| Name | Sex | Colour | Registration | Foaling Date | Reg Status | Competition Status |
|---|---|---|---|---|---|---|
| OLOUGHLIN KAREN | Mare | BAY | 11068 | Stud Book | Deceased | |
| OLSLAND CINDY LOU | Mare | BAY | 12335 | Stud Book | Deceased | |
| OLSLAND GAYTAN | Mare | BAY | 8043 | 01/09/1968 | Stud Book | Deceased |
| OLSLAND PENNY | Mare | BROWN | 8044 | 01/10/1965 | Stud Book | Deceased |
| OLSLAND TRIXIE | Mare | CHESTNUT | 12336 | Stud Book | Deceased | |
| OLSSON AFTER MIDNIGHT | Gelding | TAFFY | 267263 | 07/11/2023 | Stud Book | Eligible |
| OLSSON ALLIE | Mare | TAFFY | C2-266558 | 11/11/2013 | Second Cross | Eligible |
| OLSSON FAIRY FLOSS | Mare | BAY | 267264 | 04/09/2023 | Stud Book | Eligible |
| OLSSON HUSTLER | Gelding | BROWN | C2-266559 | 05/01/2017 | Second Cross | Eligible |
| OLTAKIM ALEC | Gelding | BAY | 47822 | 15/09/1972 | Stud Book | Not Eligible |
| OLTAKIM SIR SARS | Gelding | BLACK | 47823 | 26/12/1972 | Stud Book | Not Eligible |
| OLTAKIN CRYSTAL | Mare | GREY | 5171 | 01/01/1966 | Stud Book | Deceased |
| OLTAKIN JEWEL | Mare | GREY | 5170 | 01/01/1969 | Stud Book | Deceased |
| OLWEN | Mare | BAY/GREY | F26663 | 25/01/1981 | Foal Recorded | Not Eligible |
| OLY | Mare | CHESTNUT | F9552 | 01/11/1976 | Foal Recorded | Not Eligible |
| OLYMPIA | Mare | BLACK | 13109 | Stud Book | Deceased | |
| OLYMPIA HAZE | Mare | BROWN | F34486 | 19/02/1983 | Foal Recorded | Not Eligible |
| OLYMPIAN | Gelding | BAY | 121282 | 02/04/1993 | Stud Book | Not Eligible |
| OLYMPIC DANCER | Mare | BROWN | BP-78307 | 08/10/1990 | Breeding Purposes Only - Stud Book | Not Eligible |
| OLYMPIC GIRL | Mare | BROWN | 21325 | Stud Book | Deceased | |
| OLYMPIC GOLD | Gelding | CHESTNUT | 54246 | Stud Book | Not Eligible | |
| OLYMPIC OLLIE - HSH | Gelding | BROWN | 153881 | 02/10/2000 | Stud Book | Eligible |
| OLYMPIC PRIDE | Mare | CHESTNUT | 17966 | 16/10/1972 | Stud Book | Deceased |
| OLYMPIC SID - HSH | Gelding | CHESTNUT | 153882 | 26/09/2000 | Stud Book | Not Eligible |
| OLYMPUS | Gelding | BAY | 54715 | 05/09/1972 | Stud Book | Not Eligible |
| OLYMPUS LIGHT | Gelding | CHESTNUT | 46856 | 01/04/1971 | Stud Book | Deceased |
| OMA POPPED THE CORN | Mare | BLACK | C1-255979 | 29/09/2016 | First Cross | Not Eligible |
| OMAGH ABBY | Mare | BROWN | 28668 | 01/09/1971 | Stud Book | Deceased |
| OMAGH CHARITY | Mare | GREY | 28667 | 01/08/1965 | Stud Book | Deceased |
| OMAGH JOLSON | Stallion | BROWN | F13444 | 10/09/1977 | Foal Recorded | Not Eligible |
| OMAGH MARY | Mare | BROWN | 7196 | Stud Book | Deceased | |
| OMAGH MARY POPPINS | Mare | CHESTNUT | 7197 | 01/01/1966 | Stud Book | Deceased |
| OMAH KHYAMME | Gelding | BAY | 52776 | 01/09/1977 | Stud Book | Not Eligible |
