🎨 Modifiers
Color Modifiers
Modifiers alter the appearance of the base coat but do not dilute it.
Flaxen (F)
Flaxen is a recessive modifier that lightens the mane and tail of chestnut horses.
Inheritance
| Genotype | Result |
|---|---|
| F/F | Flaxen |
| F/f | Carrier |
| f/f | Non-Flaxen |
Because flaxen is recessive, a horse must inherit a flaxen allele from both parents in order to visually express it.
Expression
Flaxen only affects chestnut horses. Bay and black horses may carry flaxen but will not visually express it.
Silver (Z)
Silver is a dominant modifier that affects black pigment. It lightens the mane and tail while having no effect on red pigment.
Inheritance
| Genotype | Result |
|---|---|
| Z/Z | Silver |
| Z/z | Silver |
| z/z | Non-Silver |
Only one copy of silver is required for expression.
Expression
Chestnut horses may carry silver but will not visually express it because they do not produce black pigment.
Sooty (Sty)
Sooty is a dominant modifier that adds dark hairs throughout the coat. Expression can range from subtle dark shading to heavy darkening across the entire body.
Inheritance
| Genotype | Result |
|---|---|
| Sty/Sty | Sooty |
| Sty/sty | Sooty |
| sty/sty | Non-Sooty |
Only one copy is required for expression.
Expression
Sooty affects bay and chestnut based horses but any color can be a carrier.
Sooty Bay
Sooty Dark Bay
Liver Chestnut
Sooty Buckskin
Chocolate Palomino
Gray (G)
Gray is a dominant modifier that causes progressive depigmentation over time.
A gray horse is born its original colour and gradually lightens as it ages.
Inheritance
| Genotype | Result |
|---|---|
| G/G | Gray |
| G/g | Gray |
| g/g | Non-Gray |
Only one copy is required for expression.
Expression
Gray can occur on any base colour.
Examples:
- Black → Gray
- Bay → Rose Gray
- Chestnut → Rose Gray
The horse's original color remains genetically present underneath the graying process.
Black Base Graying Process
Bay Base Graying Process
Chestnut Base Graying Process
Gray Final Forms
