I always use Frontline on my Boxers, but I ran out after spraying my male. I had some Hartz flea and tick spray, so I sprayed my 85 lb. female Boxer hoping to get rid of the fleas until I could get to the vets office the next morning. Immediately after spraying my dog she could not walk or hold her head up. I realized the Hartz was killing her. I took her to the bathtub and washed it off. She shook for about an hour. I squirted water down her with a baster and got her to eat some of her favorite dog biscuits. I took her to the vet the next morning and he told me I was lucky I didn’t spray her and go to bed. That he has had numerous people whose animals had died after being sprayed with Hartz. I am still upset and I threw everything away with a Hartz label. I notified Walmart, but all they could say is they are sorry. I plan on calling Hartz, but I am sure they will do nothing. I just want other pet owners to be aware they can kill their animal trying to help them.