I don't have any quotable information on Anipryl usage in ferrets and
  why it doesn't work,
 
Anipryl (L-Deprenyl HCl) is a drug targeted to supress the pituitary
glands release of a hormone called ACTH.  (The pituitary gland is a small
gland at the base of the brain that coordinates several different hormone
producing glands in animals) In dogs and certain other species,
suppressing the release of ACTH can be an effective treatment for
hyperadrenocorticism (Cushings disease from the human literature).  This
drug is effective only in some dogs because they suffer from a hormone
secreting tumor in the pituitary gland (usually a microadenoma if memory
serves me well), that produces too much ACTH.  When too much ACTH is
produced, then the adrenal glands are receiving signals to produce too
much of the hormones they are responsible for (in dogs this is cortisol
and other related compounds).
 
Ferrets do not have Cushings disease, but rather a different form of
hyperadrenocorticism.  In ferrets, the pituitary is normal, but the
adrenal glands develop tumors *within* the adrenal glands ( 45% benign
hyperplasia, 45% carcinoma and approx 10% adenomas).  These tumors do not
respond to ACTH stimulation, but instead they produce their hormones
without influence from the pituitary gland.
 
Since the adrenal tumors in ferrets are not following the hormone signals
from the pituitary, using Anipryl to reduce the output of ACTH hormone
from the pituitary will be fruitless when used in ferrets.
 
  but there's an excellent explanation on how Lupron works right here in
  the file area.  Look there for Lupron.pdf.  While it's written so that
  even us laymen can get a grasp on how Lupron works, I think it goes
  into enough of the technicalities that even a vet would appreciate it.
 
If this file is not enough techincal information for your veterinarian,
there have been several technical write ups in veterinary journals that
will provide more details.
 
Mike McBride, DVM
[Posted in FML issue 3575]