This is a little odd to explain; it's not so much a health concern, but I'm curious if anyone else has ever experienced this particular phenomenon. I have two horses, one TB, one Irish Sporthorse. The TB is a dark bay, the ISH is a dapple gray. Both have this one spot on the left sides of their necks where they will inexplicably get a damp, sweaty spot. It's more or less in the area where you would give an IM injection, but the spot will show up at odd times, without any obvious cause. Both horses had that spot bleach from the sweat, the grey has a little orangey patch and the bay turned mousy in that area, about the length of a pen and a couple of inches wide. What's odd is that this year it seems less pronounced in the TB, who hasn't been in work, but the ISH's is about the same as last year. Does this make sense? Any thoughts? The ISH has a microchip, and for a while I'd thought that it was from the place where the chip had been embedded, but I realized that 1) it was the wrong place and 2) the TB has had this since before the ISH, and has no microchip. Is it just a long term reaction to a vaccination? Why would it stick around for that long?