Feline herpesvirus-1 (FHV-1) corneal stromal disease is managed with topical antiviral therapy as the foundation, with multimodal escalation for progressive or melting disease. All antiviral drugs used in cats are off-label, and success in treating ocular herpesvirus in humans does not translate directly to FHV-1. MSD Vet Manuals
Topical antivirals are the primary treatment for FHV-1 stromal keratitis. Trifluridine (trifluorothymidine) is a pyrimidine analog that inhibits viral DNA polymerase and achieves therapeutic stromal concentrations through good corneal epithelial penetration. Its main drawbacks are the need for frequent administration and stinging on application, both of which can limit compliance in cats. MSD Vet Manuals Ganciclovir is substantially more efficacious against FHV-1 in vitro than acyclovir or cidofovir and is available as a 0.15% ophthalmic gel; it can also be compounded as a 0.5% solution with the addition of interferon alpha-2B. MSD Vet Manuals Acyclovir is not the topical antiviral of choice due to poor efficacy against FHV-1. MSD Vet Manuals Valacyclovir is contraindicated in cats — it is toxic and caused early termination of a clinical trial for humane reasons. Journal of the…+1
Systemic antiviral therapy with famciclovir is supported for FHV-1 keratitis. Orally administered famciclovir has resulted in improved clinical scores and reduced viral load in naturally infected cats. Journal of the… The veterinary literature does not specify an exact dose in the provided sources, but famciclovir is the systemic antiviral of choice given the toxicity profile of alternatives.
When FHV-1 stromal disease is complicated by secondary bacterial infection and keratomalacia (corneal melting), multimodal therapy is required. Progressive infectious keratitis warrants a combination of topical antibiotics, topical anti-collagenolytics, systemic antibiotics, systemic analgesics, and consideration of surgical stabilization techniques. Veterinary Opht… Photoactivated chromophore for keratitis–corneal cross-linking (PACK-CXL) is an established adjunctive therapy for infectious keratitis with stromal melting when medical management is insufficient. Veterinary Opht…
Corticosteroids are contraindicated when active FHV-1 replication is present. Topical corticosteroids induce viral reactivation, potentiate corneal penetration of the virus, and increase susceptibility of keratocytes to viral infection. BMC Veterinary… If eosinophilic keratitis is concurrently present — which occurs in at least 76.3% of FHV-1-positive cats — antiviral medications are specifically recommended when there is evidence of viral replication, particularly if corneal ulcers are present, before initiating immunosuppressive therapy. BMC Veterinary…+1 Topical cyclosporine, used as an alternative immunosuppressive in eosinophilic keratitis, carries its own adverse effects including irritation, chemosis, conjunctival hyperemia, and blepharitis. BMC Veterinary…
In vivo confocal microscopy (IVCM) can characterize the microanatomic extent of stromal disease — hyperreflective punctate opacities, inflammatory cells in all epithelial layers, and anterior stromal dendritic cells are present in FHV-1 herpetic keratitis and absent in unaffected corneas, which can help guide monitoring of treatment response. American Journa…
Enucleation remains the endpoint for end-stage disease. A central descemetocele with a nonvisual, painful globe secondary to chronic FHV-1 keratitis is an indication for enucleation when conjunctival flap surgery is not feasible. Journal of the…
| Drug/Intervention | Protocol | Key Evidence | Key Caveat |
|---|---|---|---|
| Trifluridine (topical) | Frequent topical application | Therapeutic stromal concentrations achieved | Stings on application; compliance issues in cats MSD Vet Manuals |
| Ganciclovir (topical) | 0.15% gel or compounded 0.5% solution ± interferon alpha-2B | Superior in vitro efficacy vs. acyclovir and cidofovir MSD Vet Manuals | Off-label MSD Vet Manuals |
| Famciclovir (oral) | Oral administration | Improved clinical scores and reduced viral load in naturally infected cats Journal of the… | Dose not specified in available sources |
| Acyclovir (topical) | — | Not efficacious against FHV-1 MSD Vet Manuals | Not recommended MSD Vet Manuals |
| Valacyclovir (oral) | — | — | Toxic to cats; contraindicated Journal of the…+1 |
| PACK-CXL | Adjunctive procedure | Established adjunct for infectious keratitis with stromal melting Veterinary Opht… | Requires specialist equipment Veterinary Opht… |
| Topical corticosteroids | — | — | Contraindicated with active FHV-1 replication BMC Veterinary… |
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