| OMAHA BOGART | Gelding | DUN | 64814 | 01/05/1978 | Stud Book | Deceased |
| OMAHA CHANDIE | Mare | BROWN | 65135 | 01/02/1978 | Stud Book | Deceased |
| OMAHA GATSBY | Gelding | PALOMINO | 64813 | 01/01/1978 | Stud Book | Deceased |
| OMAHA HAZE | Gelding | BAY | 80479 | 21/09/1991 | Stud Book | Deceased |
| OMAHAS PRIVATE BUNNY | Mare | CHESTNUT | C1-242314 | 13/11/2006 | First Cross | Not Eligible |
| OMALLEY - HSH | Gelding | GREY | 196235 | 15/11/2010 | Stud Book | Not Eligible |
| OMALLEYS MINX | Mare | BROWN | 231534 | 30/11/2009 | Stud Book | Not Eligible |
| OMALLEYS TOUCH - HSH | Gelding | BAY | C2-190879 | 29/02/2008 | Second Cross | Not Eligible |
| OMAN | Stallion | GREY | 129887 | 16/11/1996 | Stud Book | Eligible |
| OMANI ORGANZA | Mare | GREY | 127808 | 25/11/1996 | Stud Book | Not Eligible |
| OMANI SHADELL | Gelding | GREY | SM-127620 | 22/12/1992 | Special Merit - Stud Book | Not Eligible |
| OMANI STYLISH GODESS | Mare | CHESTNUT | 115269 | 05/12/1989 | Stud Book | Not Eligible |
| OMANI STYLIST | Mare | GREY | 124391 | 17/10/1994 | Stud Book | Not Eligible |
| OMAR | Stallion | GREY | 1691 | 07/09/1959 | Stud Book | Deceased |
| OMAR GAWD | Mare | BAY | C1-248416 | 12/12/2012 | First Cross | Not Eligible |
| OMAR SALEIM | Gelding | GREY | 50415 | 25/08/1975 | Stud Book | Not Eligible |
| OMAROO BULLSEYE | Gelding | BLACK | C2-266222 | 11/01/2020 | Second Cross | Not Eligible |
| OMAROO CONDO - HSH | Gelding | CHESTNUT/TAFFY | C1-259557 | 28/10/2016 | First Cross | Eligible |
| OMAROO EXTRA - HSH | Gelding | BAY | 266223 | 01/10/2018 | Stud Book | Not Eligible |
| OMAROO JESSIE | Mare | BROWN | C2-265852 | 06/01/2021 | Second Cross | Eligible |
| OMATANGI DELTA | Mare | BAY | 161339 | 04/10/2001 | Stud Book | Eligible |
| OMBA | Mare | BROWN | 8140 | 01/08/1970 | Stud Book | Deceased |
| OMBRE | Stallion | CHESTNUT | F9425 | 14/07/1977 | Foal Recorded | Not Eligible |
| OMBRE ROSE | Mare | BROWN/BLACK | 73852 | 04/11/1980 | Stud Book | Deceased |
| OMBRE SHIRRAY | Gelding | CHESTNUT | 36779 | 07/01/1976 | Stud Book | Not Eligible |
| OMBRE TWO | Stallion | CHESTNUT | F18886 | 17/08/1979 | Foal Recorded | Not Eligible |
| OMEGA | Gelding | BLACK | 29379 | 09/09/1972 | Stud Book | Not Eligible |
| OMEGA JAY | Mare | CHESTNUT | F44355 | 30/10/1987 | Foal Recorded | Not Eligible |
| OMEGA MAJIC MOMENTS | Mare | CHESTNUT | 73323 | 20/07/1981 | Stud Book | Not Eligible |
| OMEGA MARINA | Mare | CHESTNUT | 21032 | 19/10/1971 | Stud Book | Deceased |
| OMEGA SHEEN | Mare | PALOMINO | 38003 | 03/11/1969 | Stud Book | Deceased |
| OMEGA SUNSET | Mare | PALOMINO | 21031 | 27/10/1969 | Stud Book | Deceased |
| OMEGAS CONDUCTOR | Gelding | CHESTNUT | 263914 | 14/10/2022 | Stud Book | Eligible |
