Most [all?] cultures agree. "Dog" is an insult across many languages, which indicates it's lower status. Never heard of "cat" being a standalone insult.
Also, "cathouse" is another name for whorehouse.
Also, see the response about the spanish usage of 'gata'
edit: this is much too serious of a response to this funny of a thread, I should throw some humor in here somewhere ;)
As a side note - I've particularly become interested in the negativity of "dog" after trying to trace the origin of the proverb "The Dogs Bark but the Caravan Moves On", which is pretty common in my language (not common in English). Was surprised to find out it originated in Arabic and found it's way to many other languages.
It can mean, for example, variations on "Don't be so timid", "Stop expressing your fears", and "Take more risks".
Indeed, I have heard "Don't be a bitch" be used in almost the exact same way.
So when you call somebody a 'pussy' for not having the courage to do something that has _nothing_ to do with felines or vaginas. (As most people commonly seem to think). Being a 'pussy' is short for 'pusillanimous', nothing to do with cats at all…
I feel like it's a wash. Dogs have more favorable sentiments expressed about them, and more negative ones, because they have SUCH personalities that it's polarizing.
A cat that has an outgoing personality will often be compared to a dog, conversely, only a meek, quiet dog would be referred to as a cat.
I suppose there could have been cultures where a cat occupied a place in the day-to-day social hierarchy (and not just in a religious sense). But if so that sense has been lost to us. For obvious reasons I wouldn't expect such a relationship to have been anywhere near as pervasive as with dogs.
"You're a dog", is generally a comment about someone doing anything to get what they want, for entrepreneurs this is probably a good thing. I've often heard this used in a respectful way in meaning that even though you bent the rules, you came out on the winning end.