FCV-VSD

From Felipedia

A kitten with systemic caliciviral disease, showing upper respiratory disease, facial oedema and ulceration of the pinna^[1]

Same kitten as above, with limb oedema due to FCV-VSD

Feline calicivirus infection (FCV) is a common disease in catteries and a common cause of presentation of kittens and young cats to veterinary clinics worldwide. A rare, but potentially lethal variant of this disease is FCV-associated virulent systemic disease (FCV-VSD), an acute and severe syndrome which is often fatal to cats^[2]. It has been described as being caused by a virulent strain of calicivirus called FCV-Ari^[3].

In contrast to the relatively mild symptoms that characterize infection of cats with the usual field strains of FCV, infection with virulent systemic FCV (VSD) is devastating, with mortality rates ranging between 33% and 60%. Adult cats that were previously vaccinated against calicivirus infection were prominently affected in these outbreaks, and adult cats were at higher risk for severe disease and death as compared with kittens. In addition to ulceration and nasal or ocular discharge, signs characteristic of VS-FCV infection include profound fever, anorexia, marked subcutaneous edema (especially of the limbs and face), icterus, alopecia, crusting, and ulceration of the nose, lips, pinnae, and feet^[4].

Clinical signs and lesions of VS-FCV infection are likely to result from a combination of epithelial (cytolytic) and endothelial injury^[5]. They include oral ulceration, facial oedema, nasal or ocular discharge, anorexia, pyrexia (often >40⁰C), and ulcerative dermatitis to the face and limbs. In rare cases, there may also be severe respiratory distress, jaundice and gastrointestinal signs. Adult cats appear to be more seriously affected than kittens^[6].

An outbreak of VS-FCV has been reported at a veterinary teaching hospital in France^[7]. The initial case was referred to the hospital, presenting with severe depression, fever, facial and limb edema, crusting, mucopurulent nasal discharge, oral ulceration and dyspnoea. Within 10 days, 2 cats (one owned by a veterinary student and one that had visited the hospital 3 days previous) presented with similar disease symptoms. These 3 cats all died or were euthanized without a confirmed diagnosis. The fourth case presented 3 days after a visit to the hospital, and FCV was confirmed. At that point, the possibility of hospital-acquired infection was assessed, and 3 additional hospitalized cats were found to be infected. The hospital was then closed to cats for 19 days and disinfected. An eighth cat owned by a veterinary student who was working in the hospital during this period also contracted the virus and was hospitalized at a private clinic. Of the 8 affected cats, 3 died, 2 were euthanized, and 2 recovered. As indicated, 2 cases never in the affected hospital occurred in cats infected by their owners (veterinary students present at the hospital). The virus from this outbreak was characterized, and found to be the same in all cases. This outbreak illustrates the highly contagious nature of this virus^[8].

Diagnosis of FCV-VSD is based on clinical signs, isolation of calicivirus via PCR and exclusion of other causes of acute upper respiratory disease, such as Chlamydia, FHV. In post-mortem diagnoses, hepatocellular necrosis, acute interstitial pneumonia and the presence of free pleural and abdominal exudate are commonly found^[9].

Fort Dodge (USA) have recently reported a dual-strain calicivirus vaccine which reduces systemic disease in infected cats (Huang et al, 2010).

References

1. ↑ Dean, R (2005) Feline calicivirus - a new clinical syndrome. The Feline Centre, University of Bristol
2. ↑ Huang, C et al (2010) A dual-strain feline calicivirus vaccine stimulates broader cross-neutralisation antibodies than a single-strain vaccine and lessens clinical signs in vaccinated cats when challenged with a homologous feline calicivirus strain associated with virulent systemic disease. JFMS 12:129-137
3. ↑ Pedersen, NC et al (2000) An isolated epizootic of hemorrhagic-like fever in cats caused by a novel and highly virulent strain of feline calicivirus. Vet Microbiol 73:281-300
4. ↑ Dawson, S, et al (1994) Acute arthritis of cats associated with feline calicivirus infection. Res Vet Sci 56:133-143
5. ↑ Karnovsky, M (1965) A formaldehyde-gluteraldehyde fixative of high osmolarity for use in electron microscopy. J Cell Biol 27:137-138
6. ↑ Hurley, KP et al (2004) An outbreak of vurulent systemic feline calicivirus disease. JAVMA 224(2):241-249
7. ↑ Pesavento, PA et al (2004) Pathologic, Immunohistochemical, and Electron Microscopic Findings in Naturally Occurring Virulent Systemic Feline Calicivirus Infection in Cats Vet Pathol 41:257-263
8. ↑ Reynolds, BS, et al (2009) A nosocomial outbreak of feline calicivirus associated virulent systemic disease in France, J Feline Med Surg 11:633
9. ↑ Hurley, KF (2003) Update on feline calicivirus: new trends. Vet Clin Small Anim 33:759-772