Dogs that are physically fit and vigorous in their youth through middle age are more vigorous and healthy as elderly dogs, all other factors being equal. In the UK, cancer and cardiac problems seem to be the most frequent causes of premature death.Like its native relative the Hortaya Borzaya, the borzoi is relatively sound breed. OCD, hip and elbow dysplasia have remained almost unknown, as were congenital eye and heart diseases before the 1970s. However, in some countries modern breeding practices have introduced a few problems. These dogs naturally experience enormous growth surges in the first year or two of their lives. It is now widely accepted that forcing even faster growth by feeding a highly concentrated, high-energy diet is dangerous for skeletal development, causing unsoundness and increased tendency to joint problems and injury. Being built primarily for speed, borzois do not carry large amounts of body fat or muscle, and therefore have a rather different physiology to other dogs of similar size (such as the Newfoundland, St. Bernard, or Alaskan Malamute).