My Crazy cat...what on Earth Is Going On?!?!?

I have worked with animals hospitals and vet clinics and acting out can be a common behavior. Older cats (she would be considered a senior due to her age) can become aggressive or terratorial if they have a sickness, or pain, perhaps from arthritis, diabetes or thyroid issues. Or, it could be as simple as the heat being out. A senior cat bloodwork lab may provide some insight.

Keep track of odd behaviors, if she is having trouble going to the bathroom, witholding pee, or peeing very frequently, not eating/drinking or over eating and being constantly thirsty... it could help you find a pattern to see what is going on.

is she defending something? Is he trying to get too close to someone she considers "hers" like you or the baby?

Second or third or whatever vote for a trip to the vet. Kitties often act strangely when they aren't feeling well and especially at her age it's worth getting checked out. It might even be worth getting him checked out, perhaps HE has an underlying health issue that your female cat can sense and doesn't want around. If neither of those options turn up any answers then maybe they need a bit more space. This can be as simple as adding more vertical space in your home - a shelf or what have you for hanging out on etc - or as dramatic as having separate litter boxes as well as separate places for each cat to eat and sleep.

It's definitely not the heat. Cats are perfectly comfortable in the heat and actually prefer it. Their fur keeps them cool.

My cat doesn't have another one to push around, but he does get very vocal and starts running around like crazy when he gets constipated. One other time he did the same thing with a urinary tract infection.

Just keep an eye on it and see a vet if there's no improvement.

Offer them both bowls of ice cubes. It will be something totally new, they'll each have their own, and they will be so busy experimenting with the ice they hopefully won't notice they're in the same room together. Having repair folks in the house is certainly going to be upsetting to both cats so be sure to keep them out of the foot traffic and noise with plenty of resources. If she's having trouble using the cat box she's probably trying to make sure he's nowhere near it to pester her during her lengthy attempts. An extra cat box might be in order too. If things persist a UTI might be causing her distress and agitation poor girl :<

Maybe she is going through a mid life crisis..lol .I cannot imagine what it causing it unless she is not well and he is just who she has decided to take her illness out on!!! Is she eating regularly?? Drinking normal amounts of water?? Does she have diarrhea or is she constipated? Anytime behavior changes like this, it is a good idea to just keep an eye on them and see if something else develops. She is getting to be a pretty mature cat...so it could be a host of issues that goes along with cats as they age.
Good luck!!

haha cats are ridiculous sometimes! we have a cat who insists on smacking our dog in the face no matter what- every chance he gets. sometimes i think cats have to establish dominance even though they've had another animal friend for a long time. maybe it is just the heat....hopefully it is :) it could also be what sara b said- she could be protecting whats "hers"...or she could just be losing her mind! good luck!

It would be good to get her checked out by a vet and have some bloodwork done. Hyperthyroidism can cause agitation and vocalizing at night, for example.

My parents cat flips out when she gets a little constipated or when her anal glands get full. Like crazy howling, hissing, running around.

Have you noticed plenty of poop in the box? Could be that the heat has dehydrated her a bit?

That's all I've got. She seems a bit young and it seems too quick of an onset for feline dementia.

You can always call your vet and see what they think. It is probably worth checking it out especially since the yowling in the middle of the night may be some kind of distress. We saw some odd behavior when our cat had a urinary tract infection and much later when she had kidney disease. (The kidney disease eventually killed her but she was 21 by then and had lived with it a while.)

Our cat was not bothered that much by our babies until they were mobile and able to hit or bother her. In the past we had cats not get along after one went out to the vet and came back smelling different (even though they were mother and daughter!). I believe there are ways to reintroduce them slowly but you may need to keep them separated for a while until you sort out the problem. I can't give you details but I think some online research may help there. We had friends with 2 cats that got along and then they got a 3rd cat. None of the 3 cats got along and after cat #3 went to a new home the first 2 continued to not get along. It seems like any new thing can throw things off.