Dogs are easier to train than cats, what to do if they hear a red alert signal or if there is a decompression. My former neighbor had a dog (german shepard) that could call 911 if she passed out. As much as I love them, a german shepard would be too big for a starship. Beagles might be perfect, poodles better still. Poodles are the second most intelligent breed and smaller than number one (Australian sheep dog).