Horse breed been produced. Such restrictions have led to legal challenges in the United States, sometime based on state law and sometimes based on antitrust laws. Horses can crossbreed with other equine species to produce hybrids. These hybrid types are not breeds, but they resemble breeds in that crosses between certain horse breeds and other equine species produce characteristic offspring. The most common hybrid is the mule, a cross between a "jack" (male donkey) and a mare. A related hybrid, the hinny, is a cross between a stallion and a jenny (female donkey). Most other hybrids involve the zebra (see Zebroid). With
What A Summer What A Summer What A Summer (foal in 1973) was an American Thoroughbred Champion racehorse who defeated both male and female competitors. She was bred in Maryland by Milton Polinger. She was a gray out of the mare Summer Classic who was sired by Summer Tan. Her sire was What Luck, a multiple stakes winning son of U.S. Racing Hall of Fame inductee Bold Ruler. What A Summer is probably best remembered for her win in the Grade II $65,000 Black-Eyed Susan Stakes over stakes winners Dearly Precious and Artfully on May 14, 1976. What A Summer was trained very