Hello, my 15 year old cat Agnes has always been very sweet. I have a second cat that is 18 years old and the two have gotten along very well with one previous exception a few years ago. After the older cat had an overnight stay at the vet, Agnes greeted her back home with hissing, growling and swatting. The older cat just sat there unresponsive until the growls turned to sniffing and other curious behavior and the two were back to being friends after a day or so. Yesterday, Agnes became EXTREMELY aggressive toward the older cat. This was the situation: A lot of electrical work was being done in my apartment - a lot of noisy power tools were ripping out parts of walls and multiple groups of workmen were around. Agnes was starting to get really skittish and I was afraid she was going to run into the midst of things and get hurt, so I put her in the only room with a door - the bathroom. After a few minutes, the older cat also showed signs of getting antsy so I thought it best to put them both out of harm's way. This was a very bad idea. As soon as I stepped into the bathroom holding the older cat, Agnes screeched at her and tried to climb up my body to get at her. It scared the living daylights out of me. I got agnes off my leg and the older cat back out the door and just put the older cat where I could see her until the workmen left. Then I let Agnes out of the bathroom and there was some hissing growling and swatting - which I expected - but after a few minutes she seemed to have calmed down and the two were OK together again. Then 30 minutes later, Agnes went on the attack again - not just hissing and growling but attacking. I want to believe that this is just a fearful reaction to the disruptions in the house and that it will go back to normal in a day or so. There was another outburst in the middle of the night and I had to separate the two cats completely. Right now, the older cat is isolated in the bathroom which I hate to leave her in, but I couldn't leave for work with Agnes still showing signs of belligerance. I thought it best to give Agnes the space to run around the apartment in the hopes that she'll have a chance to calm down. One Footnote. There will be at least one more hour of electrical work going on in the house either today or tomorrow. My plan now, is to give her time and space and see what happens. If she doesn't calm down once the house is back to normal, I'll take her to the vet, but given her advanced age, I'm scared to death that this might be some kind of kitty dementia. Any advice?