# Cat flu: signs, spread and vaccination

> Cat flu is an upper respiratory infection caused mainly by feline herpesvirus and calicivirus. Learn the signs, spread, vaccination and when to see a vet.

Source: https://panduanhewan.org/en/pet-health/cat-flu/ · Updated 25 September 2026 · English · Bahasa Indonesia: https://panduanhewan.org/id/kesehatan-hewan/flu-kucing/
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**Review status:** Compiled from the listed veterinary and health organisations’ guidance; not yet reviewed by a veterinarian.

**Caution:** General information for owners, not a substitute for examination, diagnosis or treatment by a veterinarian. If your animal seems very unwell, in pain, struggling to breathe or may have been poisoned, contact a vet immediately.

## Key points

- More than 90% of cat flu cases are caused by feline herpesvirus (FHV-1), feline calicivirus (FCV), or both.
- Cat flu spreads easily from sick cats, from healthy-looking carrier cats, and on objects such as food bowls, bedding and clothing.
- Kittens, unvaccinated cats and cats in shelters or multi-cat homes are most at risk.
- FHV and FCV vaccines are core vaccines; they do not always prevent infection, but they greatly reduce how severe the disease is.
- Cat flu does not spread to people and is not related to influenza viruses, but a sick cat still needs to see a vet.

## When should you see a vet?

- See a vet immediately if your cat is struggling to breathe or breathing fast, is very lethargic, has stopped eating and drinking, or if a kitten shows any flu signs.
- Your cat will not eat, because a blocked nose and mouth ulcers make eating hard.
- Eyes look painful or cloudy, or your cat blinks a lot or keeps them shut, because cat flu can cause corneal ulcers.
- Ulcers on the tongue or in the mouth, heavy drooling, or difficulty swallowing.
- Fever, coughing, or signs that are not improving or are getting worse.
- An elderly cat, or a cat with another illness such as FIV or FeLV, showing flu signs.

## What is cat flu and what causes it?

Cat flu is an upper respiratory infection caused mostly by feline herpesvirus (FHV-1) and feline calicivirus (FCV). International Cat Care (ICC) says more than 90% of upper respiratory infections in cats are caused by one or both of these viruses, often with a secondary bacterial infection. Bacteria such as Chlamydia felis and Bordetella bronchiseptica can also be involved. The Cornell Feline Health Center notes that up to 97% of cats are exposed to herpesvirus during their lives. Infection is most common where many cats live together, such as shelters, breeding catteries and feral colonies. Most cats recover, but ICC warns that cat flu can occasionally be life-threatening.

Evidence: [International Cat Care — Cat flu – upper respiratory infection](https://icatcare.org/articles/cat-flu-upper-respiratory-infection) · [Cornell Feline Health Center — Respiratory infections](https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/respiratory-infections)

## What are the signs of cat flu?

The main signs of cat flu are sneezing, discharge from the nose and eyes, red eyes, fever, lethargy and poor appetite. PDSA also lists painful eyes from corneal ulcers, mouth ulcers, a sore throat and coughing. According to ICC, herpesvirus tends to affect the eyes more severely, while calicivirus often causes ulcers on the tongue; in very young kittens, calicivirus can cause severe pneumonia. In Indonesia, a case report in the Udayana University journal Indonesia Medicus Veterinus describes a kucing kampung (local domestic cat) with herpesvirus that stopped eating, was lethargic, sneezed and had eye and nose discharge. A Bandung study in the UGM journal Jurnal Sain Veteriner recorded calicivirus cases with red ulcers on the tongue and mouth.

Evidence: [PDSA — Cat flu](https://www.pdsa.org.uk/pet-help-and-advice/pet-health-hub/conditions/cat-flu) · [International Cat Care — Cat flu – upper respiratory infection](https://icatcare.org/articles/cat-flu-upper-respiratory-infection) · [Indonesia Medicus Veterinus (Universitas Udayana) — Laporan Kasus: Penanganan Flu Kucing akibat Feline Herpesvirus pada Kucing Kampung](https://ojs.unud.ac.id/index.php/imv/article/view/86088) · [Jurnal Sain Veteriner (UGM) — Angka Kejadian dan Karakteristik Lesi Patologi Calicivirus pada Kucing (Felis catus) di Vee Vet Bandung Periode Agustus–September 2024](https://journal.ugm.ac.id/jsv/article/view/101759)

## How does cat flu spread in multi-cat homes and shelters?

Cat flu spreads through contact with sick cats, with healthy-looking carrier cats, and through contaminated objects such as food bowls, bedding and clothing. ICC explains that the viruses can survive for days in the environment and on objects. Most cats that recover become carriers. Herpesvirus carriers can shed the virus again when stressed, while calicivirus carriers usually shed it for weeks to months. Cornell notes that calicivirus is found in about 10% of cats living in small groups, but in up to 90% of cats in crowded places such as shelters and catteries. The Merck Veterinary Manual adds that overcrowding and stress increase the risk of disease.

