I thought I'd throw this out there and see what you guys think.
My mother has a border collie mix (we think) named Gypsy. She was found wandering around a small town here in Arkansas after a tornado and they never found her owners. She's probably 8 years old or so, and has a luxating patella and is definitely a lap dog-- not a very active dog at all. Even when I take her to a field to run around, take her to play with other dogs, she stays pretty close to us. When we adopted her, the woman at the rescue told us that she had recently been walked by an elderly man with a cane and she was perfectly behaved. We found her at an adoption event, totally calm, not at all concerned with the people walking by.
My mother has MS and her balance is not great. She walks with a cane, so this dog seemed to be the perfect temperament and speed for her-- older, chill, not very active. My father passed away a few years ago, my sister moved out to college, and my mother's springer spaniel died of lymphoma last summer. Mom needed a companion, so she brought Gypsy home and this dog has been absolutely perfect. They adore each other, Gypsy stays out of the trash, food, never has had an accident in the house, gets along with every other dog she's met and loves the people who come to my mom's house. She's a bit of a jumper, but I work on that every time I go over there. My mother also has excellent vocal control over her-- like most other BCs that I've met, it seems eerily like she understands English. She was definitely a family dog.
Now that she's comfortable with us, she gets very very very excited to see a leash and even more excited to go out on one. For potty breaks, and for general outside time, my mother doesn't leash her. I'm not thrilled about that, but that dog stops on a dime with one word from my mom, the neighbors know her, and my mother knows the other dogs in the area (it's pretty communal that way). So I don't worry too much about her. However, if my mother wants to take her anywhere outside the immediate vicinity, to walk around the neighborhood or go to the store, Gypsy pulls on the leash. If I'm walking at normal person speed, she's pretty ok after a couple of minutes. But when my mother goes at "unsure balance" speed, I'm afraid Gypsy's going to pull her down.
I know the key to this is loose leash training or an attention heel. I work with her when I can, and my sister tries to when she's home from college. I also think, like River, she'd get a ton better with constant, regular exposure so that the walk is no big deal.
Here's what I'm wondering. Is this a case where a flexi-lead might not be a terrible thing? Gypsy isn't a bolter, and doesn't seem to pull because it's the end of the leash, but because she walks at a more normal pace. The flexi would allow my mother to get down the stairs and start walking without Gypsy pulling her down. As Gypsy gets too far ahead, she's easy to call back. My mother is not great at training, but she wants to better-- it's just too hard for her to do it while Gypsy is pulling her. I just want my mother to be able to comply with leash laws, and take her dog out to places without being pulled down. The street isn't busy, and Gypsy stays out of it. I'm also getting her a sporn harness; she has an Easy Walk, but you don't have much leverage with that.
I'm not sure if using a flexi would just mean an increased chance of injury or if it would help. Again, I know that training is the real answer here, but I'm trying to work out solutions in the meantime as well as something to use concurrently.
"In these bodies, we will live; in these bodies we will die.
Where you invest your love, you invest your life." --Marcus Mumford