Cat Flu: Comprehensive Guide To Causes, Symptoms, And Care

Early recognition and gentle support create a soothing path to feline wellness.

By Shinta

Created on Sep 2, 2025

Early recognition and gentle support create a soothing path to feline wellness.

Cat Flu (Feline Upper Respiratory Infection): Causes, Symptoms, and Care

Feline upper respiratory infection, commonly referred to as “cat flu,” is a highly contagious disease complex affecting cats of all ages. Though not related to human influenza, its symptoms and impact can be dramatic for felines, especially kittens and those with weakened immune systems. Understanding the causes, recognizing early signs, and employing effective management and prevention strategies are vital to protecting your feline companions.

What Is Cat Flu?

Cat flu encompasses viruses and bacteria that infect the upper respiratory tract of cats, commonly leading to sneezing, eye and nasal discharge, fever, and more. While often mild, cat flu can become severe, particularly in kittens and cats with other health conditions.

Main Causative Agents

Feline herpesvirus-1 (FHV-1): Also known as feline viral rhinotracheitis, is a major cause of cat flu with the potential for chronic carrier states.
Feline calicivirus (FCV): Contributes to a large proportion of cases and is known for producing oral ulcers and, less commonly, severe, systemic disease.
Bacterial contributors: Bordetella bronchiseptica and Chlamydophila felis are common bacterial culprits, often alongside viral infection.

How Is Cat Flu Spread?

Cat flu viruses and bacteria are highly contagious and easily transmitted through direct contact with infected cats, their saliva, nasal or eye discharge, or contaminated objects (food bowls, bedding, grooming tools). The viruses can survive on surfaces for several days, making strict hygiene essential, especially in multi-cat environments.

Contact with infectious droplets from sneezing or grooming.
Contaminated surfaces in homes, catteries, shelters, and breeding establishments.
Carrier cats, who appear healthy but shed the virus intermittently, especially during stress.

Risk Factors

While any cat can develop cat flu, some are at higher risk:

Kittens or unvaccinated cats.
Cats from multi-cat households, catteries, or shelters.
Felines under stress, pregnant, or with compromised immune systems.

Signs and Symptoms of Cat Flu

Clinical presentation varies depending on the causative organism(s) and the catâs immune status, but classic symptoms include:

Sneezing and nasal discharge (clear, yellow, or green).
Eye discharge (watery or purulent) and conjunctivitis.
Fever.
Loss of appetite (due to reduced sense of smell and oral pain).
Lethargy.
Mouth ulcers (especially with FCV), drooling, or difficulty eating.
Sore throat, cough, or voice change.
In severe cases: dehydration, difficulty breathing, pneumonia.

Diagnosis of Cat Flu

Your veterinarian makes a clinical diagnosis based on symptoms and examination. Sometimes, nose, throat, or eye swabs are sent for laboratory testing (PCR or culture) to confirm the specific viruses or bacteria involved, especially for outbreaks or persistent cases.

Physical exam to rule out other causes of respiratory illness.
Swab tests for virus and bacteria identification, if necessary.

Treatment of Cat Flu

Most cat flu cases are managed with supportive care tailored to your catâs symptoms, as no drugs directly eliminate the main viruses. The goals are to keep your cat comfortable, treat secondary infections, maintain hydration and nutrition, and relieve discomfort.

Supportive Care

Keeping cats warm, clean, and comfortable in a quiet area.
Cleaning eyes and nose gently with damp cotton to remove discharge.
Enticing to eat with highly aromatic, soft foods (kitten foods, fish in oil, gentle warming to enhance smell); consider pureed and warmed food for ease.
Pain relief as prescribed; sore throats and eyes are common.
Maintaining hydration. If the cat wonât drink or eat, hospitalization and intravenous fluids may be required to prevent dehydration.

