Going in is a check for cancers and STDs. STDs because they can lead to cancers. Like HPV. Herpes is another one. Both can be carried around asymptomaticly. Men, more so, with HPV. There’s a threat to both health and fertility here, hence the concern.
By the numbers, less sex, less gyn visits are necessary. Post menopausal? You go only if you notice a problem.
So you have a cat. She’s spayed, lives with another spayed cat, and both are indoors only. Even as a human she wouldn’t be making those visits. That and preserving cat fertility isn’t a big concern.