Viral infections in the cornea are seen most commonly in cats. The infection is caused by Feline Herpes virus, which cannot infect humans. Feline Herpes virus also can cause cat flu symptoms.

Most cats (reportedly up to 70%) have Feline Herpes Virus, but few show symptoms of the infection. For various reasons, most commonly stress, the infection becomes clinical. Some cats show upper respiratory tract signs, others just show eye signs, in one eye or both eyes.


Feline Herpes Virus infection in the eye often presents with classical signs. Diagnosis can be usually made on the clinical signs. A specific test for Feline Herpes Virus infection is available. This is called a PCR (polymerase chain reaction) test.


1. Anti–viral Medications: In some cases the treatment of viral keratitis can be extremely frustrating. In some cases there can be little if any response to treatment, and in these cases we believe that the virus is resistant to the medication and we will need to try another anti-viral medication.

2. Lysine: Is an amino acid, which has been show to reduce the amount of virus replication. It seems to reduce the severity and duration of Feline herpes virus infection. The most beneficial use of lysine is to reduce recurrence or viral infection in cats.

3. Immune stimulation: Via a drug that seems to stimulate the immune system to fight off the herpes virus infections.

4. Antibiotics: Often antibiotic treatment is required, as we have found many cases of viral keratitis often have secondary Chlamydia infections. To eradicate this infection antibiotics are used.

Possible complications

1. Corneal sequestration – also called Feline keratitis nigrum: In this condition black or brown spots develop in the cornea. Persian cats seem especially prone to developing corneal sequestrums. These lesions can develop sometimes months after herpes virus infections. In most cases surgery with the operating microscope is required to remove the discolored cornea.

2. Eosinophilic Keratitis: This is an unusual complication where white spots develop in the cornea. The white spots are composed of eosinophils, white blood cells that are generally associated with allergic conditions. Medications will be required to resolve this complication.