Feline Herpesvirus 101 (FHV)

Was your cat just diagnosed with feline herpesvirus (FHV-1)?

Don’t worry – it’s not contagious to you; however, it’s very contagious to other cats!

To clarify, feline herpesvirus isn’t a sexually transmitted disease. It’s a virus infection that is similar to the human virus that causes cold sores. Feline herpesvirus most commonly affects the eyes, the respiratory tract and the gastrointestinal tract. Rarely, feline herpesvirus can potentially affect the skin, the reproductive tract, and the musculoskeletal tract1,2. In cats, clinical signs can be seen within 2-5 days of exposure to the virus. The most common clinical signs seen from feline herpesvirus include:

  • Sneezing
  • Runny eyes
  • Pink eyelids (e.g., conjunctivitis)
  • Lethargy
  • Fever
  • Not eating/anorexia
  • Weight loss
  • Drooling
  • Dehydration
  • Increased respiratory effort
  • Loud, snoring-like breathing
  • Severe ulcers on the eyes (less common)
  • Rupture of the cornea (rare)
  • Lameness (rare)
  • Dermatitis
  • Death (rare)

What’s your cat’s risk of getting feline herpesvirus?
Feline herpesvirus is a virus that is more commonly seen in the spring and summer, when kittens are born. Young, unvaccinated kittens are more at risk for this infection, as are immunosuppressed cats (due to feline immunodeficiency virus [FIV], feline leukemia [FeLV] or feline infectious peritonitis [FIP]). Also, multi-cat households or certain cat-crowded environments (again, such as shelters, catteries, outdoor feral cats) are more likely to have problems with feline herpesvirus.

Feline herpesvirus is just one of the many types of causes of feline upper respiratory infections (URI). Other causes of feline URI include:

  • Feline calicivirus (FCV), a virus
  • Chlamydia, a bacteria
  • Rarer organisms such as Bordatella bronchiseptica or Mycoplasma

So, if you just adopted a cat from a shelter or purchased a cat from a cattery or breeder, know that transmission to your other household cats can occur when you bring a new cat into the environment. That’s because feline herpesvirus is extremely contagious and infectious. It’s typically transmitted by bodily fluids (such as discharge from the nose or eyes) or by aerosolization (e.g., sneezing)3. Sometimes unsanitary conditions due to inappropriate disinfection can further the spread of this common infection (e.g., in a cattery or shelter).How long will feline herpesvirus last?
Unfortunately, it can take an average of 7-10 days before clinical signs of feline herpesvirus resolve3. Also, just like when you get cold sores when you are stressed, know that some cats can have relapses of clinical signs of herpesvirus even years later, as the virus hides in the body (is latent).

Treating feline herpesvirus
Unfortunately, there is no cure for feline herpesvirurs, as treatment is symptomatic and supportive. Some helpful hints?

  • Quarantine: Keep your newly adopted cat away from other cats due to the contagious nature of this disease.
  • Nursing care: If your cat is showing signs of nasal or eye discharge, make sure to keep your cat kept free of discharge. Blot away any discharge with a damp paper towel or terry cloth rag. This is important to help prevent the nostrils from being blocked up from nasal crusting.
  • Moisture: Take your cat into the bathroom while you’re taking a hot shower (Note: NOT into the shower, but into the bathroom). This way, the steam can help humidify the nasal passages and make your cat breathe better.
  • Tasty food: With herpesvirus, your cats can eat whatever they want! Try to tempt your cat to eat with tasty canned tuna (in water), meat-based human baby food or any kind of tasty canned food. [Editor’s note: Make sure to check with your veterinarian first if your giving your cat anything new.]
  • Seek veterinary attention: If you notice abnormal squinting, tearing, redness to the eyes, drooling, not eating, etc., get to a veterinarian immediately! That’s because corneal ulcers or conjunctivitis may need topical antibiotic ointments (e.g., terramycin, oxytetracycline, erythromycin, etc.). Topical, ophthalmic anti-viral ointments can also be used (e.g., cidofovir, etc.). In severe cases, where a secondary bacterial infection occurs (e.g., pus coming from the eyes or nostrils), oral antibiotics may be necessary (just like human colds, viruses typically don’t need antibiotics initially). Keep in mind that antibiotics can often cause cats to lose their appetite, or develop vomiting and diarrhea.

