A newborn foals legs are already 80 to 90% of the length they will be when full grown.
Horses like classical music.
The oldest horse was named Old Billy. He was a cross breed, he was born in 1760 and lived to 62.
The oldest pony ever recorded was named Teddy E. Bear. He lived to be 55 and was owned by Kathy Pennington of Virginia Beach, VA. He was still alive in 1998.
The World's Largest Horse was a purebred Belgian stallion named Brooklyn Supreme. He stood 19.2hh (6'6") at his withers. He weighed over 3,200 pounds and is entered in the Guiness Book of World Records. He was foaled in 1928 and died in 1948. He lived in Iowa, USA. (I'm not sure about this one as the stats are always changing and no one can seem to find out who the REAL tallest horse is)
Oldest winning thoroughbred racehorses:
The 18-year-olds - Revenge, at Shrewsbury, England 1790; Marksman, at Ashford, Kent, England, 1826; and Jorrocks, at Bathurst, Australia, 1851.
Also at 18yrs old; Wild Aster won three hurdle races in 1919, and Sonny Somers won two steeplechases in February 1980.