Horse Health: Mammary Gland Tumors in Mares

My mare is 14 yrs old 1 year ago she presented with symptoms of mastitis (bacterial infection) and clear draining fluid but she wasn't in foal or had a foal at foot the mammary gland was not painful or ulcerated in any way. She was treated with anti-biotics but these did not clear her symptoms. A lump developed in one side of her mammary gland lab tests were done on the fluid again which was draining from the teat and came back only as bacterial infection. She developed a temperature and became depressed she was put on potassium iodide in preparation for an operation to remove the suspected granuloma the potassium iodide seemed to relieve her of infection better than anti-biotics, she was taken to theatre and the mass was removed which was full of nasty liquid which was tested and this came back with possibility of neoplasia (the mass was full of sulphites), the central part of the mass was tested and this came back as an aggressive neoplasia. We are now 3 months on and the operation site is not healing fully as it was left open to drain there is now a mass which can be felt unsure if this is scar tissue or tumour which has returned. She has had to have antibiotics several times and is now kept on potassium Iodide as this seems to be the only effective treatment which keeps her happy. My mare has now developed a thirst but other than this she is maintaining her weight, eating well, shiney coat and bright in her eyes if not quiet for her but still has enthusiasm.. She is a beautiful mare and advice is that she will lose condition when the neoplasia metastisies however the tumour which was removed was the size of a melon and externally had no effect on her she maintained her weight, shiney coat, ate well only her personaity changed and now I feel I have got used to her new personaility and have to remind myself of the horse she was although she is still a horse who knows what she wants and is still stroppy so hasn't completely lost her personality. Unfortunately as this is a rare cancer in horses prognosis is difficult I wish I had a crystal ball as I only want to do the best for my mare. Studies in to this dreadful desease would help.