Are you interested in showing your English Mastiff? If so, you should first check to see if he is full bred and registered with the AKC (American Kennel Club). If he has not been registered, contact the AKC to find more about the organization and what is involved in registration. In general, all purebred dogs are eligible for the American Kennel Club (AKC) association registration as long as his litter has been registered. If you purchase a dog under the assumption that it is a purebred dog then you should have received an individual dog registration application from the seller. You will need to complete the application and submit it to the AKC along with fees and any other requirements. Dogs can also be registered online. Simply go to the AKC website and check for registration information. For medical records, if needed, contact your vet Sayville, NY. Or schedule an appointment here St. Francis Hospital for Animals.