Evidence Library / Condition guides
Condition guide · Cats
FHV-1 keratitis in cats: where UVC fits.
A guide for veterinary teams
80%
of infected cats become lifelong carriers, with the virus latent in the trigeminal ganglia
Dendritic
ulcers following the corneal nerves are considered pathognomonic for FHV-1
Recurrent
disease is common: stress or immunosuppression can reactivate the virus
Feline herpesvirus-1 is a leading cause of recurrent corneal ulcers in cats. UVC can reduce the microbial load on the corneal surface, but there is no published clinical data on UVC for FHV-1 yet, and antiviral therapy remains the standard of care.
What it is.
FHV-1 causes ocular and upper respiratory disease, particularly in kittens. Around 80% of infected cats become lifelong carriers, and stress or immunosuppression can reactivate the virus. It is a true corneal pathogen: dendritic ulcers, which follow the corneal nerve endings, are considered pathognomonic and can progress to larger, slower-healing geographic ulcers.
Why it’s hard to treat.
- PCR on conjunctival or oropharyngeal swabs has limited sensitivity and false negatives are common, so diagnosis is largely clinical.
- Antiviral options, such as topical ganciclovir every four hours or oral famciclovir, need frequent dosing, and cats metabolise famciclovir poorly.
- Chronic complications include corneal sequestra, eosinophilic keratitis and dry eye.
- Supportive care often includes antibiotics, lubricants and pain relief alongside antivirals.
Where UVC fits.
UVC inactivates viruses, bacteria and fungi on the surfaces it reaches, and viruses need the lowest exposure of all. Photon’s view is that a 5-second treatment can lower the viral and bacterial load on the cornea and support faster healing of herpetic ulcers. UVC only treats the surface it is pointed at. It does not reach latent virus in the trigeminal ganglia or treat systemic disease, so it complements antiviral therapy rather than replacing it.
What the evidence doesn’t show yet.
- There is no published study yet of UVC in cats with FHV-1 keratitis. Photon reports that studies are under way.
- The 2026 clinical study included 3 cats and measured bacterial load, not viral load.
- Antiviral therapy remains the standard of care for FHV-1.
Sources
- Vet Times, 20 January 2026
- Klimova Z, Stavinohova R. Ophthalmology: corneal ulcers in feline patients
- Journal of Feline Medicine and Surgery, 2011
- Feline herpesvirus-1: ocular manifestations, diagnosis and treatment options
About this guide
Written by Photon Therapeutics for veterinary professionals. It summarises published evidence and is not a substitute for clinical judgement. Photon Therapeutics makes the PhotonUVC Vet device.
The evidence.
Veterinary clinical study · 2026
Single 5-second UVC treatment cuts bacterial load in dogs, horses and cats
Median 96.5% drop in bacterial count across 34 eyes at a UK referral hospital.
Safety study · 2021
Effect of therapeutic UVC on corneal DNA
No detectable DNA damage in mouse corneas after three daily 15-second treatments.
Systematic review and meta-analysis · 2021
Safety and efficacy of UV light for superficial infections: systematic review
53 studies reviewed; adverse event rates with UV similar to standard treatment.
Bring PhotonUVC Vet into your practice.
A 5-second, non-contact UVC treatment for corneal infections in dogs, cats and horses.