A recent thread on the Ferret Adrenal/Insulinoma Mailing List has been the
vena cava ligation and the high mortality rates that have been reported with
this procedure.  Dr. Charles Weiss wrote an explanation of the conditions
under which this procedure can be performed safely.  Dr. Weiss wrote this
post on July 26, 1998, for FML and FAIML readers and their veterinarians.
For those of you who are new to the list, Dr. Weiss is in Potomac, Maryland.
He is highly respected for his expertise in ferret medicine.
 
                           VENA CAVA LIGATION
 
I have performed about 10 of these procedures to date.  All the ferrets
have survived and are doing well.  In my opinion vena cava ligation can be
a life saving technique which should be performed with select cases.  The
right adrenal gland in the ferret is normally attached to the vena cava,
which makes it a technically difficult surgery.  Although difficult, an
experienced ferret surgeon usually can perform this procedure without
ligating the vena cava, with very good success.  I do not feel the vena cava
should be ligated routinely, or because the adrenal tumor is "attached" to
the vena cava (it is virtually always attached to the vena cava).  On
occasion we see very large right adrenal tumors which almost completely
occlude (obstruct the blood flow through) the vena cava.  In these cases
the tumor grows over weeks or months slowly occluding more and more of the
blood flow through the vena cava.  When this occurs over this time frame
the body develops collateral circulation (other small new blood vessels
that bypass the vena cava).  Therefore when the vena cava is almost
completely occluded I feel it is usually safe to ligate it in the ferret.
The other alternative is closing the ferret up and calling it an inoperable
tumor (which is giving the ferret a death sentence).  With the option of
vena cava ligation virtually all adrenal tumors are operable.  This is
really a benefit to the patient since even malignant adrenal tumors rarely
spread and complete removal is usually curative.
 
When used appropriately I feel this is a life saving technique which has
minimal complications.  But, it's important to remember that a ferret with
a large adrenal tumor is a very ill animal (even if it comes on so slowly
that the owners do not notice many symptoms).  Although this is a very
stoic species which does not always display pain as we do, this is a life
threatening condition.  In a case like this there are always risks
associated with anesthesia and surgery, because it is such a serious
condition.  In my opinion, in such a case, surgery with vena cava ligation
is the best chance to save the patient's life and give the ferret a good
quality of life post- operatively.
 
Charles Weiss, DVM
[Posted in FML issue 2391]