For a photo to be considered kitty-porn it must be obviously sexual- like some sort of sexual act or close-ups of genitals and nothing else.
Are you sure? Look at the kitty-porn web site: http://www.kittyporn.org
It doesn't look that way to me.
For those of you who aren't sure they are willing to click on the link, I think that this site was developed to make fun of filtering software. You can also look at it as a parody on porn sites. In any case, you can keep all the pictures from it on your computer that you want, and the most you can be accused of is liking cats. Not even you cat will think that they are porn--well, maybe a few of them if you have a really nutty RRR cat.