Preventing feline herpesvirus
Prevention: Help prevent feline upper respiratory infections, like herpesvirus, through appropriate vaccination protocols. Work with your veterinarian to make sure your kitten or cat is healthy, and is up to date on vaccines.

When in doubt, the prognosis for feline herpesvirus is good with supportive care.

A veterinary exam is a must in a newly adopted or purchased cat.

If you have any questions or concerns, you should always visit or call your veterinarian -- they are your best resource to ensure the health and well-being of your pets.


  1. Scott FW. Feline Calicivirus Infection. In Blackwell’s Five-Minute Veterinary Consult: Canine & Feline. Eds. Tilley LP, Smith FWK. 2007, 4th ed. Blackwell Publishing, Ames, Iowa. pp. 476-477.
  2. Norsworthy GD. Feline Rhinotracheitis Virus Infection. 496-497.
  3. Feline Upper Respiratory Infection. Accessed August 24, 2015

Reviewed on:

Friday, September 11, 2015

Feline Herpesvirus Real-time PCR test, FHV RT-PCR Test

Product Image

Feline Herpesvirus Real-time PCR test kit is to detect FHV in cats. which is rapid, accurate and easy-to-operate. Sensitivity 100%, Specificity 100%.

Basic information

Feline herpesvirus (FHV, FHV-1) is a highly contagious virus that is one of the major causes of upper respiratory infections (URIs) or cat flu in cats.This virus is ubiquitous and causes disease in cats all over the world. See also Upper respiratory infections (URIs, Cat flu) in cats. Together, FHV and feline calicivirus cause the vast majority of URIs in cats.

Key facts of the Feline Herpesvirus Real-time PCR test kit

Feline Herpesvirus Real-time PCR test kit Components

Item # Item Qty
1 PCR reaction solution 120ul
2 Negative Control 50ul
3 Positive Control 50ul
4 Exogenous Gene Control 50ul
5 Sample buffer 1ml
6 Enzyme mix 10ul
7 Kit user manual 1set

What is FHV and how it is spread

Feline herpesvirus (FHV) is a virus that mainly causes acute upper respiratory infections (URIs) in cats, although it has been associated with some other diseases also (see below). The virus is readily transmitted between cats through:

  • Direct contact – through contact with saliva, ocular or nasal secretions
  • Inhalation of sneeze droplets
  • Sharing or food bowls and litter trays
  • A contaminated environment (including bedding and grooming aids) – this is less important with FHV than FCV as the virus is fragile can probably only survive for 1–2 days in the environment

What are the clinical signs of FHV infection

  • Acute upper respiratory infection – acute URI is the most common manifestation of FHV infection. Typical signs include conjunctivitis, ocular discharge, sneezing, nasal discharge, salivation, pharyngitis, lethargy, inappetence, fever and sometimes coughing. Signs may last from a few days to a few weeks and shedding of the virus typically continues for around 3 weeks. Clinical disease with FHV is generally more severe than that seen with FCV.
  • Keratitis – although relatively uncommon, one manifestation of chronic (long-term) FHV infection that is seen in a number of cats is conjunctivitis and keratitis (infection and inflammation of the cornea – the clear part at the front of the eye). Although keratitis can have a number of different causes, FHV infection causes the development of multiple small branching corneal ulcers (called ‘dendritic keratitis’) and this is considered diagnostic of FHV infection.
  • FHV-associated dermatitis – a rare manifestation of chronic (long-term) FHV infection is the development of skin inflammation and ulceration. This is most commonly seen around the nose and mouth but can affect other areas such as the front legs. This is only seen rarely.

How is FHV infection diagnosed?

In most cases, a specific diagnosis of FHV infection will not be required. The presence of typical signs of URI is enough for a presumptive diagnosis of FHV (and/or feline calicivirus – FCV) infection. If a specific diagnosis is required, ocular or oral swabs can be submitted to a veterinary laboratory where the virus can be grown in culture or, more commonly, detected by Feline Herpesvirus Real-time PCR test (a molecular technique for detecting the genetic material of the virus). Evidence of the virus may also be present in biopsies and can be useful for the diagnosis of FHV-associated dermatitis (skin infection).

