Answer:
It has not been proven scientifically yet; as far as science knows we the humans are the only "animals" that cry for reasons of emotion. It could be that animals don't have emotions.
Another answer
Certain animals do have emotions, for instance; cats and dogs do get depressed and won't eat if say their master leave them in a kennel while on vacation or illness. Dogs get happy and wag their tails when they want to play etc. this is an emotion. Otherwise they wouldn't have any personality if they didn't have emotions.