Cat Flu: Sneezes and Sniffle or Something More Serious?

 From your own experience, you know there’s a big different between having a head cold and the flu. It’s the same for cats. Cats can get upper respiratory tract infections (a ‘cold’ in plain English) that are mild and don’t need treatment, but catching cat flu is a whole different story.

What Causes Cat Flu?

Traditionally cat flu is a viral disease, caused by feline Calici virus and feline Herpes virus. But now two bacteria, namely Chlamydia and Bordetella, are acknowledged as causing flu-like symptoms in cats. 

Even tiny microbes have individual characteristics and these quirks can make cat flu tricky to pin down,

• Chlamydia: This is related to bugs that cause ill health in people, but you can relax because this particular variant is ‘species specific’, meaning it only infects cats.
• Feline Calici Virus: This virus is constantly changing and adapting, which makes it hard for the vaccine manufacturers to keep up. Indeed the latest strain, VSD (or Virulent Systemic Disease) targets lung tissue causing pneumonia and severe fever.
• Bordetella: This is related to the human whopping cough bug, but don’t worry, these bugs rarely (if at all) swap between the species.
• Feline Herpes Virus: This is more straightforward than Calici virus, as there’s only one strain which is well covered by the cat flu vaccination.

How Do Cats Catch Flu?

Did your Mum tell you to cover your mouth when you sneezed?

This is because of droplet dispersal, which is how flu bugs spread. The flu bugs love to hitch a ride on the moist droplets ejected in a sneeze, or indeed in saliva or a runny nose. Most flu bugs happily survive on surfaces for seven days, just waiting for the next cat to come along and sniff or lick and pick up infection. The key point here is that cats don’t need direct contact, with infection acquired from contaminated bowls, grooming tools, or surfaces. Typically, the incubation period from contact to illness is around two weeks.

What are the Symptoms?

Remember what it feels like to have proper flu? Well that’s pretty much how your cat feels.

• Conjunctivitis.
• Bunged up nose.
• Sore throat.
• Achy joints.
• Fever.

In addition, specific complications include:

• Dehydration.
• Secondary pneumonia.
• Ulcers: On the tongue and on the surface of the eye.
• Loss of appetite.

Is Cat Flu Dangerous?

Yes and no!

An adult cat with a strong immune system will feel rough for a few days, but with TLC (tender loving care) will soon shake off the infection. These cats are often sniffly and sneezy, and perhaps lose interest in food, but with careful nurturing they do just fine.

Those most at risk of serious illness are the very young or adults that are vulnerable because of pre-existing health conditions. Some drugs designed to fight the inflammation associated with IBD or skin allergies, or indeed chemotherapy drugs used against cancer, directly suppress the immune system leaving the cat with its defense's down and open to attack.

How is Cat Flu Treated?

There’s no medical cure for cat flu and it’s up to the cat’s immune system to fight off infection. Therapy is aimed at making the cat more comfortable and treating complications such as pneumonia.

• Lysine: This is a new treatment which makes it harder for the herpes flu virus to replicate (breed), thus limiting the amount of virus in the cat. Feline herpes virus uses arginine to reproduce, but lysine antagonizes and decreases arginine’s availability.
• Mucolytics: These are drugs, e.g. Dissolving, which break down mucous and make it easier for the cat to breathe.
• Antibiotics: These don’t kill viruses and therefore don’t directly treat cat flu. (The exception is Chlamydia which responds to the tetracycline family of antibiotics). However, they may be needed against secondary infections such as pneumonia.

However, lysine has limited benefits against viruses other than herpes virus, and the flu vaccine gives good protection against the latter. So if your cat is vaccinated and catches cat flu, the illness is probably due to a bug other than herpes virus and lysine is unlikely to be helpful.