Star Trek has a strange affection for cat-based aliens, starting with Star Trek: The Original Series Season 2, Episode 1 "Catspaw" which features an alien disguised as a shapeshifting giant feline. Star Trek: The Animated Series leaped into the concept with both feet by creating not one, but two specific cat-like species: the Caitians and the Kzinti. That, in turn, has led to a weird flirtation with canon, as other Star Trek projects confirmed the Caitians as official while muddying the waters at the same time. As with most things associated with The Animated Series, the franchise treated them as a dirty little secret, and edged around their status even while periodically showing them onscreen.
Source：https://www.cbr.com/star-trek-caitians-explained/
