On Wednesday, May 25 my 7 year old Chinese Crested Mocha died of renal failure . It happened so insidiously and quickly, I had no time to act.,However I know now that he had the toxins in his system for a while. I have a feeling that it may be due to the Hartz Ultra-Guard flea drops that I used on him in the fall and this spring. I am so sick about this and mad at myself for not researching this product before using it. Over the winter he started having foul smelling breath.. I cleaned his teeth and the bad breath continued. I now know that the bad breath was a sign of toxins in his system and not a dental problem. Just a few weeks ago I noticed he was losing weight and I started giving him soft food. He was eating and seemed healthy with no serious problems. Then on Saturday May 21 he had a seizure. He came out of it OK and I made an appointment for him to see the Vet for a check up and to schedule an appointment to get his teeth cleaned.. I thought the seizure may have been due to him not eating from a dental problem. The vet checked him over and we scheduled him to come in the next day for a teeth cleaning. The next day he did not seem right so we did a blood test which showed that he was in severe renal failure and the vet said that he only had a week to live.. The next day he went into convulsions and I had to put him to sleep.. I am sick about this and so mad at myself for using the flea drops. Most of the cases I read on this site had a more immediate effect on the dog and hurt them , but in this case it was over time. That is, if this is what killed him.. I was wondering if anyone knows if an autopsy would show whether it was the flea medicine that caused this problem. I have five other dogs that do not seem to be affected and I used the product on them too.. Maybe some dogs are more sensitive to it than others. However I will never use it or any other chemical on my dogs. This was a very hard experience to go through and should have known better, however,last year I almost had a dog die from a Tick Borne disease. I would appreciate any feedback from this and some ideas of alternative flea and tick prevention.