Animals seem to have little (no) ability to imagine or reminisce, that is, "mental time travel". As far as we know, they won't regret nor hope. (Many may recall or anticipate.) Therefore, many aspects of emotion that we are familiar with are simply unavailable. We dwell an awful lot in the past and in the future!
While it is probably impossible to know (or even describe?) how animals feel, I am convinced that there are certain limitations to the range and depths that are reasonable to assume.
One way to talk about this is to distinguish between affect and feeling / emotion. I think that will make things a bit clearer. Affect being a hard-wired "biological" mechanism.