Feline Herpesvirus - Understanding FHV-1

What is Feline Herpesvirus?

Feline herpesvirus type 1 (FHV-1), also known as feline viral rhinotracheitis (FVR), is one of the most common and important infectious diseases of cats worldwide. It's a highly contagious virus that primarily causes upper respiratory tract infections, but can also affect the eyes and, in rare cases, other organ systems.

FHV-1 is responsible for approximately 80-90% of infectious upper respiratory diseases in cats, making it the most significant viral pathogen in feline respiratory disease. Understanding this virus is crucial for all cat owners, especially those with multiple cats.

How Cats Contract Feline Herpesvirus

Transmission Methods

Direct Contact:

• Nose-to-nose contact with infected cats
• Sharing food and water bowls
• Mutual grooming
• Contact with nasal or ocular discharge

Indirect Contact (Fomites):

• Contaminated surfaces (bowls, bedding, toys)
• Human hands and clothing
• Grooming tools and carriers
• Virus can survive hours on surfaces

Aerosol Transmission:

• Sneezing and coughing release viral particles
• Close proximity in confined spaces
• Shelter and boarding facilities
• Cat shows and breeding catteries

Mother to Kitten:

• During birth (vaginal secretions)
• Through nursing
• Early close contact

High-Risk Environments

• Animal shelters
• Breeding catteries
• Boarding facilities
• Multi-cat households
• Outdoor cats with contact with strays
• Recently adopted shelter cats

Acute vs. Chronic Infection

Acute Primary Infection

The initial infection typically occurs in kittens or previously unexposed adult cats:

Timeline:

• Incubation period: 2-6 days after exposure
• Acute illness: 10-20 days
• Viral shedding: 1-3 weeks

Symptoms:

• Sudden onset sneezing
• Nasal discharge (initially clear, then thick and purulent)
• Conjunctivitis (red, inflamed eyes)
• Ocular discharge
• Fever (103-105°F/39.4-40.6°C)
• Lethargy and depression
• Loss of appetite (due to inability to smell)
• Oral ulcers (less common)
• Coughing

Recovery:

• Most cats recover with supportive care
• Immunity develops but is not complete
• Virus establishes latency

Latent (Dormant) Infection

After recovering from acute infection, approximately 80-95% of cats become lifelong carriers:

Latency Characteristics:

• Virus hides in nerve tissues (trigeminal ganglion)
• Cat appears completely healthy
• No viral shedding occurs
• Cannot infect other cats during latency
• Will test negative on most diagnostic tests

Chronic/Recurrent Infection

Latent virus can reactivate during stress, causing recurrent outbreaks:

Reactivation Triggers:

• Stress (moving, new pets, boarding)
• Illness or immunosuppression
• Corticosteroid treatment
• Pregnancy and lactation
• Environmental changes
• Crowding and poor ventilation

Recurrent Symptoms:

• Usually milder than primary infection
• Sneezing and nasal discharge
• Conjunctivitis and eye discharge
• May have chronic rhinitis
• Intermittent viral shedding (reinfects other cats)

Clinical Signs and Symptoms

Respiratory Signs

Upper Respiratory Symptoms:

• Frequent sneezing (most common)
• Nasal discharge (serous to mucopurulent)
• Nasal congestion and difficult breathing
• Snoring or noisy breathing
• Reverse sneezing
• Decreased sense of smell (leads to anorexia)

Chronic Nasal Changes:

• Permanent nasal turbinate damage
• Chronic rhinitis
• Nasal deformity in severe cases
• Bacterial secondary infections

Ocular (Eye) Signs

Conjunctivitis:

• Red, inflamed conjunctiva
• Squinting and eye discomfort
• Clear to purulent discharge
• May affect one or both eyes
• Can become chronic

Corneal Involvement:

• Corneal ulcers (dendritic pattern characteristic)
• Keratitis (corneal inflammation)
• Corneal scarring
• Vision impairment in severe cases
• Symblepharon (adhesions between eyelid and cornea)

Severe Complications:

• Keratoconjunctivitis sicca (dry eye)
• Sequestrum formation (dead corneal tissue)
• Blindness (rare but possible)

