Coat Length. Keep an eye on his coat, and if it doesn’t get long and stays at roughly the same length throughout the year, then the chances are that your dog is a double-coated breed. Double Coated Breeds. A lot of herding, hunting, and working dogs are double-coated. German Shepherds, Labradors, Beagles, Terriers, Collies, and Sheepdogs are all double-coated, and if you’re in any doubt, a quick Google search will tell you if your dog is double-coated. The Grooming Opinion. If you’re still unsure about whether or not your dog is double or single-coated and needs to have a haircut for Summer, pay a visit to your local dog groomer. As soon as they see your dog, they’ll be able to tell you if he does or doesn’t need a trim and whether he’s wearing a double or a single coat.