Feline herpesvirus (FHV-1) is a common cause of eye and upper respiratory infection in the cat. This virus is very common in the cat population, but it is not contagious to people and other species of animals such as dogs. Herpesvirus is easily passed from one cat to another through sneezing, coughing, grooming and/or simply being in close contact with an infected cat. Clinical signs associated with infection can vary greatly between cats. Some cats affected with FHV-1 may only have mild conjunctivitis of one or both eyes. Other cats with more severe forms of the disease may show ocular (eye) and nasal (nose) discharge, conjunctivitis (inflammation of the white part of the eye), coughing, sneezing and corneal ulcers. Corneal ulcers can be very painful and serious enough to cause noticeable scarring on the normally clear cornea. An infected corneal ulcer may even progress to cause perforation (rupture) of the eye.
An estimated 80% of cats are a carrier of the disease. The disease can go into temporary remission; however, stress and illness may reactivate the virus, causing repeated infections or recurrences of the clinical signs throughout life. Repeated or chronic infections have been associated with diseases such as dry eye, symblepharon (adhesion of the conjunctiva to itself or to the cornea), corneal sequestrum (an abnormal brown plaque formation on the cornea) and eosinophilic keratitis (an immune-mediated condition of the cornea).
The definitive diagnosis of feline herpesvirus infection is accomplished by laboratory testing. Many tests are available through a professional diagnostic laboratory. They include virus isolation, fluorescent antibody (FA) testing, serology such as ELISA or serum neutralizing titers and polymerase chain reaction (PCR) testing. It is important to realize that these tests may have false negative results. On the other hand, certain cats in the carrier state, but without apparent clinical signs may also test positive for some of these diagnostic modalities.
Treatment for herpesvirus is aimed at controlling clinical signs and reducing secondary complications. It is important to note that there is no cure for herpesvirus and once infected your cat has the virus for life. Some animals will never have clinical disease after the initial infection, while others may have frequent recurrences. Cat’s that have recurrent outbreaks often have a stressful trigger that can be identified (new pets in the household, houseguests, remodeling, etc.) and avoiding the stressor can reduce the number of outbreaks. Typically, therapy includes antiviral drops or ointment applied to the affected eye(s). Antiviral drops/ointments work by stopping viral replication, they do not kill the already present viral organisms and resolution of clinical signs depends on the present virus dying off which may take multiple weeks to completely occur. Occasionally oral antiviral medications are used in cases that do not respond to topical drugs. L-lysine is an amino acid dietary supplement that has been shown to inhibit viral replication in a laboratory setting. There are no studies indicating that giving Lysine as a supplement will benefit cats with herpes virus, however, many owners feel it does reduce outbreaks and there are no known side effects. Vaccination against herpesvirus infection is included in the typical feline vaccination schedule. This vaccine minimizes the clinical signs of the herpesvirus infection but does not prevent future outbreaks. The vaccination does not necessarily prevent infection nor can it cure cats already infected with the herpesvirus.
If you have any questions or concerns regarding Feline Herpes Virus, please call us at Eye Care for Animals.