Systemic Signs

• Fever (especially during acute phase)
• Lethargy and depression
• Anorexia (due to nasal congestion affecting smell)
• Dehydration
• Weight loss
• Secondary bacterial pneumonia (rare)

Kittens and Immunocompromised Cats

More severe disease possible:

• Pneumonia
• Systemic disease
• Higher mortality rate
• Permanent eye damage
• Failure to thrive

Diagnosis

Clinical Diagnosis

Often diagnosed based on:

• Characteristic clinical signs
• History of exposure or stress
• Response to treatment
• Presence in high-risk population

Laboratory Testing

PCR Testing (Polymerase Chain Reaction):

• Detects viral DNA
• Most sensitive and specific
• Conjunctival or nasal swabs
• Can distinguish FHV-1 from calicivirus

Virus Isolation:

• Gold standard but less commonly used
• Requires specialized laboratory
• Takes 3-7 days for results

Serology (Antibody Testing):

• Limited use due to high vaccination rates
• Cannot distinguish infection from vaccination
• Doesn't confirm active infection

Cytology:

• Conjunctival scrapings
• May show inclusion bodies
• Suggestive but not definitive

Differential Diagnosis

Must distinguish from:

• Feline calicivirus
• Chlamydia felis
• Bordetella bronchiseptica
• Mycoplasma
• Allergies or foreign bodies

Treatment

Antiviral Therapy

Famciclovir:

• Most effective antiviral for FHV-1
• Oral medication 2-3 times daily
• Reduces viral shedding and severity
• Well-tolerated in most cats
• Expensive but highly effective

Topical Antivirals:

• Idoxuridine (eye drops)
• Trifluridine (eye drops)
• Cidofovir (less common)
• For corneal ulcers and keratitis

Supportive Care

Nutritional Support:

• Encourage eating (warm, smelly foods)
• Hand-feeding or syringe feeding
• Appetite stimulants if needed
• Ensure adequate hydration

Nasal/Eye Care:

• Gently clean discharge with warm water
• Humidifier or steam therapy
• Nasal decongestants (veterinary approved only)
• Eye lubrication

Hydration:

• Subcutaneous or IV fluids if dehydrated
• Encourage water intake
• Wet food for additional moisture

Antibiotics:

• For secondary bacterial infections only
• Not effective against virus
• Commonly prescribed: doxycycline, amoxicillin

Symptomatic Treatment

• Anti-inflammatory medications
• Pain relief (especially for corneal ulcers)
• Nebulization therapy
• Supplemental oxygen (severe cases)

L-Lysine Supplementation

Controversial Topic:

• Historically recommended
• Recent studies question efficacy
• May not reduce viral replication
• Some cats show benefit
• Consult your veterinarian

Vaccination

Core Vaccine Status

FHV-1 vaccine is considered a core vaccine for all cats:

Important Facts:

• Does NOT prevent infection
• DOES reduce severity of disease
• DOES reduce viral shedding
• Protection is not absolute
• Requires regular boosters

Vaccination Schedule

Kittens:

• First vaccine: 6-8 weeks
• Booster: Every 3-4 weeks until 16 weeks
• Initial series crucial for protection

Adult Cats:

• Booster at 1 year after kitten series
• Then every 1-3 years depending on risk
• High-risk cats: annual boosters
• Low-risk cats: every 3 years acceptable

High-Risk Cats Requiring Annual Vaccination:

• Multi-cat households
• Breeding cats
• Show cats
• Boarding or daycare
• Shelter or rescue cats

Vaccine Types

Injectable (Subcutaneous):

• Modified live or killed virus
• Provides systemic immunity
• Most commonly used

Intranasal:

• Modified live virus
• Provides local immunity
• Faster onset of protection
• May cause mild sneezing (3-5 days)
• Good for high-risk, rapid protection needed

Prevention and Management

In Multi-Cat Households

Preventing Spread:

• Isolate infected cats immediately
• Separate food, water, litter boxes
• Disinfect all surfaces regularly
• Wash hands between handling cats
• Use separate grooming tools

Disinfection:

• Bleach solution (1:32 dilution) effective
• Allow 10-minute contact time
• Wash all bedding and toys
• Replace or disinfect carriers

