The subtle changes that most often mean a cat needs a vet soon are measurable ones: how much food disappears from the bowl, how many clumps and stools come out of the litter box, whether the coat is still being maintained, and whether the cat has quietly moved its life to a new hiding place. The line between watching and calling is not how alarming the change looks. It is whether the change has a number and a direction — and most of them do, if somebody has been writing the number down.
I keep a cheap kitchen scale under the bathroom sink and a spiral notebook on the counter near the coffee maker, and the two minutes that costs me each week has caught more than any amount of staring at my cats ever did. When I first started fostering, I was the person who called the clinic and said "she's just not herself." I could hear the receptionist trying to turn that into an appointment slot. She can't triage an adjective. She can triage "she's eaten about a third of her normal intake for three days and she's down four ounces since last Sunday."
So this is not a list of symptoms to memorize. It's a way of turning the vague thing you're noticing into something a veterinarian can act on, and knowing exactly where the watching ends.
The four things I actually track
Not seven. Not a spreadsheet with forty columns. Four, because those are the ones that shift first and the ones the clinic asks about.
Weight, once a week, same day
Stand on the scale holding the cat, subtract your own weight, write it down. That's it. A baby scale is nicer if you foster litters, but the bathroom scale works on a full-grown cat well enough to catch a trend over three or four weeks.
Here is what the number buys you: a cat can lose a meaningful amount of body weight before it looks thin to your hands. Fur is a very good liar. I have put my palms on a cat, felt ribs, thought "fine," and then looked back at the notebook and seen four straight weeks of downward drift. Any steady downward drift across several weeks is a call, even if the cat is eating, even if the coat looks good, even if the cat is behaving normally. That's the whole point of the number — it doesn't care what you think you see.
Food in, measured
I don't free-feed, except for the one cat who has never in his life overeaten and would be miserable on a schedule. For everyone else, a measured scoop in the morning and a measured scoop at night, and I look at what's left before I refill.
You're not looking for "she seems to be eating less." You're looking for "a quarter cup left in the bowl two mornings running, when she normally licks it clean." Write it down. A cat who leaves a little food and then cleans the bowl the next day is a cat with a data point, not a cat with a problem.
The box, counted
This is the one I'd keep if I could only keep one. Scoop at the same time every day and count. Clumps in, stools out. You'll know your cat's normal within a week — two clumps and one stool, three clumps, whatever it is — and a change from that baseline is louder than almost anything else in the house.
Two things I notice with my hands, not my eyes. First, size: small hard stools produced more often, or a clump that's noticeably smaller than usual, tells you something shifted before the cat looks unwell. Second, smell. I'm not being flip. A change in the odor of the box — sharper, sweeter, more ammonia — is one of those things your nose flags before your brain does, and it belongs in the notebook with a date next to it.
Coat and skin, by hand
Once a week, run your palm against the grain from the base of the tail up to the shoulders. You're feeling for grit, dander, mats, and grease. A cat that stops grooming shows it there first — a greasy patch at the tail base, a mat behind one shoulder that wasn't there last week, a coat that feels dull instead of slick. Same hand-check for the flanks: a cat who flinches when you run a flat palm along the belly or who suddenly doesn't want to be picked up under the chest is telling you something, and it isn't "she's being moody."
Cats hide illness, so the early signs are boring
A cat in the wild is a small predator and a small prey animal at once. Showing weakness gets you followed. That's the reason the first signs are almost never dramatic — a cat that feels bad does the cheapest possible version of normal. She still eats, just a little less. She still jumps on the counter, just not as often. She still comes to the bed, just not every night. She sleeps in a slightly tighter curl, in a slightly warmer spot, for slightly longer.
That's why the boring stuff in the notebook matters more than the dramatic stuff you'd notice anyway. By the time a cat is obviously sick — sunken eyes, a coat that's gone to pieces, a cat who won't get up — the interesting part of the timeline is weeks behind you, and the vet is working with less.
The other thing I've learned is that cats don't hide in the same order. Some go off food first. Some hide first. Some just get quieter in a way that's hard to name until you look at the notebook and realize the cat hasn't been on the windowsill in nine days.
Where watching stops
A day of watching is fine. A day of watching is not a strategy — it's a deadline. Before you decide to watch, write down what number would make you call, and give yourself 24 hours to hit it or not.
"I'll keep an eye on it" with no number attached is how a week disappears.
