| Registered Name | Owner / Club | Status |
|---|---|---|
| Oklahoma | Aidan Connelly South Roscommon | Approved |
| Oktober | Eamon McGuirk Gap of the North | Approved |
| Ol Harry Potter | Sarah Lee West Cork | Approved |
| Ola Lara | Cait Stafford Ballycanew | Approved |
| Old Camp Lucky Lilly | David Quinlan Arderin | Approved |
| Old Camp Silver Diamond | Paula Quinlan Arderin | Approved |
| Old Court Nancy | Lee Galavan The Rower | Approved |
| Old Court Nelly | Lee Galavan The Rower | Approved |
| Old Farm Just William | Gerard Kavanagh Foxborough | Approved |
| Old Long Hill To Texas | Helen O'Byrne Waterford | Approved |
| Old Meadow Grace | Madeleine Bradley Killcarrick | Approved |
| Old Meadow Joe | Margaret Hayes Clonshire | Approved |
| Old Mill Bouncer | Cathleen Herbert Abbeylands | Approved |
| Old Mill Mir | Cathleen Herbert Abbeylands | Approved |
| Old Orchards Greg | Gemma Kelly Border Counties | Approved |