Not bad, but...
...not very entertaining either. I don't think this is bad enough to get blammed, but it's not really something out of the ordinary either. At best it reminds me of the Steven Seagal show pt. 1 (removed from NG by request of the author, I think), where Seagal accidentally punches an old man through the head and then spends the whole day with the corpse stuck around his arm. This is short, it's not excessive enough in violence to be funny, and while I guess you intended a surprise in the ending when the cat's still stuck to the guy's arm, it's very predictable.
If you want to redo this, I'd recommend you make it somewhat longer, and add a real build-up in violence from the guy trying to get the cat off his arm - starting with hitting it, maybe pulling it, and then just snapping to different scenes where he does increasingly crazy stuff to get rid of the cat. Right now, he just shoots it in the head. That pretty much establishes straight off the bat that he's not going to get the cat off his arm, if it can survive a gunshot to the head. I think there's two directions you can go with the ending, and eitherway it should be longer; 1) the character goes on with his life and spends the rest of it with the cat on his arm (you could show stuff like graduation, his wedding, a desk job, children or grandchildren who also have cats stuck on their arms - nonsensical, but funny), or 2) he gives up on trying to remove the cat from his arm, and something stupidly funny happens so the cat lets go after all. Just some personal brainstorms.
Your work isn't bad, but maybe a little unimaginative.