So far (almost 5 years), I've had no problems with dog toenails and silnylon tent floor. I do keep my dog's toenails clipped as short as possible and clip them every 10-14 days (frequent clipping makes the "quick" recede so you can cut them shorter). I'm more concerned about the dreaded Labrador tail-wag when he wakes up in the mornings, which I keep thinking is going to rip the tent apart! It hasn't yet, which is a tribute to Tarptent (former tent) and to Six Moon Designs (current tent).

As for dirt, I comb my dog (there's a small pocket comb in his pack) at bedtime. He loves it; it prevents his bringing any creepy-crawlies into the tent; and it keeps a lot of loose dog hair out of the tent. I also keep a small size packtowel in my dog's pack in case he's wet. My dog is part of my sleeping system to keep me warm! If he should get really muddy at bedtime (something I work hard to prevent--he's normally leashed in camp), he would be sleeping outside well away from me, whether I'm under a tent or tarp!