First, respect what fussiness can mean in a senior cat
A senior cat who turns fussy is not simply being difficult. Her sense of smell fades with age, so food that once announced itself now seems bland, and sore teeth, feeling unwell, or a stomach that handles rich food poorly can all make her walk away from a bowl she would once have emptied. Before changing foods, weigh her and think back over the last few weeks: fussiness with weight loss, vomiting, or drinking changes deserves a vet check first, because switching diets can mask a problem that needs attention. Once illness is ruled out or being managed, the job is to make a suitable senior food smell stronger, feel easier, and arrive without pressure.
Make the new food easier to want
Cats judge food heavily by scent and temperature, and both work in your favor. Serve the new senior food at room temperature or warmed very slightly so its aroma lifts, rather than straight from the fridge with its smell muted. Offer small amounts more often instead of one large portion that sits and stales, and try the texture variations senior ranges offer, since a cat refusing chunks in gravy may accept a soft pate she can lap without chewing hard. Feed in her quiet usual spot, keep other pets from hovering, and lift the bowl away calmly after a while instead of leaving rejected food down all day, which teaches her that waiting produces something different.
Swap slowly, one variable at a time
A sudden full-bowl change is the usual reason a new senior food gets rejected and the cat gets an upset stomach at the same time. Start with a spoonful of the new food at the edge of her familiar meal, or in a tiny side dish beside it, and let curiosity do the work over several days. If she eats it and her litter tray stays normal, increase the new share in small steps across a week or longer, slowing down at any stage where she hesitates or her stool softens. Introduce one new food at a time rather than rotating several, because with a fussy senior you need to learn exactly which scent and texture she accepts, and that lesson is lost if everything changes at once.
Track acceptance like information, not a battle
Keep a simple note of what was offered, how much she ate, and anything that followed, from lip-licking and walking away to a settled, finished meal. Weigh her weekly during the change, because a fussy cat can quietly eat less overall even while appearing to nibble, and a falling weight changes the conversation back to her vet. Never let a healthy senior cat go without eating while you hold out for the new food: a cat who refuses everything for a day, especially one carrying extra weight, needs her familiar food restored and prompt vet advice. The swap is a negotiation you are meant to win slowly, not a standoff.
Keep every feeder on the same plan
Gradual swaps unravel when one person offers the planned mix, another gives a full bowl of the old favorite, and a third adds treats that fill her up before meals. Agree the steps once, write them where the food is stored, and give each day's feeding to a named person who records what actually happened. That shared discipline is what turns scattered attempts into one readable trial. KinsLe keeps the plan intact through Care Teams, where each feeding can be assigned and marked done with a note on the mix she got and how much of the new senior food she finished.