What do chickenpox, cold sores, and feline eye infections have in common? The answer is herpesvirus. But don’t worry, just because you’ve had a case of the chickenpox, it doesn’t mean you need to track down and inform all your previous sexual partners. Unless you particularly want to, that is!

You’re probably wondering what all this has to do with cats.

Feline herpesvirus type 1 (FHV-1) is found in around 80% of cats worldwide, and is one of the most common causes of chronic and recurrent ocular infections.¹ As is the case with human cold sores caused by herpes simplex virus (HSV), cats infected with FHV-1 may show no signs of infection, experience an isolated clinical infection, or go on to have sporadic flare-ups over the course of their lives. And for the latter cases, life can become pretty unbearable.

Unlike bacterial infections, which are typically cured through the judicious application of antibiotics, viral infections are often more challenging to deal with. Treatment often consists of supportive care and time, which, when your cat is suffering from regular episodes of squinting, inflammation, discharge, and pain, feels frustratingly inadequate. But thanks to some new research, there may be a new option for tackling this type of chronic infection, in the form of a common cold sore treatment.

Cold Sores and Cat Eyes

Although human cold sores and feline eye infections are caused by different strains of herpesvirus, they will often have a similar response to medication. Of course, treating an eye with an ointment designed to go on the mouth isn’t something that would ordinarily be recommended, and we all know how it feels to have something in your eye that doesn’t belong there.

In a recent study published in Research in Veterinary Science, the topical drug 1 % penciclovir cream (Fenlips®) was trialed on a number of cats to determine how well this preparation was tolerated by the patients, and how effective it was against ocular infections caused by FHV-1. The results are very promising.

Fenlips has been used off-label to treat feline eye infection in the past, but its safety and effectiveness have not been properly researched. This study combined both historical information (retrospective study) from over 100 cases where Fenlips had been used to treat ocular infections in clinical practice, with clinical testing (prospective study) of seven cats to assess their tolerance to Fenlips, compared with an ophthalmic ointment (DuraTears®).

The Retrospective Study

A survey of cat parents who had used Fenlips to treat their cat’s eye infection showed that an overwhelming 80% reported the treatment to be effective, and only 15% reported any adverse effects to the medication, all of which were mild and short-lived.

The Prospective Study

The seven healthy cats used in this study were treated with a known ophthalmic ointment in one eye and Fenlips in the other for a period of 10 days. Although some cats showed some initial signs of sensitivity at the start of treatment, these signs were mild and resolved quickly, and no adverse reactions were seen even after 31 days of treatment.

Additionally, the concentration levels of penciclovir in the tear film persisted at therapeutic levels for around 8 hours, meaning that this treatment would not need to be applied more frequently than three times a day.

Why Is This Good News?

With treatments for viral ocular infections in cats quite limited in availability and effectiveness, it’s great news for owners of FHV-1 sufferers to have an over-the-counter treatment they can safely rely on, without the need for repeat check-ups and prescriptions for a chronic condition. However, we would urge caution.

Although this new study indicates that Fenlips appears to be safe and effective for ocular use in cats, this does not negate the need for a proper examination and diagnosis. For cats requiring long-term and repeated treatment for a diagnosed condition, having easy access to an effective treatment would be a huge relief for owners. But, FHV-1 is only one possible cause of eye infections and ocular problems in cats, and skipping a vet examination could cost your cat their vision or even their eye.

Corneal ulcers are another common eye problem seen in cats. If not managed and monitored correctly, these ulcers can penetrate through the cornea and cause permanent damage, often resulting in enucleation (removal of the eye).

So if your cat suffers from chronic and recurrent eye infections from FHV-1, Fenlips for the eye might be music to your ears.

Always speak to a vet before administering ANY medication to your cat. Feline eyes are extremely sensitive, so it’s vital to get the correct diagnosis, or you could make it worse.

*Please note that neither the scientific research discussed nor this article has been funded by Fenlips®

Did You Know?