Horse "foaming at the mouth" What does that mean when you see it?

[CharlieR]

Originally Posted by Sightseek

This is actually a positive thing and means the horse is relaxed and accepting the bit in his mouth. When a horse flexes his poll (the area between his ears) and relaxes his jaw it stimulates the salivary glands.

Thanks Sight for the info. Note, today it was a she that was relaxed. We were at Monmouth and saw Rachel doing this when schooled in the paddock that's why I was asking. Have several photos I'll try posting