| Equid | Horse Name ▲ | Breed | Age | Gender | Color | Discipline | Owner |
|---|---|---|---|---|---|---|---|
| 268522B | Oklahoma Red | Thoroughbred | SY22 (6yo) | Mare | Chestnut Overo Sabino | FR | Lissa |
| 468023B | Oktovris | Irish Sport Horse | SY23 (5yo) | Stallion | Palomino White-Spotted | EV | Rhianon |
| 219115C | Olive Branch | Noriker | SY15 (13yo) | Mare | Bay Leopard | DV | Jen |
| 028111B | Olympia | Friesian | SY11 (17yo) | Mare | Black | DG | Lissa |
| 241522C | OmegaMart | Paint Horse | SY22 (6yo) | Mare | Blue Roan Overo | WS | Morrigan |
| 526828B | OMG Johnny What CR | Quarter Horse | SY28 (0yo) | Stallion | Palomino | SR | Morrigan |
| 259418B | Ominous Haze | Connemara | SY18 (10yo) | Mare | Grey | CC | Lissa |
| 251018C | On A Whimsy | Welsh Pony | SY18 (10yo) | Mare | Bay | JP | Soleil |
| 260621B | On Impact | Hackney Pony | SY21 (7yo) | Mare | Bay | DV | Lissa |
| 059414S | On The Brink | Iberian Warmblood | SY14 (14yo) | Stallion | Bay Dun Blanket | WE | Jen |
| 398520B | On The Dot CCR | Appaloosa | SY20 (8yo) | Stallion | Bay Snowcap | WW | Merry |
| 067121S | On The Rox | Thoroughbred | SY21 (7yo) | Mare | Black | FR | Jewel |
| 236322B | Once Jurassic | Appaloosa | SY22 (6yo) | Mare | Red Dun Leopard | SR | Lissa |
| 251117C | Once Upon A December | Holsteiner | SY17 (11yo) | Mare | Bay | JP | The Orchard |
| 488327B | One Black Coffee | Thoroughbred | SY27 (1yo) | Mare | Grey | FR | Morrigan |
| 169719C | One Heckova Redhead | Paint Horse | SY19 (9yo) | Mare | Chestnut Tobiano | WW | Morrigan |
| 340419C | One Hot Luke | Quarter Horse | SY21 (7yo) | Stallion | Bay | WR | Soleil |
| 437819C | One Night Only | Quarter Horse | SY19 (9yo) | Stallion | Black | WW | Jewel |
| 347725B | One Part Wild CR | Quarter Horse | SY25 (3yo) | Mare | Red Dun Roan | WW | Morrigan |
| 371218C | One Slick Cookie | Quarter Horse | SY18 (10yo) | Mare | Grey | WE | Manders |
| 477015B | One Tough Catillac SLS | Quarter Horse | SY15 (13yo) | Stallion | Black | WW | Jewel |
| 166211C | Onomatopoeia | Arabian Pony | SY11 (17yo) | Mare | Grey | EV | Lissa |
| 433320B | Onweer M | Dutch Harness Horse | SY20 (8yo) | Stallion | Bay Sabino | CD | Soleil |
| 320318B | Onyx Heart | Thoroughbred | SY19 (9yo) | Mare | Black | DG | Soleil |
| 455524B | Oops a Daisy | Irish Cob | SY24 (4yo) | Mare | Black Sabino | CD | Soleil |
