According to Official Guinness Records,
The shortest donkey in terms of height is KneeHi (born 2 October 2007), a brown jack who measured 64.2 cm (25.29 in) to the top of the withers at Best Friends Farm in Gainesville, Florida, USA, on 26 July 2011. A registered miniature Mediterranean donkey, KneeHi is owned by James, Frankie and Ryan Lee (USA).
KneeHi was measured in the standard manner for equine animals: unshod, on even ground, to the top of the withers (to the highest dorsal process of the vertebral body), following a straight line up the fetlock (equivalent to the ankle joint) using a measuring stick with a spirit level (bubble) crossbar to ensure evenness. He was born (at a height of 16.5 in;41.9 cm) to the dam Itsy Bitsy Annie (27.5 in;70 cm) and the sire Golden Point's GP Billy Bob (29 in;73.6 in). Mediterranean miniatures were bred in Sardinia, originally to be housed indoors, typically turning grinding stones to make grain. Robert Green (USA), who first introduced the breed into the USA in 1929, is quoted as saying: "Miniature Donkeys possess the affectionate nature of a Newfoundland, the resignation of a cow, the durability of a mule, the courage of a tiger, and the intellectual capability only slightly inferior to man's."Guinness World Records Editor-in-Chief Craig Glenday was present at the measuring, which was carried out by a local vet.
For a complete list of 2011 records, please visit 2011 Guinness Records in United States.