I in a pinch tried to use hartz topical on my husky. That night she hid under the porch and I had to drag her putbe days later. Her eyes were yellow and she was very weak. I took her to thr vet and her lover numbers were extremely abnormal. The vet was skeptical on the medication working. I had to force the crushed pills down her with Pedialyte and a syringe, but thankfully she eventually recovered. I hate hartz and dont reccomend it to anyone. Anytime I see someone with it in their buggie at work I beg them not to buy it. I worry everyday about my dog now and wonder how many years I will have her. She was only 2 when thid happened.