Yes, I wanted to talk about dogs in an RPG, particularly fantasy, environment. I didn't think that the subject had been adequately and accurately covered already and I still don't. I thought I would get answers, critiques, accounts of reader's own experiences without specifically asking for them and I have. Several people have responded by talking about dogs and I find that helpful, even when we disagree. ...
I have played PCs with dogs, and have run games where PCs have had dogs. But I don't play D&D (I tend to play GURPS or TFT) so my context is different. In general I have seen no particularly problematic issues with dogs in those games, as the games tend to be about playing out situations with logical mechanics, so as long as there isn't a problematic gap in how to do that between player and GM, things are fine. The potential issues I've seen have mostly been mentioned:
* In an abstract combat system, how the dog is handled may be an issue for realism/balance. In TFT & GURPS, it's unlikely to be an issue because there are reasonable stats for dogs, wolves, dire wolves, etc., so almost any dog is going to stay where it belongs in stats if the GM knows what he's doing at all, and/or follows those stats.
* If a player wants their dog to be super-canine like Lassie or Rin Tin Tin, they may get disappointed if the GM doesn't want to indulge that.
* If a player wants their dog to be more formidable than a dog in combat, or not to be vulnerable and likely quickly killed in combat with groups of men with weapons, or monsters etc., they may be disappointed when they get killed. To me that's a feature, not a problem. As a player, I have tended to keep the risk to my dogs in mind and try to keep them out of the more dangerous situations. I also accept that the dog's liable to get killed sooner or later unless I leave it behind a lot.
* As with other animals in an adventuring party, there can be some issues of attachment and dangerous situations and how to handle them, which can either be interesting or annoying to different players. i.e. Keeping them alive may mean keeping them out of certain situations, which means making arrangements to split from them, etc.
* What you wrote about dog senses and behavior and the skill of training dogs and the skills of dogs is all a natural fit for GURPS. There are rules for their senses and skills and carrying capacity and so on. I am not aware of a great article going into detail on dogs (there is one for horses), but there may be one I don't know of. In the games I've played, the dogs who survive tend to get some detailed attention but the GM and player usually just collaborate on how that goes.