However, lifelong latent infection does not mean constant illness. Some cats have long symptom-free periods, and the virus may reactivate without visible disease. Persistent nasal symptoms alone do not establish that actively multiplying herpesvirus is their current cause either.
When to see a vet urgently
Seek prompt care if your cat has any of these signs:
- laboured breathing or open-mouth breathing;
- a painful eye, squinting or keeping the eye closed;
- clouding of the eye's surface or sudden loss of vision;
- not eating, drinking poorly and marked weakness;
- a kitten becoming lethargic quickly or developing difficulty breathing.
A painful eye needs prompt examination for a corneal ulcer. You can find a vet near you.
Overview
FHV-1 enters through the mucous membranes of the eyes and respiratory tract. After the initial infection, the virus does not disappear completely but remains latent in nerve ganglia. Stress, reduced immunity or other illnesses reactivate it and the disease recurs. This explains why the condition is chronic in many cats.
Latent virus and chronic rhinitis are distinguished. A previous infection can damage nasal structures, after which inflammation and secondary bacteria may maintain symptoms. Not every episode of rhinitis can therefore be explained by a new herpesvirus reactivation. The same cat may also have another respiratory infection or a different nasal condition.
FHV-1 spreads between cats particularly through nasal and eye secretions and close contact. Hands and objects contaminated with secretions can also transmit infection. Feline herpesvirus affects cat species and does not cause human cold sores. Routine hand hygiene is nevertheless needed when caring for a sick animal.
Causes
Chronic rhinotracheitis develops when:
- an acute herpesvirus infection has not resolved properly;
- latent virus reactivates during stress;
- immunity declines because of FIV, FeLV, older age or chronic illness;
- conditions are unfavourable, with stress, overcrowding or poor ventilation.
Recovery from the initial illness does not usually remove the latent virus, so a later recurrence does not necessarily mean the original treatment failed. Symptoms also depend on individual defences and previous tissue damage. A stressful event or positive viral test alone cannot predict how severely a cat will become ill.
Risk factors
- kittens and young cats;
- cats from shelters and breeding establishments;
- unvaccinated cats;
- cats living in crowded conditions or under ongoing stress;
- cats with chronic infections or immunodeficiency.
This list describes circumstances associated with exposure and more severe disease, rather than a definite individual prognosis. Even a vaccinated indoor cat can carry the virus. Conversely, a shelter background or previous infection does not mean a cat needs continuous medication while symptom-free. Treatment needs are decided according to actual symptoms.
Typical symptoms
Chronic FHV-1 infection causes intermittent flare-ups involving:
- persistent or intermittent nasal discharge, clear or containing pus;
- chronic sneezing and a blocked nose;
- coughing and harsh breathing sounds;
- chronic conjunctivitis and watery eyes;
- keratitis, corneal ulcers and scarring, and clouding of the eye;
- light sensitivity and reduced vision;
- reduced appetite and weight loss in severe cases.
A recurrence may mainly affect the eyes without significant nasal symptoms. However, conjunctival redness and discharge do not show whether the cornea is also damaged. Squinting, rubbing the eye and keeping it closed are therefore important observations. Do not automatically restart medicines from a similar previous episode without an eye examination.
Chronic congestion can impair the sense of smell and eating. Coughing or difficulty breathing also requires assessment for other respiratory diseases. Continuously worsening or unusual nasal symptoms should not automatically be attributed to an established herpes diagnosis. The investigation plan may then need to be expanded.
Complications and consequences
Chronic herpesvirus infection leads to:
- persistent respiratory inflammation;
- scarring and distortion of the nasal passages, causing chronic rhinitis;
- blindness from corneal scarring;
- secondary bacterial infections;
- declining general health and quality of life.
Not every carrier develops these consequences. Recurring episodes may be fairly mild, while deep corneal damage can threaten vision. Loss of sight is therefore not an inevitable consequence of long-term herpesvirus infection. Prognosis is assessed according to eye damage, nasal symptoms and other health factors.
Diagnosis at the vet
Diagnosis involves:
- PCR testing of nasal and eye samples to detect the virus;
- antibody tests;
- an eye examination for keratitis and ulcers;
- fluorescein staining to detect corneal damage;
- X-rays or CT of the sinuses in chronic rhinitis.
Antibody tests cannot reliably distinguish active FHV disease from a previous infection or vaccine response. Their value in confirming this diagnosis is therefore limited. A high or low antibody result alone does not identify the cause of current eye or nasal symptoms.
What does a PCR result show?
PCR looks for viral genetic material in the sample. A positive result may reflect viral shedding without herpes explaining every clinical finding. A negative result does not reliably rule out infection if the virus is latent or too little is being shed at the time of sampling. The sampling site and timing are matched to symptoms and laboratory instructions.
Examining the eyes and nose
Fluorescein staining helps identify damage to the corneal surface. Tear production and other eye structures are assessed if needed. Ulcer depth and healing cannot be judged reliably simply from reduced discharge. Staining may need to be repeated during follow-up before treatment ends.
