Should I keep a separate health log for each pet?

Separate the entries, not the notebooks. Keep one place the whole household writes in, and start every entry with the pet's name. Separate notebooks leave nowhere to write the things that don't belong to one pet yet: vomit nobody saw happen, or a bowl left half-full when two cats ate side by side. When you go to the vet, pull out that pet's entries, plus any "unknown" ones that could be theirs.

How do I log vomit when I don't know which cat threw up?

Don't file it under the cat you suspect. Write "unknown", then the time you found it, where, what it looked like, and take a photo. If you have a reason to suspect one cat, write it as a guess with the reason, like "likely Milo (wet chin)". If you later find out who it was, correct that entry instead of adding a new one. If any of your pets seems unwell, is vomiting repeatedly or seems off in any way, call your vet right away, even if you don't know which one it is.

How do I weigh several pets at home?

Weigh them all on the same day, on the same scale, and write each weight down with the name before you pick up the next pet. Most people can weigh a cat at home by weighing themselves, then weighing themselves holding the cat, and subtracting. A Texas A&M veterinarian recommends checking a cat at least once a month. If a pet's weight changes noticeably, talk to your vet: AAHA notes that significant changes can indicate health issues.

Health Records for Multiple Pets: What to Log When You Don't Know Which Cat Threw Up

Q: How can I tell which cat is peeing or pooping outside the litter box?

Talk to your vet first, even if every cat seems fine: peeing outside the box is a common sign of lower urinary tract disease, and a cat straining with little or nothing coming out needs a vet now. To find out which cat it is, the ASPCA suggests asking your vet about giving one cat fluorescein, a harmless dye that makes its urine glow under UV light, or temporarily confining cats one at a time. Only use dyes or food markers under your vet's direction. Longer term: one litter box per cat plus one, in different places, and feeding each cat separately.

Seven in the morning, and there's vomit in the hallway. Three cats live here: Pepper, Olive and Milo. All three are sitting by their bowls, looking like nothing happened.

"I bet it was Milo. He threw up yesterday too." "Wait, I thought yesterday was Pepper." That afternoon you call the vet, and the first question is: "Which cat, since when, and how many times?"

The way to keep health records for multiple pets is one shared log, with the pet's name at the start of every entry. When you don't know which pet it was, don't guess: write "unknown", with the time and a photo. And count every pet separately, because guidelines on when to see a vet count vomiting one pet at a time. Those three habits are the whole answer.

Homes like this are becoming more common. The American Pet Products Association's 2026 cat report says U.S. households with three or more cats are up 45% since 2018. What to record, and how often, is the same as for one pet; our guide to pet health records covers that. This post is about what's different with two, three or more: the moments when records get mixed up, and how to keep them apart.

This is a guide to keeping records, written by Memofu's developer, not a veterinarian. It is not veterinary advice. If a pet is vomiting, has diarrhea or seems unwell, talk to your vet.

Call now, even if you don't know which pet it is

Cats. The Cornell Feline Health Center says a cat that vomits and is also lethargic, weak, off its food or has blood in the vomit should be seen by a veterinarian promptly, so call rather than first working out which cat it was. A cat, especially a male, straining in the litter box with little or nothing coming out needs a vet now: the 2025 International Cat Care consensus guidelines warn that a urinary blockage can be life-threatening, that owners can mistake the straining for constipation, and that a cat blocked for more than a day starts vomiting, stops eating and turns lethargic. So if you find vomit, check whether anyone is straining in the box. Texas A&M's Pet Talk adds that retching with nothing coming up can be a sign of an obstruction.

Dogs. Cornell's Riney Canine Health Center lists repeated vomiting or diarrhea within 24 hours, especially with blood, lethargy or refusal to eat, among the reasons to head to the emergency vet. The list also includes a swollen belly with retching that brings nothing up, which can mean bloat, and eating something toxic or something that could cause a blockage, like a toy or a sock. For a suspected poisoning, the same page points to the ASPCA Animal Poison Control Center (888-426-4435) and the Pet Poison Helpline (855-764-7661); consultation fees may apply.