Feline Herpesvirus Type 1

Feline Herpesvirus type 1 (FHV-1) is believed to be the most common cause of ocular disease in cats. Multiple cat households, catteries, kittens and cats from pet stores, and feral kittens and cats are most prone to develop active FHV-1 as the disease process usually manifests itself in poorly conditioned felines as well as those that are experiencing stressful living conditions.

Article Resource:

HERPES IS ‘FOREVER’ …….. What is currently being used to ‘Manage’ feline Herpesvirus type 1 (FHV-1)?
Steve Dugan, DVM, MS, Diplomate of the ACVO

Feline Herpesvirus type 1 (FHV-1) is believed to be the most common cause of ocular disease in cats. Multiple cat households, catteries, kittens and cats from pet stores, and feral kittens and cats are most prone to develop active FHV-1 as the disease process usually manifests itself in poorly conditioned felines as well as those that are experiencing stressful living conditions. FHV-1 is associated with keratoconjunctivitis, corneal sequestration, eosinophilic keratoconjunctivitis, KCS, loss of corneal sensation, symblepharon, anterior uveitis, rhinitis, stomatitis, and ulcerative facial and nasal dermatitis. Alpha Herpesviruses such as FHV-1 cause disease by two distinctly different mechanisms: 1) cytolytic (cell-rupturing) disease which involves active viral replication and destroys the epithelial cells of the cornea and conjunctiva causing ulceration and, 2) immune-mediated disease results from the deposition of viral antigen in subepithelial tissues. FHV-1 establishes latency in the trigeminal ganglia and can travel back to the eye via anterograde axonal transport. Latency will develop in approximately eighty percent of infected cats and approximately fifty percent of latently infected cats will have spontaneous and stress-related reactivation and shedding of the virus. If recurrent, severe FHV-1 induced disease develops frequently in a cat, then laboratory testing to rule in or rule out various diseases that may decrease a cat’s immune competence and as such predispose the patient to frequent recurrences should be considered (e.g., FeLV, FIV, FIP etc).

Positive FHV-1 test results (virus isolation, immunofluorescence techniques, and conventional PCR assays) do not differentiate subclinically infected cats from those with clinical disease as a result of FHV-1 infection. In addition, PCR assays also detect vaccine strains of FHV-1. It was recently shown by Low et al that increased copy numbers of FHV-1 DNA as determined by PCR could not be identified in cats with conjunctivitis compared to cats without conjunctivitis. Because of the difficulty in establishing a definitive diagnosis of FHV-1 as the cause of ocular disease in most cats, presumption of cause is usually based upon clinical signs (particularly recurrent episodes of keratoconjunctivitis and/or the presence of respiratory signs) and response to treatment. Immunity from vaccination against FHV-1 is incomplete and temporary whether parenteral or intranasal vaccination is administered.

No consistently effective primary treatment exists for chronic viral diseases in cats. In addition, the antiviral agents currently used are virostatic versus virocidal and thus are unable to eradicate latent viral infection. Because stress is an important trigger of viral shedding and reactivation, treatment that is noninvasive and palatable is paramount to therapeutic success. Because FHV-1 can induce tissue injury directly as a result of viral cytolysis or indirectly through immunopathologic processes mediated by inflammatory cells, treatment of FHV-1 keratoconjunctivitis involves: 1) prevention of viral replication 2) immunomodulation and, 3) prevention of secondary bacterial infection.

