Ophthalmology - Special Services, Technology, & Information
Feline Herpes Virus
Feline herpes virus is a common disease in cats, causing upper respiratory infection, conjunctivitis (inflammation of the pink tissue surrounding the eye) and in some cases inflammation or ulceration of the cornea.
Feline herpes is a virus specific to cats and is not contagious to humans or other species. The virus is contagious to other cats, although most cats have been exposed to the virus at some point in their life, and have developed immunity. Kittens are often exposed early in life and then become resistant or are protected by routine vaccinations. Symptoms often include upper respiratory infection associated with sneezing and watery eyes, which may seem to completely resolve after 10-14 days. The symptoms may then return in adult cats, primarily as conjunctivitis without upper respiratory infection. Symptoms often recur due to stress from another illness, boarding or moving, or after introduction of a new cat in the home. After recovery from this initial disease, a small percentage of cats develop recurring symptoms. This is similar to people who have recurrent cold sores, which are caused by herpes simplex virus.
Diagnosis of feline herpes virus is made based on clinical signs and a complete history.
Treatment of feline herpes virus is difficult. The virus lives within a host cell and replicates by altering the cell's normal DNA. Antiviral medications must kill the virus without harming the host cells. Recovery is dependent on the animal's own immune system to eliminate the virus, although complete recovery may not be possible. For this reason, the treatment regimen must be strictly followed. Also, periodic recheck visits are required to follow progress of treatment and any complications that may occur. However, many treatment options exist, and may vary depending on the severity of the disease.
- If a corneal ulcer is present, debridement (removal of diseased tissue) may be necessary to promote healing of the cornea.
- Bacteria often invade diseased tissues and worsen the effect of a viral condition, therefore, topical antibiotics are prescribed to treat/prevent secondary bacterial infections.
- The conjunctiva becomes very swollen and inflamed. Topical anti-inflammatories may be used to decrease inflammation of the conjunctiva and reduce discomfort.
- Several oral medications are available. Oral L-lysine is an amino acid used to decrease viral replication. Oral or topical antivirals may also be used to decrease viral replication. Oral or topical interferon is sometimes also used as an antiviral medication.
Possible complications of feline herpes virus infection of the surface of the eye may include:
- Scarring ,which may affect the cornea, causing cloudiness or occlusion of the tear outflow duct, resulting in tearing.
- Chronic corneal vascularization. (Blood vessels that grow into the cornea.)
- Decreased in tear production called “dry eye”. This may be treated with topical medications.