| Registered Name | Owner / Club | Status |
|---|---|---|
| Oldcourt Velvet | Tara Connelly Foxborough | Approved |
| Oldthort Peaches | Ita Walsh Tynagh | Approved |
| Oldthort Sparkling Knight | Ita Walsh Tynagh | Approved |
| Oldtown DC | Helen Cronin Clonough | Approved |
| Oldtown Diamond Star | Patricia Irwin Hollybrook | Approved |
| Oldtown Duchess | Hetty Cope Warrington | Approved |
| Oldtown Tygo JT | Donal Kenneally Devils Bit | Approved |
| Olitha | Sinead Healion Croghan Hill | Approved |
| Oliver | Tanya Maguire Bridge | Approved |
| Oliver An Ri | Tonya Fortune Lawlor Coole Lane | Approved |
| Ollies Choice | Anna Liddy Mo Chara | Approved |
| Ollies Way | James O' Haire Celbridge | Approved |
| Olly Blue | Alice O'Connor Foxborough | Approved |
| Olmars Mandy Clover | Zara McGovern Benbulben | Approved |
| OLS Flying Vision | Sarah Conway Celbridge | Approved |