Calicivirus / Feline calicivirus (FCV)

Feline calicivirus (FCV) is one of the most common and highly contagious viral infections affecting cats worldwide. This single-stranded RNA virus primarily causes upper respiratory disease and oral ulcerations, though its clinical manifestations can range from mild cold-like symptoms to severe, life-threatening systemic illness. Calicivirus is a leading cause of feline upper respiratory infection complex, along with feline herpesvirus, and represents a significant health concern in multi-cat environments including shelters, catteries, and boarding facilities where the virus spreads rapidly among susceptible populations.

The virus is transmitted through direct contact with infected cats, exposure to contaminated environments, or contact with objects that have been contaminated with viral particles. Feline calicivirus is remarkably resilient in the environment, capable of surviving for up to one month on surfaces under suitable conditions, which contributes to its efficient spread. The virus enters the body through the eyes, nose, or mouth and rapidly infects cells of the respiratory tract and oral mucosa. Cats can begin shedding the virus and become contagious to others within one to two days after infection, often before obvious symptoms appear.

The impact of feline calicivirus on affected cats varies considerably depending on the viral strain involved and the individual cat's immune status. While many cats experience relatively mild upper respiratory symptoms that resolve with supportive care, others develop severe oral ulceration that makes eating painful, leading to anorexia and dehydration. Of particular concern are virulent systemic strains (VS-FCV) that have emerged in recent decades, which cause severe multisystemic disease with high mortality rates. Additionally, some cats become chronic carriers of the virus, continuously shedding and serving as infection sources for other cats without showing symptoms themselves.

Vaccination against feline calicivirus is considered a core recommendation for all cats, and effective vaccines are widely available as part of standard kitten and adult cat vaccination protocols. However, because the calicivirus exhibits significant genetic variability with many different strains circulating, vaccines may not provide complete protection against all strains. When infection does occur, treatment is primarily supportive, focusing on maintaining hydration, nutrition, and comfort while the cat's immune system fights the virus. Early veterinary intervention is important, particularly for kittens, elderly cats, or those with compromised immune systems, as prompt supportive care significantly improves outcomes and reduces the risk of complications.

Feline calicivirus infection is caused by a small, non-enveloped RNA virus belonging to the family Caliciviridae. This virus exhibits remarkable genetic diversity, with numerous strains circulating in cat populations worldwide. The high mutation rate inherent to RNA viruses allows FCV to evolve rapidly, producing new variants that may differ in their ability to cause disease and their susceptibility to vaccine-induced immunity. Some strains cause primarily respiratory symptoms, others predominantly affect the oral cavity, and the highly virulent systemic strains can cause devastating multi-organ disease. This variability means that cats can potentially be infected by different strains multiple times throughout their lives.

There is no genetic or hereditary predisposition to calicivirus infection, as susceptibility is determined entirely by immune status and exposure rather than genetic factors. Any cat, regardless of breed or lineage, can become infected when exposed to the virus. However, the outcome of infection may be influenced by the individual cat's immune system strength and response, which can have genetic components. Kittens born to vaccinated mothers receive temporary protection through maternal antibodies, but this protection wanes over the first weeks of life, creating a vulnerable period during which kittens are highly susceptible to infection.

Environmental and lifestyle factors play the most significant role in determining exposure risk for feline calicivirus. Cats living in multi-cat environments, including shelters, breeding catteries, and households with multiple cats, face the highest risk due to the ease of transmission in group settings. Stress associated with shelter environments, transport, or crowding suppresses immune function and increases susceptibility to infection and disease severity. Outdoor cats face exposure risk through contact with stray or feral cats that may be infected or carrying the virus. Poor ventilation, shared food and water bowls, and inadequate hygiene practices in multi-cat settings facilitate viral spread.

Several specific risk factors increase a cat's likelihood of becoming infected with or experiencing severe disease from feline calicivirus. Young kittens between two and six months of age are at highest risk due to waning maternal immunity and immature immune systems. Elderly cats and those with concurrent illnesses, particularly conditions affecting immune function, are more susceptible to severe disease. Unvaccinated cats lack protective immunity and are highly vulnerable. Cats recently introduced to multi-cat environments experience stress that compromises immunity while being exposed to new infectious agents. Immunocompromising conditions such as feline leukemia virus (FeLV) or feline immunodeficiency virus (FIV) infection significantly increase risk.

