This rat has no concept of the harm that may come to them when performing this job that has been forced upon them.

You're probably very wrong here. It is very probable that the rat feels the fear and sense of danger being experienced by her handlers around/toward the minefield (dogs and cats definitely feel the fear of their human companions), and she has been the one who has been going into that danger zone for 5 years. What she definitely doesn't know is that that danger isn't applicable to her. So 'heroic' may be very well applicable here.