[QUOTE=Moosequito;8919186]
I really needed this post two decades ago when I was studying for national pony club quiz :yes: I spent way too much time staring at three pictures of paint horses, trying to decipher the differences between them and figure out what qualified each horse as either overo, tobiano, or tovero![/QUOTE]
Apparently frame overo only exists in North America. It is a genetic mutation that occurred in Spanish horses in North America. So it is genetically totally different from tobiano. All traditional piebalds and skewbalds in Britain would be tobianos.
Both frame overo and tobiano can vary a lot in the amount of “expression” of the colour pattern. You can have overos and tobianos that are solid colour except for a small tell-tale white spot somewhere, and you can have overos and tobianos that are almost completely white. So the general rule of white or colour crossing the back applies to horses that have “good markings,” ie about 50 % white/ 50% colour, but not necessarily to minimally marked horses.
Overo patterns tend to have lacey edges, where tobiano tends to be more blocks of colour.
Minimal expression of Overo is often a big bald face and four tall white socks.
A horse expressing both tobiano and frame overo patterns can have very wild markings, that don’t fit either model.
There are also other pinto patterns, including “sabino” and “splash.” Clydesdales often have “splash,” which gives white stockings and white belly spots. I know a Clydesdale/paint cross hunter who has an unsual colour pattern that’s a result of tobiano plus splash pattern expression.
If you are trying to identify really unusual markings on a horse of unknown parentage, you might need an actual DNA test to know what you’ve really got.
You shouldn’t breed two overos, as there is a 25 % chance the foal will be born “lethal white,” and die at birth.
Pony Club is very “English” in focus. I can’t speak to the particular quiz you took, but IME English riders and Pony club folks tend to be underinformed on the intricacies of identifying pintos, compared to the Western folks :).
