Spiny mice and other pets never actually meet
Spiny mice are not good with other pets at home if 'good with' means meeting, playing, or sharing a room loose. A spiny mouse is a small desert prey animal whose defence is flight and leaping, and whose skin tears far more easily than a fancy mouse's — so contact that would merely frighten another rodent can wound this one. In a mixed household the species live parallel lives, separated by lids, doors, and routine, and the arrangement is judged a success precisely because the animals never test it.
Why this species is a harder case than most rodents
Three spiny mouse traits raise the stakes around other pets beyond the usual mouse precautions. First, the skin: spiny mice shed and tear skin as an escape mechanism, so a grab that a fancy mouse survives can leave a serious wound needing a vet. Second, the leap: a startled spiny mouse jumps far and fast, which means a handling slip near an open door can put her across a room and under furniture before anyone reacts — with the household dog already in pursuit. Third, the stress cost: as group animals who read scent and movement keenly, spiny mice living where a cat patrols their enclosure show it in hiding, reduced feeding in the open, and squabbles inside the group as tension spreads.
The separation setup a mixed home needs
Build the barrier into the room, not into your intentions. Spiny mice live in a large tank or cage with a clipped, weight-proof lid — a cat sitting on a mesh top is a predictable event, not bad luck — placed in a room whose door stays shut and which cats and dogs do not enter unsupervised at any hour. During cleaning and feeding, shut other pets out first, then open the enclosure, and move mice only inside a closed tube or carrier, never carried in hands through the house. Check lid clips and door latches as a weekly habit, and brief every household member and guest, because the person who props the door open 'for a minute' is the usual author of the disaster.
Reading stress, and acting on it early
A spiny mouse colony living too close to predator pressure advertises the problem in behaviour. Mice who abandon exposed basking and climbing spots, who feed only in dashes, who freeze at the room door's sound, or who begin fighting more inside the group are all telling you the other pets are reaching them through sight, sound, or smell. Weight drifting down across the group, or one subordinate animal growing thin because she will not come out to eat, needs action: relocate the enclosure behind a reliably closed door, add deep cover and multiple hides so no mouse must cross open ground, and remove whatever perch lets the cat watch from above.
If a spiny mouse gets out among other pets
Rehearse the escape order of operations before it happens, because the first minute decides the outcome. Remove the cat and dog from the area immediately and shut them away, close every door you can to shrink the search space, and then work quietly: a spiny mouse loose at dusk will move along walls, so place a baited humane live trap or a deep bucket trap with a ramp where she vanished, and wait rather than chasing. Any mouse recovered after possible cat contact needs a vet the same day, since punctures hide under fur and cat bites infect fast. For a mouse who reaches the outdoors, KinsLe Circle of Love connects your free account to pet lovers nearby who can keep watch and join the search while the trail is still fresh.