Medications currently used to prevent viral replication include: l-lysine (Viralys) trifluridine (Viroptic) idoxuridine interferon alpha famciclovir (Famvir) and, cidofovir (Vistide). L-lysine, a competitive inhibitor of arginine which is necessary for the replication of FHV-1, is believed to moderate disease in severe or chronically recurring cases, is safe, inexpensive, available as a paste, powder, or pills, and is typically administered at 250 to 500 mg per os BID. Trifluridine 1% ophthalmic solution causes considerable stinging when instilled in the eye, is expensive, and must be administered > 5 times per day to be effective. Idoxuridine 0.1% ophthalmic solution does not cause the same degree of stinging when compared to trifluridine, is no longer commercially available, and must be administered q 4 to 6 h to be effective. Both trifluridine and idoxuridine have low solubility, and as such, their intraocular penetration is low unless the epithelial barrier is altered. Interferon alpha administered systemically, topically or both appears to exert a virostatic effect on FHV-1 replication. Interferon alpha at 30 U per os q 24 h may help some cats with suspected chronic FHV-1 infection. Interferon alpha (600 U/ml or 30 U/gt) at 1 gt in the affected eye(s) q 4 to 6 h may also aid in the management of FHV-1 in some cats. However, this treatment modality has not been evaluated adequately in clinical trials in order to make definitive claims. Famciclovir, a prodrug of penciclovir, has been shown in preliminary studies to be safe and effective in cats with primary FHV-1 infection. Adequate clinical trials have not been performed but 1/4 of a 125 mg tablet per os q 24 h for 21 days appears to be helpful. Cidofovir 0.5% ophthalmic solution instilled BID has been shown to decrease clinical signs of ocular disease during the acute phase of infection following experimentally induced FHV-1 infection. Cidofovir is converted to an active metabolite (CDVpp) that inhibits viral synthesis by competitively inhibiting viral DNA polymerase. Cidofovir has potent antiviral effects in vitro and in vivo against several Herpesviruses of human and veterinary importance. Cidofovir at concentrations of 0.02 to 0.05 mg/dl has been shown to be extremely effective against FHV-1 infection of feline corneal epithelial cells in vitro. Cidofovir has not been approved for ophthalmic use and is only available through compounding pharmacies.

Interferon is the only medication currently used for its immunomodulatory effects in the treatment of FHV-1. Interferon has been reported to be effective in preventing recurrent FHV-1 disease when administered at 30 U per os q 24 h for seven days followed by seven days without treatment in a continuously repeating cycle.

Antibacterial agents can be used topically and/or per os in conjunction with one or more of the treatments discussed above. Any topical broad spectrum ophthalmic solution should be acceptable (e.g., tobramycin or ofloxacin). Regarding orally administered antibiotics, I prefer doxycycline at 2.3 mg/lbs per os BID for 21 days or azithromycin at 5 mg/lbs per os q 24 h for 21 days. Doxycycline has been shown to possess anticollagenase effects and subsequently may help prevent corneal stromal involvement.

Finally, because FHV-1 can cause a permanent reduction in lacrimation, a high-quality artificial tear instilled in the affected eye(s) q 4 to 6 h may help maintain a healthy ocular environment during the convalescent period.

FHV infection/feline viral infection/Herpes


Feline herpesvirus (FHV) infection, also called feline viral rhinotracheitis (FVR), is an acute and highly contagious viral upper respiratory tract disease that affects both domestic and wild cats, especially those with weak immune systems. Almost half of all upper respiratory infections in cats are related to a feline herpesvirus infection. It is spread through contact with secretions from infected cats, or through inhalation of the virus that has been released into the air from an infected cat’s sneeze. It is a highly contagious virus, but there is a vaccine that will protect cats and kittens from the disease.

How Feline Herpesvirus Infection Affects Cats

Feline herpesvirus (FHV) infection, also called feline viral rhinotracheitis (FVR), is an acute upper respiratory tract disease that affects both domestic and wild cats. FHV is highly contagious among cats and tends to attacks animals with weakened immune function. It is most frequently diagnosed in multi-cat households and in cats kept in crowded, unsanitary conditions.

Cats infected by FHV show classic signs of upper respiratory tract disease, including acute onset of sneezing, inflammation and irritation of the membranes lining the eyelids and nasal cavity and increased salivation. A fluxuating fever may be present, and a thick, yellow-ish nasal and ocular discharge usually occur as well. Affected cats tend to lose their appetites because their sense of smell is adversely affected by the inflammation and congestion. Some cats will become depressed, listless and lethargic. In most cases, the initial clinical signs will persist for approximately one week before they subside. However, periodic recurrence of clinical signs is fairly common.

