I have a wonderful yellow Lab, Hoover*, who is just a couple days shy of 18 months. Luckily, he is mine for life. We are trainees with our local canine search and rescue group, and hope to be fully qualified as a search team within the next year. I’ve wanted to do this for a long time because I really enjoy training dogs, and I’d like my dog-training hobby to have some useful application.
We’re also a foster family for Golden Retriever Rescue of Fairbanks. If you go to http://www.grrf.org/ and scroll down a bit you can see ‘‘Sable 2,’’ our current foster – an incredibly sweet and easy Lab mix puppy. ‘‘Buddy 9,’’ our foster before that, is farther down the page and is officially adopted now, as are many previous foster dogs. As a foster family, we provide love and whatever training is needed for the time we have the dog – anywhere from a few days to a couple months. For some dogs, we are definitely a doggie-manners boot camp; others just need to know they are loved as they await the right permanent home. Hoover loves the company, and it keeps him accustomed to getting along with other dogs, which is important for his future career as a search dog.
As for why Labs are popular as guide dogs for the blind, helper dogs for disabled folks in wheelchairs, and other service areas: Labs are typically very friendly to strangers, neither aggressive nor shy, and not particularly bothered by loud noises (a car backfiring isn’t much different than a gunshot, which a Lab easily learns to tolerate), so they adapt well to accompanying humans in daily life, even in cities. Retrievers were bred to work closely with a human, so they are much easier to train than breeds which were developed for jobs where they work more independently. Retrievers also have to wait long periods of time in duck blinds, so working, then waiting quietly under a chair, then working again is not too difficult a stretch for them. They have plenty of stamina for long days with lots of walking, but are also laid back enough to tolerate the waiting periods. They are a convenient size, neither too short nor too tall. Labs also require a minimum of grooming. (That’s something I’m really appreciating now, after having golden retrievers for 30 years before ending up with a Lab this time around. Those feathers were beautiful, but I LOVE not having to keep them unmatted and free of sticker-bush branches and burrs.) Golden retrievers are also popular as guide dogs; the two breeds are very similar in temperament and trainability. German shepherds used to be the standard guide dog breed; they may have lost favor partly because their typical life span is now a couple years less than that of Labs or goldens, an important consideration for a dog which requires so much training before starting his/her career.
Why not border collies? I’d guess it’s because the typical border collie is much more intense than a typical Lab, more likely to be nervous and flustered by commotion, and more likely to nip (it’s a herding instinct). They vary in size, but most are a little too short to be a comfortable height to guide an adult. (Maybe that could be fixed by a longer handle on the harness, though?) Or maybe the trainers just don’t like being fixed with the Border Collie STARE. 
Border collies do certainly have the brains and the trainability. They are known throughout the dog-training community as a breed that definitely needs a job to keep their very able minds occupied.
Before anyone gets upset, YES, these are generalizations. Not every Lab has the temperament to make a good guide dog, and not every border collie is high strung. Dogs are individuals, BUT a large part of dog temperament is genetic, so there is a ‘‘typical’’ personality for each breed even though individuals will vary. (Guide dog schools typically run their own breeding programs because the success rates are much higher when the puppies have been bred with the purpose of perpetuating the particular traits that are desired.) The type of Lab best suited for guide work is a bit more laid-back than the type that wins field trials. (A German shepherd trainer whom I know through Search and Rescue training told me her favorite way to get a new SAR dog is to find a shepherd who has washed out of guide dog training due to having ‘‘too much drive.’’)
*Anyone who wonders about the name ‘‘Hoover’’ has never seen a Labrador retriever eat. 
I also hoped that he’d turn out to have a nose like a vacuum for scent work, and he IS doing really well. He loves to use his nose.