| OMEME | Mare | BAY | 16219 | Stud Book | Deceased | |
| OMEN | Stallion | PALOMINO | F14087 | 13/01/1978 | Foal Recorded | Not Eligible |
| OMEN MAY | Mare | BROWN | 3014 | Stud Book | Deceased | |
| OMEN VALLEY JO ANNE | Mare | CHESTNUT | 62583 | 01/01/1975 | Stud Book | Deceased |
| OMEN VALLEY LIBERTY - HSH | Mare | BAY | 239832 | 25/11/2013 | Stud Book | Not Eligible |
| OMEN VALLEY LINDY LOU | Mare | BAY | 67560 | 13/12/1980 | Stud Book | Deceased |
| OMEN VALLEY ROXANNE | Mare | BROWN | 67561 | Stud Book | Deceased | |
| OMEN VALLEY STRIKER | Gelding | CHESTNUT | F39380 | 23/08/1984 | Foal Recorded | Not Eligible |
| OMEO ABAGAIL - HSH | Mare | BROWN | 42973 | 21/11/1973 | Stud Book | Deceased |
| OMEO ABEL MAN - HSH | Stallion | GREY | 42970 | 30/04/1975 | Stud Book | Not Eligible |
| OMEO AMBER - HSH | Mare | BROWN | 42971 | 04/12/1976 | Stud Book | Deceased |
| OMEO BARBIGAL - HSH | Mare | BROWN | 44528 | 01/08/1970 | Stud Book | Deceased |
| OMEO BELLE - HSH | Mare | BROWN/BLACK | 138072 | 02/11/1999 | Stud Book | Not Eligible |
| OMEO BILLIE JOE - HSH | Gelding | BROWN/BLACK | 130987 | 06/05/1999 | Stud Book | Not Eligible |
| OMEO BILLY BAR | Gelding | BAY | 63113 | 15/10/1978 | Stud Book | Deceased |
| OMEO BLACKBIRD - HSH | Mare | BLACK | 118096 | 23/03/1990 | Stud Book | Deceased |
| OMEO BLUE - HSH | Mare | BLACK | 7818 | 01/08/1968 | Stud Book | Deceased |
| OMEO BLUE BELL | Mare | GREY | 7817 | Stud Book | Deceased | |
| OMEO BOBBY BEE - HSH | Mare | BAY | 47475 | 01/12/1976 | Stud Book | Not Eligible |
| OMEO BOBBY STRAW - HSH | Mare | PALOMINO | 60489 | 01/03/1978 | Stud Book | Not Eligible |
| OMEO BROWNIE | Mare | BROWN | 7820 | Stud Book | Deceased | |
| OMEO BUSHMAN | Gelding | BAY | 25933 | 01/01/1968 | Stud Book | Deceased |
| OMEO CAB - HSH | Mare | BLACK | 111632 | 25/08/1988 | Stud Book | Deceased |
| OMEO CHAMPAYNE | Mare | CHESTNUT | 74960 | 02/10/1981 | Stud Book | Not Eligible |
| OMEO CHATTER BOX | Mare | CHESTNUT | 7815 | Stud Book | Deceased | |
| OMEO CLASSIC - HSH | Mare | BAY | 124279 | 03/01/1995 | Stud Book | Eligible |
| OMEO CLOUD | Mare | GREY | 15884 | 01/08/1971 | Stud Book | Deceased |
| OMEO CLOVER | Mare | CHESTNUT | 1223 | Stud Book | Deceased | |
| OMEO COPPER | Mare | CHESTNUT | 7825 | Stud Book | Deceased | |
| OMEO DAWN | Mare | CHESTNUT | 16051 | 01/08/1970 | Stud Book | Deceased |
| OMEO DILLY DALLY - HSH | Stallion | BAY | 43433 | 28/12/1971 | Stud Book | Deceased |
| OMEO DISCO - HSH | Mare | BAY | 47474 | 02/03/1975 | Stud Book | Deceased |
| OMEO DIXIE | Mare | CHESTNUT | 12154 | 01/08/1968 | Stud Book | Deceased |
| OMEO DRUMMER - HSH | Stallion | GREY | 46730 | 30/09/1975 | Stud Book | Not Eligible |