Overview Feline Coronavirus infection is ubiquitous in domestic cats, and is particularly common where conditions are crowded. While most FCoV-infected cats are healthy or display only a mild enteritis, some go on to develop feline infectious peritonitis, a disease that is especially common in young cats and multi-cat environments. Up to 12% of FCoV-infected cats may succumb to FIP, with stress predisposing to the development of disease. Disease signs The ‘wet’ or effusive form, characterised by polyserositis (abdominal and/or thoracic effusion) and vasculitis, and the ‘dry’ or non-effusive form (pyogranulomatous lesions in organs) reflect clinical extremes of a continuum. The clinical picture of FIP is highly variable, depending on the distribution of the vasculitis and pyogranulomatous lesions. Fever refractory to antibiotics, lethargy, anorexia and weight loss are common non-specific signs. Ascites is the most obvious manifestation of the effusive form. Diagnosis The aetiological diagnosis of FIP ante-mortem may be difficult, if not impossible. The background of the cat, its history, the clinical signs, laboratory changes, antibody titres and effusion analysis should all be used to help in decisionmaking about further diagnostic procedures. At the time of writing, there is no non-invasive confirmatory test available for cats without effusion. Disease management In most cases FIP is fatal. Supportive treatment is aimed at suppressing the inflammatory and detrimental immune response. However, there are no controlled studies to prove any beneficial effect of corticosteroids.

Coronaviruses are well known for their potential to change their host or tissue tropism, resulting in unpredictable new diseases and changes in pathogenicity; severe acute respiratory syndrome and feline coronaviruses, respectively, are the most recognized examples. Feline coronaviruses occur as 2 pathotypes: nonvirulent feline enteric coronaviruses (FECVs), which replicate in intestinal epithelium cells, and lethal feline infectious peritonitis viruses (FIPVs), which replicate in macrophages. Evidence indicates that FIPV originates from FECV by mutation, but consistent distinguishing differences have not been established. We sequenced the full genome of 11 viruses of each pathotype and then focused on the single most distinctive site by additionally sequencing hundreds of viruses in that region. As a result, we identified 2 alternative amino acid differences in the putative fusion peptide of the spike protein that together distinguish FIPV from FECV in >95% of cases. By these and perhaps other mutations, the virus apparently acquires its macrophage tropism and spreads systemically.

A full history of the management practices and the prevalence of upper respiratory tract disease ( URTD ) at 218 rescue shelters, breeding establishments and private households with five or more cats was recorded. Oropharyngeal and conjunctival swabs and blood samples were taken from 1748 cats. The prevalences of feline herpesvirus ( FHV ), feline calicivirus ( FCV ), Chlamydophila felis and Bordetella bronchiseptica were determined by PCR on swab samples. An ELISA was applied to determine the prevalence of antibodies to B bronchiseptica . The rates of detection by PCR of each pathogen in the cats in catteries with and without ongoing URTD were, respectively, FHV 16 per cent and 8 per cent; FCV 47 per cent and 29 per cent; C felis 10 per cent and 3 per cent; and B bronchiseptica 5 per cent and 1·3 per cent; the seroprevalences of B bronchiseptica were 61 per cent and 41 per cent, respectively. There was evidence that FHV , FCV and B bronchiseptica played a role in URTD . The risk factors associated with the disease were less than excellent hygiene, contact with dogs with URTD , and larger numbers of cats in the cattery or household.

Overview Feline calicivirus (FCV) is a highly variable virus. More severe, systemic forms of FCV infection have been observed recently. Infection Sick, acutely infected or carrier cats shed FCV in oronasal and conjunctival secretions. Infection occurs mainly through direct contact. Disease signs The main clinical signs are oral ulcers, upper respiratory signs and a high fever. Feline calicivirus may be isolated from nearly all cats with chronic stomatitis or gingivitis. Cats with ‘virulent systemic FCV disease’ variably show pyrexia, cutaneous oedema, ulcerative lesions on the head and limbs, and jaundice. Mortality is high and the disease is more severe in adult cats. Diagnosis Diagnosis of FCV can be achieved by virus isolation or reverse-transcriptase PCR. Viral RNA can be detected in conjunctival and oral swabs, blood, skin scrapings or lung tissue using PCR. Positive PCR results should be interpreted with caution, as these may be a consequence of low-level shedding by persistently infected carriers. The diagnosis of virulent systemic FCV disease relies on clinical signs and isolation of the same strain from the blood of several diseased cats. Disease management Supportive therapy (including fluid therapy) and good nursing care are essential. Anorexic cats should be fed highly palatable, blended or warmed food. Mucolytic drugs (eg, bromhexine) or nebulisation with saline may offer relief. Broad-spectrum antibiotics may be administered to prevent secondary bacterial infections. Feline calicivirus can persist in the environment for about 1 month and is resistant to many common disinfectants.

Overview Feline panleukopenia virus (FPV) infects all felids as well as raccoons, mink and foxes. This pathogen may survive in the environment for several months and is highly resistant to some disinfectants.Infection Transmission occurs via the faecal-oral route. Indirect contact is the most common route of infection, and FPV may be carried by fomites (shoes, clothing), which means indoor cats are also at risk. Intrauterine virus transmission and infection of neonates can occur.Disease signs Cats of all ages may be affected by FPV, but kittens are most susceptible. Mortality rates are high - over 90% in kittens. Signs of disease include diarrhoea, lymphopenia and neutropenia, followed by thrombocytopenia and anaemia, immunosuppression (transient in adult cats), cerebellar ataxia (in kittens only) and abortion.Diagnosis Feline panleukopenia virus antigen is detected in faeces using commercially available test kits. Specialised laboratories carry out PCR testing on whole blood or faeces. Serological tests are not recommended, as they do not distinguish between infection and vaccination.Disease management Supportive therapy and good nursing significantly decrease mortality rates. In cases of enteritis, parenteral administration of a broad-spectrum antibiotic is recommended. Disinfectants containing sodium hypochlorite (bleach), peracetic acid, formaldehyde or sodium hydroxide are effective.