My cats love spinach almost as much as cat treats, is it okay for them to eat it?
http://petplace.netscape.com/articles/artShow.asp?artID=1764 says:
Here is another similar article:
http://petplace.netscape.com/Articles/artShow.asp?artID=232
My Schnurri likes to eat vegetables once in a while. He’s eaten green beans and lettuce and some others, and it seems fine. I think the best tip from those articles is to plant some grass for your cat… She’ll get her fill of greens and you won’t have to give her spinach.
I didn’t find spinach here, but there are several plants that aren’t toxic to cats. There is also a page on the site of the 50000 plants that are toxic to cats.
http://www.cfainc.org/articles/plants-non-toxic.html
My cat has eaten some of the toxic things(dalpheniums for sure) and puked them out soon after. I think if your cat is eating the spinach and not puking, there isn’t any harm in it.