Lantern Ring Selection - Sentience Solely Required?

Is sentience a major factor in the selection process of any of the Lantern Corps rings?  This question has been on my mind since reading Dex-starr's origin story.  The cat is from Earth and appears to be a normal, average Earth cat until he is taken by the ring, doles out 'justice' to the murderers, and is show having thought balloons.  So, do power rings make selections based on sentience alone or does the candidate have to be intelligent, self-aware, and able to reason?  I like Dex-starr, don't get me wrong, but to the best of my knowledge, not just any living creature can be a lantern.  Sure, there's lanterns like Leezle Pon and Despotellis along with Bzzd and Matris Ater Clementia.  Of course, there's also Mogo and Dkrtzy.  The things that all of these have in common is not only are they sentient (they have the ability to percieve and sense things), but they are all intelligent and able to communicate.  If that's the case with Dex-starr, then he is either a) not really of Earth or b) an evolved Earth cat which unfortunately happened to be taken by a red power ring.  So what's the deal?  Basically, nearly every living creature has the lowest level of sentience.  They can sense, feel, percieve their surroundings to some degree.  But shouldn't Lantern selection require more like self-awareness or conciousness?  Or maybe, since this all revolves around the emotional spectrum, perhaps all that is required is really emotional awareness?  Animals can emote, but do they understand what it's all about?  Strange questions, I know, but it'd be nice to have a clearer understanding regarding the Rage Kitty.