Without American Kennel Club registration papers, it might not be easy to tell if your dog is a purebred Labrador retriever. The breed is consistently the top dog in AKC registrations, and there's a lot of cross-bred or Lab lookalikes out there. Check a would-be Lab against the AKC breed standard. Temperament is also a tip. The AKC describes the typical Lab as "active, friendly and outgoing." To get a final determination, take advantage of a simple DNA test that can reveal a dog's genetic background.
Labrador Retriever Standard
The AKC standard for the Labrador retriever calls for a male dog maturing between 22.5 to 24.5 inches tall at the shoulder, with females slightly smaller at 21.5 to 23.5 inches high. Male dogs weigh between 65 to 80 pounds, with females weighing between 55 and 70 pounds. These dogs appear strong, well-balanced and well-muscled, with good, proportionate "bone." The dog has a wide skull and a powerful jaw. His feet are compact but strong, with arching toes.
Lab Mixed Breeds
Sometimes mixed breed dogs with Lab in their backgrounds are hard to distinguish from the purebred canine. The best way to tell the difference is by close inspection of the head, tail and coat. Labs have a double coat, with the undercoat much softer than harsh, water-repellent top coat. The short, straight coat of the genuine Lab has no feathering.
The tail is another giveaway. Labs sport an otter tail, which is quite heavy at the base and tapers near the end. Purebred Labs always carry their tails at the same level as their bodies, not over their backs or straight up. The purebred Lab boasts a square head with a short muzzle. Ears always hang and are never upright.
Purebred Labs come in three solid colors: black, yellow and chocolate. Any other colors, or blend of colors, signify a mixed breed. While a purebred Lab might have a tiny white spot on the chest, that's it for any other coloration. If a purported Labrador retriever has any white feet or white on his face, that's a sign he's not a purebred dog.
Order a DNA test kit for your "Lab" and find out whether or not he's got mixed blood. A canine genetics testing company will send you a box with swabs for obtaining a sample, along with instructions for use. Simply swab the inside of your dog's mouth and put the swab in the container provided in the kit. Mail it back to the company, and you should have the results back in several weeks.