Medications and Advanced Support

Antibiotics: Prescribed if there is evidence of secondary bacterial infection (purulent discharge, fever, lethargy), or to prevent complications.
Eye drops/ointments: May be prescribed for severe eye involvement.
Anti-inflammatories: These may help reduce fever and discomfort.
Mucolytics or nasal drops: To support breathing by breaking up mucus and clearing passages.
Steam therapy/nebulisation: Placing the cat in a steamy bathroom or using a vaporizer helps loosen mucus and relieve nasal congestion.

When Is Hospitalization Needed?

Persistent lack of appetite (more than 2â3 days).
Severe dehydration or inability to drink.
Severe breathing difficulty, cyanosis (bluish gums), or extreme lethargy.
Require feeding tubes, oxygen supplementation, or intravenous fluids.

Prevention of Cat Flu

Prevention focuses on vaccination, reducing exposure, and hygiene:

Vaccination: Core vaccines protect against FHV and FCV. While vaccination may not prevent infection, it substantially reduces disease severity and viral shedding.
Isolate infected cats in multi-cat environments to reduce risk of spread.
Reduce stress for all cats, as stress can trigger virus shedding in carriers.
Maintain rigorous hygiene (clean surfaces, bowls, and hands between handling cats).
Routine veterinary check-ups support early identification of illness and optimize immunity.

Long-Term Carrier State

Following apparent recovery, most cats infected with FHV, and some with FCV, become carriers. Carrier cats may show no signs but intermittently shed virus, particularly during stress, surgery, or immunosuppressive treatment, risking infection to other cats. In some breeding colonies and shelters, carrier cats represent a significant source of continued infections.

**Characteristics of Feline Respiratory Virus Carriers**
Virus	Carrier State	Virus Shedding	Clinical Signs
Feline Herpesvirus (FHV)	Almost all infected become carriers	Intermittent, especially during stress	Occasional mild URI flare-ups
Feline Calicivirus (FCV)	50% may be carriers (often short-term only)	Continuous or intermittent	Usually inapparent, but may recur

Key Points for Cat Owners

Most cats recover fully with prompt supportive care, but vulnerable cats (young, old, immunocompromised) can develop serious complications.
Chronic or recurrent symptoms are possible, especially if the cat becomes a carrier.
Preventing spread is essential, particularly in multi-cat homes and breeding colonies.

Home Care Tips

Isolate sick cats, clean food bowls and litter trays frequently.
Encourage fluid and food intake; offer favorite, aromatic foods.
Keep the cat warm, dry, and stress-free.
Gently clean any discharge from nose and eyes several times a day.
Follow all treatments as prescribed by the veterinarian. Do not stop antibiotics prematurely.
Do not use medications intended for humans or other animals; always check with your vet first.
Avoid contact between healthy cats and items used by sick cats.

Frequently Asked Questions (FAQs)

Q: Can humans catch cat flu?

A: No, cat flu is specific to felines and cannot infect humans. However, viruses and bacteria can live on your hands, clothing, or surfaces and be transmitted to other cats, so good hygiene is vital.

Q: How long does cat flu last?

A: Acute symptoms can last 7â21 days, depending on the cat’s immune response and whether complications arise. Some cats can remain carriers for life.

Q: Is vaccination 100% effective?

A: Vaccination greatly reduces disease severity and viral shedding but does not always provide full protection, as viruses can mutateâand carriers may still shed virus despite being vaccinated.

Q: When should I see a veterinarian?

A: Seek veterinary care if your cat stops eating or drinking, is lethargic, shows severe breathing difficulty, or if symptoms worsen or persist beyond a few days despite care.

Q: Can I care for a cat flu carrier with other cats?

A: While it is possible, you must be vigilant about hygiene, isolation when the carrier is unwell, and ensure all other cats are fully vaccinated and kept healthy to minimize risk.

References and Further Reading

For detailed information about specific viruses and up-to-date advice, consult with your veterinary professional or trusted resources on feline health.

References

Author

Shinta

Shinta is a biotechnologist turned writer. She holds a master's degree in Biotechnology from Karunya Institute of Technology and Sciences and a PG Diploma in cellular and molecular diagnostics from Manipal University. Shinta realised her love for content while working as an editor for a scientific journal.

Read full bio of Shinta