We had a little girl come to our shelter with severe "chemical burns" from
a flea collar.  Whether it was her own personal allergic reaction to the
chemicals, or the chemicals themselves, we don't know.  The burns are now
gone but she still has a scar around her neck from them.  Of course, most
owners would have taken the collar off when they realized it was
irritating, but not these people.
 
SP
[Posted in FML issue 2546]