Generally a workable pairing, with one instinct to manage
Australian Shepherds have a better starting point with cats than many herding breeds, because their herding style relies more on presence, positioning, and eye than on gripping and heel-nipping. In practice, most Aussies who are introduced to cats properly learn the household rule — this cat is family — and keep it reliably.
The instinct does not vanish, though. It wakes up when a cat runs. A bolting cat looks, to a herding brain, like stock breaking from the group, and an Aussie may give chase and try to turn or block her even with no intention to harm. The risk in that moment is real anyway: a cornered cat can injure a dog's eyes, a chase down stairs can injure both animals, and a cat who is pursued daily lives under chronic stress even if she is never touched.
Starting points that predict success
A puppy raised in a home with a confident cat has the easiest path, because the cat teaches the rules during the puppy's most impressionable weeks and the adult dog grows up with those rules built in. An adult Aussie with a known history of living calmly with cats is nearly as good a bet — ask the rescue or previous owner specifically, and ask what calmly meant in practice.
Harder cases include a dog with a strong chase history outdoors, a cat who has never seen a dog and flees from everything, and any household where the cat is elderly, unwell, or unable to use high furniture and escape routes. None of those rules the pairing out, but each one lengthens the introduction and lowers the odds that the animals should ever be left alone together.
Running introductions the Aussie way
Begin with scent and separation: the cat keeps her core territory, the dog lives outside that door, bedding is swapped, and meals happen near the shared door so each animal pairs the other's smell with good things. Then use a gate or screen the dog cannot push through, keeping early sessions short and boring — you want the dog to glance at the cat, sigh, and look for something else to do, rewarded generously whenever he chooses to look away.
Progress to the dog on a long line in the cat's room only when barrier sessions are genuinely dull, and always with the cat free to leave and able to reach shelves, a cat door, or a dog-free room without crossing the dog's path. Practice the interrupt cues — name, recall, leave it — in easier settings until they hold under excitement, because the first real chase is the wrong classroom.
Living together once the truce is established
Feed separately, permanently. An Aussie who is relaxed about his own bowl may still guard high-value food from a cat who wanders over, and a cat's food left accessible will be eaten by the dog the first day and every day after.
Watch the cat's behaviour as your ongoing report card. A cat who moves around the house freely, eats normally, and uses her usual resting places is coping. Hiding, appetite changes, avoiding rooms the dog uses, or toileting outside the box suggest the arrangement is costing her more than it appears, and the separation plan needs tightening while you reassess.
If a chase ever ends in contact — the dog pinning or mouthing the cat, or the cat raking the dog's face — separate them and reset the introduction to the barrier stage, and have any cat who was grabbed checked by a veterinarian the same day, since bite injuries can be deeper than they look.
When the household shares duties for both animals, KinsLe's Family Sharing puts the cat's dog-free rooms, the dog's feeding spot, and the current stage of their introduction in front of every family member, so one person's shortcut does not undo weeks of careful work.