Lysine competes with another amino acid, arginine, that herpes virus must have in order to reproduce.

Lysine has been demonstrated to decrease the severity of ocular symptoms associated with herpes virus infection (1) and reduce viral shedding during periods of disease recurrence (2). Depending on symptoms, other medications such as topical antiviral drugs, topical polysulfated glycosaminoglycans, topical nonsteroidal anti-inflammatory drugs or topical interferon may be used. In some cases the ocular diseases resulting from feline herpes virus may require surgical intervention.

The key to managing the clinical signs associated with feline herpes virus is controlling the cat's environment. Cats exposed to multiple cats (indoor-outdoor cats), cats in multiple cat households, or cats that are frequently introduced to new cats are difficult to keep disease free.

Reducing stress by maintaining a stable routine is helpful in preventing recurrences of disease.

Keep in mind that it is the nature of the virus to see recurrences of the disease and periodic treatment is often necessary.

What is feline herpes virus?
Feline herpes virus is an upper respiratory virus of cats. It is also known as rhinotracheitis virus. It is very common among cats, especially in environments where there are multiple cats or new cats are constantly interacting. The virus is spread through the air and replicates in the upper respiratory tract (nasal area, tonsils). The conjunctiva of the eye is also affected during the primary infection. Clinical signs of infection include sneezing and ocular and nasal discharge. In most cases the primary infection resolves with no residual ocular lesions. However, depending on the age when the cat is affected, the serotype of the virus (infectivity or strength of infection), and other factors, there may be various ocular signs. In very young cats, adhesions of the eyelids to each other or to the cornea may occur. Adult cats may experience recurrent conjunctivitis or corneal ulcers. The virus remains latent in the nerves that serve the eyes. When a cat is stressed or exposed to new serotypes (different strains) of herpes virus, the ocular disease can recur. There is some evidence that eosinophilic keratitis, plasmacytic-lymphocytic keratitis, corneal sequestrum, and some cases of anterior uveitis may be associated with feline herpes virus infection.

How do cats get feline herpes virus?
Most cats are affected as kittens, contracting the infection from their mothers. Stray cats, multi-cat households, and cats from households where new cats are constantly introduced are more likely to suffer infection. Feline herpes virus is not contagious to dogs or to humans but only affects cats.

How is feline herpes virus diagnosed?
History and clinical signs can diagnose ocular diseases caused by feline herpes virus. Aside from history and clinical signs, diagnostic tests for feline herpes virus include virus isolation, immunofluorescent antibody testing, polymerase chain reaction testing, serology, and cytology. Testing can be expensive and is generally reserved for specific cases. Tests that may not specifically detect the presence of herpes may be used to detect ocular disease caused by herpes. These tests include a Schirmer tear test (measuring tear production), corneal staining, and conjunctival biopsy.

How is feline herpes virus treated?
Treatment for feline herpes virus infections is nonspecific and generally directed at controlling secondary bacterial infection. A topical antibiotic such as tetracycline or erythromycin may be prescribed for use in the eye. Systemic antibiotics may also be prescribed.