Ocular Herpes

Ocular herpes is an infection of the eye caused by the Feline Herpesvirus. Herpesvirus is usually the cause of recurrent cases of conjunctivitis and/or persistent corneal ulcers.

Similar to herpes in humans, when a cat becomes infected with the Herpesvirus he/she never gets rid of the virus. Thus your cat, once initially infected, will always be a carrier of the virus. This means that your cat can infect other cats who are not immune to the virus and your cat can also become ill over and over again. Usually the virus will remain dormant in the body and will only produce illness in the affected cat at times when the cat is stressed, already ill, or immuno-compromised in some way. This virus can not only infect the eye but can also produce respiratory illness (Feline Viral Rhinotracheitis) and a host of other diseases.

Ocular herpes produces the same symptoms and type of illness as is seen with bacterial conjunctivitis. If your cat has conjunctivitis that regular antibiotic treatments do not seem to work on, and/or your cat has persistent bouts of conjunctivitis that do not seem to go away, your cat may be infected with Feline Herpesvirus. The main differences between the conjunctivitis caused by a bacteria and conjunctivitis caused by a virus is that viral conjunctivitis is harder to treat (regular antibiotics will not rid your cat of this infection as antibiotics work on bacteria not viruses), never really goes away, and is usually seen as a chronic illness.

Note: Feline Herpesvirus is specific to cats, you can not catch herpes from your cat.

Symptoms to look for:

  • Tearing of the eye
  • Discharge from the eye
  • Redness and inflammation of the eye
  • Ulcers in the eye
  • Cloudiness of the eye


Ocular herpes is difficult to treat. Mainly because treatment does not rid your cat of the virus. As it is not uncommon for secondary bacterial infections to occur while the Herpesvirus is present, your vet may still prescribe antibiotics for your cat. Thus you may see some initial improvement through antibiotic treatment, however, this improvement may be short lived (as the medication only works on the secondary infections) if the virus is not also combatted. Thus your vet may also prescribe anti-viral medications to treat the disease. He/she may also suggest l-Lysine supplementation. l-Lysine is a food supplement which can interfere with viral replication and may help in the long run.

Precautionary measures:

The best way to prevent infection with the Herpesvirus is to keep your cat indoors and keep his/her vaccinations up-to-date. Also, if you bring another cat into your home, make sure the new cat is healthy before introducing him to your current cat.