What is the white patch?

[jbramhall]

reading a future post down below gave me idea to post my horse and see if any of you wise lot can give me your ideas as to what you think the white marking on my mare is. She is 2years 7months, dont know if you can tell but there is her bay hair striking through it.

Please excuse the old-ish photo ( and her hooves, they were later seen too) but can see the marking better here.

 

[Echo Bravo]

Many bay or chestnut horses have these, don't worry about it, must go way back in the breeding