Help! My Kitten Has Cat Flu

Updated June 6, 2021

‘At A Glance (Details Below)’

What Is Cat Flu?

  1. Cat flu isn’t influenza or a cold, it’s either a herpesvirus or calicivirus
  2. Symptoms include fever, not eating, and eye or respiratory infection
  3. Many infected cats become virus carriers or have lifelong problems
  4. Rarer conditions caused by cat flu include arthritis, gingivitis, eye damage, stillbirths & abortion

Now dive deeper.

A stray kitten was found in a backyard a few weeks ago. Like most people do, her finders never hesitated to give her a home. Straight away, however, they knew something was wrong.

That’s her pictured above and below. She’s obviously miserable, but it’s the second photo that shows what’s really going on. This is ‘cat flu’.

You probably diligently vaccinate your cat against flu but do you know what it is? Cat flu is nothing like what most people think. For a start, it’s not flu!

Common Symptoms Of Cat Flu

Cat flu just looks like a severe cold until you take a closer look. It causes:

cat flu symptoms
Mouth ulcers, conjunctivitis and nasal discharge in a poor kitty with cat flu
  • Fever, lethargy and not eating or drinking
  • Clear or yellow-green discharge from the eyes and nose
  • Sneezing, coughing and difficulty breathing (read the other causes of sneezing in cats here)
  • Ulcers on the mouth, tongue and occasionally the eyes

But that’s not all. These nasty viruses sometimes do a lot more damage. Other important effects can be:

  • Arthritis
  • Viral pneumonia
  • Stillbirth, abortion or birth defects

And yet, there’s still even more. Most of the time it doesn’t go away…

How Long Does Cat Flu Last?

For a simple, uncomplicated case of flu, a cat might be back to normal in seven days. However, in most cases, secondary bacterial infection of the eyes, nose, sinuses or chest increases both the severity and duration of the illness.

Cat flu is treated by:

  • TLC, fluid and nutrition support
  • Antibiotics and eye ointments for secondary infection
  • Bathing and steaming to reduce buildup of secretions
  • More TLC

Most of these cats will still make a full recovery, although they suffer quite a bit in the process. For many, though, and especially the young or neglected, long-term problems persist.

Long-Term Effects of Cat Flu

  • Chronic rhinitis is a nasal infection that persists for life
  • Stunted growth is common in infected kittens
  • Stomatitis-gingivitis complex is a severe mouth infection
  • Most cats who get infected will carry the virus for life

If there’s just one thing I want all cat owners to understand about flu, it’s this last point about carriers.

How Cats Catch Flu

Cat flu is spread in the saliva of apparently healthy carrier cats. Nearly every cat who got cat flu once will carry and spread the virus for life. Carriers are estimated to represent around 30% of all cats.

It’s not their fault. It’s up to all of us to know where the real risk is and stop it. Here’s what I do…

How I Prevent Cat Flu

The viruses spread both directly from cat to cat and indirectly via objects, people and the environment.

  • I assume that every cat I see could be a carrier
  • I wash my hands between each cat and change my coat regularly
  • I use an isolation room for known infected cats
  • I clean and disinfect all equipment after every cat I see
  • I change my clothes when I get home
  • I ask breeders to test their breeding stock for carriers
  • I get my kittens from trusted sources like good breeders or the Animal Welfare League

I hope now you understand why a good cattery never mixes cats or uses anything that can’t be disinfected.

I’m sorry if this all sounds a bit like a scare story. It’s all gospel truth but we’re in danger of forgetting how things once were. If you want to read more, visit an old page where I featured three cats with rare consequences of cat flu or here for other causes of mouth ulcers.

Related: Why Kittens Often Have Runny Eyes

Have something to add? Comments are welcome below and will appear within 24 hours.
By Andrew Spanner BVSc(Hons) MVetStud, a vet in Adelaide, Australia. The information provided here is not intended to be used as a substitute for going to the vet. If your pet is unwell, please seek veterinary attention.


8 Replies to “Help! My Kitten Has Cat Flu”

  1. Having just moved house with a 10year old cat, I bought a cat harness online to help settle him safely in the garden. The aim was to show him the back garden and fields in the hope he would stay away from main road. The harness proved useless with the first fitting. Although it looked a tight fit he wriggled out of it. He had cat flu as a kitten and continues to have a runny eye 10 years on. Is it safe to return the cat harness or would that be endangering other animals?

    1. Hi Pamela. That’s a very good question and I wish more people thought of this. You are right of course – once a carrier, always a carrier. In fact, even cats with no symptoms pose a risk as there are plenty of carriers out there you can’t tell. Therefore, any product used on a cat cannot be safely returned regardless of their outward health.

  2. I have recently taken in a six and a half year old cat who was being rehome by a woman near my grandaughter and having lost my other cat wanted another now it turns out he may have this virus he is aggressive hissing and spitting plus growling is drooling all over the place he is on vets meds but is it best to have him put down I am in a real dilemma he is so beautiful I am a widow and disabled so if you were me what would you do truthfully yours linda

  3. Helped quite a bit with our 15 plus-year-old feral female. Has mouth ulcers that we will have our vet look at–I had the coronavirus last January and we noticed symptoms in the female some weeks later. Too, our two other cats share eating bowls and are asymptomatic, so will be interesting to hear our vet’s opinion.
    Thanks again for helping us narrow down the problem(s), extremely helpful.
    Best regards,

    1. Thanks Gene. I’m glad it was useful. As an update, I don’t think the novel coronavirus (or even the feline version) is likely to be related. Good luck.

  4. We have just moved into a house in France. The woman next door died and left 3 cats who get fed twice a day my a french man the cats live outside. Since we have been here the 2 females have had 2 lots of kittens! Not spayed! A kitten came in to our garden in the most fearful state of cat flu he was put to sleep. My question having had permission from new house owner do I have them all put to sleep????

    1. Hi Penny. Many kittens survive cat flu although they will often have ongoing effects of the infection. However, these aren’t usually bad enough to worry about euthanasia. Some kittens may not survive the acute phase and need emergency euthanasia but you will reduce this by providing vet care and good nutrition. If homes can be found for the kittens it’s worth persevering.
      This might also interest you: successful stray cat management case study

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