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Cat Flu (Upper Respiratory Tract Disease)

cat fluAlso known as upper respiratory tract disease, cat flu is a general term used to describe a common set of symptoms of the upper respiratory tract. Cat flu is very similar to the colds and flu that affects people. 

Cat flu is seen most often in young kittens, senior cats, crowded environments such as cat shelters where close proximity to other cats as well as increased levels of stress increases the rate of transmission. Cats with weakened immune systems are also at greater risk. If healthy adults do contract cat flu, they generally recover quickly, however, kittens, senior cats and those with weakened immune systems can become quite sick.

What causes cat flu?

Cat flu is caused by several pathogens (disease-causing organisms) including viruses, bacteria, and mycoplasma.
The most common causes are:

Feline herpesvirus and feline calicivirus are by far the most common cause of cat flu, being responsible for 80% of cases. Feline herpesvirus typically is the most severe of the two. Co-infections and secondary bacterial infections are also common.

How is cat flu spread?

  • The pathogens responsible for cat flu are highly contagious and can easily spread via direct or indirect contact.
    Direct contact: Infection is passed from a sick or carrier cat via eye, nasal, and mouth discharges. It is possible for infected dogs to pass bordetella on to cats and vice versa.
  • Indirect contact (fomites): Contaminated food bowls, bedding etc. Calicivirus is resistant to many disinfectants and can live in the environment for long periods of time.
  • Chronic carriers/shedders: Cats who have been exposed to feline herpesvirus or calicivirus can shed the virus even after they have recovered. There is more information on carriers/shedders later in the article.

What are the symptoms of cat flu?

Many of the causes of cat flu have overlapping symptoms. However, some causes have individual symptoms. For example, mouth ulcers are often seen in a cat with of feline calicivirus, whereas eye ulcers are seen with feline herpesvirus. Cats with FCV may also develop a limp.

Generalised symptoms:

  • Fever: When an infection takes hold, the body responds by increasing its temperature. This can make your cat feel generally unwell.
  • Anorexia (loss of appetite): A cat with the flu will often lose his appetite. This is made worse by the nasal discharge, which affects the cat's sense of smell.
  • Dehydration: Sick cats can quickly become dehydrated as they don't tend to drink as much when they are feeling unwell.
  • Lethargy and depression.

Other symptoms of cat flu:

Calicivirus can cause transient arthritis in cats which can result in limp. This condition is known as 'limping syndrome'.
Calicivirus may also result in ulceration of the paws.


mouth ulcers in cat

Ulcerations of the mouth and tongue may develop, making eating painful. Gums may become inflamed (gingivitis) and red and your cat may salivate (drool) excessively due to ulcers. Calicivirus is usually responsible for mouth ulcers.

eye discharge in cats

A thick, sticky eye discharge also occurs with cat flu. Eyes become red and inflamed (conjunctivitis). Pain, squinting, sensitivity to light can develop if your cat has developed corneal ulcers due to herpesvirus infection.
Nose: Sneezing and nasal discharge are common symptoms of cat flu.
The virus causes inflammation of the mucous membranes (rhinitis), accompanied by nasal discharge, which may be clear or thick. This can make breathing difficult.

Complications of cat flu:

Inflammation in the lungs can lead to secondary bacteria taking hold and pneumonia developing. Symptoms of pneumonia can include the following:

  • Difficulty breathing
  • Rapid breathing (tachypnea)
  • Blue tinge to the gums and tongue
  • Rattling breathing sounds

How is cat flu diagnosed?

Your veterinarian will perform a physical examination of your cat and may make a diagnosis based on present symptoms. To determine the exact pathogen, he/she may take a throat or eye swab to send off to a laboratory for testing. This isn't always deemed to be necessary as treatment is often similar regardless of the pathogen involved.

  • Fluorescein is an orange dye which your veterinarian may put in your cat's eyes to look for corneal ulcers.
  • X-rays may be taken to evaluate the lungs for pneumonia.

How is cat flu treated?

Treatment depends on the cause of the cat flu. There are no drugs to treat viral infections, and supportive care is necessary to alleviate symptoms while your cat fights the infection. This includes keeping the nose clear of discharge. A stuffed up cat will often lose his appetite, therefore, it is important that you do everything you can to encourage your cat to eat and drink. If your cat refuses to eat or drink, then seek veterinary advice immediately.

