I did call the vet right after it happened. He came out and said this was the 5th hematoma he has seen in a month and until then had never seen a hematoma in his practice! Strange and he can't figure out what is causing them. I really think my mares edema travelled from her front legs directly to her butt and that there is a correlation here that all started with a high nail. Long story short , vet is doing nothing. Said it should resorb with time. Sometimes draining can do more harm than good. Said if it was a pendulous hanging hematoma he would consider draining but my horses he said are not that bad. So not really sure if this is a good idea to do nothing but I am watching it. On my own, I am still cold hosing it on warmer days and also putting epsom salt poutice on it a couple times a week, letting it sit a few days, then washing it off. Hoping it will go down. Worried though...