A woman on a FB group lost her horse to this, it was misdiagnosed by 2 vets, her vet was out of town, but when he came back he knew immediately what it was. I have posted her story and photos in the comment below this. http://veterinarynews.dvm360.com/swamp-cancer-increasing-threat-equine-pythiosis "Swamp cancer": The increasing threat of equine pythiosis Know when to suspect this fungal infection so you can prevent its generally fatal consequences Mar 01, 2011 By Kenneth Marcella, DVM DVM360 MAGAZINE 123 Next Pythiosis is a relatively uncommon fungal-like infection causing cutaneous or subcutaneous, gastrointestinal, respiratory or multisystemic disease in many species of animals including humans. Horses are most commonly infected, and the devastating tumor-like nodular skin masses seen in these cases are likely to be remembered long after the actual name of the organism—Pythium insidiosum—is forgotten. The extremely rapid rate of growth of these lesions and the generally fatal outcome in these cases makes remembering this disease crucial for equine practitioners since early recognition and appropriate treatment are the only hope for survival for infected horse More in the above link.