Start by taking the jump out of her day
An older Domestic Shorthair that can no longer jump up needs her favourite places brought down to her, not encouragement to try harder. Stiff hips and shoulders, weaker hind legs, and sore joints can turn a once-easy leap onto a bed or windowsill into a scramble, a slip, or a quiet decision to stop using that spot altogether. The first fix is practical: map where she actually wants to go in a normal day, then remove the vertical gap on each of those routes.
Walk the route as she does. The sofa arm she launched from, the storage box under the window, and the step onto the bed may each be a different height, and a solution that works for one may be too steep for another. Note where she pauses, crouches without springing, or turns away, because that hesitation tells you which climb hurts or frightens her most.
Build steps and ramps she will trust
Wide, stable steps work well for an older Domestic Shorthair because each rise is small and she can pause halfway. Choose steps with a non-slip surface, enough depth for all four paws, and no wobble when she leans on the edge. Place them flush against the bed or sofa so there is no narrow gap for a back foot to catch, and leave them in exactly the same position so she learns the route by memory as much as by sight.
A ramp suits a longer, lower climb, such as up to a raised feeding or resting platform, provided the slope is gentle and the surface grips under her claws. Test it yourself with a hand pressed firmly as she would land. If the ramp flexes, slides on a wooden floor, or ends in a sharp drop at the top, fix that before expecting her to use it.
Put essentials on one floor
Food, water, rest, and toileting should not require a jump or a flight of stairs for an older Domestic Shorthair that can no longer jump. Move a low-entry litter tray to the same level as her main bed, set bowls where she can reach them without climbing onto a raised stand, and add a second warm resting place at floor level so she is not forced to choose between comfort and effort. Keep these essentials away from noisy appliances and busy doorways, because a cat who finds the climb hard will also avoid a route that feels exposed.
If your home spans several floors, do not carry her up and down as the main plan unless she is relaxed being held and you can support her chest and hindquarters securely. Repeated lifting under the belly can press on a sore abdomen and can startle a cat whose balance is already uncertain. A complete set of essentials on the floor where she spends most time is kinder and more reliable.
Watch how she uses the new routes
An older Domestic Shorthair may need several quiet days to trust steps she has never used. Let her investigate without placing her on them, and reward use of the lowest step with calm praise or a small piece of her usual food placed there. If she bypasses the steps and still tries to jump, block the old launch point with furniture moved slightly, rather than scolding her for a habit she has kept for years.
Contact a veterinarian promptly if the loss of jumping arrives suddenly, if she cries out, drags a leg, stops using the litter tray, hides, or stops eating. A gradual change over months points to a slower mobility problem to discuss at a senior visit, while a sudden change in an older Domestic Shorthair deserves a same-day call. Note when you first saw the hesitation, which heights she can still manage, and whether mornings are harder than evenings, because that pattern is useful information rather than a vague worry.
Keeping those dated mobility notes, her weight trend, and her current feeding and resting setup together in KinsLe Pet Passport gives the veterinarian a clear packet to review when you discuss her jumping.