I don't know if animals are happier in general, so much as they simply are. Mostly, they live in the moment, it seems to me. Some are probably happier than others, by human standards—domesticated cats and dogs with good owners/people, for instance.
I haven't spent much time contemplating the thought, I suppose. It's an interesting question—thanks for asking!
Thank you for your input, Tessara! I've seen that whenever we cover a worry and solve the problem, we have new worries. The poor worry about not having something to eat and the rich worry about who knows what, but they worry, I'm sure, I'm not just comforting myself. Lol.
Perhaps as domesticated animals have no worries of being chased by tigers, they have worries about food and strangers passing by, their owners leaving them alone when they go to work, etc.