In persistent rhinitis, imaging and, where needed, nasal endoscopy or a tissue sample help investigate other inflammation and tumours too. A positive herpes PCR does not make these tests unnecessary. Blood tests may assess general condition and other illnesses, but do not alone locate the cause of nasal symptoms.
Treatment and follow-up
Treating a flare-up
Treatment is selected according to whether the problem is eye surface damage, active viral disease, chronic rhinitis or secondary bacterial infection. The vet may prescribe topical or oral antiviral medication, such as famciclovir. The choice depends on the nature of the lesion and whether the cat can receive treatment safely. An antiviral does not remove virus latent in nerve ganglia.
Antibiotics are used when needed for secondary bacterial infection, but do not work against herpesvirus. Persistent nasal discharge alone is not a reason to repeat the same antibiotic without reviewing the situation. If response is poor, the original diagnosis, actual medication use and other possible causes are assessed.
Safe eye care
A corneal ulcer needs its own treatment and monitoring. Do not start corticosteroid eye drops or use an old product before veterinary assessment, as corticosteroids can delay ulcer healing. A protective collar may prevent rubbing. Increasing pain or cloudiness during treatment requires immediate contact with the practice.
Support at home
Gently wipe visible discharge with clean, dampened soft material according to care instructions. Do not rub the eye's surface or forcibly remove firmly attached crusts. Keep a record of appetite and the amount actually eaten. Palatable, slightly warmed food may help a congested cat eat, but avoid forcing food.
If your cat does not receive enough nutrition or fluid, treatment may require fluid therapy, nutritional support or hospital monitoring. Do not wait at home trying to treat breathing difficulties with steam. The treating vet provides a written plan explaining when a recurrence can be managed as agreed and which signs require a new examination.
Lysine is not recommended routinely for herpesvirus prevention or treatment because benefit has not been demonstrated. A balanced diet supports general health, but a separate supplement or course of vitamins does not replace investigation of symptoms. Delaying treatment can be significant, particularly with eye damage.
Prevention
- Vaccinate your cat: cat flu vaccination is a core vaccination.
- Reduce stress through a regular daily routine, as few house moves as possible and gradual adjustment to new conditions.
- Support immunity with good nutrition and care.
- Treat respiratory and eye infections promptly.
- Quarantine new animals.
Vaccination reduces disease severity but does not guarantee prevention of infection, latent carriage or all viral shedding. Vaccination needs and arrangements for separating new cats are planned with the vet according to contacts. Carriage cannot be reliably excluded with one test taken while symptom-free.
A calm daily life is supported by individual resting and hiding places, clean litter trays, scratching opportunities and suitable play. Make changes gradually. These arrangements do not remove the virus but reduce avoidable strain.
Clean surfaces contaminated with a sick cat's secretions before disinfecting. Use a product suitable for cats' surroundings according to its instructions and contact time. Do not mix cleaning products or apply them to the animal's skin. In multi-cat households, managing hands, equipment and contacts complements vaccine protection.
Important for cat owners
Chronic feline viral rhinotracheitis is a lifelong problem requiring regular monitoring. The virus cannot be eliminated completely, but good care and measures to reduce flare-ups help maintain a good quality of life. Vaccination clearly reduces the risk of severe disease and complications.
This article provides general information and does not replace veterinary care. If you notice signs of illness in your cat, contact a vet.
Frequently asked questions
Is a herpes-positive cat constantly ill?
No. Latent carriage and active disease are different things. A cat can be symptom-free for a long time, and some flare-ups are mild. Eye pain or difficulty breathing still needs prompt investigation regardless of previous symptoms.
Does a blood antibody test confirm chronic herpes as the cause?
No. Antibodies may be present after a previous infection or vaccination, and the result alone does not demonstrate active disease. PCR results also require clinical interpretation. Symptom location, an eye examination and, where needed, investigation of other nasal diseases determine the overall assessment.
Can a cat transmit herpesvirus to a person?
Feline FHV-1 is not a human herpesvirus; it spreads between cat species. However, a sick cat may also carry other organisms. Handwashing and safe cleaning of secretions are part of routine care hygiene.
This article is for general information only and is not a guide to treatment. If you notice the first signs of illness, contact your vet.
Paw4care editorial team
Sources
- Guideline for Feline Herpesvirus Infection, ABCD, accessed 2026-11-03.
- Respiratory Infections, Cornell Feline Health Centre, accessed 2026-11-03.
- Feline Respiratory Disease Complex, Merck Veterinary Manual, accessed 2026-11-03.
- Herpesvirus Infection in Cats (Feline Viral Rhinotracheitis), VCA Animal Hospitals, accessed 2026-11-03.
- Corneal Ulcers in Cats, VCA Animal Hospitals, accessed 2026-11-03.
- Guideline for Disinfectant Choice in Feline Veterinary Hospitals, Shelters and Cat Households, ABCD, accessed 2026-11-03.
- Basic Indoor Cat Needs, The Ohio State University, accessed 2026-11-03.
- Rhinitis and Sinusitis in Cats, Merck Veterinary Manual, accessed 2026-11-03.