Feline herpes virus [FHV] is the most frequent cause of conjunctivitis and corneal damage in domestic cats. It is thought that about 70% of cats show antibodies to the virus, indicating that they have been exposed to it.
The virus is transmitted from infected cats by direct contact as well as by aerosols. Nasal, oral and conjunctival routes of infection have been demonstrated and the virus is primarily shed in the secretions from these body systems for 1-3 weeks following infection.
Important characteristics of FHV:
- Rapid rate of replication in surface cells of the mouth, nose and eye
- Severe cellular destruction ability
- Ability to produce a carrier state in cats following infection where the virus remains dormant in the cat
- Ability to recrudesce [or re-activate] from the dormant stage under conditions of stress
Following acute infection or subclinical infection, 20% of cats recover completely and 80% enter the latent or dormant phase and are asymptomatic. Of this latter group, 45% will recrudesce. Some will become an asymptomatic shedder whilst others [about 5%] show chronic or recurrent eye disease.
The typical stress events in a cat’s life that can re-activate the virus include:
- introduction of a new affected kitten or cat
- moving house
- hospitalisation or cattery accommodation
- transporting to cat shows, on holiday etc
- stress during the mating season or been sent away for mating
- a new baby in the house
- constant harassment by dogs
Ophthalmic conditions associated with FHV
The common eye problems associated with FHV include:
- Corneal sequestrum
- Eosinophilic keratitis
- Keratoconjunctivitis sicca [dry eye]
Not all affected cats show all these symptoms and thus treatment may vary according to the problems encountered. The veterinary ophthalmologist will examine your pet's eyes carefully and advise on the most appropriate treatment.