I am very sorry about you losing your pet. I am a cat owner myself, and can appreciate how much these companions can mean to a person.
You wrote a very well thought out letter, and I hope the company responds to you. This product should be taken off the shelves. I agree with some of the other posters, particularly those who work with animals, in reccomending that people stop buying Hartz products. Companies should be rewarded when they offer quality goods and services, and penalized when they don't. Thanks for writing about it here.