It's January, and it is cold, and you wake up to more snowfall. The roads have already been icy, and a new snowfall won't help the slippery factor. You are grateful for, and expect, the rock salt thrown onto the sidewalks, steps, and roads, to help with traction, and help you keep your balance and tread and you make your way to wherever you need to go. Whenever you think of rock salt, you don't think health hazard, but if you have a dog, then that does need to be a concern.
Rock salt isn't normal salt, and contains special chemicals to help it act the way it does. It definitely works to melt the ice a bit, and it helps you when you're trying to trek across that sheet of pure ice. The chemicals in the rock salt are detrimental. Take your car for example: the rock salt thrown onto the road is often kicked up into your car, and can not only scratch the car, but can also damage and discolor the paint. If it's harmful to cars, then the same principle can apply to dogs as well.
It seems obvious, but just to make sure we're all on the same page here, when dogs walk, they walk on their bare paws; and while their paws are definitely tougher than the soles of our feet, paws aren't indestructible. The rock salt for its texture alone can be harmful to dogs' paws. Just think of you walking barefoot on rock salt, and think about how uncomfortable that would be! Dogs have more crevasses in their feet, and so the rock salt is even more likely to get caught inside, and harm the pad of the foot. And then there is the chemical factor to consider. The chemicals can also damage the paw, and especially after the walk, if your dog licks its paws clean, the chemicals can get inside your dog's system. Rock salt can clearly be established as bad for your dog's paws, and even for your dog's health.
Wipe its paws before it comes inside the house, and if your dog has already licked its rock salted paws, then wipe off their mouths as well. You can also spread a thin covering of petroleum jelly on the pads of their feet before you take them out. This can work to repel some of the harmful rock salt, and just make sure to wipe their paws on a soft towel before coming back into the house.
So, you should still take your dog out for walks in the winter because it still needs fresh air and exercise. However, you should be aware of the dangers on the roads and sidewalks. If you're just aware of the issues, then you can take adequate measures to protect and prevent. Keep your dog safe and healthy, and you and your dog will be left happy!