In my youth (USA 60s/ 70s) girls and women considered homely were called “dogs.”
(Conversely girls and women considered comely were called “foxes.”)
I think the ancient origin of the derogatory use of the word, which is in the Koran and also the Bible, stems from the role of dogs in those societies – a role they still play in undeveloped areas all over the world. Often called “pariah dogs” these days, they exist as commensal animals with human tribes and villages, and live on offal, human and animal feces, and other garbage. They are not fed nor are they pets in any way. In hunter-gatherer cultures they might accompany the hunters and make themselves useful tracking, flushing, driving, and baying up game. The late Ray Coppinger posited that these pariah dogs are the original dogs, who “domesticated themselves” from wolf stock.
The job of sanitation worker is one that carries quite an onus in the ancient world, whether human, avian, or canine.
Dogs are also considered servile, so calling someone a dog indicates that they are lowly, desperately loyal creatures.
As the King’s dog’s collar was supposedly inscribed:
"I am his Highness’ Dog at Kew. Pray tell me Sir, whose Dog are you?”
I knew this as a child (from a nursery anthology) but I only as an adult realized this is a pointed little epigram upon the inflated toadies and courtiers likely to encounter his highness’ dog at close enough quarters to read his collar. It is by Alexander Pope, who had it inscribed on the collar of one of his bitch Bounce’s puppies, and then presented the pup to Frederick, Prince of Wales.
The punchline I recall is “Maybe you should pet him for a while first…”
I think the insult, like calling someone a child or a woman “catty” is that you are describing their worst qualities. Dogs are seen as servile, unthinkingly obedient, lower than humans, not to mention the hygiene issues etc. - all undesirable qualities; as children are seen as lacking common sense and worldly wisdom, simplistic, and often not polite because they just don’t know. While “catty” implies that like a cat, prone to outbursts where the claws come out and the cat lashes out viciously to scratch whatever it can reach and hurt.
There’s a hierarchy of life, and being equated to something lower on the ladder is generally an insult. But then, context is everything. Calling a loved one “baby” is different than saying they are acting like a baby.
I was visiting Egypt once and we saw a number of temples to Hathor, the Cow Godess with the ears of a cow. I mentioned that in Canada a cow was considered, slow, lazy, stupid, and fat and women would not appreciate being equated with one. The guide said “same here.”
I do not understand if the OP wanted the discussion to be limited to Abrahamic Religions.
Assuming " fairly universally" meant worldwide, - In Indian mythology Dogs have a nuanced status - revered in some stories and not in others. Have read about Dogs in Chinese and Japanese cultures too - but know very little. I know practically nothing about African cultures and dog or Native American cultures. Looking forward to learn more.
No, I didn’t mean to turn the question into any sort of religious question and was merely using Islamic cultures as an example since it seems that being called a dog in their culture is more insulting than most others. But that’s just IMO.
I was surprised to hear the term se ki, literally offspring used on TV because I’d previously only heard the term with gae (dog) presiding it and used as a profane term. Gae se ki is the Korean equivalent of Son of a bitch in English and while both terms could be used in non-profane manner, it rarely is.
As for call someone a dog is insulting, on the other side of the coin of man’s best friend, there are those who view dogs as killers, egg sucking dog, lazy, dog days of summer*, where it’s so hot, dogs will just laze around, also dog tired, food thieves, opportunists and other negative connotations.
*The origin of which has nothing to do with listless dogs:
https://www.nationalgeographic.com/animals/article/150710-dog-days-summer-sirius-star-astronomy-weather-language
At least it isn’t just me this happens to. You post the one true GQ answer that knocks it out of the park and nobody acknowledges it. This is the answer, at least in terms of modern US usage.
The one I remember is, “I wouldn’t try that. That dog would bite you.”