Calicivirus (Feline)

Feline calicivirus is a cause of upper respiratory disease, oral ulceration, and occasionally arthritis. The virus particles are spread through saliva or inhalation. Direct contact with infected cats or ingestion of the particles seems to be the primary method of transmission. Upper respiratory infections usually carry a very favorable prognosis. However, a more virulent strain can cause death in 60 percent of patients. Supportive care is the only treatment option.

Common name: Upper Respiratory Infection
Scientific name: Feline calicivirus

Diagnosis

Signalment
Feline calicivirus is most common in kittens, multi-cat households, and shelters. Many cats can be infected with the virus and not show any signs of illness.

Incidence/prevalence
Feline upper respiratory infection is a group of bacteria and viruses that cause ocular and nasal discharge. Feline calicivirus along with feline rhinotracheitis (caused by herpes virus) cause 85 percent to 90 percent of all upper respiratory infections in cats.

Geographic distribution
Feline calicivirus is present worldwide.

Clinical signs (primary, most to least frequent, scientific term, synonyms)
Nasal and ocular discharge, sneezing, fever, rhinitis (inflammation of the nasal passages), ulceration of the tongue and palate.

Clinical signs (secondary, most to least frequent, scientific term, synonyms)
Dehydration, anorexia (loss of appetite), weight loss, pneumonia, arthritis (infection of joints).

Cause>(scientific, common term)
Virus.

Organ systems affected >(most to least affected)
Respiratory tract, gastrointestinal system, musculoskeletal.

Diagnostic tests
Routine bloodwork, usually diagnosed on clinical signs.

Differential Diagosis
Feline rhinotracheitis, bordatella bronchiseptica, Chlamydophila felis.

Overview

Feline calicivirus is a common cause of upper respiratory infections in kittens, multi-cat households, and shelters. It is spread through direct contact (cat to cat) or inhalation.

Clinical signs are usually ocular and nasal discharge, sneezing, fever, rhinitis, ulceration of the tongue and palate (roof of mouth). In more severe cases, pneumonia may occur. Affected animals usually have a decreased appetite or anorexia (not eating at all). If any of these signs are noticed, seek veterinary attention. Hospitalization may be needed to provide support through the initial crisis, but upper respiratory infections usually carry a very favorable prognosis. A rare strain of calicivirus has been shown to cause multiple organ failure and cause death in 60 percent of patients. Routine vaccination is the only means of prevention.

Treatment

Home Care
If decreased appetite, lethargy (lack of energy), or trouble breathing are noticed, immediate veterinary care should be sought. Also, affected cats should be separated from any other cats in the household to minimize virus transmission. Soft delicious food (i.e. baby food) should be offered to encourage the cat to eat. Food labels should be checked to ensure there are no onions or onion powder in the list of ingredients (onions are toxic to cats). Using a humidifier in the home to help keep the respiratory passages open may help in keeping cats comfortable. Vaccines against feline respiratory viruses are available to help prevent infection.

Professional Care
Based on the kitten's/cat's history and physical exam, routine blood work should be performed. Radiographs (X-rays) of the chest may be necessary to determine if pneumonia is present. A thorough oral exam should be performed to assess if oral ulcers are present. Ulcers usually appear on the tongue, but can occur anywhere in the mouth or on the skin.

Action
Once a diagnosis of calicivirus is suspected, a treatment plan will be devised. The kitten/cat may need to be hospitalized and placed on intravenous fluids if dehydration is present. Antibiotics are not effective against viruses; however, they may be necessary to provide protection against secondary bacterial infections. Oral ulcerations may cause enough discomfort to prevent cats from eating, so pain control medication may be prescribed. Additional topical ophthalmic antibiotics may be prescribed to discourage conjunctivitis (topical medication placed on the eyes so they are no longer red and inflamed).

Outcome
With appropriate treatment, the prognosis is usually very good. In very rare instances, a more virulent strain of calicivirus can cause multiple organ failure and death in 60 percent of patients. With a mild infection, the patient may be treated with antibiotics at home. More severe cases may have to be hospitalized for supportive care. Routine vaccination is the only way to prevent infection. Cats that have been previously diagnosed with calicivirus may benefit from L-Lysine, an amino acid supplement that has been helpful in minimizing reoccurrence of infection.

References/Additional Readings
Nelson , Richard W., Couto, Guillermo C. In: Small Animal Internal Medicine. Missouri: Mosby, 2006;228-232.

Ettinger, Stephen J, Feldman, Edward C. In: Textbook of Veterinary Internal Medicine; Saunders 2000; 667-669.

Author
Marie-Andree Fecteau, DVM

Editor
Sharon Gwaltney-Brant, DVM, PhD, DABVT, DABT