5 things that help you introduce a kitten to a resident dog

A closed door removes the kitten from your dog's world completely for the first few days, so the first thing your dog learns about this new animal is nothing at all — not a shape to fixate on. Most people reach for a baby gate instead because it feels less isolating, but a gate does the opposite of what you want: it lets a full-grown dog watch, hear and smell a small, fast-moving animal it can't reach, for hours on end, which trains staring and pacing, not calm. The smooth introductions I've seen — steady old retrievers and wired-up young collies alike — always had a proper closed door for the first stretch, with litter, food, water and a hiding spot inside, not a gate the dog could plant itself at.

Smell is how cats and dogs actually clock each other, so let scent do the introductions before either animal is standing in a room. A tabby kitten I fostered last spring, Marmalade, spent four days as nothing but a smell to my lurcher, Otto, before he ever saw her — by the time they met, he was mildly curious rather than switched on, because the novelty had already worn off. Feeding both animals near the shared door at the same time does the same job: the other one's scent starts meaning 'dinner's coming', not 'unknown thing'.

A lead lets you physically stop a bad moment half a second before it happens, instead of hoping your voice is faster than a dog's legs. It isn't about expecting aggression — even the gentlest, most kitten-friendly dog can get overexcited by a small animal darting sideways, because fast, low, jerky movement flips a switch that calm walking never does, and an eight- or nine-week-old kitten has zero ability to out-manoeuvre that. Owners who skip this because 'he's soft as anything with everyone' are usually the ones who end up white-knuckling a dog who's suddenly all forward-lean and hard eyes over a kitten's dash under the sofa.

A kitten who can always get somewhere the dog physically cannot follow never has to find out, under pressure, whether this particular dog is trustworthy at close range. It protects the dog's side of the deal too — a kitten who can't escape is a kitten who eventually swats or bolts, and that's the moment that teaches a dog chasing sometimes pays off. A stair gate with a built-in cat flap, or two gates stacked with a kitten-sized gap underneath, does more for a smooth introduction than weeks of careful sessions if the kitten can't actually get away when it matters.

Weeks of uneventful meetings tell you your dog is capable of settling — they don't tell you your dog is safe unsupervised, because that only gets tested the one time the kitten does something sudden and nobody's there to interrupt it. The classic mistake is relaxing supervision right around week three or four, exactly when the kitten is getting faster and bolder and everyone's guard is lowest because it's 'been fine so far'. That mismatch — rising kitten confidence meeting falling human vigilance — is where most late introductions come unstuck.