| Sable | R 47 |
| Samoucina | S 24 |
| Samson | L 24 |
| Sandalwood | R 40 |
| Sandia | R 48 |
| San Francisco | R 47 |
| San Gabriel | R 36 |
| Santa Barbara | R 46 |
| Sarah Goodloe | R 49 |
| Sarajevo Blue | R & M 36 |
| Schneekuppe | R & M 40 |
| Seduction | R 49 |
| Sensation | R 48 |
| Serenite | R ± 48 |
| Shah Jehan | R 49 |
| Shannapin | R ± 48 |
| Shasta | R 48 |
| Shekinah | R 24 |
| Shelford Chieftain | S, R 48 |
| Sherbert | R ± 48 |
| Sheriffa | R 47 |
| Shining Waters | R 48 |
| Shot Silk | R 24 |
| Siegfried | R 48 |
| Sierra Blue | R ± 48 |
| Sierra Lakes | R ± 48 |
| Sierra Snow | R + 48 |
| Silver Elf | R 44 |
| Sirius | S 24 |
| Sir Michael | R ± 48 |
| Sir Walter Scott | L 24 |
| Siskin | R 24 |
| Small Wonder | R 40 |
| Smoothy | R & M 40 |
| Snoqualmie | R 49 |
| Snow Carnival | R 48 |
| Snowking | R 48 |
| Snow Maiden | R 44 |
| Snow White | R 24 |
| Socrates | R 40 |
| Soledad | R 44 |
| Solid Mahogany | R 48 |
| Some Love | R 22 |
| Song of Gold | R ± 48 |
| Sonny Boy | R 50 |
| Soquel | R 46 |
| Sound Money | R 40 |
| Southland | R 44 |
| Souv. de Loetitia Michaud | R 48 |
| Souv. de Mme. Gaudichau | S, R 47 |
| Spring Glow | R 44 |
| Spun Gold | R 49 |
| Spuria Alba | S 44 |
| Stardom | R 47 |
| Statellae | R 44 |
| St. Clair | L 24 |
| Stella Polaris | R 48 |
| Stipples | R 24 |
| Storm King | R 49 |
| Suez Sister | R 46 |
| Sulina | R & M 32 |
| Sunmist | R 36 |
| Surefire | R 40 |
| Sosa | R 43 |
| Susan of Hilly | R 22 |
| Suzanne Autissier | S 48 |
| Sweetseri | R & M 38 |