Supportive Management of Acute Feline Calicivirus Infection

For many cats with acute feline calicivirus (FCV) infection, treatment is largely supportive. The priority changes when fever, oral ulceration, nasal congestion, and reduced food intake begin to compromise hydration and nutrition. In severe cases, intensive nursing and supportive care may be required. 

Keep Nutrition at the Centre of Management^[1] 

Food intake can fall rapidly because fever, painful oral lesions and loss of smell from nasal congestion make eating difficult. Maintaining nutrition is therefore an important part of supportive care. 

Food can be blended, made highly palatable, and warmed to enhance its smell. Hand-feeding warm, strongly scented blended food may encourage intake. Commercial high-energy fluid diets can also be hand-fed when appropriate. 

If a cat has not eaten for more than three days, placement of a feeding tube and enteral nutrition are indicated. A naso-oesophageal tube can often be placed without sedation, although some FCV-affected cats resent the tube. Softer silicone tubes may improve tolerance, and intermittent placement is another option. An oesophagostomy tube requires a short general anaesthetic but provides easier access for feeding and medication and allows a wider-bore tube to be used away from the face. 

Correct Dehydration Before Using NSAIDs^[1] 

Severe dehydration and electrolyte disturbances warrant intravenous fluid therapy. Fluid status should be corrected before considering NSAIDs for fever or oral pain, with treatment ideally given when the cat is eating. 

Mirtazapine may be used as an appetite stimulant at 2 mg/cat orally every 24 hours, with dosing every 48 hours in cats with renal or hepatic dysfunction. 

Maropitant is sometimes used in cats with upper respiratory signs because of a possible role of substance P in these conditions. 

Relieve Nasal Congestion 

Nasal congestion can further reduce food intake by impairing the cat’s ability to smell food. Nebulisation with saline every 4–6 hours for 15 minutes can rehydrate the upper respiratory tract, loosen secretions, reduce congestion, and improve comfort. An enclosed environment such as an igloo or a home nebuliser can be used when practical. Steam therapy is another option for home care. 

Nasal discharge should be gently cleaned several times a day using physiological saline, with an ointment applied around the nostrils when needed. In severely congested cats, nasal saline flushing may provide additional relief. When nasal secretions are thick and mucoid, mucolytics such as bromhexine may help. 

Antibiotics Have a Specific Role 

Antibiotics are not routine treatment for FCV itself. They may be considered when severe disease is accompanied by suspected secondary bacterial infection, such as mucopurulent nasal discharge. Nasal discharge culture is not considered useful for selecting treatment, so empirical antibiotic choice should take into account appropriate respiratory and oral penetration. 

ISCAID recommends oral doxycycline at 10 mg/kg every 24 hours or 5 mg/kg every 12 hours for 7–10 days in acute cases when fever, lethargy or anorexia occur concurrently with mucopurulent nasal discharge^[2]. 

The Treatment Goal: Maintain Intake and Comfort 

Most cats with acute FCV infection can be managed with supportive measures, but severe dehydration, persistent anorexia or marked respiratory congestion should prompt more intensive intervention. Early attention to fluid status, nutritional intake and comfort can help prevent these problems from becoming more difficult to manage.

References:

1. Hofmann-Lehmann R, Hosie MJ, Hartmann K, Egberink H, Truyen U, Tasker S, Belák S, Boucraut-Baralon C, Frymus T, Lloret A, Marsilio F. Calicivirus infection in cats. Viruses. 2022 Apr 29;14(5):937. https://www.mdpi.com/1999-4915/14/5/937
2. Lappin MR, Blondeau J, Boothe D, Breitschwerdt EB, Guardabassi L, Lloyd DH, Papich MG, Rankin SC, Sykes JE, Turnidge J, Weese JS. Antimicrobial use guidelines for treatment of respiratory tract disease in dogs and cats: Antimicrobial Guidelines Working Group of the International Society for Companion Animal Infectious Diseases. Journal of veterinary internal medicine. 2017 Mar;31(2):279-94. https://academic.oup.com/jvim/article-pdf/31/2/279/66668346/jvim14627.pdf