Feline viral rhinotracheitis (FVR) is an upper respiratory or pulmonary infection of cats caused by Feline herpesvirus, also called Feline herpesvirus 1 (FeHV-1), of the family '' Herpesviridae''. It is also commonly referred to as feline influenza, feline coryza, and feline pneumonia but, as these terms describe other very distinct collections of respiratory symptoms, they are misnomers for the condition. Viral respiratory diseases in cats can be serious, especially in catteries and kennels. Causing one-half of the respiratory diseases in cats, FVR is the most important of these diseases and is found worldwide. The other important cause of feline respiratory disease is '' feline calicivirus''. FVR is very contagious and can cause severe disease, including death from

pneumonia Pneumonia is an Inflammation, inflammatory condition of the lung primarily affecting the small air sacs known as Pulmonary alveolus, alveoli. Symptoms typically include some combination of Cough#Classification, productive or dry cough, ches ...

in young kittens. It may cause flat-chested kitten syndrome, but most evidence for this is anecdotal. All members of the family

Felidae Felidae ( ) is the Family (biology), family of mammals in the Order (biology), order Carnivora colloquially referred to as cats. A member of this family is also called a felid ( ). The 41 extant taxon, extant Felidae species exhibit the gre ...

are susceptible to FVR; in fact, FHV-1 has caused a fatal

encephalitis Encephalitis is inflammation of the Human brain, brain. The severity can be variable with symptoms including reduction or alteration in consciousness, aphasia, headache, fever, confusion, a stiff neck, and vomiting. Complications may include se ...

lion The lion (''Panthera leo'') is a large Felidae, cat of the genus ''Panthera'', native to Sub-Saharan Africa and India. It has a muscular, broad-chested body (biology), body; a short, rounded head; round ears; and a dark, hairy tuft at the ...

s in

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

History

FHV-1 was first isolated from cats in 1958 in the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

Transmission

FVR is transmitted through direct contact only. It replicates in the nasal and nasopharyngeal tissues and the tonsils. Viremia (the presence of the virus in the blood) is rare. The virus is shed in saliva and eye and nasal secretions, and can also be spread by

fomite A fomite () or fomes () is any inanimate object that, when contaminated with or exposed to infectious agents (such as pathogenic bacteria, viruses or fungi), can transfer disease to a new host. Transfer of pathogens by fomites A fomite is any ...

s. FVR has a two- to five-day

incubation period Incubation period (also known as the latent period or latency period) is the time elapsed between exposure to a pathogenic organism, a chemical, or ionizing radiation, radiation, and when symptoms and signs are first apparent. In a typical infect ...

. The virus is shed for one to three weeks postinfection. Latently infected cats (carriers) will shed FHV-1 intermittently for life, with the virus persisting within the trigeminal ganglion. Stress and use of

corticosteroid Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex of vertebrates, as well as the synthetic analogues of these hormones. Two main classes of corticosteroids, glucocorticoids and mineralocorticoids, are invo ...

s precipitate shedding. Most disinfectants, antiseptics and detergents are effective against the virus.

Clinical signs

Initial signs of FVR include

cough A cough is a sudden expulsion of air through the large breathing passages which can help clear them of fluids, irritants, foreign particles and Microorganism, microbes. As a protective reflex, coughing can be repetitive with the cough reflex fol ...

ing, sneezing, nasal discharge,

conjunctivitis Conjunctivitis, also known as pink eye or Madras eye, is inflammation of the conjunctiva, the thin, clear layer that covers the white surface of the eye and the inner eyelid. It makes the eye appear pink or reddish. Pain, burning, scratchiness ...

, and sometimes fever (up to ) and loss of appetite. These usually resolve within four to seven days, but secondary bacterial infections can cause the persistence of clinical signs for weeks. Frontal

sinusitis Sinusitis, also known as rhinosinusitis, is an inflammation of the mucous membranes that line the sinuses resulting in symptoms that may include production of thick nasal mucus, nasal congestion, facial congestion, facial pain, facial pressure ...

and empyema can also result. FHV-1 also has a predilection for

cornea The cornea is the transparency (optics), transparent front part of the eyeball which covers the Iris (anatomy), iris, pupil, and Anterior chamber of eyeball, anterior chamber. Along with the anterior chamber and Lens (anatomy), lens, the cornea ...

l epithelium, resulting in corneal ulcers, often pinpoint or dendritic in shape. Other ocular signs of FHV-1 infection include conjunctivitis, keratitis, keratoconjunctivitis sicca (decreased tear production), and corneal sequestra. Infection of the

nasolacrimal duct The nasolacrimal duct (also called the tear duct) carries tears from the lacrimal sac of the eye into the nasal cavity. The duct begins in the eye socket between the maxillary and lacrimal bones, from where it passes downwards and backwards. ...

can result in chronic epiphora (excess tearing). Ulcerative skin disease can also result from FHV-1 infection. FHV-1 can also cause abortion in pregnant queens, usually at the sixth week of

gestation Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). It is typical for mammals, but also occurs for some non-mammals. Mammals during pregn ...

, although this may be due to systemic effects of the infection rather than the virus directly. In chronic nasal and sinus disease of cats, FHV-1 may play more of an initiating role than an ongoing cause. Infection at an early age may permanently damage nasal and sinus tissue, causing a disruption of

cilia The cilium (: cilia; ; in Medieval Latin and in anatomy, ''cilium'') is a short hair-like membrane protrusion from many types of eukaryotic cell. (Cilia are absent in bacteria and archaea.) The cilium has the shape of a slender threadlike proj ...

ry clearance of

mucus Mucus (, ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both Serous fluid, serous and muc ...

and bacteria, and predispose these cats to chronic bacterial infections.

