Honestly, ever since Trump won the GOP presidential nomination in '16, so much everything on the news I've heard has been kind of a "Oh... Well, I guess that's a thing now" that I just don't question the craziest stories the same way I might have otherwise.

When this first circulated back a little while ago, my first thought was "Sheez guys... We have, what, a very, very small handful of schools that are putting in litterboxes, and as we haven't heard anything from the students or teachers themselves, I guess folks in those classrooms are for whatever reason fine with this kinda thing... Can we like move on to something a little more relevant now?". Didn't even think to fact-check if it was actually happening or not with the way everyone was going on about it until like ...just now, I think.

I'm both quite relieved it was a hoax, while being even more disappointed with conservatives (sadly, they have quite the track record of disappoints) that so many of them let such a farce go this far. If you're going to open your mouth and say something, and you're going to say it loudly to a lot of people, you really should know what the heck you're talking about.

That does change things a bit, but only marginally so. You obviously aren't going to be able to create a new dovetail joint, unless you have a lot of time and patience and also get a jigsaw. A better route to go would be just buying some wood screws, and drilling pilot holes and running screws through some of the teeth of the back board into the edges of the drawer. Make sure you account for the board sticking out the back instead of being flush with your edge boards in your measurements.

Other thing you could do is just pick up a new board to use as the back instead of one with teeth in it, but the teeth shouldn't give a problem.

Sure! If I were you, I'd pick up a circular saw, pop off the back of the drawer, cut the drawer down to size at the rear now that it doesn't have the back installed, and reinstall the back onto the now shortened drawer.

You may also need screwdrivers for removing the back, or if it was nailed a crowbar or hammer with a claw on it for prying it open.

Definitely drill pilot holes into the drawer edges before you try screwing the back of the drawer back onto the shortened drawer. You can drill pilot holes with a rotary drill and some drill bits.