Symptoms of Feline Herpesvirus Infection

The most common initial sign of FHV infection is the sudden onset of sneezing fits, accompanied by eyelid spasms or squinting (blepharospasm), conjunctivitis (inflammation and redness of the membrane lining the inner surface of both eyelids) and ocular discharge. Nasal discharge and inflammation of the mucous membrane of the nose (rhinitis) is also quite common. These initial symptoms frequently are closely followed by anorexia, fever, cough, overall malaise and, if the affected feline is pregnant, abortion. The clinical signs of feline herpesvirus infection can resemble flu-like symptoms, and for this reason FHV infection is sometimes referred to as “feline influenza.” The initial symptoms generally last for about one week.

After the initial signs of feline herpesvirus infection resolve, many cats develop secondary bacterial or other infections. These infections tend to localize to the eyes, nose and mouth and can persist for weeks. Corneal ulceration can also occur. Many of these infections wax and wane, usually recurring during times of stress or immunosuppression. Others become chronic and can stabilize or worsen with time. Like other herpesvirus infections, FHV typically remains latent in an infected cat’s system for life. Future outbreaks of clinical disease may or may not occur. Cats that become pregnant or experience other stressful medical, emotional or environmental conditions, are predisposed to recurrence of clinical disease.

Causes & Preventing Feline Herpesvirus Infection

Almost one-half of all feline upper respiratory tract infections involve feline herpesvirus. Infection by this virus is caused by direct contact with secretions from infected cats through oral, nasal or conjunctival exposure. Feline herpesvirus is highly contagious between cats. FHV infection is perpetuated by latent carrier cats that harbor the virus indefinitely.

The best way to prevent severe FHV disease is routine vaccination with a modified live or inactivated virus vaccine. This vaccine can be started in young kittens, with annual boosters. The vaccine does not prevent infection by the virus but does prevent development of severe upper respiratory disease. Owners should also take steps to reduce environmental stressors that may adversely affect their companion cats. Of course, any clinically affected cat should be strictly isolated from all other cats until the infection is resolved.

Treating Feline Herpesvirus

The treatment goals for cats with FHV infection are to stop viral replication, prevent or resolve secondary bacterial infections, relieve pain and minimize recurrence of clinical disease. This highly contagious disease can become life-threatening, especially in kittens. While there currently is no cure for FHV infection, there are treatments that can alleviate the painful symptoms and resolve any secondary bacterial infections that develop.

VIZOOVET helps with many of the symptoms with FHV damaged lids and eyes. It helps very quickly with the pain. It reduces the inflammation and redness. The eyes will soon look clear and moist, andthe drops don’t leave a gooey residue, and they are easy to use. The bottle contains enough drop to last for 4 applications per eye, so for a whole day. The most common reaction from cat owners that have used VIZOOVET is that they are soothing. VIZOOVET drops have some advantages over other remedies in that there are VIZOOVET IS SAFE.


Not contagious to Humans

Feline herpesvirus is infectious and contagious between cats but is not zoonotic and thuys does not present a risk to humans. The prognosis for cats infected by feline herpesvirus is generally quite good, as long as appropriate nutritional support and fluid therapy are provided. Owners should recognize that this disease can recur periodically, particularly during periods of stress, illness or immunosuppression. Young kittens with undeveloped immune systems and older cats with weakened immune systems tend to be affected more severely by the virus and thus have a poorer prognosis.

Treatment and Prevention

Treatment is largely directed toward the signs of illness, but broad-spectrum antibiotics are useful if secondary bacterial infections are involved. Antihistamines may be prescribed early in the course of the disease. Nose and eye discharges should be removed frequently for the comfort of the cat. Treatment with a mist (nebulization) or saline nose drops may be recommended to help remove hard secretions. Nose drops containing a blood vessel constrictor and antibiotics are sometimes prescribed to reduce the amount of nasal secretion. Eye ointment containing antibiotics may also be prescribed to prevent corneal irritation produced by dried secretions from the eye. If corneal ulcers occur in feline viral rhinotracheitis infections, eye preparations containing antiviral medication may be prescribed, in addition to other antibiotic eye preparations. If the cat has great difficulty breathing, it may be placed in an oxygen tent. Your veterinarian may need to inject fluids if your cat is dehydrated. Cats that are unwilling to eat may require additional medications or a feeding tube.

