[nagdu] Italian greyhound guide dog?

[Tracy Carcione]

I would really be curious how small a dog could work effectively as a
guide.  Could a small, sturdy dog do the job?  Could a 20-pounder manage? 
I've been imagining my hypothetical corgi guide, thinking how, when I put
him under my chair, he'd be *all the way under my chair, without even his
paws sticking out.
I know the old story of how Buddy saved Morris Frank by pulling him up an
embankment away from a runaway carriage, but I can't remember anytime my
dogs have physically pulled me out of danger.  I know they've frequently
pushed or tugged me in the right direction, and I know they've helped me
balance when climbing over a snowdrift.  But I can climb over snowdrifts
without a dog, and some little dogs can pull pretty hard on a leash.  It
would have to be big enough so I wouldn't tromp on it with my big feet,
and long-legged or fast enough to keep up a good pace for a mile or two,
when required. I just wonder.  In the crowded urban spaces I'm usually in,
smaller is better.
Tracy