The mechanism of calicivirus infection begins with viral particles entering through the mucous membranes of the eyes, nose, or mouth. The virus preferentially infects epithelial cells lining the respiratory tract and oral cavity, where it replicates within cells before causing cell death and release of more viral particles. This cellular destruction produces the characteristic ulcerations seen in the mouth and may damage nasal passages and airways. The resulting inflammation triggers sneezing, nasal discharge, and conjunctivitis. In cases of virulent systemic strains, the virus spreads beyond the respiratory tract to affect blood vessels, causing vasculitis that leads to widespread organ damage, edema, and potentially fatal systemic inflammatory response syndrome.

Early warning signs of feline calicivirus infection can be subtle and may initially go unnoticed, particularly by cat owners who are not specifically watching for illness. The first indications often include mild sneezing, slight increase in ocular or nasal discharge, and a subtle decrease in activity or appetite. Some cats develop a mild fever that may not be apparent without temperature measurement. These early symptoms can develop within two to six days following exposure to the virus and may be dismissed as a minor cold or temporary upset. Because cats instinctively hide signs of illness, owners may not recognize the developing infection until more obvious symptoms emerge.

As the infection progresses, more recognizable and common symptoms become apparent. Frequent sneezing, often in clusters, is one of the most noticeable signs. Clear nasal discharge may become thickened or appear yellow-green if secondary bacterial infection develops. Eye involvement produces watery or mucoid ocular discharge, redness, and squinting. The hallmark symptom of calicivirus infection is the development of ulcers in the mouth, particularly on the tongue, hard palate, and gums. These painful ulcers appear as red, raw areas that may be difficult to see without close examination but cause significant discomfort that affects eating and drinking.

Behavioral changes associated with calicivirus infection reflect the cat's discomfort and malaise. Decreased appetite is common, partly due to nasal congestion impairing the ability to smell food and partly due to pain from oral ulcers making eating uncomfortable. Increased sleeping and reduced activity indicate the cat is fighting infection. Some cats become clingy and seek more contact with owners, while others withdraw and hide. Excessive drooling may occur due to oral pain, and some cats paw at their mouths or show reluctance to open their mouths. Changes in vocalization, including hoarseness or reluctance to vocalize, may be noted if the throat is affected.

Physical signs visible to observant owners include discharge crusting around the nose and eyes, which may appear brownish when dried. The cat's third eyelid may become visible due to inflammation or general malaise. Examination of the mouth, if tolerated, may reveal red, ulcerated areas on the tongue or gums. Bad breath often develops due to oral lesions. Weight loss may become apparent if the cat refuses food for several days. An unusual symptom somewhat specific to calicivirus is limping syndrome, where the virus affects joints, causing lameness that may shift between legs and typically affects kittens more than adults. The affected joints may appear swollen.

Symptom progression varies depending on the viral strain and individual immune response. Mild cases may resolve within seven to ten days with appropriate supportive care. More severe cases may see worsening oral ulceration with lesions spreading across the tongue and throat, making eating impossible without intervention. Secondary bacterial infections may develop, causing more severe nasal and eye discharge and potentially pneumonia. Virulent systemic FCV causes rapid deterioration with high fever, severe facial and limb swelling, jaundice, bleeding tendencies, and multiple organ failure. Chronic carriers may show no symptoms or have only intermittent mild signs despite continuously shedding virus.

Certain symptoms indicate a medical emergency requiring immediate veterinary care. Complete refusal to eat or drink for more than 24 hours in an adult cat, or less in kittens, risks dangerous dehydration and hepatic lipidosis. Labored breathing, open-mouth breathing, or blue-tinged gums suggest pneumonia or respiratory distress requiring urgent intervention. Signs consistent with virulent systemic FCV, including facial swelling, skin ulceration, sudden lameness in multiple legs, or yellow discoloration of the skin or gums, necessitate emergency care. High fever, collapse, or signs of severe dehydration such as skin tenting and sunken eyes are medical emergencies. Any kitten showing respiratory symptoms should be evaluated promptly due to their vulnerability to rapid deterioration.

When a cat presents with symptoms suggestive of calicivirus infection, the veterinary examination begins with a thorough physical assessment and history taking. The veterinarian will measure vital signs including temperature, heart rate, and respiratory rate. Examination of the eyes, nose, and mouth looks for characteristic findings including ocular and nasal discharge, oral ulcerations, and inflammation. The chest is auscultated to detect any lung involvement suggesting pneumonia. Lymph nodes are palpated for enlargement, and the limbs are examined for joint swelling if lameness is reported. Questions about vaccination history, potential exposure to other cats, living situation, and timeline of symptom development help form a clinical picture.