You don't need to know which pet it was before you call. Say exactly that: "One of our three cats, we don't know which." If you can't tell whether several vomits came from one pet, assume they might have, and call. If several pets are sick at once, say that too. If your clinic is closed, call an emergency vet.

Should you keep a separate health log for each pet?

Separate the entries, not the notebooks. Keep one place the whole household writes in, and start every entry with the pet's name.

A notebook per pet sounds tidy until something happens that doesn't belong to one pet yet. Vomit nobody saw happen. A bowl left half-full when two cats ate side by side. With nowhere to write it down, it stays in the head of whoever found it. The same thing happens when each person in the house keeps their own notes or uses a different app.

One shared log still lets you pull out a single pet's history later, as long as every entry names the pet. That pet's history, plus any "unknown" entries that could be theirs, is what goes to the vet. The FDA's advice to pet owners is to keep a list of every drug your animal takes, including over-the-counter products and supplements, and to bring it to the vet. In a multi-pet home, that means one list per pet.

Why count vomiting separately for each pet?

Because the vomiting guidelines below all count one animal at a time.

The Cornell Feline Health Center says a cat that vomits more than once a week, or that vomits and is also lethargic, weak, off its food, has blood in the vomit, is drinking more, is urinating more or less, or has diarrhea, should be seen by a veterinarian promptly. A Texas A&M veterinarian says there's no hard and fast rule, but a cat that vomits more than a couple of times a month, or shows other signs of illness, needs to be seen. For dogs, Cornell's Riney Canine Health Center says vomiting even once a week may be a sign of disease.

The numbers don't agree. What they share is the unit: one pet.

Say three cats share a home and there were three vomits this week. If each cat threw up once, no single cat is over Cornell's once-a-week line. If one cat threw up three times, that cat is. To the family it's the same "three times this week", but it tells the vet two very different things. If any of those entries say "unknown", one cat three times hasn't been ruled out, and three cats vomiting in the same week is worth telling your vet too (more on that below). And if something seems wrong, call even when the count is low.

Changes work the same way. Texas A&M adds that a cat whose vomiting suddenly changes in frequency should also be seen. You can only notice a change if you know that cat's usual pattern.

So do combinations. Cornell lists diarrhea alongside vomiting as one of the signs that a cat should be seen promptly. One cat vomiting while another has diarrhea is a different story from one cat doing both, and a log that doesn't name the pet can't tell them apart. If you don't know which it was, say so when you call.

Sometimes the most useful fact is that several pets are sick at once. The Merck Veterinary Manual's pet owner edition notes that digestive infections spread between animals, most often through direct contact or food or water contaminated with feces. Among noninfectious digestive diseases, it says, usually only one animal is affected at a time; the exceptions are diseases linked to eating too much or to poisons, where several animals living together can be affected. If several pets are vomiting, tell your vet that too. When it happens over several days, "all three threw up" is only visible when each pet's entries sit side by side.

How do you log vomit when you don't know which pet it was?

Don't file it under the pet you suspect. Write "unknown", then the time and place you found it and what it looked like, and take a photo.

Sometimes you have a hunch. Milo's chin was wet. Olive left her breakfast. Even so, if "probably Milo" goes into Milo's record and it was really Olive, Milo's count is one too high and Olive's is one too low. Write down how sure you are instead.

How sure	When to use it	Example entry
Confirmed	You saw it happen, or only one pet was in the room	Milo (confirmed)
Likely	You didn't see it, but you have a reason to suspect one	Likely Milo (wet chin)
Unknown	You have no idea	Unknown (one of the three)

An entry like this reads the same no matter who writes it:

Unknown (one of three) · Sept 28, 7:10 am · hallway · vomited once · food, not a hairball · photo taken · logged by Sam

Take the photo. Texas A&M's Pet Talk notes that vomit with foreign material in it can point to a more serious problem, especially alongside other signs, so what it looked like matters to your vet. A photo also records the time for you.

