The tagging situation for the foo dog, or Chinese guardian lion, is messy right now; it currently is implied by three separate variations, the komainu, shisa dog, and shishi dog. All of these are different things, but the border between them - especially between Komainu and Shishi - can be very fuzzy, and they often mean different things in different places - Japanese people will call the actual Chinese guardian lion statues Komainu, for example.
In Japan, they were paired and did look different... but over time they've grown to look virtually identical, often differentiated only by one having its mouth open and one having its mouth closed. Both shishi and komainu are often just called komainu now as a result. Shisa are specifically the Okinawan variation, which can be more distinct... but plenty are only tagged with Foo dog and not all of them are so obvious. The wiki for foo dog also links to the same image twice, which only has one foo dog in it, to differentiate between different possible appearances...
I'm kind of leaning towards the solution being aliasing them all together under one tag, possibly just 'Guardian lion' or 'Guardian lion dog'; this situation is confusing and difficult to navigate, and I don't think most users can be expected to know the difference and tag them appropriately - in part because there often is no difference. This is reflected by the fact that the entry for the Shishi dog (which aren't dogs, they're definitionally lions, that's what shishi means) is actually describing a Shisa dog, and there are possible Shisa in the Shishi tag and vice versa. The biggest issue is that many of the artists drawing them don't know the difference and will call them whatever they want.
Updated