Why do these apes think we don't feel pain?

Dear George,
I am a very senior lady cat of 19 years young and despite living all these years there is one particular thing (amongst many) about apes that utterly confounds me. Why do so very many apes (including rather too many vets) come out with nonsense statements such as "they don't feel pain like we do" ? All I know is that pain hurts and makes me miserable.
How else can a mammal feel pain? Do apes have sole rights to both the feeling of pain and its alleviation? Where does this crazy ape belief come from? After all, felines and simians are still mammalian and have similar nervous systems.
We cats do show our pain and discomfort albeit with more dignity and less fuss than apes, who can't resist screaming, jabbering and yelling about anything and everything in their strange primate world. I tell my apes when I hurt, I have trained them to be observant, but I really would like to know why so many apes believe that only apes feel pain in a way that deserves attention?
George, where did this insane belief come from?

Kind regards, Angel of Everycat (http://everycat.blogspot.com)

Dear Angel,
Humans are dumb animals - dumb meaning foolish. They are also the most arrogance species in the world. They think they are special and different, forgetting that they are just mammals like us. So because they think this way, they believe we don't feel pain. All living creatures feel pain. As you say, it is just that we deal with pain in a dignified and silent manner, unlike them.
This is particularly important for older cats who may have painful conditions like arthritis. Cats with arthritis may not even limp. The only sign maybe a reluctance to jump on or off the bed. Or just relative immobility in the cat bed. We are so brave and stoic that we suffer without symptoms but a vet has just published a paper suggesting that older cats sometimes need painkillers even though they are not limping. So, hey you human pets reading this, start doing a bit of simple observation and empathy.
You may be interested in the attached illustration of the tree of life. Traditionally, humans show this with humans at the top, on the grounds, they think, that they are top animal. A friend of mine, evolutionary scientist Charles Purrwin, has reorganised this so show the top species. What is it - cats, of course. Purrwin says I can publish this here. You can see the gorilla on the left and a little below, in his proper place well below cats, a sort of stick man - Homo non sapiens.
Yours ever,
George
PS. Lovely green eyes and a very good joke on your subsequent comment, Angel.