The word "vermin" refers to small animals or insects that are considered pests or nuisances, often causing damage or spreading disease. Full definition
History: Chinese Crested origin is China (since 13th century) and was often used as a stomach warmer to drive out sickness and also used as a hunter of vermin as a «Chinese Ship Dog». (puppy-basics.com)
These feisty dogs were bred to hunt vermin of any size or shape. (hillspet.hk)
This breed wasn't only limited to hunting foxes, though, as it was used to hunt otters and other vermin in the surrounding areas. (breedersclub.net)