Map his routes, then fix the surfaces on them
Do not start by buying things; start by watching where your stiff-jointed dog actually goes. For most dogs it is three routes: bed to water, bed to garden door, and bed to wherever you spend the evening. Those routes should become continuous grippy paths — runners, rugs with non-slip backing, or interlocking mats — with no polished gaps at doorways where he must hurry or turn. Turns are where stiff dogs slip, so widen corners rather than forcing tight pivots around furniture, and move anything he has to step over, from shoe racks to toy boxes, off the route entirely. In the garden, check the step down at the door and the path surface in wet weather; a shallow ramp and a clear, lit path turn a daunting toilet trip into an easy one.
Rest, warmth, and one-level essentials
Bring everything he needs onto the level where he spends the day: bed, water, food, and outdoor access, so stairs become a choice rather than a requirement, and fit a gate so he is not tempted to follow you up alone. His bed should be supportive and thick, at floor level, in a warm spot away from drafts and cold external walls, with space to stretch fully and turn without climbing over bolstered sides. Add a second simple resting mat in the room where the family gathers, because a stiff dog will lie on a hard floor near you in preference to a perfect bed in an empty room — and hours on hard flooring undo your good work. A low night light on the route to the door helps the careful, stiff first steps of a midnight trip.
Eating, drinking, and daily handling
Set bowls on a non-slip mat at a height where he eats with his head level and comfortable — for most dogs that is simply floor level on a mat that stays put, for tall dogs a modest stand — in a quiet corner he can reach without crossing slippery kitchen tile at speed. Keep nails short and trim the hair between his pads weekly; grip begins at the foot, and no rug compensates for skates for feet. Dry his legs and paws after wet outings and give him a warm room to recover in, because cold, damp muscles guard stiff joints. If he is groomed at home, work on a non-slip surface at a height that spares you both, in short sessions with rest breaks.
Keep the layout, review the dog
Once the house works, keep it working: photograph the layout, resist rearranging his corner for visitors, and tell guests not to call him quickly across slippery floors for a fuss. Then review the dog himself, not just the furniture — if stiffness is new, one-sided, rapidly worsening, or paired with appetite loss, weight change, yelping, or a leg held up, that is a veterinary appointment, not another home adjustment. Gradual morning stiffness that eases with gentle movement belongs in the notes for his senior check, with dates. Writing the new routes, bed place, and handling rules into his profile helps everyone keep them, and KinsLe Family Sharing makes those home changes visible to the whole family in one shared place.