Here we have a disturbing piece musing on the omnipresent theme of death. Portrayed is a deceased kitten, stuffed, wearing the clothes of a human being and staring forward ceaselessly with glass eyes, a toy mouse held in it's paw. What can this mean?

Obviously, the cat is dead. That much is evident. Therefore, I take the cat to represent death. The fact that the cat is stuffed and rigidly assigned to a position makes me think that the OP is making a statement about rigid, static perception of death. Note that the dead animal is not even stuffed in a position it could take while alive. Supporting this point is how the dead cat is dressed: death cannot be allowed to simply be, instead, it must be molded into a shape we are comfortable with and dressed up as something else. It's obvious. The OP is mocking religious perceptions of the existence of the afterlife. In the immortal words of the hivemind, "SO BRAVE."

But I digress. Returning to the piece, at the center of the image are the glass eyes. The animal's real eyes within the context of the piece do not exist. Instead, we have glass eyes, unseeing facades, lies -- and they are affixed to the cat, which is to say, death. This demonstrates the irreligion of the OP, and his mockery of the idea that the dead are watching us.

This is all pretty basic stuff, but in order to discern the symbolic meaning of the toy mouse we must go deeper. Perhaps it represents something relevant to the OP's individual perception of death? Perhaps it means that the OP has a weird fetish for mice, a secret that shall die with him? Perhaps the mouse is simply part of the aforementioned abstract symbolism of the costume as a whole? I think the answer may be seen in the fact that the item is a MOUSE, being held by a cat. What do cats do? They chase mice. The mouse is the goal. The mouse, here, therefore, represents purpose in life. Notice that it is a toy. It is fake. It, like the set of glass eyes before it, is a lie. OP is making a subtle remark on how meaningless life is. It is being held by the costumed version of death, which of course suggests that meaning given to life by some notion of an afterlife to follow death is futile, and that meaning cannot be found there.

TLDR: OP subscribes to an atheistic school of existentialist thought, and this picture is an attack on religious perception of death.

Edit: Grammar.