Categories: Infection

What percentage of cats have herpes?

The question in the title is online and appears to be asking for the percentage of cats that are suffering from or have suffered from the herpesvirus group. It causes feline viral rhinotracheitis – FVR.

One study states ‘33% of the cats with respiratory tract disease were FCV positive’ 2. Another states: ‘Following exposure to FHV-1, more than 80% of cats become persistently infected’.3. A further study in Brazil states: ‘FHV-1 alone was isolated from 38.2% (21/55) of the animals that tested positively’.4. Another study states: In clinically normal cats, prevalence rates of FCV and FHV were about 50.00%… [FHV is the herpes virus] 5.

Photo in public domain.

The leading article (at the date of this article) as far as Google’s algorithm is concerned ( states that 80-90% of cats are estimated to have herpes virus-1 (FHV-1). That is saying that up to nine out of ten domestic cats carry the herpes virus. It sounds shocking. It may be true because the acute infection stage is followed by a ‘lifelong persistence of the viral genome latent form in nervous and lymphoid tissues’. This is described as the chronic carrier state. In plain language the germ remains dormant inside the cat and is woken up under certain circumstances.

“Almost all the cats who have been infected with FVR will become chronic carriers. FVR lives and multiplies in the cells and lining of the throat.” 1

The virus can be reactivated during times of stress, illness, surgery etc. when the cat might show signs of mild URI. Vaccinations do not eliminate the carrier state.

So if 90% of cats have herpes it is would appear that it is dormant in the majority of these cats. I don’t know the percentage. states that some studies have shown positive blood titers for herpes at over 90% in shelter cats. A blood titer shows the level of antibodies in the blood in this case for the herpes virus. Antibodies are part of the immune system and indicate the presence or past presence of a pathogen in this case the herpes virus. It confirms that the cat at one stage or currently was exposed to the herpes virus.

Shelter cats are particularly likely to become infected as they are living in close quarters and the virus is highly contagious.

There is no doubt that the herpesvirus group is very prevalent. It is one of two major viral groups (the other being the calicivirus group) that is responsible for 80-90% of all URIs.

Also the most common cause of conjunctivitis in cats (pink eye) is the herpesvirus (FHV-1).


The answer to the question in the title is possibly 80-90% of cats. Shelter cats and feral cats in colonies are more vulnerable to this infectious disease. I say ‘possibly’ because I have not read the actual studies supporting this figure despite searching for them. Other studies seem to arrive at lower figures of around 33-50%. This is still a high percentage.

Note: 1 — Cat Owner’s Home Veterinary Handbook 3rd edition.

Note: 2 – A Study of Feline Upper Respiratory Tract Disease with Reference to Prevalence and Risk Factors for Infection with Feline Calicivirus and Feline Herpesvirus [link]

Note: 3 — Feline herpesvirus-1: Ocular manifestations, diagnosis and treatment options

Note: 4 — Isolation and identification of feline calicivirus and feline herpesvirus in Southern Brazil

Note: 5 — Molecular and clinical study on prevalence of feline herpesvirus type 1 and calicivirus in correlation with feline leukemia and immunodeficiency viruses

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Michael Broad

Hi, I'm a 71-year-old retired solicitor (attorney in the US). Before qualifying I worked in many jobs including professional photography. I have a girlfriend, Michelle. I love nature, cats and all animals. I am concerned about their welfare.

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  • FHV-1 can be successfully treated with drops consisting of a water based solution of 2% azithromycin antibiotic and 2% Voltaren. But this must be applied as early as possible ideally within the first 24 hours of the infection appearing. Oral 500 mg of azithromycin is also effective. 200 mg in the case of a small kitten. Sorry, but you can't get any such drops from your vet. You have to make them up yourself, but your Vet can administer the oral azithromycin. The diluted Voltaren prevents tissue damage to the eye. Do not use full strength Voltaren.

    • One slight problem -- antibiotics are used to treat bacterial infections, not viruses. Antibiotics do nothing to stop a virus from reproducing or being spread further. Anyone taking any medical advice from this website gets what they paid for, and truly deserves it.

      • I don't think he is saying that you bloody pest. He is saying that viral infections lead to secondary infections and this is both a preventative measure and a possible cure because it is hard to distinguish between viral and bacterial infections in cats as they merge (viral leads to bacterial). Vets often administer antibiotics under these circumstances. So piss off you arrogant idiot. "The Fact Police" - my arse.

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