Originally Posted by BackwoodsBaby
okay I was going to do that when she goes to the vet for shots and check up. But still what would you guess?
The vet doesn't test for it, you have to pull hairs and send them to a lab. It is hugely important that you do this - if your mare is positive, and the stallion is positive, then you have a one in four chance of a foal that will die a slow, painful death within 72 hours of birth. Lethal White Overo - Horse Coat Color
In terms of colour, no, it is not definite that the foal would be grey. I would assume that the stallion is only carrying one grey gene, since you said he has thrown coloured foals. That would give you 50% chance of grey. You said that he was palomino when born - a relatively easy colour to work with in terms of genetics. Crossed with your mare, there is a 50% chance the foal will be chestnut/sorrel, and 50% chance the foal will be palomino. Adding this in to the grey part, you have a 50% chance of grey, 25% chance of palomino, and 25% chance of chestnut.