If you keep more than one cat, ICC advises isolating a sick cat in one room with its own food bowls and litter tray. The room should be easy to clean; ask your vet which disinfectant is safe for cats. ICC also stresses disinfection and careful hygiene when nursing a sick cat, because the viruses can be carried on clothing. Shelters, breeders and people caring for unowned cats may need extra measures, such as isolating new arrivals and vaccinating early, planned together with a vet.

Evidence: [International Cat Care — Cat flu – upper respiratory infection](https://icatcare.org/articles/cat-flu-upper-respiratory-infection) · [PDSA — Cat flu](https://www.pdsa.org.uk/pet-help-and-advice/pet-health-hub/conditions/cat-flu) · [Cornell Feline Health Center — Respiratory infections](https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/respiratory-infections) · [Merck Veterinary Manual (cat owner version) — Feline Respiratory Disease Complex (Feline Viral Rhinotracheitis, Feline Calicivirus)](https://www.merckvetmanual.com/cat-owners/lung-and-airway-disorders-of-cats/feline-respiratory-disease-complex-feline-viral-rhinotracheitis-feline-calicivirus)

## When should a cat with flu see a vet?

Take your cat to a vet as soon as you notice flu signs, and urgently if it is a kitten, is struggling to breathe or has stopped eating and drinking. PDSA stresses that kittens should be seen quickly because they can deteriorate fast. According to ICC, a cat that will not eat may need hospital care, as poor nutrition slows recovery; a blocked nose makes it hard for a cat to smell its food. Vets usually diagnose cat flu from the signs after ruling out other causes, and may take a throat or eye swab for laboratory testing. PDSA suggests waiting outside the clinic's waiting room so that other cats are not infected.

Your vet decides on treatment, which mainly aims to keep the cat comfortable while its body fights the virus. PDSA explains that antibiotics do not kill viruses, so they are only given if the vet suspects a bacterial infection. Do not give medicines or eye drops without your vet's advice. With treatment, signs often improve within one to two weeks, but Merck notes that severe cases can last up to six weeks. Some cats are left with permanent damage inside the nose and a long-term runny nose (chronic rhinitis), or have flare-ups when stressed.

Evidence: [PDSA — Cat flu](https://www.pdsa.org.uk/pet-help-and-advice/pet-health-hub/conditions/cat-flu) · [International Cat Care — Cat flu – upper respiratory infection](https://icatcare.org/articles/cat-flu-upper-respiratory-infection) · [Merck Veterinary Manual (cat owner version) — Feline Respiratory Disease Complex (Feline Viral Rhinotracheitis, Feline Calicivirus)](https://www.merckvetmanual.com/cat-owners/lung-and-airway-disorders-of-cats/feline-respiratory-disease-complex-feline-viral-rhinotracheitis-feline-calicivirus)

## Can vaccination prevent cat flu?

Vaccination does not always prevent infection, but it greatly reduces the risk of severe cat flu and is a core vaccine for all cats. The WSAVA 2024 vaccination guidelines table lists herpesvirus and calicivirus, together with panleukopenia, as core cat vaccines worldwide. WSAVA says kitten vaccination should start no earlier than 6 weeks of age and be repeated until 16 weeks, while ICC and PDSA give 8–9 weeks as a common starting age. After that, cats need boosters on a schedule set by your vet. Cornell notes that herpesvirus vaccination also reduces virus shedding, which helps protect other cats in the home. PDSA adds that cats that have already had flu still benefit from vaccination.

In Indonesia, cat vaccination is offered by veterinary clinics and by some local government facilities. For example, the Batam city puskeswan (animal health centre) lists cat vaccination among its services, and the mobile animal clinics launched in July 2026 by the Jakarta food security, marine and agriculture office (Dinas KPKP) offer check-ups and vaccination. Ask about the vaccine type, schedule and cost before you go, and keep your cat's vaccination record for the next appointment.

