If your horse has developed a tumour, sarcoid or has proud flesh it may require removal. This will be done generally either by surgery or cryosurgery.
Traditional surgical methods of removal will require some form of anaesthesia either local or general. The lump or tumour is then removed via excision. Cryosurgery on the other hand is where the target area is frozen, thawed and then refrozen to damage the tissue and cause it to slough or fall off. Most commonly liquid nitrogen is used for this procedure.
Your veterinary surgeon will discuss the particular issues related to your horses lump or tumour.