New Cat Introduction:

• 2-week quarantine minimum
• Veterinary examination before introduction
• Ensure current vaccinations
• Monitor for symptoms

Stress Reduction

Critical for preventing reactivation:

Environmental Management:

• Consistent routine and environment
• Multiple resources (litter boxes, feeding stations)
• Vertical space and hiding spots
• Feliway or calming pheromones
• Gradual changes when unavoidable

Minimizing Stressors:

• Avoid overcrowding
• Provide enrichment and play
• Maintain health and nutrition
• Regular veterinary care
• Proper introductions of new pets

Nutrition and Immune Support

• High-quality, balanced diet
• Adequate protein and amino acids
• Omega-3 fatty acids
• Antioxidants and vitamins
• Maintain healthy weight

Living with a Carrier Cat

What to Expect

Lifelong Considerations:

• Cat remains infected for life
• Periodic flare-ups possible
• May shed virus intermittently
• Can infect other cats during shedding
• Requires ongoing monitoring

Quality of Life:

• Most carriers live normal, healthy lives
• Flare-ups usually manageable
• With proper care, excellent prognosis
• Chronic cases need more intensive management

Managing Flare-Ups

• Recognize early signs
• Initiate treatment promptly
• Reduce stress immediately
• Supportive care at home
• Veterinary consultation if severe

Protecting Other Cats

• Full disclosure when rehoming
• Inform boarding facilities
• Careful introduction of new cats
• Maintain vaccinations for all cats
• Monitor for signs of illness

Copenhagen-Specific Considerations

Climate Factors

Danish Weather Impact:

• Cold, damp weather may trigger flare-ups
• Indoor heating reduces humidity (dry air irritates)
• Seasonal changes can cause stress
• Keep indoor environment stable

Environmental Management:

• Use humidifiers during heating season
• Maintain comfortable temperature
• Avoid drafts
• Provide warm, cozy spaces

Veterinary Resources

• Excellent veterinary care in Copenhagen
• 24/7 emergency services available
• Advanced diagnostics (PCR testing)
• Experienced with FHV-1 management
• Famciclovir readily available

Urban Cat Considerations

• Higher density multi-cat households
• Apartment living (less space can mean more stress)
• Limited outdoor access (generally protective)
• Access to quality veterinary care

Prognosis

Acute Infection

Uncomplicated Cases:

• Excellent prognosis
• Recovery in 10-20 days
• Becomes latent carrier
• Normal lifespan expected

Complicated Cases:

• Corneal damage may be permanent
• Chronic rhinitis possible
• May require ongoing management
• Generally good quality of life

Chronic/Recurrent Cases

• Usually manageable with treatment
• Quality of life generally good
• May require periodic antiviral therapy
• Stress management crucial
• Regular veterinary monitoring

Severe Cases

• Kittens: higher mortality risk
• Immunocompromised: guarded prognosis
• Severe ocular disease: vision loss possible
• Pneumonia: requires intensive care

Conclusion

Feline herpesvirus is a common and highly contagious disease that affects cats worldwide. While there is no cure and most infected cats become lifelong carriers, the disease is usually manageable with proper veterinary care, antiviral treatment when needed, and stress reduction.

Key Points to Remember:

• FHV-1 causes most feline upper respiratory infections
• Highly contagious through direct contact and aerosols
• 80-95% of infected cats become lifelong carriers
• Stress triggers reactivation and flare-ups
• Vaccination reduces severity but doesn't prevent infection
• Famciclovir is the most effective antiviral treatment
• Good prognosis with proper management
• Multi-cat households require special precautions

Understanding FHV-1 allows cat owners to recognize symptoms early, seek appropriate treatment, and create an environment that minimizes stress and recurrence. With proper care, most cats with herpesvirus live long, healthy, and happy lives.

Is your cat showing signs of upper respiratory infection? Contact MyPeterinarian in Copenhagen for expert diagnosis and treatment of feline herpesvirus. Our experienced team provides comprehensive care including PCR testing, antiviral therapy, and stress management strategies to keep your cat healthy. Schedule your appointment today for prompt, professional care!