Man's best animated friends

Recently we've started watching the kid's show WorldWord with PeanutBuddy and My Little Princess. Essentially everything in the show is made up of the letters that spell whatever it is. Like many cartoons, especially kid's shows, the main characters are all animals. Pig, Sheep, Bear, Ant, Duck, Frog and Dog all have great adventures spelling words to create the items they need. It's Dog that triggered the thought process that led to this theory.
Unlike the other characters, Dog isn't anthropomorphized. The other characters walk around on two legs, speak English and behave much like a person would. (Frog hops, but also plays piano). Dong on the other hand walks on all four legs, like a real dog, and while he shows more intelligence than an average dog communicates only with whines, yips, barks and body language. It occurred to me that the amount of anthropomorphization of dogs in cartoons varies widely, but they are often less anthromorphized less than other animals.
Nearly Human:
Nearly human dogs speak English, occasionaly wear clothes, walk upright and interact with human society as equals. In some cases they occasionally slip into more conventional dog mode, but usually that's for effect rather than a part of their usual behavior. Examples of this include Brian Griffen from Family Guy. Brian is a full member of the family, drives a car, dates human women and writes for the NewYorker. He also asks "Whose leg do I have to hump to get a drink around here?" and barks when it's appropriate. The other two examples of this are more interesting because they provide a contrast to other dogs in their own shows. Goofey and Scrappy Doo are both dogs who behave like humans in a world where other dogs are kept as pets. The dogs in this category are dogs because the conventions of the show require it, but they are essentially humans in a furry suit.
More than a mere beast
These dogs act with human emotion and intelligence, but usually walk on all four legs, and communicate in near human language. Scooby Doo, for example, shows fear, gluttony, and a sense of humor, but he usually walks on all four legs and ruh ro Raggy is almost Uh oh Shaggy. These dogs are closer to hybrids - wolfmen - than the other types.
Genius Dog
These are dogs who are esentially dogs with just a little bit more going for them. They communicate and behave like a normal dog, but with more human like emotions and motivations. Pluto, Dog (from WordWorld), and Santa's Little Helper all fall into this category. They are more than just animals, but they are far from human or even hybrid.

I'm not sure if there's a significance to this observation, or if there's even a theory that I can build from this. The level of anthropomorphization in any given cartoon may relate to how the society that creates the show feels about those traits that are typically canine. (Loyalty, bravery, obedience etc). Or maybe it's related to our familiarty to canines and wanting them to remain as pets and not be anthropormorphized like other animals.