[QUOTE=foxhavenfarm;5682369]
I looked on the UC Davis site and Animal Genetics, Inc and couldn’t find anything on brindle or chimeraism. Would definitely test if there is such a test.[/QUOTE]
DNA testing - you take some from mane, some from cervical swabs and some from blood. Maybe also some skin samples. You would have to phone the lab and state you want to check for chimerism and they will tell you the kind of samples you need. If you get 2 DNA profiles, you have a chimera. When you send the samples in, you may also need to state on the package that you are specifically checking for chimerism so it helps the lab (follow their instructions in that regard - they may not want it stated either so blind results are pure). Labs are very careful in their testing protocols and do their due diligence with double and even triple testing if they think it necessary.
Chimerism results from there being twins, with one twin being absorbed by its sibling while in utero. No, not absorbed, that’s the wrong word - -they technically MERGE, but the weaker twin’s DNA only is present in certain organs. Usually, it results in certain parts of the body, such as the skin, having the DNA from the dominant twin (the living) and the sex organs might have the DNA of the absorbed twin. Or just a kidney, depends where it ends up.
It’s a problem when the DNA of the “absorbed” twin is in the sex organs, because offspring from chimerics will have a different DNA profile from the mother.
The only way to check is to obtain DNA from the sexual glands (cervical swabs) and compare to DNA from the skin and blood. ESPECIALLY important if you plan on breeding this mare in the future.
This problem just happened to a woman in the U.S. She nearly went to jail because the State claimed she was falsifying records because her kids did not have the DNA profile proving she was the mother. Turns out, she was chimeric and her absorbed twin’s DNA was in her ovaries and sexual organs (as proven by her cervical swabs), while her blood, skin, and swabs from her mouth showed a separate profile. This is only known to be in about 40-50 people in the entire world, but it presents a problem for science who at first thought DNA was an irreputable identifying factor in individualism. Chimerism is nature’s monkey wrench.
A mare may still be chimeric as the DNA in her kidneys (For example) may the only difference in the entire body and you’re not going to test her kidneys at all as that is far too invasive. However, from a breeding perspective, if you have a mare who has qualities and abilities you really like, it would be important that her skin and mane DNA is the same as her sex organs because it’s HER DNA you want passed on to her foals, not that of her absorbed, weak twin who could look like a mule for all you know.