Famciclovir for Cats with Feline Herpesvirus (FHV-1)

This article is for educational purposes only and does not promote or advertise any prescription-only veterinary medicine. Treatment decisions should always be made in consultation with a veterinary surgeon.

Famciclovir is an antiviral medication used by veterinary surgeons in the management of feline herpesvirus (FHV-1), a common and often recurrent viral infection in cats.

Although originally developed for human medicine, famciclovir may be prescribed for cats under the veterinary cascade where clinically appropriate.

What is feline herpesvirus (FHV-1)?

Feline herpesvirus is one of the most common infectious causes of upper respiratory and ocular disease in cats. Exposure is widespread, particularly in multi-cat environments such as shelters, breeding households, and rescue settings.

Following initial infection, most cats become lifelong carriers. Periods of stress, illness, or immunosuppression may trigger reactivation, leading to recurrent clinical signs.

Signs of feline herpesvirus

Clinical signs can vary in severity but commonly include:

• Watery or thick ocular discharge
• Squinting or signs of eye discomfort
• Sneezing and nasal discharge
• Reduced appetite
• Lethargy during flare-ups

In some cases, more severe ocular disease may develop, including corneal ulceration, requiring closer monitoring and additional treatment.

How famciclovir works

Famciclovir is an antiviral medication that interferes with viral replication. In cats with FHV-1, this may help reduce the severity and duration of clinical signs.

It does not eliminate the virus from the body but may support clinical management during active disease when used appropriately.

When might famciclovir be used in cats?

Veterinary surgeons may consider famciclovir in cases where:

• Clinical signs are moderate to severe
• Flare-ups are frequent or recurrent
• Ocular involvement is significant
• Supportive care alone is insufficient

It is often used as part of a broader management plan, which may include supportive care, ocular treatments, and management of secondary bacterial infections where indicated.

Dosing and treatment duration

The dose and duration of famciclovir treatment vary depending on the individual patient and severity of disease.

Treatment may be short-term during flare-ups or used intermittently in recurrent cases.

Treatment selection and dosing decisions should always be made by the prescribing veterinary surgeon, and owners should follow the dispensing instructions carefully.

Side effects and safety

Famciclovir is generally well tolerated in cats. Some individuals may experience mild gastrointestinal upset.

As with all prescription medications, it should only be used under veterinary supervision.

Practical management tips

• Minimise environmental stress where possible
• Maintain good hygiene in multi-cat households
• Monitor for early signs of recurrence
• Follow veterinary treatment plans consistently

Early intervention during flare-ups may help improve comfort and reduce disease severity.

Understanding the veterinary cascade

In some cases, medications not specifically licensed for cats may be prescribed where no suitable licensed alternative is available. This is known as the veterinary cascade and is a regulated prescribing framework used by veterinary surgeons.

When to speak to your vet

• Persistent or worsening eye discharge
• Signs of eye pain or squinting
• Reduced appetite or lethargy
• Frequent recurrence of symptoms

Prompt veterinary assessment can help prevent complications and support long-term management.