Diagnostic testing can confirm calicivirus infection, though diagnosis is often made clinically based on symptoms in straightforward cases. Swabs taken from the throat, mouth, or conjunctiva can be submitted for polymerase chain reaction (PCR) testing, which detects viral genetic material and confirms infection. Viral isolation through cell culture is another option, though less commonly performed due to time requirements. Blood tests including a complete blood count and chemistry panel assess overall health status and detect complications such as dehydration, secondary infection, or organ involvement in severe cases. Chest radiographs may be recommended if pneumonia is suspected based on respiratory symptoms or auscultation findings.

Differentiating calicivirus from other causes of upper respiratory disease is important for prognosis and management. Feline herpesvirus causes similar respiratory symptoms but classically produces more severe eye involvement including corneal ulcers, and does not typically cause oral ulceration. Chlamydophila felis causes conjunctivitis and respiratory symptoms but presents differently on detailed examination. Bordetella bronchiseptica infection produces respiratory symptoms, particularly coughing. Bacterial infections can cause nasal discharge and respiratory signs. In some cases, multiple pathogens may be involved simultaneously, complicating diagnosis. Chronic oral disease from other causes may resemble calicivirus-induced stomatitis. Testing for FeLV and FIV may be recommended to rule out underlying immunosuppression.

Confirmation of calicivirus infection and assessment of severity guides treatment decisions and prognosis. Positive PCR testing confirms viral presence, though it should be noted that some healthy carrier cats also test positive. Strain identification through genetic sequencing can be performed in outbreak situations or suspected virulent systemic disease but is not routine. Assessment of disease severity considers factors including hydration status, ability to eat and drink, respiratory involvement, and systemic signs. In suspected VS-FCV cases, additional testing may include coagulation profiles, liver and kidney function tests, and imaging studies to assess organ involvement. The veterinarian uses all available information to determine whether outpatient supportive care is sufficient or hospitalization is needed.

Initial treatment for cats with feline calicivirus infection focuses on addressing immediate concerns and stabilizing the patient. Dehydration from fever, reduced drinking, and increased respiratory fluid losses is addressed through fluid therapy, which may be subcutaneous for mild cases or intravenous for more severely affected cats requiring hospitalization. Nutritional support is crucial, as cats with oral ulcers or nasal congestion often refuse food. Warming food to enhance aroma, offering highly palatable or strong-smelling foods, and using appetite stimulants may encourage eating. Severely affected cats may require assisted feeding through syringe feeding or temporary feeding tube placement to prevent hepatic lipidosis from prolonged anorexia.

Medical management of calicivirus infection is primarily supportive, as no specific antiviral medications are routinely effective against FCV in clinical settings. Antibiotics do not kill the virus itself but are commonly prescribed to prevent or treat secondary bacterial infections that frequently complicate viral respiratory disease. Broad-spectrum antibiotics such as doxycycline or amoxicillin-clavulanate are typical choices. Eye drops or ointments may be prescribed if conjunctivitis is significant. Anti-inflammatory medications may help reduce fever and discomfort. Pain medication is important for cats with painful oral ulcers, helping maintain appetite and comfort. L-lysine supplementation has been advocated historically but current evidence does not support its efficacy, and some studies suggest potential harm.

Surgical intervention is not part of standard calicivirus treatment, as this is a medical condition managed through supportive and symptomatic care. However, in rare cases of severe complications, procedures may become necessary. Cats developing pyothorax (pus accumulation in the chest) from secondary bacterial pneumonia may require chest tube placement and drainage. Placement of an esophagostomy or gastrostomy feeding tube may be performed if a cat requires prolonged nutritional support but cannot eat due to severe oral ulceration. These procedures are performed under anesthesia once the cat is stabilized sufficiently to tolerate the procedure safely.

Supportive care measures significantly impact recovery and comfort during calicivirus infection. Maintaining a warm, quiet, stress-free environment supports healing. Humidification or steam therapy from a bathroom can help loosen nasal congestion and ease breathing. Gentle cleaning of discharge from the nose and eyes several times daily keeps the cat comfortable and helps maintain appetite by allowing them to smell food. Nursing care including keeping bedding clean and dry, encouraging rest, and providing easily accessible food and water supports recovery. Isolation from other cats prevents spread and allows the sick cat to recuperate without stress from social interactions.

