Time for me to geek out on basic economics again. I’ve been on a Top Gear kick and I’m currently watching the North Pole special. Richard is taking a sled dog team to the north pole and Jeremy and James are racing him in a truck (in order to be the first people to drive a car to the North Pole).Their big advantage is that they can drive as hard as they want, whereas Richard is limited by how hard the dogs can go. Hypothetically he could push them harder and get their faster, but to do so would be cruel. This got me thinking.
The car is what economists call capital, whereas the dogs are labor. Strictly speaking the dogs are capital as well, but due to our enlightened modern ethical precepts we’re morally concerned with their welfare. Remember Planet of the Apes? Those damn, dirty apes had been thought of like chattel slaves, and the folly of that was shown by their taking over the earth. Legally, if your sled dogs won’t run, you can get rid of them. Putting them down might be considered cruelty to animals and thus illegal (I’m not sure), but it would certainly be considered immoral by many westerners. If we think about a labor-capital continuum, dogs are closer to the labor side than cattle, and a car is all the way over at capital.
So capital has a different moral standing than labor (or “quasi-labor” like dogs), but does that mean there’s no possibility of cruelty?Running the truck into the side of a glacier won’t make an engineer cry, but it would create work for a mechanic and wrecker operator (assuming they decide to recover it). “But wait,” you say, “jobs are awesome! JOBS!”
But I put it to you: jobs aren’t good. If they don’t pay the mechanic, then they’re making him (or her) suffer. To make someone work is to be cruel. But in the real world nobody makes mechanics do their work, people induce them to do that work by making it worth their time. Mutually advantageous trade is beautiful and kind. (Okay, that’s only certain with euvoluntary exchange).
Oh! And an I, Pencil moment: The truck made it to the north pole, allowing two middle aged, out of shape men, to make a journey that otherwise probably would have killed them. Through gains from trade, and capital that both represented and applied embedded knowledge, in order to reach a destination that has been visited by no more than a few dozen humans.
Notes On Liberty 
I really like this post but I have to disagree. The dogs are still capital. Some people may have moral qualms about using them in certain ways but they remain capital. Labor is essentially a rental agreement. I agree to exchange 8 hours of my day for X dollars and at the end of the day I get to leave. The dogs, as property, have no such luxury. They cannot go home early, they do not get days off, they cannot alter or change their agreement. They exist to be used as their owner sees fit. This may seem harsh but it is simply reality.
The “enlightened modern ethical precepts” you mention are purely subjective and a vast majority of the living human population of the world would not bat an eye at being cruel to these “Sled dogs” anymore than most westerners would bat an eye at eating a hamburger.