I used Hartz flea and tick drops on my cat. I applied them per the instructions; starting between the cat’s shoulder blades and down her spine.
My cat became very, VERY lethargic. She just laid down and wouldn’t move. I had to pet her constantly to make sure she didn’t go unconscious.
Within two to three days, all the fur on her back had fallen out where the flea and tick drops were applied. To this day she still has a small bald spot between her shoulder blades, and when the weather warms up and she starts to shed, she loses fur most noticibly down her spine, creating a semi-bald stripe down her back, similar to the effects she had when I first used the product.
Beware this product. It’s terrible.