🪽 White Patterns
Tobiano (TO)
Tobiano is a dominant white pattern gene that creates smooth, rounded white patches that often cross the topline.
Inheritance & Expression
| Genotype | Result |
|---|---|
| TO/TO | 75% Medium Tobiano 25% Expressive Tobiano |
| TO/n | 50% Minimal Tobiano 50% Medium Tobiano |
| n/n | No Tobiano |
Characteristics
- Rounded white patches
- White legs
- White crossing over the topline
- Dark head with normal facial markings
Then literally repeat the same structure for:
Splashed White (SW)
| Genotype | Result |
|---|---|
| SW/SW | 75% Medium Splash 25% Expressive Splash |
| SW/n | 50% Minimal Splash 50% Medium Splash |
| n/n | No Splash |
Sabino (SB)
| Genotype | Result |
|---|---|
| SB/SB | 75% Medium Sabino 25% Expressive Sabino |
| SB/n | 50% Minimal Sabino 50% Medium Sabino |
| n/n | No Sabino |
Frame Overo (O)
| Genotype | Result |
|---|---|
| O/O | Lethal White Syndrome |
| O/n | 50% Minimal Overo 50% Medium Overo |
| n/n | No Overo |
Since O/O is lethal, there is no expressive category for homozygous horses because they won't survive.
Tovero
Tovero is not a separate gene.
A Tovero horse inherits both Tobiano and one or more Overo-type pattern genes.
Common Combinations
- Tobiano + Frame Overo
- Tobiano + Splashed White
- Tobiano + Sabino
- Tobiano + Multiple Overo Genes
Characteristics
Tovero horses commonly display:
- Tobiano body markings
- Extensive facial white
- Blue eyes
- Irregular body patterns
- Mixed pattern characteristics
Because Tovero is a combination rather than a single gene, no two Toveros look exactly alike.
White (W20)
Instead of being a visible pattern itself, W20 increases the expression level of other white patterns.
Examples:
- Minimal → Medium
- Medium → Expressive
A horse carrying W20 may produce larger markings than a horse with the same pattern but without W20.
Then Appaloosa should work differently:
Leopard Complex (LP)
LP determines whether a horse can display Appaloosa characteristics.
Inheritance
| Genotype | Result |
|---|---|
| LP/LP | Strong Appaloosa Expression |
| LP/n | Moderate Appaloosa Expression |
| n/n | No Appaloosa |
PATN1
PATN1 controls how much white patterning develops.
| Genotype | Result |
|---|---|
| PATN1/PATN1 | High White Coverage |
| PATN1/n | Moderate White Coverage |
| n/n | Low White Coverage |
Example Outcomes
| LP Status | PATN1 Status | Possible Result |
|---|---|---|
| LP/n | n/n | Varnish Roan, Minimal Blanket |
| LP/n | PATN1/n | Blanket, Spotted Blanket |
| LP/LP | PATN1/n | Leopard |
| LP/LP | PATN1/PATN1 | Fewspot, Snowcap, Extensive Leopard |
Roan (RN)
Roan is a dominant pattern gene that mixes white hairs evenly throughout the body while typically leaving the head and lower legs darker.
Inheritance
| Genotype | Result |
|---|---|
| RN/RN | Roan |
| RN/n | Roan |
| n/n | Non-Roan |