According to Official Guinness Records,
The most numbers correctly identified by a horse in one minute is 19 and was achieved by 'Lukas', who was assisted by his owner and trainer Karen Murdock (USA) at Walnut, CA, USA, on 16 June 2010.
'Lukas' is a seventeen-year-old thoroughbreed gelding.
For a complete list of 2010 records, please visit 2010 Guinness Records in United States.