Grumpy cat

Do cats get grumpier (like grandpa) when they get older?

Patches is such a little witch nowadays to all the other cats. She hisses at them if they even step one foot inside the same room as her and she'll be across the room on top of the tree.

Heck, even just now, Luna left the room and Patches began growling at the window perch then hopped up on there.

She still hisses at Beauty...she's been doing this since Beauty got back from the animal hospital last October. We foamed shampoo all the cats as a "fresh smell" start, but no change in Patches.

It's very possible. How old is Patches? It could be that she doesn't feel well. Have you taken her to the vet recently for a check up? It could be that she is getting pain in her joints, or maybe she just doesn't like the "young-uns" messing with her. Maybe their energy is too high for her. I would get her checked out though. The fact that she growled at the window perch. It could have been a "I hate these other cats" kind of growl, or it could have been "darn, I know this is going to hurt" growl.

I would get her checked out just to make sure.

I recently took her last October. After we moved I had heard a "clicking" sound in her front paw.

The vet determined that it wasn't broken, but that she has slight arthritis in one of her hind legs. The clicking sound is from her putting all her weight on the front paws to make up for the pain in the back.
She's been on the Cosequin regimine since and after another checkup the joint had greatly improved.

B thinks that she might be losing sight and her growling is due to that.