A search found these:
http://www.vetsoftware.com/acvc2002-hess2.htm
 
including:
>Enalopril (0.5 mg/kg PO q 48h) or Captopril 1.6 mg/kg (1/8th of a
>12.5 mg tablet PO q 48h) can be used to decrease afterload.  This is
>the starting dose.  Eventually, increase frequency to q 12 - 24 h.  Can
>cause lethargy.  If the ferret becomes lethargic from hypotension, the
>dose should be decreased to once every third day.
 
http://www.ferretnews.org/cardiomyopathy.html
 
including
>Treatment of cardiomyopathy involves medication to remove accumulated
>fluid, such as the diuretic furosemide.  Vasodilators to modulate blood
>pressure are also often used, such as Nitrol or captopril.  Digitalis
>derivatives can be helpful to increase the strength and efficiency of
>the failing heart.
 
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?
cmd=Retrieve&db=PubMed&list_uids=7982459&dopt=Abstract
 
>Eur J Pharmacol. 1994 Jul 11;259(3):309-13.
>Effects of bradykinin receptor agonists, and captopril and thiorphan in
>ferret isolated trachea: evidence for bradykinin generation in vitro.
 
>Farmer SG, Broom T, DeSiato MA.
>Zeneca Pharmaceuticals Group, Wilmington, DE 19897-2300.
>Bradykinin B2 receptor agonists, but not a B1 receptor agonist, were
>potent spasmogens of ferret isolated trachea...
 
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?
cmd=Retrieve&db=PubMed&list_uids=3279179&dopt=Abstract
Looks to be a similar subject
 
http://circ.ahajournals.org/cgi/content/full/92/9/2660
is on L ventricular relaxing.  The study was on cavies but in google
there is a ferret mention, so perhaps there is some info for anyone who
is interested.
 
Dog and cat dosing (but not ferret for this med) are in:
http://info.med.yale.edu/yarc/vcs/miscellaneous1.htm
 
This drug was developed from pit viper studies.  Mark Plotkin is someone
I spent jungle time with in Suriname back in '78 when we were both
students so it was weird but understandable seeing this particular
old friend show up in the search:
http://www.principalvoices.com/voices/mark-plotkin-white-paper.html
[Posted in FML issue 4780]