Alternative and complementary approaches may provide additional support alongside conventional treatment. Nebulization with sterile saline can help loosen respiratory secretions and provide airway moisture. Nutritional support with high-calorie recovery diets helps maintain body condition. Gentle physiotherapy including position changes for recumbent cats prevents complications from prolonged lying. Environmental enrichment appropriate to the cat's energy level supports mental wellbeing during recovery. Some practitioners use interferon omega, an immune modulator, though evidence for efficacy in FCV specifically is limited. Any complementary approaches should be discussed with the treating veterinarian to ensure they do not interfere with primary care.

Treatment decisions consider several important factors. Severity of illness determines whether outpatient or inpatient care is appropriate, with hospitalization recommended for cats unable to eat or drink, showing respiratory distress, or demonstrating signs of systemic involvement. The cat's age and overall health status influence treatment intensity and prognosis. Presence of other cats in the household affects isolation recommendations and may prompt preventive measures for housemates. Financial considerations may influence choices between treatment options. For cats with suspected virulent systemic FCV, aggressive intensive care is necessary but prognosis remains guarded even with treatment. In cases of severe or unresponsive disease, quality of life considerations and potential for humane euthanasia may need to be discussed.

Recovery timeline for feline calicivirus infection varies based on disease severity and individual patient factors. Mild cases in otherwise healthy adult cats often show improvement within five to seven days, with complete resolution of symptoms within two weeks. More severe cases, particularly those requiring hospitalization or involving significant oral ulceration, may take three to four weeks for full recovery. Kittens and elderly or immunocompromised cats may experience prolonged illness and slower recovery. Cats with secondary bacterial complications may require extended antibiotic treatment before full recovery is achieved. Limping syndrome, when present, typically resolves within several days as joint inflammation subsides.

Post-treatment care requirements extend beyond the acute illness phase. Cats should be kept indoors and isolated from other cats during recovery to prevent spread and allow undisturbed healing. Medication courses should be completed as prescribed, even if the cat appears to have recovered, to prevent complications and antibiotic resistance. Follow-up veterinary visits may be recommended to confirm resolution, particularly for more severely affected cats. Nutritional support should continue until the cat is eating normally and regaining any lost weight. Gradual return to normal activity is appropriate once energy levels normalize, though excessive stress should be avoided during the recovery period.

Several factors influence prognosis in calicivirus infection. Age significantly impacts outcomes, with very young kittens and elderly cats facing higher risk of complications and mortality. The specific viral strain involved affects severity, with most circulating strains causing manageable disease but virulent systemic strains carrying mortality rates of fifty percent or higher even with intensive treatment. Vaccination status prior to infection influences disease severity, as vaccinated cats typically experience milder illness. Underlying health conditions, particularly FeLV, FIV, or other immunocompromising diseases, worsen prognosis. Timing of veterinary intervention matters, with early supportive care improving outcomes compared to delayed treatment.

The long-term outlook following calicivirus infection requires consideration of potential sequelae and carrier status. Most cats recover fully and return to normal health, though some retain chronic effects. A significant proportion of recovered cats, estimated at half or more, become chronic carriers, shedding virus from the oral cavity for months to years or even lifelong. These carrier cats may appear healthy but serve as infection sources for susceptible cats, which has important implications for multi-cat households or breeding catteries. Some cats develop chronic stomatitis (mouth inflammation) following infection, causing ongoing oral pain and requiring long-term management. Cats that recover retain immunity to the specific strain they were infected with but may still be susceptible to other strains.

Vaccination represents the primary means of preventing feline calicivirus infection and is considered a core vaccine recommended for all cats regardless of lifestyle. Standard vaccination protocols begin with a series of kitten vaccinations starting at six to eight weeks of age, with boosters every three to four weeks until sixteen weeks of age. Adult cats receive initial vaccination followed by a booster one year later and subsequent boosters every one to three years depending on risk assessment and vaccine type used. Vaccination does not guarantee complete protection due to the numerous FCV strains circulating, but it significantly reduces disease severity when infection occurs. Intranasal vaccine formulations are available and may provide faster local immunity.

