Well, my black lab Kazzi will be 7 on November 19th (we just had our 5th anniversary in July,) and last weekend when I went out with my dad and stepmom, she was unable to jump up into my dad's Ford F-150 truck (its rather high off the ground.) She's been reluctant to jump up in it for the last few months, but generally does so after some encouragement. I've put her on a glucosamine supplement for her joints because she doesn't like me grooming her hind end anymore, which is where most of the hair collects. Anyway, after about 5 minutes of encouragement, she put her paws up on the running board, but made no attempt to jump, so I lifted up her hind end and she was able to get in the truck.
Later in the same day she was able to jump up in the truck, albeit reluctantly, and she can get out just find. She can also get up on this little grooming bench my dad made me, but if I try to groom her hind lift leg (I use a furminator and steel comb) she leans away from me, even though I'm not applying much pressure at all. Also, she still plays and runs about, but not like she did when she was younger.
Right now, we don't have to deal with more than one or two steps in a day, which she seems to be fine with (in and out of the house) but I'm concerned that when I finally get a job somewhere it could get worse.
I've thought about calling the Seeing Eye about it, but we don't go many places save for on the weekends (I'm way out in the country, not really anywhere I can go by myself, save walking around the neighborhood) and Kazzi's work is still wonderful, its just these physical problems that seem to be appearing, and I wanted some input from dog users who've been with a "middle aged" dog before, or just input in general.