Horses with the greying allele {denoted with a G} can be born with any
base color. The Grey gene is dominant, in other words it only requires one copy of
the Grey gene to produce a grey horse. Subsequently, to be grey a foal MUST have a grey
parent. A foal of two grey parents has a 25% chance of being homozygous for grey and thus
producing only greys. NOTE: In order to be homozygous the foal must inherit a grey gene
from each parent.
Horses go through many shades of grey while maturing.
Since the greying gene almost totally "masks" effects of the
other color genes, it is important to distinguish any white markings while under six
months. For this reason, greys are not normally selected for use in pinto breeding
programs. See illustration:
GREY TOBIANO VS. SILVER DAPPLE TOBIANO
GREY "GG or Gg"/
TOBIANO "TT or Tt" |
BLK "EE or Ee"/SILVER "ZZ or Zz"/
TOBIANO "TT or Tt" |
|
 |
Note consistency of color on head |
Note dark "mask" on head |
A progressive action, the hair of grey horses gradually turns grey, at
various stages many will show dappling patterns. Miniature and Shetland breeders should
not confuse a dappled grey with a SILVER DAPPLE. See illustration:
DAPPLE GREY VS. SILVER DAPPLE
BLACK "EE or Ee"/
GREY "GG or Gg" |
BLACK "EE or Ee"/
SILVER "ZZ or Zz" |
 |
 |
Note greying of
color on head |
Note dark "mask"
on head |
Breeders use the area around the eyes as a guide to color identification
of greys. The head area generally starts to grey first. Later the horse will have a
mixture of white and colored hairs throughout the body and one must not confuse this stage
with ROAN. See illustration:
GREY VS. ROAN
BAY "AA or Aa"/
GREY "GG" or Gg" |
BAY "AA or Aa"/
ROAN "Rr" (RR is lethal) |
 |
 |
Note greying of color
on head |
Note natural bay
color on head |
