Jim, There are almost no or no documented cases of vitamin A toxicity
in ferrets; they appear to differ from humans in that regard.  You can
find more in the FHL Archives.  The only cases that even approach
documentation that I know of off-hand were with a British breeder who
constantly fed game liver and there were no necropsies or testing done
there if memory serves.  A Pubmed search of "Vitamin A" toxicosis ferret
mustela brings up no results, nor do several variations on that search
theme.
 
Alternative cases of ferrets not doing well with very high amounts of
such oils have been proposed such as an imbalance of oil types, or a
problem with too much of another nutrient that a ferret would not
normally get in high amounts.  You can also find those in the archives.
 
Nancy, There is a LOT in the FML and FHL Archives on diet hazards to
pass along.  Also, show them issues of Ferrets magazine and the IFC CD
transcription which mention the kidney risks of raisin or grape eating
(the work of Dr. Tom Kawasaki) and the ASPCA poison control document on
the kidney risks for dogs.  If they talk with the manufacturers they will
find that a number are modifying foods to reflect current knowledge.
 
Send a letter to the Petco corporate head veterinarian telling what
they are doing and which store it is.
 
-- Sukie (not a vet)
Ferret Health List co-moderator
http://www.smartgroups.com/groups/ferrethealth
FHL Archives fan
http://ferrethealth.org/archive/
replacing
http://fhl.sonic-weasel.org
International Ferret Congress advisor
http://www.ferretcongress.org
[Posted in FML issue 5170]