Feline Herpesvirus (FHV)
Feline herpesvirus 1 (FeHV-1) is classified under the Subfamily: Alphaherpesvirinae, and genus: Varicellovirus. FeHV-1 infection causes feline viral rhinotracheitis (FVR), which not only accounts for approximately half of all diagnosed feline viral upper respiratory infections, but is also an important cause of ocular lesions in cats. FeHV-1 typically affects kittens (after they are about 2 months of age) and juvenile cats.
Sample: Conjuctival swab, Oropharyngeal swab
Modes of transmission
The main source of infection are oronasal and ocular discharges of cats with acute or reactivated latent infection. Because FeHV-1 is relatively short-lived outside the cat, the environment is usually not a long-term source of infection.
During acute infection ulcerations in mucosae and the cornea and stromal keratitis can be observed. Acute respiratory FeHV-1 infection is characterized initially by fever, inappetence, and sneezing, followed by serous nasal discharge. Occasionally coughing and dyspnea may occur. In addition, oral replication of the virus can result in excessive salivation and drooling of saliva. FeHV-1 replicates extensively in the mucosae of the upper respiratory tract and generally causes severe upper respiratory disease. Ocular infection is characterized by acute hyperemic conjunctivitis, leading to ocular discharge and chemosis, and the formation of branched epithelial ulcers, resulting in serious corneal damage. Exposure of pregnant queens can lead to abortion and in neonatal kittens, the infection is associated with high mortality rate.
A hallmark of alpha herpesvirus biology is that acute infection is followed by lifelong persistence of the viral genome in latent form in nervous and lymphoid tissues. The reactivation of latent FeHV-1 is the result of stress. The reactivation frequency rates have been reported to be 18% and 40%, depending on a type of stressor. The administration of corticosteroids has been reported to lead to reactivation in 70% of the latently infected cats.
Broad spectrum antibiotics should be administered in all acute cases to prevent secondary bacterial infections. Intake of food is also important, since infected cats develop anorexia. In cats with severe clinical signs, the restoration of fluids and electrolytes is required. Nasal decongestants and eye drops or ointments should be administered. Antiviral therapy is also necessary.
Passive immunity persists for 2 to 10 weeks. After that period vaccination is recommended, followed by yearly boosters. All cats entering the cattery should have an up-to-date vaccination record.
FeHV-1 infection is one of the most widespread viral infections in cats.
Vögtlin, A., Fraefel, C., Albini, S., Leutenegger, C.M., Schraner, E., Spiess, B., Lutz, H., and Ackermann, M. (2002). Quantification of feline herpesvirus 1 DNA in ocular fluid samples of clinically diseased cats by real-time TaqMan PCR. J. Clin. Microbiol. 40, 519–523.