Star Trek is, and will always be, a show about people. The pets of Star Trek could always be relied upon to bring the show down to the human level. Even though the original series was a human drama, it wasn’t until the Next Generation era that pets were bought in, so that their antics can serve as a down-to-Earth counterpoint to the life-and-death sci-fi adventures.
“How fleeting are all human passions compared with the massive continuity of ducks.”
-Dorothy L. Sayers
I'm always reminded of that quote from Sayers by the pets of Star Trek (and I will not explain the context of the quote.) Animals are eternal. The future world of Star Trek would be confusing and terrifying to a human time traveller from the present, but a cat or a dog would assimilate to the Star Trek universe very easily, as long as there were still humans with laps to sit in.
And humans with laps to sit in there are.
In fact, in the 31st century, the most distant future covered by the Star Trek universe, a furry companion reminds us that spacebound humanoids a thousand years hence are just like us, and as relatable as any other character. No advancement or evolution in the next millennium will change the basic human inclination to dote on the small and furry quadrupeds that share our living spaces.
These six pets include three cats, two dogs, and a fish, and though they are not sentient (they are sentient… more on that later,) and do not comprehend, they make the rich world of Star Trek what it is.