<http://www.newscientist.com/article/mg19526124.200-dog-contraceptive-signals-end-to-castration.html>
  or
http://tinyurl.com/yw8d4x

Article below.  Permission to crosspost.
Dog contraceptive signals end to castration    
11 July 2007   
NewScientist.com news service   

Linda Geddes Lyon

Male dogs can breathe a sigh of relief. The days of removing their
testicles to stop them breeding or to curb aggressive behaviour may be
numbered. A contraceptive implant that halts testosterone and sperm
production for months at a time is expected to gain European approval
within weeks, while steps are being taken to enable the drug to be sold
in the US.

[Remainder of article removed due to copyright limitations and because
it's enough off-topic that it doesn't warrant the space anyhow, but is
available at above link. Unknown whether this can apply to ferrets,
though ferrets are typically altered for other reasons as well. BIG]

__,_._,___

He who learns must suffer. And even in our sleep, pain that cannot
forget falls drop by drop upon the heart. And in our own despair, and
against our will, comes Wisdom by the awful Grace of God...Aeschylus

[Posted in FML 5667]