Join Date: Aug 2009
Location: secret mountain valley
The best person to ask about this is your vet, they will be able to tell you if they think they can get clean margins which is often the difference between curative removal and aggressive recurrance. I will say that I have seen lots of them removed from the perineal area (where you say she has hers) and they do really well. The surgery is usually done under sedation with the horse standing rather than under general anesthesia which makes it much safer.
As far as the ones around her mouth, that may be trickier because you'd need to keep her off feed/give mash for a long time during recovery, but you say they don't seem to bother her so I'd personally let those be.
I haven't heard about Cimetidine for melanomas, are you sure you're not thinking of Mast Cell tumors? It is commonly given for management of these tumors as they secrete histamine and Cimetidine is a histamine blocker. Maybe I'm just not familiar with that use though, would be cool to learn something new!!