While the Pembroke Welsh Corgi and the Cardigan Welsh Corgi appear similar, they are in fact two distinct breeds that developed separately centuries ago in geographically distinct areas of Wales. They are part of the cultural heritage of Wales and each breed deserves to be preserved and protected like any cultural treasure.
One of the many breed characteristics that distinguish Pembrokes from Cardigans is color. In accordance with the breed standard, the acceptable colors for Pembrokes are self colors in red, sable, fawn, black and tan with or without white markings. (Please consult the Pembroke breed standard for more detail)
Cardigans come in more colors including blue merle and brindle which have never occurred in purebred Pembrokes. Since canine geneticists have proven that both of these traits are dominant, it is virtually impossible for either color to suddenly appear in a litter of Pembrokes. Blue merle or brindle Pembrokes are a result of crossbreeding which is not condoned by the Pembroke Welsh Corgi Club of America, the Cardigan Welsh Corgi Club of America or their members. These puppies are mixed breed dogs and are not eligible to be registered in the AKC Stud Book and cannot compete in AKC Conformation, Herding, or Companion events as purebred Pembroke Welsh Corgis.
(This statement is based on the Color Statement written by Barbara Merielel, DVM, which appears on the Cardigan Welsh Corgi Club of America's website. With permission, the PWCCA has adapted this statement to reflect the perspective of the PWCCA.)