It doesn't really look a very savage dog, this one: the crouched front and raised tail suggest play, not attack. It lies on the threshhold of the House of the Tragic Poet in Pompeii, as it probably did in life. The casts of its cousins, preserved in the volcanic ash, have been found alongside the remains of their masters. Dogs were everywhere in antiquity. Most of them would have been working dog-- guard dogs, ratters, hounds for hunting--but some were indeed kept purely as pets. 'Noisy dogs', Homer calls them, but wrote one of the earliest, and most touching, anecdotes of this interspecies affection with the incident of the dog Argos, who alone recognizes his returning master Odysseus, and dies wagging his tail.
The world of the past was harder on animals than the present age, however. A medieval verse recommends disposing of all dogs at nine years old: 'And when he is commyn to that yere, have hym to the tanner, For the best hownde that ever bikke hade, at 9 yere he is full badde.' One recalls, too, Chaucer's Prioress, where a reluctance to see a pet beaten provokes comment: 'Of smale houndes hadde she hat she fedde/with rosted flessh, or milk and wastel-breed,/but soore wepte she if oon of hem were deed,/or if men smoot it with a yerde smerte/and al was conscience and tendre herte.' The early Muslims were also hard on dogs, considering them unclean animals.
Unclean, of course, they are. A dog encountering something really foul on the ground will either roll in it or eat it, and when you try to remedy their uncleaness with a bath it's like the martyrdom of St. Sebastian: the creature crouches there, eyes cast up to Heaven--'If it be thy will, o Lord!'--while buckets of warm water drench its innocent head. They are messy, proverbially shameless, can be noisy, and never happier than when chasing some small helpless furry thing.
I like dogs. Cats, too, but dogs more, probably because dogs like humans more. An animal behaviourist I once read declared that really they're attached to being fed, not to their owners, but this I found simply annoying. I've seen dogs refuse treats when they fear their owners are about to leave; kennels will tell you that they can go off their food for days, or develop ulcers, waiting for their people to return. They are pack animals, and it makes perfect sense for them to have a strong emotional attachment to other members of their pack. I suppose the commentator wanted to avoid the kind of sentimental anthropomorphizing many people indulge in, but I think he fell into the opposite error. A dog is not a 'furry person', and it does not have the same kind of mind and emotions as a human--but that does not mean it has no mind or feelings at all.