Had not "heard" of it, but I just know from other areas of my life, that meds easily become less effective as the disease or virus or bacteria evolve and mutate to the point that frequently the meds dont work as well. This is why I personally rotate Revolution with Canimax, and I even will rotate Sentinal into the mix. Not ever had an issue with heartworms or any other parasites, but I still keep my fingers crossed and say a prayer! |