The Ancient Egyptians created all sort of hybrid gods way before we even engaged in genetic splicing. But all we did with that science was to make genetically-modified tomatoes and the like.
Anyway the long-ago Egyptians worshipped the cat god, Bastet She reigned over the home. She was shielding and motherly. She was also violent, but her nurturing side predominated. So I think we should cut her some slack. Bastet–not to be confused with Bastid, as in “That Bastid took my package off the front porch–generally got depicted as entire cat. Sometimes, though, she was modeled as a woman with a cat’s head. It was kinda like a ancient version of Mr. Potato Head(tm).
The ancient Egyptians also bowed down to Anubis. Anubis had a dog’s head plopped down on a man’s body. Anubis reigned over the dead. That seems rather dreary, but mostly only pharaohs and really rich Egyptians got to enter the afterworld. These rulers and elites brought boat loads of wealth and food with them to Anubis Land. So perhaps the realm of the dead really was a happening place after all.
Bastet and Anubis mostly hid themselves in their divine worlds. Occasionally though, the hurly-burly masses got so involved in their daily lives that they forgot to give the cat god, Bastet, and the half-dog god, Anubis, the required sacrifices and devotion. At these times, Bastet and Anubis manifested themselves to neglectful peasants as if to say, “Yah boo, I reign over you.”
The way-back Egyptians called these manifestations as “Reigning Cats and Dogs.” Over time, the more observation Egyptians noted that these two gods mostly appeared when torrents of rain came down. So over time, “Reigning Cats and Dogs” transformed into “Raining cats and dogs.” Now you know.
– Paul De Lancey, The Comic Chef, Ph.D.