I used HArtz Ultra Guard on my girl Jazzy. Within 3-4 days she seemed to not feel herself. She lost appetite, walks like everything hurts, I have had to hold a water dish up to her to feed her from my hand and am now cooking all foods for her as she would not eat dry or moist food. I cannot think of anything else that could have done this..she slipped getting in the but shows NO sign of any injury, we have done all blood work, stool samples etc.. to find it all normal – kidneys, liver, no infection, no heart worm, no nothing but she become weak, lost 12lbs and has not wanted to move until tonight. I put the drops on her on August 23rd, vet said it may take a month to work out of her system. I can only hope that this will work out of her system and she will be ok…deep in my heart I think this did this to her…called Hartz, they were jsut so friendly it was sick….made you think that they know something is wrong….I WILL NEVER EVER DO THIS TO AN ANIMAL AGAIN IN MY LIFE….this is so wrong, I wish I had seen this sight before I used this product…I just hope she makes it. We adpoted her from our neighbor that passed away knowing she loved us and our boys and would have a great life before meeting back up with him…..please don;t make it sooner than later – we still want to play with her….