 In the 1970s , the breed began to be revived through increased public interest . Breed societies have been established in the United States , Canada , the Netherlands , France , and Germany , and in 1996 the first World Shire Horse Congress was held in Peterborough . The first use within the breed of artificial insemination through frozen semen was with several Australian mares in 1997 . Between the 1920s and 1930s and today , the Shire has changed in conformation . The Clydesdale was used for crossbreeding in the 1950s and 1960s , which changed the conformation of the Shire and most notably changed the feathering on the lower legs from a mass of coarse hair into the silky feathering associated with modern Shires . At the peak of their population , Shires numbered over a million . In the 1950s and 1960s , this number declined to a few thousand . In the United States , the Shire population dropped significantly in the early part of the 20th century , and continued to decline in the 1940s and 1950s . Between 1950 and 1959 , only 25 horses were registered with the US registry . However , numbers began to increase , and 121 horses were registered in the US by 1985 . 
