Little Einstein the miniature pony may be just 20 inches tall, but that hasn't stopped him becoming a huge star.
The tiny horse, from New Hampshire in the US, has previously captured the hearts of millions, including celebrities like Oprah Winfrey, who invited him on her hit TV show.
Now his pursuit to find buddies and his life at home with owners Charlie Cantrell and Rachel Wagner in Gilmanton, New Hampshire, will be published in a new a book to rejoice his birthday.
'This has been a extraordinary year for us and for Einstein,' said Mr Cantrell, 44, who bought Einstein for their small farm along with his wife Rachel.
'Einstein is the smallest horse on record ever to endure and when the news got out to the media the level of interest was incredible. 'The average weight of a newborn tiny horse is 18lb. The average height at birth is 21 inches.
Einstein is all the amazing because he shows no dwarf characteristics and is simply a very small miniature horse. His mother Finesse stands a comparatively tall 32 inches and his dad Painted Feather measures 30 inches
Guinness approached us straight after the original press that surrounded Einstein,' said Mr Cantrell. 'He can't be formally recognised as the smallest stallion until he is four, but we are both relatively sure that he has stopped growing.'
'You see the adorable thing about Einstein is that he doesn't seem to be too conscious of his height at all. 'However, due to his odd size he can't mingle around with other horses because it would be dangerous and he might get trampled underfoot.
