This really is the right answer. We dont actually know. We can attempt to translate behaviours and biological mechanisms we know from humans to animals but in the end we cant ask them so we dont know.
If emotions are defined as hormonal responses then we could say "yes", but that would reduce human complexity to basic chemistry which is too simplistic.
Well, they also have very obvious and complex behavioral responses, as well as similar brain activation to humans. It's extremely likely that animals experience emotions.
Sure, we don't really know, but then we're getting into the 'philosophical zombie' question.