Cat flu - signs, diagnosis and treatment

What causes cat flu and how does it spread?

Cat flu can be caused by several different types of infectious agents, both viruses and bacteria. The main causes of cat flu are feline herpes virus (FHV-1) and feline calicivirus (FCV). It is estimated that about 80-90% of cat flu cases are caused by these viruses. However, the bacteria Chlamydofila felis, Bordetella bronchiseptica and Mycoplasma spp can have a part in cat flu. The bacteria often come after the virus, when the cat's immunity has been reduced by the viral infection. The viruses are usually transmitted by direct or close contact between cats, but the virus may also survive for short periods in the environment.

Many of the cats infected with the herpes virus become chronic carriers, and they can continue to spread the virus even after they are no longer ill, especially if they are exposed to stress (for example, travel, major changes in the cat's environment, operations, etc.). The cat can secrete the virus up to a couple of weeks after being exposed to stress.

Signs of cat flu

From the time your cat may come in contact with the infection. It takes about 2-10 days before the disease breaks out.

• Sneezing
• Nasal discharge
• Discharge from their eyes (ocular)
• Conjunctivitis
• Lethargy
• Inappetence
• Fever
• Occasionally they may also develop ulcers in their mouth, drooling, coughing

Diagnosis of cat flu

If the cat has typical signs of feline flu, especially if several cats in the same household have become ill, the vet will usually suspect cat flu. Samples can be taken from the cat in the acute phase (when the cat has recently started to show signs) to try to find which infectious agent is causing the problem. For example, swabs can be taken from the eyes to rule out causes such as Chlamydophila felis. This can be a good idea if you have more than one cat. If you only have one cat and it is not very ill, a sample is rarely taken.

If the signs do not resolve, then further investigation will be needed to identify the underlying cause. The cat may need sedation or a general anaesthetic in order to examine the nose and throat, for example, to check for foreign bodies, a polyp, tumour or dental problem. Endoscopy, x-rays and computed tomography (CT) can be very helpful in these cases. They allow any necessary samples to be collected from the nasal passages.

Cats can unfortunately get chronic problems and despite investigations, it is not always possible to determine the cause of recurrent or chronic feline flu.

Treatment of cat flu

Treatment depends on your cat’s signs. It usually involves supportive treatment at home. It is important that the cat gets enough nutrition. Cats that are unwell are often reluctant to eat. The smell of food usually stimulates cats to eat and this will be affected if they have cat flu. If they have ulcers in their mouth, eating may be uncomfortable. Offer your cat warmed soft foods; adding warm water or warming it to room temperature can help. If your cat will not eat their normal food, offer them oily fish, chicken or a special diet like Royal Canin Recovery diet or Hills a/d. These are high calorie diets, so they only require a small amount, and they have a strong aroma, which often tempts cats to eat.

Keep their eyes and nose clean, and if possible, they should stay indoors and rest. Nasal drops with saline solution (without a prescription at the pharmacy) can sometimes provide some help. If your cat seems lethargic, it may be wise to take the temperature of the cat 1-2 times a day. Read our guide to doing a physical examination of your pet. It is important not to give human medication to your cat, as it can be harmful. Please seek veterinary advice in the first instance, if you are concerned about your cat.

A course of antimicrobials may be prescribed by your vet if a secondary bacterial infection is present. Your vet might also talk to you about doing a blood test to check your cat’s red and white blood cell count and to check their hydration. They may suggest checking if your cat is a carrier of Feline leukaemia virus (FeLV) or Feline immunodeficiency virus (FIV).

Can cat flu be prevented?

• Vaccination: prevention of cat flu is the best option for your cat. Like most vaccines, the cat flu vaccine will not protect your cat 100% so you may still see some mild flu signs. However, vaccination significantly reduces the severity of the signs and limits the spread of the infection
• Large groups: these increase the risk of cat flu outbreaks. If your cat needs to board at a cattery, ensure that you ask about infectious disease measures prior to their visit
• More than one cat in a household: keeping them separate, especially with highly social cats is not always possible and may cause stress, but may help to reduce the risk of spreading the infection. Use separate food bowls and litter trays, and clean them frequently
• Avoid stress: they can cause a flare up. There are a number of general things that you can do to reduce stress. Provide plenty of hiding places. Use pheromone therapy, such as a Feliway or a Zenifel diffuser. Make sure that your cat’s litter tray, feeding bowl and water bowls are out of the line of sight of other cats.
• Rescued animals: some cats are exposed to cat flu as a kitten; this can be quite common in rescue and feral cats. They can also become carriers of the virus as they get older and may suffer from flare ups over the years. Other cats are carriers and shed the virus but do not show signs
• Quarantine new cats: check that any new cat does not have signs, sneezing, watery eyes or runny nose, before taking it home. If possible, keep the new cat separate from the other cats for the first week. For this to work, you need to be careful with hygiene, use different food and water bowls for the cats, wash your hands and preferably change clothes
• Cleaning: if you need suspect a cat flu infection, or need to clean an area where a cat has been showing signs, mechanical cleaning (scrubbing off all visible dirt) and disinfection with, for example, Virkon, is important to kill any potential infectious agents

When to see your physical veterinarian

• If your cat has signs of respiratory disease

Still worried?

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