In the equine world a chimera is a horse created from two genetically-different
DNA types, believed to occur when non-identical twin embryos fuse into one. …
The common patterns of coats chimera are not passed on to offspring since they result
from an anomaly that occurs in the womb, not genetic heredity.
According to the research team that this is the case with chimerism. It is closely linked
to the twins of domestic livestock and whose prevalence and consequences are not yet
known for horses.
Chimerism can be described as a genetic condition that occurs when the two
Zygotes (fertilised eggs) are fertilised and then combine to form a single normal zygote.
The resultant person therefore will have two distinct cells, each of which has
an individual genetic constitution.
In the majority of cases that have been documented the cells from different
organs or other regions of the body are able to have different DNA, as though
two entities were present within one body.
In general, it is caused from exchanging hematopoietic stem cell via placesntal
flow between dizygotic twins (blood the chimerist) or through the combination
of two embryos at the early phases of growth (true Chimerism).
There are times when chimeras differ twigs within the coat. This distinctive patterns
of the coat are more usual and, for instance the twin embryos were chestnut and bay.
Although, in some instances, the phenomenon is seen in cattle and dogs this unique
coat is an inheritance. The DNA test of males and dandruff samples may reveal two
individuals, and the blood test will reveal if the sample is a chimera. Chimeras can
also have distinct bi-colored coats.