What is the diagnosis and treatment for Feline Herpesvirus (FHV) conjunctivitis?

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Last updated: April 18, 2025View editorial policy

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From the Guidelines

Feline herpes conjunctivitis should be treated with topical antiviral medications and supportive care to prevent complications and improve quality of life. The treatment of conjunctivitis, including feline herpes conjunctivitis, is ideally directed at the root cause, and early detection and treatment can be both sight saving and, in select cases, lifesaving 1. For mild cases, topical antiviral medications like 0.5% cidofovir or 0.1% idoxuridine eye drops can be applied 4-6 times daily until symptoms resolve, typically 2-3 weeks.

Key Considerations

  • Oral L-lysine supplements (250-500mg twice daily) can help inhibit viral replication.
  • For severe cases, oral famciclovir (40-90mg/kg twice daily for 7-14 days) may be prescribed.
  • It is essential to keep the affected eye clean by gently wiping away discharge with warm saline solution.
  • Feline herpesvirus-1 (FHV-1) remains dormant in cats after initial infection and can reactivate during times of stress or illness, so minimizing stress, maintaining good nutrition, and keeping vaccinations current are important preventive measures.
  • If symptoms like squinting, redness, discharge, or cloudy corneas are observed, veterinary care should be sought immediately as untreated infections can lead to corneal ulcers and potential vision loss.

Treatment Approach

The use of topical antibiotics or corticosteroids should be avoided because antibiotics can induce toxicity, and corticosteroids can potentially prolong adenoviral infections and worsen HSV infections 1. Instead, treatment methods should be directed at the root cause of the conjunctivitis, and supportive care should be provided to manage symptoms and prevent complications.

From the Research

Feline Herpes Conjunctivitis

  • Feline herpesvirus 1 (FHV-1) is a common cause of ocular and upper respiratory disease in cats and kittens, and a potential cause of eosinophilic dermatitis 2.
  • The systemic anti-herpes drug, famciclovir, has been shown to be effective in the clinical management of disease attributable to FHV-1, including conjunctivitis, keratitis, corneal sequestra, rhinosinusitis, and FHV-1 associated dermatitis 2, 3.

Treatment Options

  • Oral famciclovir has been used to treat signs considered referable to FHV-1 in cats, with a positive impact on the patient's condition 2.
  • Topical ganciclovir ophthalmic gel has been shown to be effective in reducing clinical ocular disease scores and corneal inflammation in cats with experimental ocular FHV-1 infection, with similar efficacy to oral famciclovir treatment 4.
  • A combination treatment of oral famciclovir, L-lysine, ophthalmic acyclovir, and subcutaneous amoxicillin plus clavulanic acid has been found to be clinically effective for the treatment of naturally occurring active FHV-1 infection in cats 5.

Efficacy and Safety

  • Clinical improvement was subjectively graded as marked in 51% of cats treated with famciclovir, with a median time to improvement of 7-10 days 3.
  • Adverse effects potentially attributable to famciclovir administration were reported in 10 cats, with no significant differences in hemograms and biochemistry panels between treatment groups 3, 4.
  • The antiviral combination treatment with famciclovir, L-lysine, and ophthalmic acyclovir, and antibacterial drug appears to be safe and effective for the treatment of naturally occurring active FHV-1 infection in cats, with no adverse clinical effects reported 5.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Comparative Efficacy of Topical Ophthalmic Ganciclovir and Oral Famciclovir in Cats with Experimental Ocular Feline Herpesvirus-1 Epithelial Infection.

Journal of ocular pharmacology and therapeutics : the official journal of the Association for Ocular Pharmacology and Therapeutics, 2022

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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