They're also frequently much more emphatic than people I mostly work with as a programmer. ;-)
No, really: I own two cats now, and I grew up with dogs, cats, horses and goats around and it led me to believe that animals generally do dream, do have emotions and are generally able to understand or feel emotions of others. They also do think, they do try to predict the future, and they do learn on their own, sometimes frighteningly quickly.
But it's convenient to believe otherwise and even people who should know better tend to forget about it during the meals. Just try to imagine how eating a burger would feel with a thought like: "ok, now I'm eating something that was smarter and more emotional than my 2yo niece".
Behavioural studies in animals are a fascinating field. I can't back it up with citations right now, but I'm pretty sure horses and dogs are not the only animals to read human facial expressions. Chimps, cats, parrots - you name it - if it's been in close contact with humans for any length of time, I wouldn't be surprised if it learnt how to read our emotions.