Calicivirus Infection in Cats

white cat

Upper respiratory tract problems are very common among cats, and these problems are usually seen in the form of infections. Calicivirus, called FCV for short, is one of the common causes of upper respiratory tract infection in cats. This infection causes problems such as sneezing, runny nose and eyes, painful sores in the mouth, or a sudden limp in cats. Calicivirus is highly contagious and can spread quickly among cats. For this reason, it is considered one of the most serious ailments in cat shelters. Calicivirus infection is a completely treatable disease, but does not cause symptoms in most cats. That’s why sometimes it can be difficult to treat.

What is Calicivirus?


Feline calicivirus is a highly contagious viral pathogen that affects cats. It belongs to the family of RNA viruses called Caliciviridae. Some types of calicivirus can infect other animals or humans, but feline calicivirus only affects cats.

FCV often affects cats’ upper respiratory tract and oral cavity. However, although it is rare, it is seen that it affects other systems of the body. After infection, the virus typically incubates for 2 to 6 days until symptoms appear. When the disease starts, this usually lasts for 2-3 weeks. Throughout this entire process, the disease is contagious. Even after 50% of cats have fully recovered, they continue to carry the virus. This process can last for a few months, or it can continue until the end of the cat’s life.

FCV carrier cats usually show no symptoms, but they can transmit the disease to other cats. However, when female FCV carrier cats become pregnant, the virus is passed on to their offspring.

Calicivirus Symptoms


Cats infected with calicivirus often develop flu-like symptoms in humans. Nasal congestion, runny nose and eyes, sneezing, loss of appetite and general tiredness are some of them. Cats that are highly infected may have more severe symptoms. The disease can reach serious dimensions, especially in kittens or older cats. Adult cats, on the other hand, are milder. The most common calicivirus symptoms are as follows.

  • Runny nose
  • Eye discharge
  • Conjunctivitis
  • Sneeze
  • Loss of appetite
  • Weight loss
  • Ulcers around the mouth
  • Excessive drooling due to ulcer
  • Fire
  • Limping
  • Lesions in certain areas of the skin

Calicivirus infection usually causes upper respiratory tract infections in cats. However, in cases where the infection is severe, pneumonia can also be seen. Calicivirus infection can cause painful ulcers in various places, especially on the tongue. Because of this pain, cats experience loss of appetite and excessive drooling. FCV can also cause stomatitis, which is an inflammation of the mouth and lips.

Limping and fever are seen in some cases of calicivirus infection. In addition, some cats may develop a more serious type of infection called FCV-VSD, which causes a lethal systemic infection. This infection affects major organs, causing skin lesions, loss of appetite, fever and jaundice. FCV-associated infections become chronic in some cats, with periodic symptoms exacerbated.

Causes of Calicivirus Infection

There are several different strains of feline calicivirus, and all are highly contagious. A cat can contract FCV when it comes into direct contact with aerosolized droplets from an infected cat’s saliva, eye or nose discharge, or sneezes. The virus enters the cat’s body through its nose, mouth, or eyes.

Feline calicivirus is commonly seen in environments with large numbers of cats. Animal shelters and veterinary clinics are considered high-risk locations. In places where many such cats coexist, a single cat’s illness is sufficient for the disease to spread. Cats who have received all the vaccines of the FVRCP vaccine may have some immunity to calicivirus. The letter C in the name of this combined vaccine is an abbreviation for calicivirus. However, because there is more than one strain of feline calicivirus, the vaccine is not completely protective. However, vaccinated cats can still get calicivirus, but the disease is milder in these cats.

Diagnosis and Treatment of Calicivirus Infection

In general, the veterinarian makes a diagnosis by looking at the cat’s symptoms. Nasal and eye discharge and ulcers around the mouth are the most common symptoms. However, sometimes a swab is taken from the mouth, nose, and eyes of the sick cat and tested for the presence of the virus. X-rays may also be required to rule out other possible ailments in cats with limping.

There is no cure for feline calicivirus. However, supportive treatment is applied for the cat to get through the process comfortably. The emergence of secondary bacterial infections such as pneumonia is also prevented by supportive treatment.

Cats with mild upper respiratory tract infections are usually treated at home. Nasal spray, eye drops and anti-inflammatory drugs are used to relieve inflammation in the eye. Anti-biotic therapy may also be required to treat secondary infections. Loss of appetite occurs because infected cats cannot taste or smell normally. In addition, sores around the mouth prevent cats from eating comfortably. Appetizers can be used for cats that do not eat enough food. Strong flavored and soft foods should be preferred for a healthy diet until the cat recovers.

Cats with severe disease may require intensive care. These cats are usually treated with serum. In cats with pneumonia, treatments for better breathing are applied. Cats that do not eat are usually placed in a feeding tube.

Feline calicivirus infection may clear up completely, but some cats may be carriers even if they fully recover. Usually carriers are for a short time, but some cats can remain carriers for life.

The most effective method of protecting cats from calicivirus infection is regular vaccinations. Although the vaccine does not provide complete protection against calicivirus infection, it helps to relieve symptoms and ease the infection. Cats with calicivirus infection should be quarantined so that they do not infect other cats. The places where there are many cats should be cleaned in detail and routinely, and the environment should be disinfected with disinfectants that are not harmful to animals during cleaning.

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