[minnesota_bound]

Cats have diseases that cause people to go insane.
https://www.theatlantic.com/magazine/archive/2012/03/how-your-cat-is-making-you-crazy/308873/

A parasite found in cat feces has been linked with psychosis, schizophrenia, and bipolar disease. ... But some people, men and women, can go from obsession to madness.
https://www.mdlinx.com/internal-medicine/article/2612

[Magnum44]

[LongWayHome]

Thanks for those links.

[MarMema]

I think you nailed it.