Environmental prevention measures are crucial in multi-cat settings where calicivirus spreads most efficiently. Thorough cleaning and disinfection with products effective against non-enveloped viruses, such as dilute bleach solutions or accelerated hydrogen peroxide products, reduces environmental viral load. Proper ventilation in catteries and shelters minimizes airborne transmission. Avoiding overcrowding reduces stress that suppresses immunity and limits contact between individuals. Quarantine protocols for new arrivals protect resident cats from introduction of new infections. Separation of sick cats from healthy populations during outbreaks limits spread. Avoiding sharing of food bowls, water dishes, and grooming tools between cats reduces fomite transmission.

While no specific dietary measures prevent calicivirus infection, nutrition supporting overall immune function helps cats resist disease. Feeding a complete and balanced diet appropriate for life stage provides essential nutrients supporting immune health. Adequate protein intake is particularly important for immune function. Antioxidant vitamins including A, C, and E support immune responses, though supplementation beyond dietary needs is not proven beneficial. Maintaining healthy body condition through appropriate caloric intake keeps cats in optimal health. Probiotics may support general immune health through gut immune function, though specific protection against respiratory viruses is not established.

Regular health maintenance contributes to calicivirus prevention through both vaccination compliance and general health monitoring. Annual veterinary examinations ensure vaccination status remains current and allow early detection of any health issues. New cats should be examined and brought up to date on vaccinations before introduction to multi-cat households. Testing for FeLV and FIV identifies immunocompromised cats that need additional protection and monitoring. Stress reduction through environmental enrichment and stable routines supports immune function. Prompt veterinary attention for any respiratory symptoms allows early intervention before severe disease develops and prevents prolonged shedding to other cats.

Early intervention strategies help limit the impact of calicivirus when it does occur. Recognizing early symptoms and seeking veterinary care promptly improves outcomes for individual cats and allows implementation of isolation procedures that protect other cats. In outbreak situations in shelters or catteries, testing can identify infected and carrier cats, allowing strategic separation to break transmission chains. Post-exposure prophylaxis with vaccination may provide some protection if administered very early after exposure, though efficacy is uncertain. Boosting vaccination of at-risk populations during outbreaks may help limit spread. Working closely with veterinarians experienced in shelter or cattery medicine optimizes outbreak response strategies.

Daily management of a cat recovering from calicivirus infection or living as a chronic carrier requires attention to several key areas. During acute illness, daily medication administration must occur reliably, with pain medication and antibiotics given at appropriate times and doses. Monitoring food and water intake helps ensure adequate nutrition and hydration, with intervention needed if consumption drops. Cleaning nasal and ocular discharge several times daily keeps the cat comfortable and maintains ability to smell food. Monitoring overall demeanor, activity level, and symptoms helps track recovery progress and identifies any worsening that warrants veterinary contact. For chronic carriers, ongoing observation for recurrence of symptoms guides decisions about isolation and treatment.

Home environment modifications support recovery and ongoing management. During illness, providing a warm, quiet, easily accessible space away from household activity allows undisturbed rest. Litter boxes should be nearby to prevent exertion. Food and water should be placed close to resting areas and served at room temperature or slightly warmed to enhance aroma. Humidifiers or time in a steamy bathroom helps loosen nasal congestion. For multi-cat households with a recovering or carrier cat, decisions about long-term separation versus reintegration require careful consideration of transmission risks to other cats. Thorough cleaning of all shared items and spaces reduces environmental viral load.

Maintaining quality of life during and after calicivirus infection involves balancing necessary care with the cat's comfort and wellbeing. Gentle interaction and reassurance provide emotional support during illness. Minimizing stressful procedures and handling reduces cortisol that can suppress immunity. Offering favorite foods, even if just small amounts are eaten, provides both nutrition and pleasure. As recovery progresses, gradually reintroducing normal activities and enrichment supports return to normal life. For cats with chronic sequelae such as ongoing stomatitis, pain management allows continued enjoyment of daily activities. Recognizing individual preferences and adjusting care accordingly optimizes quality of life.

Ongoing monitoring requirements depend on disease course and outcome. During acute illness, daily assessment of symptoms, appetite, hydration, and overall status guides care decisions. As recovery progresses, monitoring for any return of symptoms identifies relapse early. For chronic carriers, periodic veterinary examinations assess for development of chronic oral disease or other complications. Awareness of symptoms in other household cats allows early detection if transmission occurs. Documentation of symptoms, treatments, and progress provides valuable information for veterinary visits. Understanding which changes warrant immediate veterinary contact versus home monitoring empowers owners to respond appropriately to developments.

