This quote is taken from the original poster's post: "I'm pretty dog savey, being a dog groomer for four years and vet assistant for two. I'd also say I'm trail savey after hiking the A.T. But with a dog it may be a whole nother experience."
I would argue that this person is well-qualified to take a dog on the trail, having a knowledge of the different breeds, basic veterinary care, and having thru-hiked the AT. That he sought out advice is another sign of his responsible nature. The problem is that he's being dissuaded from attempting the hike with a dog all together, not encouraged to go forward with proper planning and preparation. That is the key, not abandoning the dream. This person just needs to select the right dog and prepare adequately, as you would select the right person to hike with and prepare adequately.
THis is from one of the anti-dog on the trail types posted above: "BEFORE you commit to such an action as wanting to take a dog along on a long hike READ and then RE-READ some of Jack Tarlins's advice on taking a dog while on a thru-hike. He brings up many points most people who are wanting to hike with a dog HAVE NOT considered, from the perspective of the one who wants to take the dog on a thru-hike, to the ones a dog impacts while also on a hike, and from the dog's prospective...."
That bold section betrays poster's anti-dog agenda. It assumes the dog owner has no consideration for others on the trail or in the back country, which is generally untrue in my vast experience. Most dog owners who love their dogs enough to want them with them as much as possible, especially outdoors, are quite concerned with how their dog interacts with others they encounter during their outings. And these type of dog owners almost always consider how the trip will impact the dog's health. We are no more irresponsible or inconsiderate than other people.
But, yes, there are some on this thread who do seem genuinely concerned for the well-beling of the dogs. I did not say "all" betrayed an anti-dog agenda. In any event, I will always advocate for experiencing the wild with a dog or dogs.