Does the fact that many non-human animals have pituitary disprove Cartesian Dualism?

[Belacqua]

No, I am not claiming that dogs and cats don't feel pain, I am being critical of that claim. Descartes famously argued that no animal except human beings feel pain. In my opinion, that suggestion was ridiculous back then, and it's even more ridiculous now.

Whether animals with much simpler brains than cats and dogs, such as fishes or insects, can feel pain is another question entirely.

It makes sense to me that animals feel pain. They certainly react as if they do.

The difference is that when animals feel pain they react according to instinct. They yell, or run, or hide, or lick the wound, or whatever they do. 

Humans feel the pain and they also think about it with concepts. So you'll go very quickly through the process of "Ouch, what's that, something's wrong." You might judge that the thing that hurt you shouldn't have done it. Or you'll be angry that you weren't more careful. You might remember another time you were hurt, or you might get morbid thoughts about the fragility of life. You might get pissed off that you have to stop and take the day off due to migraine, and then life seems unfair. 

So when people feel pain -- or have some other bad physical thing going on -- they don't just feel that thing. They also have lots of accompanying thoughts. These thoughts could be for the better (e.g. "I'd better get this thing checked out"). Or they might make things more depressing (e.g. "Why did God do this to me?").