I looked up the actual reg:
 
http://airconsumer.ost.dot.gov/
 
24877 Federal Register / Vol.  68, No.  90 / Friday, May 9, 2003 / Rules
and Regulations
 
"Certain unusual service animals pose unavoidable safety and/or public
health concerns and airlines are not required to transport them.  Snakes,
other reptiles, ferrets, rodents, and spiders certainly fall within this
category of animals."
 
They do not specify what these "unavoidable safety and/or public health"
are, but it looks like they are presuming that an escape from one of the
preceding, could be difficult to contain and cause a lot of commotion.
However a monkey does not fit that category?  Do they have a better PR
rep than ferrets?
 
Personally, I would never trust my loving companions to the horrors
of the airline.  Now if there are any airline workers on the list I
apologize, but baggage handlers are not known for their gentleness or
competency.  Losing baggage is one thing, but a pet...
 
James, Melissa & Kassidy
 
Loving:  Bebe, Jako, Riley
Missing: Wheezer, Pym, Ricki
[Posted in FML issue 4147]