I have a thirteen year old black and white paint horse. He has one partial blue eye, and today when I went out to see him I noticed the blue has turned to light mint green. It was fine on Sunday, and today its not. He doesn't seem bothered by it, and he reacts to my hand going by his eye, it's not red or swollen or anything unusual. Has anyone else ever heard of this?
I don't know about horses, but I know that my blue eyes sometimes appear more greenish or more grayish, depending on what the weather/land is like outside (sunny, cloudy, green in the spring, dry and brown in the winter, etc) and what color clothing I'm wearing.
It's good your calling the vet. It may turn out to be nothing...or it may turn out to be something. LOL, not much help, am I?
I don't know if it would relate....but in humans there's supposedly only two colors, brown and blue. It was thought there was green too, but it's been proven that they are actually blue eyes. And reading the eyes to determine the health of an individual is called iridology. If a blue eye on a person were to go green it would indicate that the person is consuming something that the body is unable to process and it gets stuck in the body for a little while till it can find it's exit.
Maybe horses experience the same thing? I really don't know. But if so then perhaps there's something that he's eating that is slightly toxic to him? I don't know, but it's something to at least consider and possibly rule out. Perhaps some semi-toxic plants in the pasture just popped up, or maybe something is being absorbed through the skin. Just some ideas to ponder for ya.