| Name | Color | Sex | Year of birth | Microchip | Sire | Dam | Breed | Breeder |
|---|---|---|---|---|---|---|---|---|
| Aconcagua | chestnut | f | 1966 | All Serene | Prescription | Thoroughbred | Chile | |
| Aconite | bay | f | 1826 | Thoroughbred | Great Britain | |||
| Acquaforte | chestnut | f | 1936 | Blenheim II | Althea | Thoroughbred | Italy | |
| Acqualina Beauty | bay | f | 2003 | Montjeu | Coolamon | Thoroughbred | Ireland | |
| Acquasparta | chestnut | f | 1941 | Sans Crainte | Acquaforte | Thoroughbred | Italy | |
| Acquit | f | Thoroughbred | ||||||
| 1344-3 Acquitaine | bay | f | 1999 | Colonial Affair | Arctic Eclipse | Thoroughbred | USA | |
| Acrobat | c | Thoroughbred | ||||||
| Acropolis | chestnut | c | 1952 | Donatello 2 | Aurora | Thoroughbred | Great Britain | |
| Acrosstheborder | d.-bay | f | 2004 | Include | Canadian Envoy | Thoroughbred | USA |