I've been thinking about this one, and I think I added the equipment tag to a bunch of questions under my theory of "all Pets.SE questions should have at least 2 tags" (which was discussed in chat at some point).
Each question should have a tag relating to the species of animal in the question (dog, cat, rabbit, fish, etc), and a second tag relating to the subject of the question.
For example, leash-training is a popular tag, but leash training dogs is very different in method and popularity from leash training cats or other animals. It's useful to be able to search for both leash-training and cats if I'm training my cat.
I suspect I had a handful of questions with one tag and what they had in common was that they weren't really about a specific type of pet, but about the equipment that was used with them (and that tag already existed).
I'm leaning towards believing that the questions should be tagged with the species that they are applicable to, (even if, with the diabetes blood sugar meter, that's pretty much everything) but I'll open a new question about that.