Diagnosis

Diagnosis of FVR is usually by clinical signs, especially corneal ulceration. Definitive diagnosis can be done by direct immunofluorescence or virus isolation. However, many healthy cats are subclinical carriers of feline herpes virus, so a positive test for FHV-1 does not necessarily indicate that signs of an upper respiratory tract infection are due to FVR. Early in the course of the disease,

histological Histology, also known as microscopic anatomy or microanatomy, is the branch of biology that studies the microscopic anatomy of biological tissue (biology), tissues. Histology is the microscopic counterpart to gross anatomy, which looks at large ...

analysis of cells from the tonsils, nasal tissue, or nictitating membrane (third eyelid) may show inclusion bodies (a collection of viral particles) within the nucleus of infected cells.

Treatment and prevention

Polyprenyl immunostimulant is the only currently-approved treatment in the US for feline rhinotracheitis caused by herpesvirus. Effectiveness was demonstrated in a clinical study with cats experimentally infected with feline herpesvirus: 20 cats were treated with polyprenyl immunostimulant and 20 received a placebo. The study established that the severity of the disease was lower in the group treated with polyprenyl. Safety was demonstrated in 390 personally-owned cats from 2 days to 16 years of age, residing in 10 states.

Antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting pathogenic bacteria, bacterial infections, and antibiotic medications are widely used in the therapy ...

s are commonly used to prevent secondary bacterial infection. There are no specific

antiviral drug Antiviral drugs are a class of medication used for treating viral infections. Most antivirals target specific viruses, while a broad-spectrum antiviral is effective against a wide range of viruses. Antiviral drugs are a class of antimicrobials ...

s in common use at this time for FVR, although one study has shown that ganciclovir, PMEDAP, and

cidofovir Cidofovir, brand name Vistide, is a topical or injectable antiviral medication primarily used as a treatment for cytomegalovirus (CMV) retinitis (an infection of the retina of the eye) in people with AIDS. Cidofovir was approved for medical ...

hold promise for treatment. More recent research has indicated that systemic famciclovir is effective at treating this infection in cats without the side effects reported with other anti-viral agents. More severe cases may require supportive care such as intravenous fluid therapy, oxygen therapy, or even a

feeding tube A feeding tube is a medical device used to provide nutrition to people who cannot obtain nutrition by mouth, are unable to swallow safely, or need nutritional supplementation. The state of being fed by a feeding tube is called gavage, enteral f ...

. Conjunctivitis and corneal ulcers are treated with topical antibiotics for secondary bacterial infection.

Lysine Lysine (symbol Lys or K) is an α-amino acid that is a precursor to many proteins. Lysine contains an α-amino group (which is in the protonated form when the lysine is dissolved in water at physiological pH), an α-carboxylic acid group ( ...

is commonly used as a treatment; however, in a 2015

systematic review A systematic review is a scholarly synthesis of the evidence on a clearly presented topic using critical methods to identify, define and assess research on the topic. A systematic review extracts and interprets data from published studies on ...

, the authors investigated all clinical trials with cats as well as ''

in vitro ''In vitro'' (meaning ''in glass'', or ''in the glass'') Research, studies are performed with Cell (biology), cells or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in ...

'' studies and concluded that lysine supplementation is likely not effective for the treatment or prevention of feline herpesvirus 1 infection.

Vaccine

There is a

vaccine A vaccine is a biological Dosage form, preparation that provides active acquired immunity to a particular infectious disease, infectious or cancer, malignant disease. The safety and effectiveness of vaccines has been widely studied and verifi ...

for FHV-1 available (

ATCvet The Anatomical Therapeutic Chemical (ATC) Classification System is a drug classification system that classifies the active ingredients of drugs according to the organ or system on which they act and their therapeutic, pharmacological and chemica ...

code: , plus various combination vaccines), but although it limits or weakens the severity of the viral shedding, it does not prevent infection with FVR. Studies have shown a duration of immunity of this vaccine to be at least three years. The use of

serology Serology is the scientific study of Serum (blood), serum and other body fluids. In practice, the term usually refers to the medical diagnosis, diagnostic identification of Antibody, antibodies in the serum. Such antibodies are typically formed in r ...

to demonstrate circulating

antibodies An antibody (Ab) or immunoglobulin (Ig) is a large, Y-shaped protein belonging to the immunoglobulin superfamily which is used by the immune system to identify and neutralize antigens such as bacteria and viruses, including those that caus ...

to FHV-1 has been shown to have a positive predictive value for indicating protection from this disease. The combination vaccine, Purevax RC, against feline viral rhinotracheitis and feline calicivirus was authorised for medical use in the European Union in February 2005.

Preventing spread of virus

Most household disinfectants will inactivate FHV-1. The virus can survive up to 18 hours in a damp environment, but less in a dry environment and only shortly as an

aerosol An aerosol is a suspension (chemistry), suspension of fine solid particles or liquid Drop (liquid), droplets in air or another gas. Aerosols can be generated from natural or Human impact on the environment, human causes. The term ''aerosol'' co ...

References

External links

''Feline Upper Respiratory Disease'' from The Pet Health Library
{{DEFAULTSORT:Feline Viral Rhinotracheitis Cat diseases Animal viral diseases Herpesviridae Vaccine-preventable diseases