The third installment in our series on viral diseases in cats focuses on feline herpesvirus infection.
【Feline Herpesvirus Infection】
This infection is caused by feline herpesvirus type 1 (FeHV-1) and is also known as “feline viral rhinotracheitis.”
Together with feline calicivirus and feline chlamydia, it forms part of upper respiratory infections, commonly referred to as “cat flu.”
＜Symptoms＞
Nasal discharge
Continuous sneezing
Eye discharge
Conjunctivitis and keratitis
Stomatitis
Loss of appetite
Fever
Conjunctivitis is typically present in both eyes, and in severe cases, eyeball rupture can occur. If stomatitis worsens, there may be increased drooling and strong bad breath. Severe cases are also at a higher risk of developing pneumonia.
In young kittens or cats with weakened immune systems, secondary bacterial infections or mixed infections can exacerbate the symptoms.
＜Transmission Routes＞
The virus is transmitted nasally or orally through nasal discharge, eye discharge, and saliva from infected cats. Moreover, since herpesvirus can remain latent in the trigeminal ganglion, infected cats can harbor the virus for life. Even if the symptoms appear to resolve completely, a decrease in immunity can cause the herpesvirus in the trigeminal ganglion to reactivate, leading to new symptoms and making the cat a source of infection again.
＜Diagnosis Methods＞
There are several diagnostic methods, including serological tests (virus neutralization tests, indirect immunofluorescence assay), virus isolation, and PCR tests. Virus isolation is considered the most reliable method.
＜Treatment Methods＞
There is no effective treatment for herpesvirus itself; thus, supportive care aims to alleviate current symptoms and allow the cat to recover using its own strength and immune system.
Supportive care may include fluid therapy to correct dehydration, nutritional support, administration of non-steroidal anti-inflammatory drugs to alleviate pain and inflammation, and administration of interferon.
Recently, new antiviral eye drops that target and disrupt the replication of the herpesvirus DNA have become available. Oral administration of L-lysine is also believed to be effective, and it may be beneficial to take it as a supplement.
In addition, broad-spectrum antibiotics may be used to prevent secondary bacterial infections or mixed infections as previously mentioned.
＜Precautions＞
FeHV-1 can be easily killed by most commercial disinfectants (such as alcohol-based disinfectants) and detergents. However, because it can remain latently infected inside the body, disinfecting the living environment, including toilets and dishes, cannot eliminate the virus within the cat. Maintaining usual hygiene and minimizing stress can help prevent recurrence.
＜Prevention Methods＞
FeHV-1 prevention is possible with vaccination. Ensuring kittens are properly vaccinated can help prevent the disease, though it may not completely prevent infection. To avoid immune imbalance, it’s important to minimize stress and consider supplements that support immune health, which may help in preventing the onset of the disease.
