I never once implied or said the OP would harm her dogs. I simply commented that I personally disagree and hate when professionals encourage people to exercise dogs specifically on concrete instead of trimming or dremeling nails. IMO, it is not worth the damage that could be done, and I just truly hate when professionals encourage it. That was the vice I had. I never said anythign insulting, nor would I, to the OP. I was only trying to offer helpful advice as the rest have done, as well as warn that exercising on on concrete alone without trimming or dremeling is probably not the best choice. It is a long process, and it can be scary to think you might accidentally cut your dog, but regular trimming or dremeling is absolutely necessary when the nails become too long. Trust me.. it took over 2 months to get my brother's dog's nails back to an okay length. They were to the point they were curling underneath the pad, and the quicks were very, very long. I had to visit twice a week to trim them regularly (our dremel broke), and there was once or twice in those many times I knicked it enough that a small dot of blood would show. The dogs certainly didn't like it, but I knew it was necessary.
The only other option I'm personally aware of is that when the dogs go under for teeth cleaning, if their nails are long, black and hard to trim, I ask the techs to do it while the dog is under. If they do have to cut the quick to get them back to appropriate length, the dog is under and won't feel it.
My dogs may just have hard nails, or I am lucky that my animals are not exposed to as much concrete, but I've never had them walking on concrete alone do the trick.
It is to my understanding that there must be excessive amount of exercise done on concrete to actually buffer down the nails. Now, when I say excessive, that certainly can be swayed by the fact that my dogs are likely on concrete a lot less than someone that may live in a city and must walk their dogs on concrete multiple times daily. I also said what I said due to the fact that it is something you hear professionals directing people to do frequently, to exercise more on concrete, and I just feel that is a poor thing for them to do, instead of properly instructing how to maintain good nail length, as I just personally cringe at teh idea of exercising my dogs on concrete any more than necessary.