Herpes Virus in Cats: Symptoms and Treatment

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What mental picture does the words “herpes virus” conjure up?

In my mind I see a snuffling, sneezing, snotty-nosed kitten whose eyes are gummed shut. This is because herpes virus is one of the two viruses commonly linked to cat flu (the other being calici virus).

But herpes virus also stars in its own solo show and causes an illness known as viral rhinotracheitis. Whilst the latter sounds impressive, it basically describes the symptoms because ‘rhino’ means nose, ‘trache’ means windpipe, and ‘-itis’ means inflammation. Pull these altogether and feline viral rhinotracheities (FVR) means an inflamed nose and a sore throat – sounds a lot like flu, doesn’t it?

The Startling Statistics

Vaccination against feline herpes virus I is considered ‘core’ or essential, and little wonder when you look at these statistics.

• Feline herpes virus is so widespread that in some areas 90% of cats are exposed to it.
• Of the cats exposed to herpes virus, 80% become lifelong carriers and a risk to other cats.
• Of the 80% that are carriers, 50% experience a flare up of symptoms at times of stress.

The moral of the story? Get your cat vaccinated!

Signs and Symptoms 

For those cats not protected by vaccination, the symptoms can vary depending on the cat’s age and the strength of their immune system. Kittens and young cats usually show the symptoms associated with full blown cat flu, which includes gummy sore eyes, snotty nose, sore throat, breathing difficulties, and fever.

Older cats with a stronger immune system may fight off infection only for it to get a grip if they are stressed or their immune system dips for some reason. Thus, once infected with herpes virus it can pose a lifelong problem.

Herpes virus has a predilection for eyes and is a common cause of conjunctivitis. These cats may have regular flare ups where the eyes become red and inflamed (the signs can sometimes be confused with an allergy) and produce a sticky discharge. Exceptionally unlucky cats can have long term corneal inflammation which leads to scar tissue formation and impaired vision.

Definitive Diagnosis

If your cat is not vaccinated and has upper respiratory signs typical of herpes virus then your vet may make a ‘presumptive’ diagnosis. This is because knowing the exact cause of the infection doesn’t necessarily change the treatment, and so the extra cost of swabs is not always justified. However, if for any reason a definitive diagnosis is necessary then swabs taken from the eye or mouth can aid identification.

Nursing a Cat with Feline Herpes Virus

Home nursing of the cat with FVR is make or break. Usually these cats feel lousy and have lost their sense of smell, which means they lose their appetite and hitch a ride on a downward spiral of deterioration.

Whilst there is not drug proven to kill herpes virus (more of this shortly) the vet may prescribe antibiotics against secondary bacterial infections and to protect the cat at risk of pneumonia. In addition, ask your vet if decongestants are appropriate. Usually this is a powder you mix with food that helps to break down mucus and snot. This makes it easier for you to keep kitty’s nose clean, which helps her smell food and eat.

Keep her nose as clean as possible, and wipe her eyes with cotton balls soaked in boiled water, as often as needed to prevent the eyes gumming shut. To help her appetite chose smelly foods such as fish, and warm it up so that it gives off even more odour. Hand feeding usually goes down a storm as cats love the attention, and also try touching food to her gums so she gets the taste in her mouth.

Stress suppresses the immune system which allows the herpes virus to get a hold, so keep stress to a minimum and consider using synthetic feline pheromones such as Feliway to keep the cats chilled.

Treatments for Feline Herpes Virus

So what has modern veterinary medicine got to offer when it comes to the treatment of feline herpes virus?

• Antibiotics and eye drops: Whilst antibiotics don’t kill the virus, they do help the beleaguered cat with a secondary chest infection. Likewise, inflamed eyes are more vulnerable to infection so antibiotic eye drops can help.
• Antiviral eye drops: Products containing ganciclovir (Ganciclovir ophthalmic gel) and trifluorothymidine (TFT) have an antiviral action and can help reduce the viral load in the eyes of cats with FHV conjunctivitis. This is the best chance of settling sore eyes down when they flare up or if the virus creates an ulcer on the surface of the eye.
• Antiviral tablets: The use of antiviral drugs in cats is controversial but drugs such as famcyclovir (Famvir) may help in some cases. However, this is a relatively new treatment and the evidence that it helps is sketchy at best.
• Interferon: Interferon helps to activate the immune system and the body’s natural defences. Whilst interferon is unlikely to do harm, neither has it been proven beneficial in treating FHV.
• L-Lysine: Wouldn’t it be great if supplementing the diet with a simple amino acid could cure FHV? Initial lab tests seemed to indicate that L-lysine did just that when added to culture plates containing feline herpes virus. However, results in the live animal are less convincing and it seems L-lysine doesn’t offer the hope we once thought. Again, it’s unlikely to do harm but equally don’t expect it to help.

In short feline herpes virus is the gift that keeps on giving, and since there is no cure then prevention by vaccination is by far the best option.