The older dog did not apply for a puppy, and the fairest introduction acknowledges that. He keeps seniority in every practical sense: his territory is entered gradually, his possessions stay his, his signals end interactions, and the adults do the tedious work of teaching the puppy manners so he never has to escalate to keep his peace. She, meanwhile, learns from day one that calm behaviour around him earns more of his company, while bouncing, grabbing, and chasing make the fun adult in the room remove her.
Parallel Walks Before Face-to-Face
Start outdoors on neutral ground, a quiet street or path neither dog owns, with two handlers. Walk in the same direction at a distance where he notices her without fixating, perhaps across the street, and let the gap narrow gradually over the walk only if both dogs stay loose and able to look away, sniff, and take treats. Parallel movement lets them gather information without the pressure of a head-on greeting. If he glances and disengages, that is success worth rewarding, not a failed meeting. A brief closer sniff can come once walking together looks boring, followed immediately by more walking so arousal does not stack. Repeat these walks on a few days before expecting them to share indoor space for long, and keep leads slack where safe, because tight leads add tension both dogs can feel.
Arranging the House in His Favour
Before she comes home, install the geography of respect: gates that give him rooms she cannot enter, his bed placed where she cannot claim it, separate feeding stations used from the first meal, his toys and chews kept genuinely his, and a puppy pen or crate where she can be contained happily with her own things. Feed them apart, train her apart, and give him his walks, games, and sofa time with you at undiminished levels, because a dog who loses his person to a puppy has real grounds for resentment. Supervise all shared time at first, and separate them when you cannot watch, without treating separation as punishment for either dog. High-value items are the classic flashpoint, so chews, food toys, and favourite finds are enjoyed in separate spaces until their relationship is proven over months, not days.
Teaching Her to Read Him
His signals are her curriculum: turning his head away, moving off, a low growl, a hard stare, showing teeth, or snapping at air are escalating sentences in a language she must be helped to obey. The moment she ignores an early, polite signal, step in cheerfully, call or guide her away, and give her something else to do, so he learns that his quiet signals work and she learns they are final. Never scold him for warning her; warnings are the safety system functioning. Reward her heavily for the behaviours you want repeated: lying down near him, glancing and looking back at you, playing with her own toy in his presence, and settling on her mat while he rests. End joint sessions while they are still succeeding, several short good sessions a day teach faster than one long one that frays.
The First Weeks and the Longer Friendship
Expect a curve rather than a verdict: tolerance first, then routine, then, in many households, genuine companionship, shared walks, parallel naps, and play he initiates on his terms. Keep reviewing whether his life is as good as it was before she arrived, appetite, rest, enjoyment of walks, and willingness to be in shared rooms, and adjust her access if any of those dip. If conflict appears, growling over resources, guarding you, fights that need separating, go back to more management and parallel walks and consider professional behaviour help early rather than after positions harden. Notes on walks, signals, and shared sessions help the household stay consistent, and those notes fit naturally within the Care Teams notes KinsLe holds for both dogs.