Hopefully it will be benign(sp). Man, I hate when I'm right.....We have a mare on the farm with a similar lump on her head just behind the eye but below the base of her ear. The vet said it was probably no big deal as long as it didn't get real hard, imobile or start growing. I hope yours will be the same.
Hi equest 94
I am hoping you will get this but I see the posts are very old so perhaps you won't. My gelding has developed an identical lump to your mare. Like yours it came up suddenly, he was ever so slightly lame for a few days then totally sound again and has been ever since, that is about a month ago, i only noticed the lumps two weeks ago so it must have appeared after the lameness. I am sure it was not there at the time he was lame so there may or may not be associated. My gelding is given to great bouts of spring fever and at the time was galloping every day around the field leaping and bucking n who knows what! At the time of the lameness I thought it was a stone bruise or a twist as the lameness resolved quickly. Like you I have been unable to find out any more info. Was wondering how your mare fared and what you find out on further investigation?