Feline Herpesvirus Infection, FHV (Cat Flu Caused by Herpesvirus Infection) in cats
- Occurrence: common
- Location of illness: General/Whole body, Head/Neck
When to visit the vet?
Non-urgent see a veterinarian within 2–3 days
If the condition worsens / symptoms persist, consult a veterinarian.
Definition
Feline Herpesvirus infection (FHV) is a viral disease in cats that primarily affects the upper respiratory tract and is commonly known as part of the cat flu complex.
The most important facts at a glance
Feline herpesvirus infection (FHV), also known as cat flu, is caused by a highly contagious DNA virus that spreads mainly through direct Contact with infected cats or contaminated objects. Young, old, or immunocompromised cats are particularly at risk. After infection, the virus affects the mucous membranes of the respiratory tract and can cause symptoms such as Sneezing, nasal discharge, and conjunctivitis. The virus can remain latent in the body and become active again under stress or with a weakened immune system.
Diagnosis is based on clinical symptoms, and definitive confirmation can be made through PCR tests. Therapy focuses on relieving symptoms and supporting the immune system, as there is no specific antiviral therapy. If necessary, fluid therapies and antibiotics are used against secondary bacterial infections. For prevention, vaccination is one of the most effective measures to reduce the risk of infection. Regular cleaning measures and stress reduction also contribute to prevention.
The prognosis is usually good, with most cats recovering within one to three weeks. However, some cats can remain carriers of the virus and show symptoms again when stressed. Chronic eye problems or respiratory diseases can be long-term complications that require ongoing therapy. Regular veterinary check-ups are important to monitor the cat’s health status.
Causes
Feline herpesvirus, also known as feline rhinotracheitis virus, is a DNA virus from the Herpesviridae family. It is highly contagious and spreads mainly through direct Contact with infected cats or contaminated objects. The virus is found worldwide and affects cats of all ages, although young kittens, older cats, and immunocompromised animals are particularly vulnerable.
After infection, the virus enters the mucous membranes of the upper respiratory tract, where it multiplies and causes symptoms such as Sneezing, nasal discharge, and conjunctivitis. A special feature of herpesviruses is their ability to enter a latent state. This means the virus can remain in the cat’s body without causing immediate symptoms. Under stress or when the immune system is weakened, the virus can be reactivated, leading to a new outbreak of the disease.
The main route of transmission is direct Contact with infected secretions, such as nasal or eye discharge. Indirect transmission can occur through contaminated food and water bowls, bedding, or toys. Since the virus does not survive long in the environment, direct transmission plays a larger role.
Symptoms
Symptoms of an FHV infection are usually mild to moderate, but can cause serious complications in severe cases or in untreated animals. The most common symptoms include Sneezing, nasal discharge, eye discharge, and conjunctivitis. These symptoms usually appear 2 to 6 days after infection.
Additionally, affected cats may show Fever, loss of appetite, and lethargy. In severe cases, Pneumonia can occur, characterized by Cough and respiratory distress. Chronic infections can lead to the formation of ulcers on the cornea of the eyes, known as herpesvirus-induced keratitis.
In kittens, the infection can be more severe because their immune system is not yet fully developed. In rare cases, a generalized infection can occur, which is difficult to treat and has a high mortality rate.
Diagnosis
Diagnosis of an FHV infection is usually based on clinical symptoms and a thorough medical history. The veterinarian will examine the cat and look for typical symptoms such as nasal and eye discharge. A definitive diagnosis can be made by detecting the virus in swabs from the eyes, nose, or throat using PCR (polymerase chain reaction) or virus isolation.
Although serological tests are available, they are often less helpful because many cats have antibodies against FHV due to previous infections or vaccinations. In some cases, cytology or a biopsy of the affected mucous membranes can be helpful to rule out other causes for the symptoms.
Therapy
Therapy for FHV infection primarily aims to relieve symptoms and prevent complications. There is no specific antiviral therapy that can kill the virus directly, so treatment focuses on supporting the immune system and relieving symptoms.
Fluid therapy may be necessary for dehydrated or severely affected cats. Secondary bacterial infections, which often occur with viral respiratory diseases, can be treated with antibiotics. Eye ointments or drops can be used to relieve ocular inflammation.
Antiviral medications such as famciclovir can be used in severe cases or chronic infections to reduce the viral load. Measures to support the immune system, such as L-lysine supplementation, can also help control symptoms and promote recovery.
Prognosis and follow-up care
The prognosis for cats with FHV is generally good, especially with early diagnosis and therapy. Most cats recover completely within one to three weeks. However, some cats can remain carriers of the virus and show symptoms again during times of stress or illness.
Chronic eye problems or recurring respiratory diseases can occur in some cats, especially those with a weakened immune system or other health issues. These long-term complications may require ongoing therapy and monitoring.
Prevention
To prevent feline herpesvirus infection (FHV) in cats, one of the most effective measures is vaccination. Regular vaccinations help significantly reduce the risk of infection and protect against severe courses of the disease. It is important to discuss the vaccination schedule with your veterinarian and ensure that the cat receives all necessary boosters.
The environment also plays a crucial role in prevention. A clean and hygienic environment can curb the spread of the virus. Regular cleaning of food and water bowls, sleeping areas, and litter boxes is essential. Additionally, cats that may be infected should be separated from healthy animals.
Stress reduction is another important factor. Stress can weaken the immune system and make cats more susceptible to infections. A stable and stress-free environment can help strengthen the cat’s immune system. This also includes approaching changes in the household, such as new pets or moving, slowly and carefully.
Pet owners should also ensure that new cats coming into the household are tested for FHV and vaccinated if necessary to prevent transmission to other cats. Regular veterinary check-ups also help monitor the cat’s health and respond early to potential problems.