I know there are quite a few collie owners out there. Because of the MDR1 intolerance to certain drugs - most of which seem to be in worming and flea treatments, can I ask which products you use and also how often do you flea treat? Local vet has a package which you prebuy and included in that is 12 flea treatments however others I have spoken indicate this is rather too often and it doesn't need to be as often as once a month. Any thoughts?