Caregiver support helps owners manage the demands of caring for a cat with calicivirus infection. Understanding the disease, its expected course, and realistic outcomes reduces anxiety about the unknown. Online resources and communities provide information and emotional support from others who have experienced similar situations. Financial planning for treatment costs, which can be substantial for severe cases requiring hospitalization, reduces stress around care decisions. Accepting help from family or friends with cat care tasks during intensive treatment periods prevents caregiver burnout. Veterinary teams can provide guidance on prognosis and quality of life to support difficult decisions. Recognizing that most cats recover well with appropriate care provides reassurance during the illness period.

Feline calicivirus infection does not show significant breed predisposition, as the disease is caused by an infectious agent that can affect any cat regardless of breed or genetic background. Domestic shorthairs, domestic longhairs, and all pedigreed breeds are equally susceptible to infection when exposed to the virus. The distribution of calicivirus cases across breeds reflects the general cat population rather than any breed-specific vulnerability. However, the outcome of infection may vary between individuals based on factors including overall health status and immune function, which can have some genetic influences independent of breed.

Risk factors for calicivirus infection relate primarily to environment, lifestyle, and immune status rather than breed. Cats living in multi-cat environments including shelters, catteries, and breeding facilities face highest exposure risk due to the highly contagious nature of the virus and crowded conditions. Young kittens are at elevated risk during the gap between waning maternal immunity and development of vaccine-induced protection. Elderly cats and those with concurrent illness, particularly immunocompromising conditions, may experience more severe disease. Unvaccinated cats lack protective immunity. Within pedigreed breeding populations, outbreaks can occur and spread rapidly due to the multi-cat environment and movement of cats between facilities for breeding purposes.

Screening and prevention recommendations apply equally across all breeds given the universal susceptibility to calicivirus. All cats, regardless of breed, should receive core vaccination against FCV as part of standard preventive care protocols. Testing for FeLV and FIV is recommended to identify immunocompromised individuals who may benefit from additional monitoring or modified management. In breeding catteries, quarantine protocols for incoming cats help prevent introduction of infection. New cats should be examined and vaccinated before introduction to existing cat populations. No breed-specific testing for calicivirus susceptibility exists or is warranted given the lack of breed predisposition. Focus should be on vaccination compliance, environmental management, and general health maintenance for all cats.

Several conditions commonly occur alongside or in association with feline calicivirus infection. Upper respiratory infection complex frequently involves multiple pathogens, with feline herpesvirus being the most common co-pathogen. Secondary bacterial infections often complicate viral respiratory disease, with bacteria including Bordetella bronchiseptica, Chlamydophila felis, and Mycoplasma species potentially involved. Pneumonia may develop as a complication of severe respiratory infection. Chronic gingivostomatitis, a painful inflammatory condition of the mouth, may follow or be associated with FCV infection in some cats. Cats with underlying immunocompromising infections such as FeLV or FIV may experience more severe calicivirus disease and complications.

Numerous conditions produce symptoms similar to calicivirus infection and must be differentiated for appropriate management. Feline herpesvirus infection causes upper respiratory symptoms but classically produces more severe ocular involvement including corneal ulcers, and does not typically cause oral ulcers. Chlamydophila felis causes conjunctivitis with respiratory symptoms but presents with characteristic eye changes. Bordetella bronchiseptica infection may cause respiratory symptoms, particularly coughing. Feline infectious peritonitis (FIP) can cause respiratory symptoms and fever but typically presents with different systemic signs. Oral foreign bodies, dental disease, or other causes of oral pain may mimic some aspects of calicivirus infection. Accurate diagnosis ensures appropriate treatment.

Complications of calicivirus infection can lead to secondary conditions requiring additional management. Secondary bacterial pneumonia develops when bacteria invade airways damaged by viral infection, requiring antibiotic treatment and potentially intensive care. Chronic stomatitis may develop following infection, causing persistent oral inflammation and pain that requires ongoing management and sometimes tooth extraction. Corneal ulcers may occur if eye involvement is significant. Hepatic lipidosis can develop if anorexia is prolonged, requiring intensive nutritional support. In rare cases of virulent systemic FCV, disseminated intravascular coagulation and multiple organ failure may develop. Prevention of complications through early, appropriate supportive care is preferable to managing them after development.