A book telling Einstein's story is about to be released.
Einstein was born on April 23 last year. He was born weighing less than a cat and stood as tall as a cereal box.
He is the smallest horse ever born, but he will have to wait until he turns four to make any official claim on the record as the world's smallest horse.
He weighed 2.72kg (six pounds) at birth, roughly a third of what a normal miniature newborn would weigh. The Guinness Book of Records at the time listed the smallest foal at nine pounds.
He shows no signs of dwarfism, nor was he premature, having been born three days after his due date. Everything about Einstein is in perfect proportion.
He rapidly became an international celebrity. Thousands of people poured into a small town in New Hampshire to see the little colt in the days immediately after his birth.
Since then, Einstein has become known and loved the world over, with articles in national and international papers, and many appearances on national television. He has a huge following online on social networking sites.
The book, "A Friend for Einstein: The Smallest Stallion", is scheduled to be released just before Einstein's first birthday.
The book is written by Einstein's owners, Charles Cantrell and Dr Rachel Wagner, and will celebrate his unique size and personality.
Cantrell contributed all the photographs that appear in the book.
Cantrell and Wagner will donate a portion of the proceeds from the book to an equine charity.
Wagner is a family doctor with a master's degree in special education. An avid horsewoman, she started riding at age five, when she met Judy Smith. Smith is the person who first introduced her to miniature horses and ultimately bred the pair of horses that produced Einstein.
Cantrell is a freelance writer and photographer who has travelled the world capturing images of nature. He maintains a wild animal sanctuary on his 105-acre property in the Lakes Region of New Hampshire.