A device for treating a target area of a vessel wall of a vessel within a human or animal body, the device comprising: an expandable portion for radially expanding the device from a contracted configuration allowing travel within the vessel to the target area to an expanded configuration allowing treatment of the target area; a protective sheath stretch-fitted over the expandable portion to exert a compressive force on the expandable portion for radially contracting the device from its expanded configuration to its contracted configuration, and for exerting a compressive force on the expandable portion in its contracted configuration; and at least two spaced apart treatment implements extending radially outwardly from the expandable portion, wherein in the device's contracted configuration the implements are shielded within the protective sheath, and in its expanded configuration the thickness of the sheath decreases to expose the implements for contact with the target area of the vessel wall. A protective sheath for fitting to a device for treating a target area of a vessel wall of a vessel within a human or animal body, a balloon catheter sheath loading device and method for loading a tubular sheath onto a balloon catheter, and a method of treating one or more target areas of a vessel wall within a human or animal body are also disclosed.