The breed standard dictates that it must be in perfect proportion to the body and above all it must never be too light. The greatest value is to be placed on the muzzle being of correct form and in absolute proportion to the skull. According to a UK Kennel Club health survey, cancer accounts for 38.5% of Boxer deaths, followed by old age (21.5%), cardiac (6.9%) and gastrointestinal (6.9%) related issues. In the United States and Canada as of 2012, cropped ears are still more common in show dogs, even though the practice of cosmetic cropping is currently opposed by the American Veterinary Medical Association. In March 2005 the AKC breed standard was changed to include a description of the uncropped ear, but to severely penalize an undocked tail.