Herpesvirus in cats is a highly contagious disease that is one of the most significant causes of upper respiratory infections in domesticated felines (or cat flu). Along with other viruses that cause URIs, including calicivirus, herpesvirus is responsible for the deterioration of many cats’ respiratory health.
Let’s look at how this virus is spread, its clinical signs, how the infection is diagnosed, whether there is any treatment available, and if you can do anything to prevent it.
How does a cat become infected?
The cat needs to come in direct contact with the virus particles in order to be infected. Since the virus affects the upper respiratory tract, it is present in a cat’s eye and nose discharge, as well as in the animal’s saliva. While the infection can occur via direct contact between an infected cat and a healthy one, that doesn’t necessarily happen in every case. A cat can also get the virus by using the same food or water bowl or the same litter tray as an infected peer.
How long does the infection last?
Once the cat is infected with feline herpesvirus, there is typically an incubation period of about two to five days before any symptoms are shown by the animal. During the incubation period, the body secretions of the animal are virulent, so they contain the virus — the pet is capable of infecting other animals.
While all of the cats that ever come in contact with the virus (and weren’t vaccinated against it) can become carriers, they can become latent carriers, which means that they might recover from the disease but could potentially infect other cats at some point. The virus can become active in times of stress or if the carrier’s immune system is damaged.
When the virus is reactivated, the cat will show various symptoms of a respiratory infection. Unfortunately, there are also cases where a cat might show no clinical signs at all and still be capable of infecting others.
Since the virus can survive in the living environment for as long as the material it is in remains moist, the viral particles can infect cats only for a couple of minutes to several hours. Once the saliva or discharge that were dropped on the floor dry up, the virus dies.
The clinical signs of FHV disease consist of an acute upper respiratory infection, keratitis, and an FHV-associated dermatitis. Let’s look at each.
Acute respiratory infection
The signs that are characteristic of an acute URI can last from a couple of days to a few weeks. They range from ocular and nasal discharge to pharyngitis and conjunctivitis, lethargy, fever, and inappetence. In some cases, pet parents could notice their cat coughing, which happens very rarely. The clinical symptoms manifested by a cat infected with herpesvirus are more severe compared to those shown by a cat infected with calicivirus.
Keratitis can have a wide array of causes, but it can also occur in cats that are suffering from a feline herpesvirus infection. In essence, it is the inflammation of the cornea, which is the clear part located at the front of the eye. Keratitis usually shows up in cats that have a chronic herpesvirus infection. Unfortunately, it can lead to the development of several corneal ulcers and it can affect the cat’s eyesight severely.
Dermatitis is a seldom clinical sign, meaning that it happens very rarely and only in chronic infections. It is characterized by the inflammation of skin ulceration and/or skin inflammation. This symptom happens around the mouth and around the nose, but it can also affect the cat’s front legs (especially since cats have a tendency to groom using their front legs).
While a specific diagnosis is often unnecessary, especially in cats that were never vaccinated against the disease, there are an array of tests that can be performed in this sense. However, in most cases, the veterinarian will go with the herpesvirus infection presumptive diagnosis based on the URI typical signs and the presence of a corneal infection.
A definitive diagnosis can be made thanks to methods such as PCR testing. In the latent state of the virus, the patient doesn’t show any signs, and that is why it might be almost impossible to discover whether a cat is a carrier or not. The virus is present in the cat’s saliva and nose and eye discharge for a limited amount of time, and once it disappears, it remains in her body but it cannot be detected using any tests.
There are several ways of attempting to treat this viral infection. If the cat only has several symptoms and hasn’t yet developed any bacterial complication, the treatment can be symptomatic. Topical eye medications can be used for treating conjunctivitis and keratitis and in this sense, the cat will require treatment with antiviral ophthalmic drops.
In an attempt to limit bacterial complications, the infected cat could be prescribed antibiotics although viruses do not respond to antibacterial medication. A cat might also have to be hospitalized if she is dehydrated, has a severe case of the illness, or is depressed (immunologically).
If you are allowed to take your cat home, you will have to ensure environmental humidification to deal with the cat’s airway congestion. You will also be required to wipe your cat’s eye and nose discharge often so as to prevent it from irritating the animal’s skin.
There is specific treatment, as well, and it consists of systemic antiviral therapy and topical ocular antiviral therapy. We’ve already mentioned the eye drops; systemic antiviral therapy is truly effective. There is a type of human medication (Famciclovir), an anti-herpes virus drug, and it’s been found to be safe for cats. It’s used for the management of severe acute infections.
Transmission to other cats – Prevention
If you have a cat colony you are caring for, the cat that has a herpesvirus infection needs to be isolated as soon as possible. All of the equipment and accessories that have been used by or with that specific cat should be sanitized, and the living environment has to be disinfected, as well. The microorganism doesn’t survive if you use bleach for disinfection purposes. For example, you could soak the objects that could be contaminated in a bleach solution for at least 5 minutes – the virus is killed without a doubt if you do that.
If you have come in contact with the cat, you should wash your hands with water and soap and clean under your fingernails using a nail brush. Apply an alcohol-based solution or hand sanitizer afterward.
This infection is extremely contagious, and as we have noted previously, a cat can remain a carrier for the remainder of her life. While the feline herpesvirus life expectancy is generally good, especially in cats that have perfect health and are young, it might not be so in old cats or those with a depressed immune system.
Can feline herpesvirus be transmitted to humans?
The short answer to this question is no. As with other types of viruses (including calicivirus), this one is species-specific, so it only affects cats.
Unlike some other diseases that can be fully prevented through vaccination, herpesvirus vaccines have to be repeated regularly to ensure that the cat has the right immunity. Cats that are carriers can benefit from periodic boosters with the calicivirus vaccine and the intranasal herpes vaccine as these two stimulate local immunity against the reactivation of the pathogen.
Cats that have been regularly vaccinated (every year) should be kept on the plan. If you ever intend to travel with your feline companion, have a talk with your vet. It might be a good idea to vaccinate your cat against herpesvirus (and other diseases) two weeks before your trip. If you are the pet parent of a cat that has had an FVR infection in the past, you should keep the animal indoors so as to avoid spreading the infection to cats in the neighborhood.
Even though there is no specific cure for a cat herpesvirus infection, most of the cats affected by the disease are known to respond well to the treatment and medical management of the condition throughout their lives. Follow the appropriate vaccination schedule to make sure that your cat is always protected. Get pet insurance if you don’t have it yet — the treatment can be quite expensive if your cat gets sick.