I used hartz for years on my dog not knowing anybetter! Luckily he didnt get any side effects and is still with us today but i can say the product didnt work!!! He brought us home lovely fleas. Sadly i used the same product but for cats on my kitty. I held her as she had a seizure from the topicial flea treatment. She was puking yellow foam and was very lethargic. Luckily she was tough through it and is still here today too. But i will never again use any hartz product, not even there shampoo! I have herd so many negative outcomes from using this product and i would love to see it pulled off of the shelves.