Your mother will tell you the cat is fine, and she may even mean it. But the cat does not decide whether the food gets poured, the box gets scooped or the vet gets called. A person does, and the signs that the person is slipping often show up in the bowl before they show up on the phone.
Local option: New Plan Care gives families in the St. Louis area in-home help so a parent can stay home: companionship, help with bathing and dressing, meals, and overnight care. Call (314) 405-0887.
Start with the food bag
Ask how many days a bag normally lasts in that house, then ask for a photo of the bag and the bowl on the next call. If the bag empties faster than it should, the pour may be getting heavier than anyone intended, or someone else may be feeding the animal without telling you. If it empties more slowly, a bowl may be sitting full for a long time, or the animal may be eating less. You are not judging the animal's appetite from a distance. You are checking whether the routine behind it is steady.
Read the litter box and the water
The litter box is the most honest report in the house. Ask whether it gets scooped on a regular day, whether the scoop is still where it lives, and whether the box looks like someone has touched it this week. For water, notice whether the bowl is being refilled at the usual times or only when someone remembers. A change in how much water disappears is worth writing down and passing to the vet, as an observation, without deciding what it means yourself.
Check the vet card and the calendar
Find the vet card, the last visit date and any booster or refill reminder. Ask who books the next visit, who gets the reminder call and who pays the bill when it arrives. A missed booster or a refill that never gets picked up is a routine breaking down, and it usually shows up before anyone thinks to ask about it. If there is no card, no calendar and no one who knows the vet's name, that is the finding.
Walk the daily jobs for a dog
A dog depends on a body at the door. Ask when the last walk happened, who took it, and whether the dog still goes to the door at the usual hour. A dog that stops asking, or a coat that starts to mat because no one brushes it, tells you the daily job has lost its owner. A bird cage that goes a week without cleaning, or a fish tank that no one can name the schedule for, is the same kind of problem at a smaller size.
Check tonight
Ask your mother to walk you through one day of the animal's care, from the first task in the morning to the last one at night. Listen for the steps she skips, the ones she says she will do later, and the ones that somebody else does now. Then ask for three things on the next call: a photo of the food bag, a photo of the litter box, and the vet card with the last visit written on it. Finally, ask who the family calls if the animal gets sick at two in the morning. If the answer is no one, write that down before you hang up.
What to leave with the doctor
The vet handles the animal. The doctor handles your mother. If she mentions that she has stopped feeding the animal, forgetting the walks or losing track of the vet card, tell her doctor exactly those words, along with the dates you first noticed each change. Describe what you saw, not what you think it means. Do not present it as a diagnosis, and do not ask the doctor to rule anything in or out based on a list of pet tasks. The change in daily routine is the useful part to bring.
If no one in St. Louis can check the bowl, the box and the bag on a schedule, the local help page lists the kinds of people you can ask, and the start here page shows where to begin if you are not sure.