Cat flu is a common viral illness that affects a cat’s nose, throat and eyes. Although it can resemble a human cold, it can be much more serious—especially for kittens, elderly cats and those with underlying health problems.

Prompt veterinary advice is always recommended.

What Causes Cat Flu?

Cat flu is usually caused by one or more of the following viruses or bacteria:

Feline herpesvirus (FHV-1) – often causes more severe illness and is strongly linked with eye ulcers. Once infected, cats typically remain lifelong carriers.

Feline calicivirus (FCV) – exists in many strains. It may cause mouth ulcers and occasionally lameness in kittens. Cats can shed the virus long after they appear well.

Bordetella bronchiseptica – a bacterium also involved in kennel cough in dogs. It can cause coughing and lung infections in cats.

Chlamydophila felis – usually leads to red, sore, watery eyes and mild flu signs.

These infections spread easily through saliva, mucus, sneezes, shared bowls, bedding, toys and even human clothing. Some viruses can survive in the environment for several days to weeks.

Symptoms of Cat Flu:

Signs can take up to two weeks to appear after infection and include:

• Sneezing
• Runny nose
• Weepy eyes
• Sore eyes (cat flu can cause eye ulcers)
• Low energy (lethargy)
• Mouth ulcers
• Reduced appetite
• Coughing
• High temperature (fever)
• Sore throat or difficulty swallowing (you may see your cat gagging)
• Hoarseness

Contact your vet as soon as you notice symptoms, especially if your cat:

• Is struggling to eat or drink
• Seems unusually quiet, lethargic or has breathing difficulties
• Their eyes look sore, cloudy, or are held closed
• Is under six months of age – Kittens are particularly vulnerable because their immune systems are still developing. They can catch flu from their mother, even if she shows no signs of illness. Infected kittens may become carriers for life or may suffer severe symptoms, so early veterinary attention is vital.

To protect other pets, please wait outside the clinic until you are called in.

How Cat Flu is Diagnosed

Cats are diagnosed by a vet, usually based on their symptoms and history

Treatment for Cat Flu

While there is no single cure for cat flu, supportive care helps most cats recover.

Medications your vet may use

• Anti-inflammatories to reduce fever, pain and inflammation.
• Antibiotics only if a bacterial infection is suspected.
• Mucolytics to help break down thick nasal mucus so your cat can breathe and smell food more easily.
• Eye drops to soothe sore eyes; antibiotic drops if infection is present.
• Antivirals can help in some cases of herpesvirus but are costly and need several weeks of treatment.
• Hospitalisation may be required if your cat is very unwell, dehydrated or stops eating.

Caring for a Cat with Flu at Home

Most cats can be nursed at home with your vet’s guidance.

Keep stress low

Stress can trigger flare-ups or make symptoms worse. Provide a quiet space, keep routines predictable and avoid big changes while they recover.

Clean eyes and nose

Gently wipe away discharge using cotton pads soaked in warm water. This helps your cat breathe and smell their food.

Encourage eating and drinking

Cats often go off their food when they can’t smell it. Offer warm, strong-smelling foods such as:

• sardines
• tuna
• pilchards
• roast chicken

Always check the food is warm—not hot—before offering it. Cats that refuse food may require hospital care.

Help them breathe

A steamy bathroom can help loosen mucus. Allow your cat to join you briefly while you run a shower or bath but never force them to stay if they appear stressed.

Long-Term Effects and Carriers

Some cats never fully clear the virus and remain carriers, meaning they can shed germs intermittently without appearing ill. These cats may:

• Have occasional flare-ups, especially during periods of stress
• Develop chronic nasal discharge due to long-term inflammation
• Be prone to recurring eye or mouth issues

Calicivirus is associated with long-term gum and mouth inflammation (gingivitis), which sometimes requires ongoing treatment or dental work.

Prevention: Vaccination Is Key

Vaccination is the most effective way to protect against cat flu.

• Kittens can be vaccinated from 8–9 weeks of age.
• They need two initial doses, followed by regular boosters throughout life.
• Boarding catteries require up-to-date vaccines.
• Even if your cat has had flu before, vaccination can reduce symptoms during future flare-ups.

Vaccination doesn’t guarantee total immunity, but it significantly reduces the severity of illness and helps prevent spread.