Feline Calicivirus in Cats

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Upper respiratory issues occur fairly commonly in cats and are often caused by infectious diseases. Feline calicivirus is a common virus that usually causes upper respiratory infections in cats. This highly contagious disease can easily spread throughout a population of cats, making it a major problem in animal shelter environments.

What is Feline Calicivirus?

Feline calicivirus is a highly contagious viral pathogen that affects cats. It is part of a family of RNA viruses called Caliciviridae. Some types of calicivirus can affect humans and other animals, but feline calicivirus strains will only affect cats.

Feline calicivirus most commonly affects a cat's upper respiratory system and oral cavity. However, the virus can affect other systems in the body.

Signs of Feline Calicivirus

  • Nasal discharge
  • Eye discharge
  • Conjunctivitis
  • Sneezing
  • Coughing
  • Loss of appetite
  • Weight loss
  • Ulcers in and around the mouth (tongue, gums, hard palate, lips, nose)
  • Drooling/excess saliva (due to oral ulcers)
  • Fever
  • Lameness
  • Skin lesions and ulcers (in cases of virulent systemic infection)

Cats with calicivirus most commonly develop signs of upper respiratory infection, including discharge from the eyes and/or nose, sneezing, and coughing. Severe upper respiratory infections can progress to pneumonia.

Feline calicivirus may also cause cats to develop ulcers in the mouth, especially on the tongue. It can also cause stomatitis, which is characterized by significant inflammation of the mouth and lips.

Lameness and fever occur in some cases of feline calicivirus. In addition, some cats may contract a more serious strain that causes a virulent systemic infection. This may affect the major organs and can lead to more serious issues like skin lesions and ulcers, loss of appetite, fever, and jaundice.

Feline calicivirus-related infections may be chronic in some cats. They may periodically experience flare-ups of symptoms.

It is possible for some cats to be carriers of feline calicivirus. These cats may show no signs of disease but can still transmit the virus to other cats.

Causes of Calicivirus in Cats

There are several strains of feline calicivirus, all of which are highly contagious. A cat contracts feline calicivirus via direct contact with an infected cat's saliva, eye/nasal discharge, or aerosolized droplets from sneezes. The virus enters a cat's body through the nose, mouth, or eyes. Infected female cats can also pass the virus on to their kittens.

Feline calicivirus is most commonly spread in multi-cat environments. Animal shelters, pet stores, catteries, and boarding facilities are considered high-risk spaces.

Cats that have received all boosters of the FVRCP vaccine may have some immunity as the "C" in this vaccine stands for calicivirus. However, because there are multiple different strains of feline calicivirus, not all are covered in the vaccine. Vaccinated cats can still contract feline calicivirus, but they may experience milder symptoms.

Feline Calicivirus Treatment

There is no cure for feline calicivirus, nor is there a specific treatment. If your vet suspects your cat has feline calicivirus, a blood test may be recommended for confirmation. However, treatment is supportive and specific to the cat's signs.

Cats with mild to moderate upper respiratory infections may be treated with medications and sent home under your care. Your vet may prescribe nasal decongestants, eye medications, and anti-inflammatory drugs. Antibiotics may be prescribed to prevent to treat secondary infections. Nasal drops or nebulization may be necessary for cats with nasal congestion.

Cats with upper respiratory infections often lose their appetite because they cannot taste or smell as well as usual. Oral ulcers can make eating very uncomfortable for some cats. An appetite stimulant may be recommended if your cat is not eating well. It's important to feed strong-smelling foods that appeal to your cat, and soft food is best if oral ulcers have developed.

Cats with moderate to severe signs may require hospitalization for supportive care. These cats typically receive intravenous fluids to support hydration and injectable medications to manage symptoms. Breathing treatments may be necessary if the cat develops pneumonia. A feeding tube may need to be placed if your cat is not eating.

How to Prevent Feline Calicivirus in Cats

The best way to protect your cat from feline calicivirus is to vaccinate regularly. While the calicivirus vaccine will not fully prevent contraction of the virus, it will help your cat fight off the infection and experience milder symptoms.

Cats with feline calicivirus should be kept separate from other cats to prevent the spread of the disease. Multi-cat environments should be cleaned thoroughly and routinely with pet-safe disinfectants to minimize accidental exposure.