If you later find out which pet it was, add that to the same entry ("→ Olive, added Sept 29: Alex saw her do it at 7") instead of writing a new one, or the same vomit gets counted twice.

How can you tell which cat threw up or peed outside the box?

First: if any pet seems unwell, call your vet before you try to work out who it was. For urine outside the litter box, talk to your vet first even if every cat seems fine; the ASPCA's first step is a thorough vet check. Then work through what you can do at home.

Look at each pet, one at a time. Energy, appetite, a wet chin, a bowl left full. If one pet is acting differently, that's worth an entry of its own.

Feed them separately and watch. The 2024 American Association of Feline Practitioners (AAFP) intercat tension guidelines say that even cats who get along should be separated at mealtimes, with a visual barrier or a microchip feeder if separate rooms aren't possible. You'll see who left food behind.

Confine them one at a time, briefly. For urine or stool outside the litter box, the ASPCA suggests temporarily confining cats one at a time to find out which one it is. Keep it temporary: the ASPCA warns against shutting a cat in a small room for days or weeks without doing anything else about the problem. This is for soiling, not vomit. Don't confine cats to wait for the next vomit: if vomiting keeps happening and you can't tell who, call your vet and say it's unknown.

Ask your vet about a marker. The ASPCA suggests asking your vet about giving one cat fluorescein, a harmless dye that makes that cat's urine glow under ultraviolet light. For stool, WikiVet, a veterinary education site, describes marking a cat's food with a small amount of visible, indigestible material for several days so its feces can be picked out. Do either only under your vet's direction.

Use a camera. WikiVet also mentions motion-triggered video for spots that keep getting soiled.

Don't assume that peeing outside the litter box is a behavior problem. The 2025 International Cat Care consensus guidelines say it's a common sign of lower urinary tract disease, and that disease should be ruled out before a behavioral cause is assumed. The same guidelines list a multi-cat home among the risk factors identified for feline idiopathic cystitis. Noting which cat used which spot helps here too.

To make the next time easier, give each cat its own resources. International Cat Care describes a commonly used formula for multi-cat homes: one of each key resource per cat, plus one extra, in different places. Three cats, four litter boxes.

How do you keep weights, medications and vet visits apart?

Weigh everyone on the same day. Store each pet's medication separately. At each visit, bring that pet's history, plus any "unknown" entries that could be theirs.

Weights: same day, same scale. AAHA, the American Animal Hospital Association, advises owners to weigh their pets regularly, on a home scale or at the vet's office, and to keep a weight journal to catch trends early. A Texas A&M veterinarian says most people can weigh a cat at home by weighing themselves, then weighing themselves holding the cat, and doing the math, and recommends checking at least once a month. With several pets, write each weight down with the name before you pick up the next one. Weigh three in a row and write them all down at the end, and two numbers can trade places.

Medications: separate from the start. The FDA advises storing medications for each person and each pet in the household separately, to prevent mix-ups, and not sharing one animal's medication with another unless your vet says so. It also notes that pets sometimes get into medications meant for other pets in the same household. For keeping track of who gave which dose, see our guide to preventing double doses.

Vet visits: that pet's history, plus the unknowns. "Be ready to describe what happened," says the Merck Veterinary Manual's guide to pet emergencies. In a multi-pet home, the person who saw the vomit and the person who drives to the clinic may not be the same. An entry written by whoever saw it lets the driver tell the same story. Bring the "unknown" entries too, marked as unconfirmed, and mention any other pet that was sick around the same time. For putting symptoms into words, see how to describe your pet's symptoms to the vet.

What to do this week

None of this needs special equipment. Four things you can start today:

Pick one place to write. Paper or an app, either works. Make "the pet's name comes first" a house rule.
Agree on how to write "unknown". Confirmed, likely, unknown. Three labels are enough.
Weigh everyone this weekend, on the same scale. Write each weight with the name. That's each pet's baseline.
Post the phone numbers. Your vet's and the nearest emergency vet's, next to the log or on the fridge.

Where Memofu fits

Memofu is an app for keeping pet health records and photos with your family. Here's exactly what it does for a multi-pet home. We've kept to what the app actually does today.

