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Herpesvirus Infection in Cats (Feline Viral Rhinotracheitis)

The herpesvirus infection can lead to serious health issues for cats, which is why vaccination and hygiene practices are essential to keeping our feline friends healthy. Today, our South Florida vets explain what kitty owners should know about the herpesvirus infection in cats.

Feline Viral Rhinotracheitis

Feline viral rhinotracheitis is also known as a herpesvirus infection. The condition is thought to be responsible for up to 80 – 90% of all infectious upper respiratory diseases in cats. This disease can affect your feline friend's nose, eyes, and windpipe. It may also cause problems during pregnancy. 

Symptoms of feline herpesvirus include:

  • Coughing
  • Sneezing
  • Fever
  • Eye ulcers
  • Inflamed eyes and nose 
  • Discharge from the eyes and nose 

These symptoms may be mild and start to clear up for healthy adult cats after about 5 – 10 days. However, in more severe cases, symptoms of FVR can last for six weeks or longer.

In kittens, senior cats, and immune-compromised cats, symptoms of FHV-1 may persist and worsen, leading to severe weight loss, sores inside your cat's mouth, loss of appetite, and depression. Cats that are already ill with feline viral rhinotracheitis often develop bacterial infections. 

How Vaccines Work 

Vaccines work by causing the body's immune system to recognize and fight a particular microorganism such as a virus, bacteria, or other infectious organisms. Once vaccinated, an animal's immune system is then prepared to react to future infection with that microorganism.

In other words, a vaccine acts like a true infection so the immune system can better protect your cat's body in the future. Depending on the disease, a vaccine will help prevent infection in the body or lessen the severity of the infection and encourage fast recovery.

The FVRCP Vaccination

Several different forms of the FVRCP vaccine exist, including injectable and intranasal. For your cat to receive the best protection possible against illness, they should receive their first FVRCP vaccination when they are around six to eight weeks old, then receive two more booster shots at intervals of three to four weeks, until they're around 16 to 20 weeks of age. After that, your kitten will need another booster once they reach just over a year old, then every three years throughout their lifetime. 

It is not recommended that the first vaccination be administered to a cat with an active infection, as it will not reduce the severity of symptoms and may add additional stress to your four-legged friend, complicating recovery. 

For more information about when your cat should receive vaccines, speak to your primary care veterinarian. 

Potential Side Effects 

While it's unusual for cats to experience side effects from vaccines, when reactions do occur they tend to be very mild. Most cats that do react to the FVRCP vaccine will develop a slight fever and feel a little 'off' for a day or two. It is not unusual for there to be a small amount of swelling at the injection site. 

If your cat is displaying any of the more severe symptoms of a reaction listed above, contact your primary care vet right away or visit the emergency animal hospital closest to you. 

Other Conditions That the FVRCP Vaccine Addresses

The FVRCP vaccine is an extremely effective way to protect your cat against three highly contagious and life-threatening feline diseases: feline viral rhinotracheitis (FVR), feline calicivirus (C), and feline panleukopenia (P). 

Feline Calicivirus (FCV)

This virus is a major cause of upper respiratory infections and oral disease in cats.

Symptoms of feline calicivirus (FCV) include nasal congestion, sneezing, eye inflammation, and clear or yellow discharge from the infected cat's nose or eyes. Some cats will also develop painful ulcers on their tongue, palate, lips, or nose due to FCV. Often cats infected with feline calicivirus suffer from loss of appetite, weight loss, fever, enlarged lymph nodes, squinting, and lethargy.

It's important to note that there are several different strains of FCV, some produce fluid buildup in the lungs (pneumonia), while others lead to symptoms such as fever, joint pain, and lameness.

Feline Panleukopenia (FPL)

Feline Panleukopenia (FPL) is an extremely common and serious virus in cats that causes damage to bone marrow, lymph nodes, and the cells lining your cat's intestines. Symptoms of FPL include depression, loss of appetite, high fever, lethargy, vomiting, severe diarrhea, nasal discharge, and dehydration.

