The thing with Overo is, a horse can appear to be NON overo through their phenotype (what you see) but genetically they are indeed an Overo.

You would need to have the mare and stallion tested for OLWS to be sure.

If she is negative, the stallion is negative:

0% chance of a OLWS foal

If she is positive, the stallion is negative:

50% chance of a OLWS positive foal (carrier)

If she is negative, the stallion is positive:

50% chance of a OLWS positive foal (carrier)

If she is positive, the stallion is positive:

I believe it is a 1-4 chance that your foal will be OLWS (fatal)

Im no expert, so if Im wrong someone please correct me!

Still learning myself.

Brittany