Try catching a mouse with your bare hands.I’ve had both dogs and cats who I’ve loved but I disagree with the first two.
I think Kirk would totally have a cat. I see Kirk after his day’s mission is done lounging around his quarters with a cat purring on his lap. Kirk luxuriates in life.
And a cat would just be a pointless curiosity to Spock. Owning a cat is totally illogical. But dogs have skills and are attentive. Their ethos is basically the Vulcan “we live to serve.” I could totally see Spock with a well trained German Shepherd.