Reasonable to watch for a day, with a written threshold
- One missed meal in an otherwise bright cat who is drinking, using the box, and interacting.
- A single episode of vomiting in a cat who then eats and keeps it down.
- One soft stool in a cat who is otherwise normal.
- A slightly quieter day after a vaccine, a nail trim, a houseguest, or a move — with a deadline attached.
If the threshold isn't hit by the end of that day, the watching is over and you're calling. If two things on that list are happening at once, skip the day.
Call the clinic today
- Total food refusal for 24 hours. In an overweight cat, that clock runs faster — call sooner rather than later in the day.
- Eating roughly half of normal for two or three days running, with weight drift.
- Water intake that clearly jumped and stayed up for more than a day or two. This is the one change cats genuinely can't hide, and it's one of the few I'd call about before I'd call about almost anything else on this list.
- No stool for two days, or a cat visibly straining and producing small amounts.
- Vomiting more than a couple of times in a day, or vomiting plus lethargy, or vomiting plus refusing food.
- Diarrhea lasting past 24 hours, or any diarrhea with blood in it.
- Hiding that's new — behind the water heater, under the bed, in the back of a closet — especially if the cat is skipping meals to stay there.
- A cat who stops grooming, or the opposite: a bald patch appearing on the belly or inner thighs.
- New irritability, new vocalizing at night, or a cat who suddenly won't be picked up.
- Any change in breathing you can see at rest.
Go in now, don't book an appointment
- A cat posturing in the litter box over and over and producing little or nothing. Do not wait to see if it resolves. This is an emergency, and it's more dangerous in male cats.
- Open-mouth breathing, or a cat resting and visibly working to breathe.
- A cat who can't stand, drags the hind legs, or cries out when you touch the belly or back.
- Gums that look white, gray, or yellow instead of pink. Lift the lip and look — this costs five seconds and tells you a lot.
- Repeated vomiting with nothing staying down, including water.
- Any known exposure to lilies, antifreeze, human medication, or a toxin you're not sure about. Call the clinic and go; bring the plant or the package.
- A cat pressing its head against a wall or staring at a corner, or one who is unresponsive or collapsed.
When the threshold moves
A twelve-year-old with kidney values already on the chart does not get the same 24-hour grace period as a healthy two-year-old. If a cat has an existing diagnosis, you already have a baseline and a relationship — call earlier, and say so when you call.
A few ordinary things will muddy the numbers, and it's worth knowing them so you don't either panic or explain away something real:
- A food switch can change stool volume and box output for several days. Note the switch date in the notebook so you don't read a transition as a symptom.
- A move, a new baby, a new pet, or building work will suppress appetite and increase hiding for a day or two in a sensitive cat. A day or two. Not a week.
- Summer heat will change water intake and where the cat sleeps. Look for hard cool floor tiles and windowless spots — but a cat who abandons her usual places for hard cool floor is also a cat communicating something, so check the other three numbers before you shrug.
- A multi-cat house makes intake and output genuinely hard to attribute. This is where a cheap camera over the bowl and the box earns its keep, or where you feed the one you're worried about in a closed room for a couple of days so the numbers belong to somebody.
The call itself
A clinic's phone triage runs on specifics, and you're the only one who has them. Have these ready before you dial, in this order:
- The one-sentence version: what changed, when it started, and the number.
- The current weight and the date you last weighed, plus the drift.
- What the cat is eating, how much, and whether anything changed recently.
- Box counts: clumps and stools per day, versus normal.
- Age, existing conditions, medications and supplements, and the date of the last visit.
- A video of the thing you're worried about — the straining, the limp, the breathing, the twitching. Ten seconds of video is worth more than a paragraph. Film it before you call.
Then ask the direct question: is this something that needs to be seen today? Receptionists are not being evasive when they ask you to describe it again — they're building a triage picture from your words. Give them the numbers, and if the answer is "we can fit you in Thursday," ask what would make you call back before then.
What I get wrong
I've paid for an emergency visit that turned out to be nothing, and I've thought about a change I talked myself out of for a lot longer than I'd like to admit. Both of those are the cost of doing business. The first one is money. The second one is time you don't get back.
What I've settled on is this: I would rather make a slightly unnecessary call than a late one, and the notebook is what makes the unnecessary calls rare. When you can say "her weight is stable, her box counts are normal, she's eating, and she's just hiding more," you have permission to wait a day. When you can't say that, you already have your answer.
