Hi All,
 
I'm a pharmacologist, not a vet, but I felt I had to add my two cents
worth here.  Boric acid is one of the safer pesticides from a mammalian
point of view, but to my knowledge, there is not a lot of information
available with regards to its toxicity in ferrets - most of the data come
from small rodent exposure tests.  BIG was right to jump in here - the
MSDS for boric acid is moderate, and a lot of MSDS's will give you the
heeby-jeebies for no good reason.  (If you read the one for sand, you
will never take your kids to the beach again.  And the one for table
sugar will have you banning Christmas cookies and Halloween candy.)
Still, given the lack of ferret specific data, and the fact that ferrets
tend to nose around in cracks and crevices, I would be very cautious in
the use of boric acid.
 
What I can tell you for sure from personal experience (me, not the
ferrets!), is that boric acid in the dry or concentrated liquid/spray
forms can be very painful if it gets in the eyes, and it can cause nasty
skin scrapes (the dry stuff) and rashes (liquid and dry).
 
Good luck on the bug front!
 
Liesl
[Posted in FML issue 4261]