergen-free, the Cairn Terrier is considered to be hypoallergenic. The breed sheds minimally, but because all dogs produce dander and saliva—which can trigger an allergic reaction in sensitive individuals—even hypoallergenic dogs can aggravate allergies.
The short answer is—you don't. Digging is part of the Cairn Terrier's instinct, and it's a part of terrier life. The breed standard specifies that the forefeet are larger than the hind feet—for digging, of course. Though your yard may disagree, digging isn't all bad—it's an outlet for boredom and burns a large amount of energy.
While trying to stop the excavation is futile, you can set the rules. Providing a digging-approved space for your Cairn Terrier gives her an outlet for that natural behavior, and will help protect your perfectly maintained rose beds. Train your Cairn to dig in a sandbox or designated space in the yard by hiding treats and toys in the appropriate spot and praising her when she chooses that area to mine. Redirect her to the area where she may dig each time she tries to burrow elsewhere. If no space is appropriate for digging, constant supervision may help preserve your landscaping.