The invention comprises a reflector (10)with a fastening device for an animal collar. The reflectorincludes a base plate (2) with an inner surface (4) and anouter surface. A clip (3), which is substantially U- shaped,runs over the inner surface, the end of the first leg (7) ofthe clip being fastened by- means of a movableconnection (9) to a first side of the base plate, and the end of thesecond leg (8) being suitable for being irreversiblyfastened to a side of the base plate opposite from the firstside. On the outer surface of the base plate there are tripleprisms (1). On the inner surface of the base plate thereis/are one or more spacers (6). The invention alsocomprises a collar containing an active substance which canleave the collar over the entire length. At least one of thereflectors according to the invention is fastened to thecollar. The invention also comprises a system comprising acollar containing an active substance which can leave thecollar over the entire length and at least one of thereflectors according to the invention.
