Dog-cat introductions fail more often from rushing than from any fundamental incompatibility between the species — a bad first encounter can create a fear association that takes far longer to undo than the introduction itself would have taken done properly.
Separate spaces first, always
Before any direct contact, the cat needs a dog-free base area with their own litter box, food, and a way to move around the home without necessarily encountering the dog — even after a successful introduction, this separate space should remain available as a retreat option long-term, not just during the introduction period.
Scent before sight
Swap bedding between the two animals for several days before any visual contact, letting each get used to the other's smell in a low-stakes way. This step is easy to skip and genuinely worth not skipping — scent familiarity meaningfully reduces the intensity of the first visual encounter.
The dog's obedience matters more than the cat's temperament
A dog with solid "sit," "stay," and "leave it" commands, and a demonstrated ability to stay calm on cue, makes an introduction dramatically safer than the same introduction with an untrained or highly reactive dog. If your dog doesn't reliably respond to basic commands, working on that before starting cat introductions is worth the delay.
First visual contact: controlled and brief
Keep the dog leashed, and ideally have the cat on the other side of a barrier (a baby gate, or a crack in a door) rather than fully loose in the same room. Watch for a dog who fixates, stiffens, or shows intense prey-drive focus on the cat — if you see this, end the session and get professional guidance before continuing, since this specific body language pattern is a genuine risk indicator, not something that reliably improves with more exposure alone.
Reward calm, not just tolerate it
Treat and praise the dog for calm, non-reactive behavior in the cat's presence, and give the cat an easy path to retreat if they choose to. The goal in these early sessions isn't interaction — it's both animals experiencing the other's presence without anything bad happening, repeated enough times that this becomes the expected, boring norm.
Escalate gradually over weeks, not days
Longer supervised sessions, then off-leash supervised sessions, then eventually unsupervised access, each only after the previous stage has been consistently calm for a real stretch of time. There's no fixed timeline that fits every pair — some combinations take a few weeks, others take months, and going slower than seems necessary is very rarely the wrong call.
Some combinations need permanent management
A small number of dog-cat pairings, particularly with dogs from breeds or individual backgrounds with strong prey drive toward small animals, may never be safe for unsupervised access regardless of training. Permanent separation with supervised interaction only is a legitimate, safe long-term outcome, not a failure of the introduction process.