Rainsford laughs off the idea that animals have any feelings which need to be considered. This is not surprising; he could hardly enjoy his chosen pass time if he became sentimental about the beasts he was hunting. On the island, he is genuinely horrified to find that Zaroff has carried this attitude to ghastly extremes, rationalizing his actions by dehumanizing his victims, regarding them as being as expendable as the animals he used to hunt. This was written before Hitler's rise to power in the 1930's of course, but reading it now brings to mind the Nazis herding their victims into cattle cars. Thinking of other people- or groups of people- as animals makes it possible to rationalize inhuman treatment of them.
As Rainsford struggles to outwit General Zaroff, his earlier statement is turned on its head, the hunter becoming the hunted.
*I once read that the inventors of the paintball game were inspired by T.M.D.G., but having checked several sites about paintball's origins, find no mention of this, so it may be just rumour and supposition.
*T.M.D.G. has been adapted several times for film; the image at the top of this post is from the 1932 version. This film was actually shot on the same set as 'King Kong', at the same time. It was filmed at night, while Kong shot during the day, and Fay Wray starred in both. How's that for economy?
*In light of current events, this doesn't seem quite as funny as it did before: