Feline Herpesviral Conjunctivitis

What is feline herpesviral conjunctivitis?

Conjunctivitis is a medical term used to describe inflammation of the tissues surrounding the eye. These tissues include the lining of the lids and the third eyelid as well as the tissues covering the front part of the eye or globe. Conjunctivitis may be a primary condition (caused by an infection) or may be secondary to an underlying systemic or ocular disease.

Feline herpesviral conjunctivitis is a form of primary conjunctivitis caused by the highly infectious feline herpesvirus (FHV-1). Herpesvirus infection is common in cats and is the most common cause of conjunctivitis in cats. Many cats are infected with FHV-1 and do not show any signs of clinical illness (i.e. they have a latent infection). Fortunately, less than 45% of adult cats with latent herpesvirus infection develop recurrent ocular disease such as conjunctivitis. In most cases, herpesvirus conjunctivitis is self-limiting and will resolve within two weeks.

What are the clinical signs of feline herpesviral conjunctivitis?

The most common clinical signs of conjunctivitis are squinting or closing of the eye, red, swollen tissue surrounding the eye and eyelids, ocular discharge that may range from clear to yellow-greenish in color, and upper respiratory infection symptoms such as sneezing or nasal discharge. These signs often appear suddenly and are especially common after stressful situations such as travel, boarding, surgery or illness. Chemosis, a condition in which the membranes that line the eyelids and surface of the eye appear to have fluid in them, is more commonly associated with chlamydial infections.

What diagnostic testing is indicated for feline herpesviral conjunctivitis?

Diagnosis is based primarily on medical history and physical examination. Corneal staining is often performed to look for any ulcers that may have developed. Identification of feline herpesvirus DNA by polymerase chain reaction amplification (PCR testing) is the most sensitive test available for diagnosing infection by FHV-1. Unfortunately, diagnostic testing is usually not rewarding during times of viral latency or in the absence of clinical signs. Since decreased tear film production has been associated with FHV-1 conjunctivitis, specific tests to assess the tear production may be recommended.

What is the treatment for feline herpesviral conjunctivitis?

Treatment is determined by your cat’s specific clinical signs and problems. It is important to remember that these infections are usually mild and self-limiting. However, if there are corneal ulcers, it is important to treat these appropriately. The following is a list of common treatment regimens used in treating recurrent feline herpesviral conjunctivitis:

  •  Antiviral medications are used in severe or poorly responsive cases
  • Idoxuridine ophthalmic solution
  • Vidarabine 3% ophthalmic ointment
  • Trifluridine ophthalmic solution
  • L-lysine
  • Interferon-alfa

What is the prognosis for a cat diagnosed with herpesviral conjunctivitis?

There is no cure. The therapeutic goal is to reduce the frequency and severity of recurrences. Most cats respond well to medical management and lead relatively normal lives. Minimizing the chance of infection, feeding a premium diet, supplementing the diet with l-lysine daily, reducing stressful situations and proper vaccination against preventable causes are your cat’s best defense.