Jaime - first your are right.  A rat terrier, and/or manchester terrier
and ferrets are not likely to be a good mix.  There are always that 1 in a
thousand exception where the dog seems to have been totally passed by for
its genetic hunting heritage but when your betting on your ferrets live I
think the odds are too long for me.
 
I would stay away from all if not most terriers.  You can generally divide
dogs into groups.
 
Terriers, Sporting, Working, Toy, Herding and Hounds (sight and scent, 2
different things), Miscellaneous.
 
Some dogs their breeding has diverged, with some people not breeding for
hunting ability and others breeding specifically for it.  Also some breeds
are bred to do things independently, others to work with people - will to
please helps a lot.
 
Labs - #1 dog for like 10 years are generally these days bred for pets -
however you need to watch out for dogs that seem to have a high hunt drive
(hard to do at a shelter I know).  High activity level, high ball drive,
high chase drive are indicators but could also just be a hyper dog.  In
the sporting group I would think Lab and Golden Retriever and those mixes
would be a good choice.  Maybe a spaniel or spaniel mix.  Most pointers I
think still are used a lot for hunting - not only that but their style of
hunting is sort of independent.  I wouldn't trust a sighthound - they are
bred to key in on movement.  Neither would I try any of the coonhounds.
Sometimes I wonder if a laid back basset or laid back beagle might work.
Working breeds like Rotts, Dobes and German Shepards can be very trainable
and could work.  I'd stay far far away from any Husky or Malamute's or
mixes, great family dogs but very very independent and high prey drives =
bad combination.  That actually describes a lot of dachshunds too.  Some
of the toys might work (not ones with terrier backgrounds) - look for
confident outgoing toys - not scared shivery ones.  Pugs are great at
this.  I couldn't stand the snorting and snoring but they generally have
great happy devil may care attitudes and generally just want to play and
play.  Poodles are pretty smart, with them its a personality thing I
think.  Herding breeds are highly trainable, but herding drive is just
controlled prey drive so those individual dogs with a high herding drive
may not work.  I have an Aust Shepard.  Collies, that good ol Lassie stand
by would be a good bet.  Aust Cattle dogs are a little independent and
tough.
 
Generally look for will to please and trainability - this can compensate
for a lot.  A dog that gets along with cats is a positive sign but not
definative.  Don't discount an older dog - there personalities are in
place so you know what your getting.  I got my dog at 7.5 - I specifically
looked for a certain personality and checked him out with a ferret first.
My dog is very very good - and I never ever NEVER leave them alone
together.  Everybody is out while I sleep but I'm a light sleeper and
wake up if the dog starts moving around.
 
Mary
"Animals are not brethren, they are not underlings; they are other
nations, caught with ourselves in the net of life and time,"
   Henry Beston
[Posted in FML issue 3607]