Apostrophe's... and also Japanese

I'm not sure if this post is simply going to make me look crazy, but it seems to me that there is a tendency to use apostrophes to denote a plural in some situations more than others, that I can't quite put my finger on.

For instance, on this page this blogger writes Happy Father's Day, Steve....and Happy Father's Day to all the father's, dad's, papa's and papas-to-be out there! But if you look at her other entries you'd find she uses apostrophes correctly as far as I've noticed. And while I wouldn't really blink at a sign at the market saying "ORANGE'S", I'd think it unusual if someone were to write "I picked up my dog's from the kennel yesterday" or "my kid's don't like swimming". So does the plural apostrophe denote emphasis? The fact that the pluralized noun is part of a list? Does this tendency not actually exist and I am just imagining things? What do you think?

Edit: Stop telling me it's wrong, guys, I wasn't asking if it was correct :|

Also, Japanese question: what would be a good Japanese translation for "Longhorse"? You know, like Longcat, but Longhorse. Nagaiuma? Nagai-uma? Is that a little too stupid? What would you suggest I name an exceptionally long horse? Fwiw here is the horse in question: http://famicase.com/08/softs/21.jpg