Due to their weakened immune systems, cats infected with FPL frequently develop secondary infections as well, due to the weakened state of their immune systems. Although this disease can attack cats of any age it is often fatal in kittens. 

There are currently no medications available to kill the virus that causes FPL so treating cats with feline panleukopenia involves symptoms such as dehydration and shock through intravenous fluid therapy and intensive nursing care.

Feline Herpesvirus Treatment

Similar to their human counterparts, cats that come into contact with FHV are infected for life, as there is no cure. The first infection is the most severe. Subsequent flare-ups may be caused by stress or other underlying illnesses. Treatment will focus on controlling clinical signs and reducing secondary complications. 

Anti-viral medications (both ocular and oral) and supportive care can help reduce the severity of the infection, while nebulization therapy with sterile saline (saltwater) can help treat airway congestion. For severely infected cats, intravenous fluid and nutritional therapy are sometimes necessary. 

Kittens with severe eye infections sometimes have profound, painful swelling around the eyes that requires ocular surgery

A veterinarian would typically recommend a course of antibiotics to control secondary bacterial infections from introducing additional complications. 

To address excessive discharge from the eyes and nose, gently clean these areas with some clean cotton wool and water. Your primary care vet or veterinary ophthalmologist may also prescribe eye drops or nasal drops. Steaming is also recommended for severe cases of nasal congestion. 

How Cats Can Spread Feline Herpesvirus to Other Cats

While a herpesvirus vaccine reduces the clinical signs of herpes recurrence, it does not prevent microorganisms from entering the body.

Environmental, chemical, and physiological stress can all lead to reactivation of a latent case of feline herpesvirus. Therefore, these stressors are associated with renewed replication and shedding of the infectious virus. 

This means that while your cat may not appear sick due to having the vaccine, your kitty can still spread these microorganisms to other unvaccinated cats and animals if they spend time in shelters, boarding facilities, humane societies, or other communal environments.

Reactivation also plays a key role in immune-mediated dendritic keratitis (inflammation of the cornea, the transparent part of the eye). Damage to the cornea as a result of keratitis can lead to blindness. Feline herpesvirus can also lead to conjunctivitis (an eye condition that involves inflammation of the mucous membrane that covers a cat's eyeball and lines their eyelids). 

Preventing the Spread of Feline Herpesvirus 

If your cat is a carrier of FVR, they may benefit from periodic boosters with intranasal herpes and calicivirus vaccine (up to two to three times per year), which may prevent the virus from reactivating. This can consequently decrease the likelihood of recurrent infection and of viral shedding. 

Preventing direct contact between your cat and other cats will greatly reduce the chance that your cat will become infected. Our vets also recommend maintaining good hygiene and sanitation practices, such as washing your hands thoroughly before and after petting another cat, to reduce the likelihood of spreading this disease between cats. If your cat has an FVR infection, you should keep him indoors to prevent the infection from spreading to other cats in your neighbourhood. 

If you are planning on boarding or showing your cat, consult your primary care veterinarian about the need for a booster vaccine at least two weeks before the event. 

Prognosis for Cats Diagnosed with Feline Herpesvirus 

There is no cure for herpesvirus infection. With therapeutic treatment, the frequency and severity of recurrences can be reduced. Most cats respond well to medical management of this condition and lead normal lives. 

By minimizing the risk of infection, maintaining excellent nutrition by feeding your kitty a diet recommended by your veterinarian, reducing stressful situations, and following an appropriate vaccination schedule, you can defend your cat against this disease. 

Note: The advice provided in this post is intended for informational purposes and does not constitute medical advice regarding pets. For an accurate diagnosis of your pet's condition, please make an appointment with your vet.

Do you suspect your cat may have an eye condition? Contact our South Florida veterinary ophthalmologists today to book a consultation. We also accept referrals from primary vets.

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