| Name | Color | Sex | Year of birth | Microchip | Sire | Dam | Breed | Breeder |
|---|---|---|---|---|---|---|---|---|
| Sotto Voce | chestnut | f | 1951 | Some Chance | Elocution | Thoroughbred | USA | |
| Sotzvet | chestnut | c | 2001 | 3650-1 Senat | 0834-2 Tzata | Thoroughbred | Chapaev Farm | |
| Soubrette | bay | f | 1873 | Thoroughbred | France | |||
| Soubrette | bay | f | 1873 | Thoroughbred | France | |||
| Soubrette | chestnut | f | 1932 | Pazman | Zsidolany | Thoroughbred | Hungary | |
| Soubrette | bay | f | 1984 | Nebos | Shermine | Thoroughbred | Germany | |
| Souffle | bay | f | 1949 | Fair Trial | Luncheon | Thoroughbred | Great Britain | |
| Soughaan | bay | c | 1983 | Riverman | Beaconaire | Thoroughbred | USA | |
| Sought Out | bay | f | 1988 | Rainbow Quest | Edinburgh | Thoroughbred | Ireland | |
| Souix Lynn | f | 1974 | Personality | Fingerling | Thoroughbred |