  • Even if the cause is viral, antibiotics may be prescribed to protect against secondary bacterial infections.
  • Encouraging your cat to eat and drink is extremely important. If he is not showing an interest in his regular food, try offering him the small "gourmet" canned food. Warming it up a little can help make it more appealing. There are also high-calorie products available from your veterinarian to use with sick and recuperating cats. These are usually in paste form. Read here for more information on how to get a cat to eat. Cats with mouth ulcers would benefit from soft food.
  • Nasal decongestants and vaporisers can be used to help clear discharge and ease breathing.
    If you don't have a vaporiser, run a hot shower for 10 minutes so the room gets steamy and leave your cat in the bathroom for 10-15 minutes can help loosen up congestion.
  • If your cat has developed corneal ulcers, he may be given medication to dilate the pupils which will relieve discomfort and possibly antibiotic eye drops to treat or prevent bacterial infection.
  • In severe cases, your cat may be hospitalised, given fluids to treat dehydration and correct electrolyte/acid balance as well as providing nutritional support. This may be by  encouraging him to eat with highly palatable foods (such as shredded chicken or tuna), appetite stimulants or if necessary a feeding tube, if your cat is having difficulty breathing he may require oxygen therapy.
  • Pneumonia will be treated with antibiotics as well as supportive care.

Feline Chlamydophila:

  • Antibiotic eye ointment (usually tetracycline) will be prescribed.
  • Supportive care.

Feline herpesvirus:

  • Supportive care.
  • Antiviral drugs such as acyclovir (Zovirax).
  • L-lysine is an over the counter amino acid has been shown to suppress viral replication and inhibit cytopathogenicity.
  • Removal of discharge from the nose and eyes with a warm, damp compress will make your cat more comfortable.
  • If the cat has become anorexic, force feeding may be necessary. Fluids may also be required to treat dehydration.

Feline calicivirus:

  • Supportive care.
  • Removal of discharge from the nose and eyes will make your cat more comfortable.
  • If the cat has become anorexic, force feeding may be necessary. Fluids may also be required to treat dehydration.
  • Antibiotics may be prescribed to treat secondary bacterial infections.
  • Corticosteroids and/or anti-inflammatories may be prescribed if your cat has developed transient arthritis.

How long will it take my cat to recover from cat flu?

This depends on the severity and the overall health status and age of your cat. But typically you can expect your cat to recover between 7-10 days. Some cats may go on to become chronic shedders and during these periods may develop signs of disease again, although typically milder, or in some cases, no symptoms at all but they can pass on cat flu to other cats during the period of shedding.

Cats who fail to respond to supportive care and/or antibiotic therapy should be tested for FIV or FeLV.

What is the prognosis for a cat with cat flu?

Generally, the prognosis is very good with prompt treatment. Young kittens are at the greatest risk but health adult cats usually have an uneventful recovery after a week or so.

Some cats infected with feline herpesvirus will develop chronic rhinosinusitis as a result of damage to the nasal mucosa. Symptoms include chronic nasal discharge and sneezing. This condition can be lifelong. While it may be uncomfortable for your cat, it is a condition that can be managed with antivirals, antibiotics (where necessary) and relief from nasal congestion.

What is a carrier/shedder cat?

Once a cat has contracted feline herpesvirus, he has it for life. Once he recovers from the initial infection, small numbers of the virus lie dormant in the nerves. Some cats who have previously been exposed to feline herpesvirus can occasionally shed the virus when it re-activates at some time in the future. This is usually during periods of stress such as stress (caused by pregnancy, lactation, overcrowding, poor nutrition, new family member etc.) or another sickness. They may or may not show symptoms while they are shedding depending on their overall health. Calicivirus can be shed for up to 3-18 months after infection but most cats have completely eliminated the virus by 18 months. It is possible for other cats to catch feline herpesvirus or calicivirus if he comes into contact with a cat who is shedding the virus.

Carrier cats can live a full life but care should be taken to avoid stress.

How is cat flu prevented?

Vaccinating your cat will protect it against FHV and FCV. These are covered in the regular F3 vaccination.

There is a vaccination available for Chlamydophila felis. It has side effects associated with a small percentage of cats, including lethargy, lameness, depression, anorexia, and fever, and therefore, it is only recommended for high-risk situations. The American Association of Feline Practitioners does not recommend routine use of this vaccination. Speak to your own veterinarian about this vaccination.

Proper hand washing and changing of your clothing after handling other cats — especially high-risk cats such as those in a shelter — should be practiced before handling your own cats.

Also, as a courtesy, if you are visiting multiple breeders or shelters in one day, advise them beforehand. Some breeders will ask you not to visit them if you have been to another cattery, to reduce the chances of transmitting diseases.

It is recommended that new cats to the household be quarantined for 2 weeks before being introduced to other cats.

Can I catch colds and flu from my cat?

No, it is not possible to catch a cold or flu from your cat, nor can your cat catch a cold or flu from you.

Home care:

  • Administer all medications as prescribed.
  • If you have other cats in your household, isolate the sick cat to avoid spreading the disease.
  • Always wash your hands thoroughly before and after handling cats with cat flu.
  • Never give cold medications for humans to a sick cat.
  • Keep a close eye on your cat's food and water intake. It is essential he eats if you can't encourage him to do so, speak to your veterinarian.
  • Keep the eyes and nose clear of discharge by wiping with a cotton or gauze soaked in saline solution.
  • Your cat should be confined to the indoors and allowed to rest while he recovers.