I have one ferret and two guinea pigs, and I also once hoped they might
get along.  While cleaning the guinea pig pen one day, Rikki (the ferret)
managed to wriggle his little nose through the gate, and as everyone knows,
that's all it took.  He immediately attacked my female pig, who happened to
be the closest - went right for her face, and grabbed her by her forehead!
I immediately grabbed Rikki, and forced his jaws apart to get him to let
go of Bonnie.  In his cage he went, and after catching Bonnie, checked her
carefully - to my GREAT relief she was ok.  The whorly fur on her face had
somewhat prevented him from getting a good grip on her, his teeth never
penetrating her skin, but she was badly scared and the male was squeaking
his head off!
 
Ferrets and guinea pigs DO NOT mix - Rikki saw them as DINNER!!!!  After
checking with my vet and some ferret rescue people, I was told that because
ferrets are carnivores, they recognize rodents as natural prey, and guinea
pigs are rodents... Hence, Rikki was quite prepared to kill the guinea
pigs, and most certainly would have done so had I not been right there.
 
And just as a note, ferrets recognize iguanas as food also!  My rather
large (thank God) iguana escaped his pen one day, and managed to get to a
window sill right next to the ferret condo.  Being a sunny day, Zephyr
(the iguana) decided to park on the sill to sunbathe...but his tail didn't.
Apparently it must have stuck partway through the bars, because my daughter
heard a thumping noise all the way downstairs coming from our "critter"
room, came flying up the stairs to check, and found Zeph with a bloody
tailtip on the floor (after crashing off the sill), and blood spatters in
Rikki's cage - another meal thwarted!  We had one other narrow escape with
the 2 of them when the iguana was "let out", and Rikki (who really should
have been named Houdini) managed to wedge his body through one of the gates
on his cage (now solved with swivel snaps like on a dog leash).  Another
thumping & crashing, and we discovered Rikki on top of Zephyr hanging on
for dear life!!  After prying him off, and and wiring the cage doors shut,
we discovered Zeph was unhurt, due mainly to his very thick, bumpy skin
on his shoulders and his backbone spikes, which do bend.  Rikki was named
after Rikki Tikki Tavi of Kipling's Jungle Book - the mongoose in the story
somewhat resembling a ferret, and both animals are incredibly curious as
well as fearless.  That certainly applies to ferrets!  The mongoose is used
to kill snakes - I guess Rikki felt he could do no less than to rid our
room of an iguana!
 
As far as guinea pigs recognizing their name, mine do know when I use their
name that I am referring just to that one pig, but unless I'm holding food,
they really won't come when called.  And litterbox training, I don't think,
is going to work because they are pretty active critters.  I've had guinea
pigs a number of different times, and it never worked - I cover the bottom
of the cages with pine shavings and clean at least once a week.
 
Hope this helps!
[Posted in FML issue 3450]