Evidence: [WSAVA — Core and non-core vaccines for pet cats (2024 guidelines table)](https://wsava.org/wp-content/uploads/2025/06/Cats-Vaccination-Table.pdf) · [International Cat Care — Vaccinating your cat](https://icatcare.org/articles/vaccinating-your-cat) · [PDSA — Cat flu](https://www.pdsa.org.uk/pet-help-and-advice/pet-health-hub/conditions/cat-flu) · [Cornell Feline Health Center — Respiratory infections](https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/respiratory-infections) · [Puskeswan Kota Batam — Layanan](https://puskeswan.batam.go.id/layanan/) · [Dinas KPKP Provinsi DKI Jakarta — Dinas KPKP DKI Jakarta Luncurkan 5 Unit Mobil Klinik Hewan Keliling](https://dkpkp.jakarta.go.id/news/dinas-kpkp-dki-jakarta-luncurkan-5-unit-mobil-klinik-hewan-keliling-jangkau-seluruh-wilayah-jakarta-mulai-13-juli-2026)

## Can people catch cat flu?

No. Cat flu caused by herpesvirus and calicivirus only affects cats; PDSA confirms that people and other animals do not catch it. The US CDC explains that these two viruses are not related to influenza viruses. However, cats can also be infected with influenza A viruses, including H5N1 bird flu, which is a different disease. The CDC notes that cats infected with bird flu can become severely ill and die, although the risk of people catching influenza from a cat is low. Early signs can look similar, so do not guess the cause yourself. Ask a vet to examine a sick cat, and wash your hands after touching a sick cat or possibly contaminated surfaces, as the CDC advises.

Evidence: [PDSA — Cat flu](https://www.pdsa.org.uk/pet-help-and-advice/pet-health-hub/conditions/cat-flu) · [CDC — About Cat Flu (Influenza in Animals)](https://www.cdc.gov/flu-in-animals/about/cat-flu.html)

## Sources & references

1. [International Cat Care — Cat flu – upper respiratory infection](https://icatcare.org/articles/cat-flu-upper-respiratory-infection)
2. [Cornell Feline Health Center — Respiratory infections](https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/respiratory-infections)
3. [PDSA — Cat flu](https://www.pdsa.org.uk/pet-help-and-advice/pet-health-hub/conditions/cat-flu)
4. [Indonesia Medicus Veterinus (Universitas Udayana) — Laporan Kasus: Penanganan Flu Kucing akibat Feline Herpesvirus pada Kucing Kampung](https://ojs.unud.ac.id/index.php/imv/article/view/86088)
5. [Jurnal Sain Veteriner (UGM) — Angka Kejadian dan Karakteristik Lesi Patologi Calicivirus pada Kucing (Felis catus) di Vee Vet Bandung Periode Agustus–September 2024](https://journal.ugm.ac.id/jsv/article/view/101759)
6. [Merck Veterinary Manual (cat owner version) — Feline Respiratory Disease Complex (Feline Viral Rhinotracheitis, Feline Calicivirus)](https://www.merckvetmanual.com/cat-owners/lung-and-airway-disorders-of-cats/feline-respiratory-disease-complex-feline-viral-rhinotracheitis-feline-calicivirus)
7. [WSAVA — Core and non-core vaccines for pet cats (2024 guidelines table)](https://wsava.org/wp-content/uploads/2025/06/Cats-Vaccination-Table.pdf)
8. [International Cat Care — Vaccinating your cat](https://icatcare.org/articles/vaccinating-your-cat)
9. [Puskeswan Kota Batam — Layanan](https://puskeswan.batam.go.id/layanan/)
10. [Dinas KPKP Provinsi DKI Jakarta — Dinas KPKP DKI Jakarta Luncurkan 5 Unit Mobil Klinik Hewan Keliling](https://dkpkp.jakarta.go.id/news/dinas-kpkp-dki-jakarta-luncurkan-5-unit-mobil-klinik-hewan-keliling-jangkau-seluruh-wilayah-jakarta-mulai-13-juli-2026)
11. [CDC — About Cat Flu (Influenza in Animals)](https://www.cdc.gov/flu-in-animals/about/cat-flu.html)

## Keep exploring

- [Cat vaccinations: types, schedule and benefits](https://panduanhewan.org/en/pet-health/cat-vaccinations/)
- [Rabies in dogs and cats: signs and prevention](https://panduanhewan.org/en/pet-health/rabies-in-dogs-and-cats/)
- [Neutering cats and dogs: benefits, timing and aftercare](https://panduanhewan.org/en/pet-health/neutering-cats-and-dogs/)
- [Choosing a vet and vet clinic in Indonesia](https://panduanhewan.org/en/pet-health/choosing-a-vet-in-indonesia/)
- [Domestic cat](https://panduanhewan.org/en/species/cat/)

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Cite: PanduanHewan. (2026). Cat flu: signs, spread and vaccination. PanduanHewan.org. https://panduanhewan.org/en/pet-health/cat-flu/