Every record belongs to one pet. The Health tab shows one pet at a time, and weights, medications, vet visits and care-log entries are each saved to exactly one pet. Every logging screen opens with a pet already selected, so check the name before you save.
Log "Unwell" with a symptom. Choose Vomiting, Diarrhea, Poor appetite, Low energy, Cough or sneeze, Itching or Other symptom, and add a note. The button shows how many times it was logged today. You can date an entry up to 13 days back by choosing the day and a time of day (morning, midday, evening or night), so add the exact time in the note.
Everyone in the circle sees who logged it and when. Owners and co-owners can log; viewers can see but not log.
Month, week and chart views for each pet. Charts covering a week up to a year show how often each pet was unwell, how often daily care like meals and potty breaks was logged, how many scheduled doses were given, and weight.
There's no "unknown pet" option. Everyone who can log writes in the same place, but every entry goes to one pet. Keep unknown and "likely" events on paper or in a shared note, and log them to the right pet once you're sure. With Memofu, that means unknowns live in a second place, so when you log one to a pet, mark the note "logged" so it isn't counted twice. A note saying "guess" doesn't keep an entry out of that pet's Unwell count or charts.
An entry can't be moved to another pet later. If it was wrong, you can delete it and log it again within 14 days of when it happened; after that, the app no longer offers delete.
The health records link is free. A link that expires after 1, 7 or 30 days shows one pet's health records to a vet or sitter: allergies and care notes, current medications, vaccines and preventives, weight, and vet visits. It doesn't include the care log, "Unwell" entries, photos, or notes on vet visits and weigh-ins.
The vet report PDF is Premium. It puts one pet's weight trend, medications, vaccines and preventives, and vet visits together, plus the last 14 days of the care log, including "Unwell" entries and their symptoms.
The free plan holds two pets per circle. From the third pet, Premium removes the limit. A plan taken out by an owner or co-owner covers everyone in the circle, and pets in loving memory never count.

Health records for the pets you've registered, including the full history, are free on every plan, and a full export is free on every plan too, for good. There are no ads, no data sales and no public feed. You can see what Memofu does on our features page and what is and isn't paid on our pricing page.

A paper notebook works too. One place to write with the pet's name first, "unknown" instead of a guess, and a separate count for each pet: keep those three and any tool will do.

One last reminder: this is a guide to keeping records, not veterinary advice. When a pet is limp or can't stop vomiting, what you need isn't the log. It's your vet's phone number.

Sources

When to go to the ER, Richard P. Riney Canine Health Center, Cornell University College of Veterinary Medicine, June 2025
2025 iCatCare consensus guidelines on the diagnosis and management of lower urinary tract diseases in cats, International Cat Care, Journal of Feline Medicine and Surgery, 2025
Gen Z and Cat Dads Are Leading Cat Ownership's Cultural Boom, American Pet Products Association, September 2026
Medication Errors Happen to Pets, Too, U.S. Food and Drug Administration
Vomiting, Cornell Feline Health Center, Cornell University College of Veterinary Medicine
When To Be Concerned About Feline Vomiting, Texas A&M College of Veterinary Medicine & Biomedical Sciences, 2021
Vomiting, Richard P. Riney Canine Health Center, Cornell University College of Veterinary Medicine
Introduction to Digestive Disorders of Cats, Merck Veterinary Manual, Pet Owner Version
Multi-cat households, International Cat Care
2024 AAFP intercat tension guidelines: recognition, prevention and management, American Association of Feline Practitioners, Journal of Feline Medicine and Surgery, 2024
Litter Box Problems, ASPCA
Housesoiling - Cat, WikiVet
5 Ways to Know How Much to Feed Your Pet, American Animal Hospital Association, 2024
Weighing In On Feline Obesity, Texas A&M College of Veterinary Medicine & Biomedical Sciences, 2021
Properly Store Medications to Keep Your Pet Safe, U.S. Food and Drug Administration
What to Do in a Dog or Cat Emergency, Merck Veterinary Manual, Pet Owner Version