In 2009 I used Hartz flea application once on my Aussie Shepard. Right away he started to act differently. He became lethargic and even started to look pal. Weeks later he was limping. I took him to the vet thinking that he hurt his foot chasing after a squirrel. To my horrible shock the Doctor informed me that he had cancer. It had spread from his neck to his upper part of his leg, and into his head. I couldn’t let him suffer.