Advantage/Advantix killing pets?

Hi,
This is my first post on this forum. My SIL's are always sending me Urban Legends and I come here to Snopes and then let them know that they had fallen victim to yet, another UL. But the last email I got from SIL was about a pet owner whose dog died from cancer from using Advantix flea treatment. It sounded like a UL to me, but I cannot seem to find anything about it on Snopes. Has anyone heard of it? I searched Critters, and Toxic chemicals, and I did a general search on "Advantix" but nothing has turned up. I would really appreciate your help in this matter.

MM