Calicivirus in cats


The Feline Calicivirus causes severe problems in the form of upper respiratory infections in cats and often occurs as a dual infection with feline herpesvirus (feline rhinotracheitis virus) or with feline chlamydiosis. The clinincal signs show cat flu-like symptoms and so is sometimes called as such. Members of the felindae family able to become infected by this disease are domestic cats and cheetahs. The feline calicivirus travels and attacks the eyes, nostrils, mouth, throat and occasionally the lungs and intestines. The infection can remain in the cat for a very long time despite the symptoms having stopped. This means they can continue to transmit the disease long after contracting the disease. Symptoms usually include nasal discharge, runny eyes, high temperatures and loss of appetite. Kittens, as well as unvaccinated cats, are the at most at risk of becoming infected. Cats with low immunity also are very susceptible to catching the feline calicivirus. Vaccines against FCV are highly recommended.


The feline calicivirus, not unlike most viruses, enters the host via contact with infected surfaces such as contaminated bowls, clothing, floors and bedding. The environment can be contaminated via infected vomiting, diarrhoea, and other excretions. FCV can enter through the mouth, nose and even the eyes. Since cats usually roam free they can come across areas with the virus without the knowledge of the owner.

The virus can survive for as long as one week away from the host thus increasing the risks of transmission. The disease is most commonly present in homes as well as in areas where many cats live together such as animal shelters. Cats can still pass on the virus, sometimes for as long as they live, following the symptoms no longer presented. The disease is not zoonotic which means it cannot be transferred to humans. For the inanimate contaminated surfaces, strong disinfectants and bleaches are required to destroy the virus effectively.


Most symptoms involve nasal and ocular discharge, along with sores and ulceration around the mouth (stomitis). Muscles may become tender and painful and there can be oedema of the face. The symptoms are similar to that of a common cold and so sneezing can occur. Limping or lameness is sometimes observed, albeit rarely, as well as depression and lethargy. There are occasionally health implications such as multiple organ problems. Kittens around the age of two to three weeks may experience something called “fading” and can show signs of anorexia and depression.

There are many strains of the feline calicivirus and the degree of their severity is noticeable depending on the different forms they take. The most feared strain of the virus is the virulent systemic feline calicivirus (VS-FCV), is highly contagious and is usually be fatal. The clinical signs include vomiting, diarrhoea and if the liver is affected; jaundice. Pneumonia may also be a result of this.

Treatment and Prevention

As with many viral infections, there is no specific treatment plan. Antibiotics may be given, not to fight off the virus but to prevent the possibility of a secondary infection. In the rare cases of dehydration, IV fluid may be administered. Owners can remove any ocular or nasal discharge to increase comfort and decongestants are sometimes given. Problems such as lameness can be reduced with anti-inflammatories. Overall, any treatment is used to support the cat’s immune system to give it the best possible chance to fight off the infection by itself.

In any case, prevention is better than cure, and a vaccination against the disease is strongly encouraged. Kittens can be vaccinated between the ages of six and nine weeks since, prior to this, they can gain immunity from their mother’s milk. Orphaned kittens may be vaccinated earlier. Boosters are required annually to provide long term protection. Prevention is not always the case with these vaccines though they cause the severity of the disease to be much milder. Animals with the disease should be isolated or quarantined to prevent further transmission.

Diagnosis and Prognosis

Signs and symptoms are initially important in diagnosing the Feline Calicivirus. Fluorescent stains show up any lesions which may be present on the eyes but diagnosis is usually confirmed using a Polymerise Chain Reaction test (PCR test) though this is not always necessary. The prognosis is usually good although with VS-FCV the incidence of mortalities is significantly increased.


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