Vaccines that protect against feline viral rhinotracheitis and feline calicivirus are available. One type is injected the other is given as drops in the nose. Cats that have received the nasal vaccine may sneeze frequently for a few days after vaccination ask your veterinarian if you should expect this or any other side effect from the vaccines. Vaccines against Chlamydia are also available these vaccines are generally used in catteries or on premises where infection has been confirmed. A combination of recommended vaccinations and control of environmental factors (such as exposure to sick cats, overcrowding, and stress) provide good protection against upper respiratory disease.

For More Information

Also see professional content regarding feline respiratory disease complex.

Trial for Best Feline Herpesvirus Treatment Could Save Shelter Cats’ Eyes and Lives


DENVER/May 28, 2020 – Shelter cats could soon benefit from a new treatment protocol for painful eye infections caused by feline herpesvirus (FHV-1). Morris Animal Foundation-funded researchers at Louisiana State University are conducting a clinical trial of three common antiviral drugs to determine which drug is best to treat the disease in animal shelters. Results of the study should help veterinarians more effectively treat this widespread, potentially blinding condition in the cat population.

“This virus can be debilitating, with outcomes pretty variable from cat to cat,” said Dr. Andrew Lewin, Assistant Professor at Louisiana State University’s School of Veterinary Medicine and principal investigator on the study. “We want to be able to make a meaningful recommendation for veterinarians to improve the welfare of these animals.”

Feline herpesvirus is a highly contagious virus in cats usually transmitted through sneezing or grooming. Like many herpesviruses, FHV-1 can infect cells and remain dormant indefinitely, often referred to as a latent infection. Because most cats have latent FHV-1 infections, many will have severe issues at some point in their lives. Afflicted cats can present with respiratory issues and discharge from their noses and eyes. In extreme cases, it can cause corneal scarring and loss of vision as well as chronic upper respiratory disease.

Shelter cats are one of the most at-risk groups for FHV-1 infections because of their high population density and close living quarters. A cat infected by FHV-1 is less likely to be adopted which in turn increases their risk of being euthanized. Previous studies using antivirals in shelter cats with FHV-1 have produced mixed results.

Dr. Lewin is taking a different approach. His study will look at more than 120 cats from animal shelters in the Louisiana area that have evidence of FHV-1 eye infections. They will be divided into four groups, each of which will receive one of three currently available antivirals (cidofovir, ganciclovir and famciclovir) or a placebo. After a week of treatment, researchers will use a scoring system to see if the cats’ eyes have improved. The team also will take eye swabs before and after treatment to measure each antiviral’s efficacy.

Next, the team will try and assess if the virus develops a resistance to the antivirals, similar to antibiotic resistance demonstrated by bacteria. Researchers will test this by swabbing the cats’ eyes and growing the virus in a lab, in the presence of an antiviral. If the virus continues to grow, that could indicate it has resistance. Researchers also will use a DNA sequencing technique to look specifically at the regions of the virus genome which would mutate if resistance developed.

Since many afflicted cats also suffer from secondary bacterial infections in their eyes, the team will sequence the DNA of any bacteria isolated from affected cats to determine if the type of bacteria present is related to response to therapy. This will help researchers assess the impact of secondary bacterial infections on the outcome of the FHV-1 infection.

“Feline herpesvirus is a huge welfare issue for shelter cats and it is important that we find a viable method to address it,” said Dr. Janet Patterson-Kane, Morris Animal Foundation Chief Scientific Officer. “We want all animals to have a chance at a full, healthy life and, because this virus has such an impact on adoptability, a study like this could do wonders for cats waiting for a permanent home.”

Morris Animal Foundation, headquartered in Denver, is one of the largest nonprofit animal health research organizations in the world, funding more than $155 million in studies across a broad range of species.

About Morris Animal Foundation

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