Start With the Scene, Not a Guess
When you find a loose stool in a tray or vomit on a rug hours later, resist naming a culprit from habit, because the cat who had a sensitive stomach last spring is not automatically responsible now. Instead, record the facts of the scene straight away: where it was, roughly when you last knew that spot was clean, what it looked like, and which cats could reach that room in between. Photograph it before you clean up. That feels unpleasant, but color, consistency, and anything visible in it are exactly what a vet will ask about, and memory blurs those details within a day.
Note what else was happening in the house. A new food, a stolen mouthful of another cat's meal, a stressful visitor, or a missed tray clean can all explain a one-off episode, and writing the context down beside the finding stops you later mistaking a single incident for a pattern.
Narrow It Down With Tray and Feeding Clues
Next, watch the shared points. Check the other trays: a cat with an upset stomach often leaves more than one sign, and the tray nearest her usual sleeping spot is a strong clue. Watch who visits the tray soon after meals, who is eating eagerly or leaving food, and who is drinking or grooming differently. In many homes the mystery resolves within a day simply because the responsible cat is the only one whose appetite or tray habits have shifted.
Feeding time gives you a cleaner test. Feed the cats in separate spots for a couple of days, with their usual food, and note who eats what and how much. A cat who picks at a separated meal she would normally finish has told you something useful, without any stressful confinement or special diet being introduced to force an answer.
When Episodes Repeat, Separate Briefly and Log Honestly
If worrying stools or vomiting keep appearing and you still cannot tell who is responsible, use short, kind separation: settle one cat at a time in a comfortable room with her own tray, water, and bedding for part of the day, rotating fairly. A clean tray and a settled cat during her turn clears her more reliably than any amount of guesswork, and most cats tolerate a quiet room with familiar smells far better than owners fear.
Log every episode in one shared place as you go: what was found, where, your leading suspect, and how sure you are, from a firm witnessed event down to an educated guess. Honest confidence levels matter, because a record that presents three guesses as certainties can send a vet down the wrong path, while a record that shows one cat linked to repeated episodes, even loosely, is genuinely helpful evidence.
Knowing When Tracking Becomes a Vet Visit
Home detective work suits an otherwise bright cat and an isolated episode. Contact your vet promptly if the stool contains blood, if vomiting repeats through a day, if any cat stops eating, becomes withdrawn, or seems to strain in the tray, or if the episodes keep recurring over a couple of weeks even without a confirmed culprit. Take your log and photos with you, and say honestly that you live in a multi-cat home and are still narrowing it down, since vets work with that uncertainty regularly and may suggest testing the most likely cat first.
Sharing those findings as they happen through KinsLe Care Teams means whoever in the house discovers the next episode adds it to the same list and marks their tray checks complete with a timestamp, so the pattern builds in one place instead of scattering across memory and guesswork.