The difference, traditionally, between sentient and not-fully-sentient in cartoons has been whether or not they talk. Mind, I’m not saying C.S. Lewis was inspired by this for The Chronicles of Narnia, but it seems to humans to be a pretty important difference. See also all the attempts to figure out how far in the past humans have talked and the attempts to get our ape cousins to talk or use sign language. However, it is also true that certain cartoon animals have long straddled that border by not talking yet routinely being shown as having just as much agency as the others. Pluto is probably the most notable of those.
As usual in shorts where Pluto is about to be horribly abused, we start with Mickey’s being pleasant and affectionate. He’s building a doghouse for Pluto when a very large (yet not, if we’re being honest, large enough) box is dropped off. It has been sent from Australia and contains a boxing kangaroo. Mickey shows an immediate and previously unknown interest in boxing and wants to start punching the kangaroo. Pluto is less into it, especially when the kangaroo turns out to be female and have a child in her pouch; Mickey suggests that Pluto fight the joey.
Now, we don’t need to be told that Pluto is not thrilled with this idea. However, we are. By Pluto. In this short, he is voiced by the ubiquitous Pinto Colvig, and it’s weird. Not just because he talks but because he makes asides to the camera. This is, frankly, what the assorted people involved behind the scenes in making the animated Peanuts decided not to do with Snoopy, who does think in words in the strip. It’s creepy when Pluto leers into the camera and mutters things.
I do not understand the concept of boxing kangaroos. Do kangaroos box in the wild? I don’t know—I would if either of my kids had gone through a kangaroo stage, I’m sure, but they haven’t. Blessedly we don’t seem to do this anymore, just as dancing bears seem to have stopped being a thing, but in the case of kangaroos, it feels as though the process was “1. Discover kangaroos exist. 2. Immediately start making them box.” Just why?
This was Disney’s last black and white short. The overlap between colour and B&W is such that it’s a lot vaguer than the transition to sound—once sound came in, that was it, but that’s not the case with colour. The overlap as a serious chunk of the market would continue for roughly three more decades from this point. This is very much Scamp Mickey era, which is fine; better Scamp Mickey than Donald Duck, Aquatic Sociopath. I shudder to think what Donald would do with a boxing kangaroo.