Diagnostic methods for feline coronavirus: a review

Abstract

Feline coronaviruses (FCoVs) are found throughout the world. Infection with FCoV can result in a diverse range of signs from clinically inapparent infections to a highly fatal disease called feline infectious peritonitis (FIP). FIP is one of the most serious viral diseases of cats. While there is neither an effective vaccine, nor a curative treatment for FIP, a diagnostic protocol for FCoV would greatly assist in the management and control of the virus. Clinical findings in FIP are non-specific and not helpful in making a differential diagnosis. Haematological and biochemical abnormalities in FIP cases are also non-specific. The currently available serological tests have low specificity and sensitivity for detection of active infection and cross-react with FCoV strains of low pathogenicity, the feline enteric coronaviruses (FECV). Reverse transcriptase polymerase chain reaction (RT-PCR) has been used to detect FCoV and is rapid and sensitive, but results must be interpreted in the context of clinical findings. At present, a definitive diagnosis of FIP can be established only by histopathological examination of biopsies. This paper describes and compares diagnostic methods for FCoVs and includes a brief account of the virus biology, epidemiology, and pathogenesis.

Figure 1

Peritoneal cavity of a cat with effusive FIP. A considerable amount of ascitic fluid can be seen in the abdominal cavity.

Figure 2

Intestines of a cat with effusive FIP. Pyogranulomatous foci are seen as punctate fibrinous plaques on the serosal surface of the intestines.

Figure 3

Pleural cavity of a cat with effusive FIP. Fibrinous serositis and adhesions of the lung with fibrin strands can be seen.

Figure 4

Kidney of a cat with non-effusive FIP. Granulomatous lesions can be seen on the capsular surface and in the parenchyma of the kidney.

Figure 5

Granulomatous colitis of a cat with effusive FIP showing infiltration of inflammatory cells.

Figure 6

Kidney of a cat with FIP. Severe degenerative and advanced necrotic changes within the lining endothelium of the convoluted tubules (mostly cytoplasmolysis). Frank patchy interstitial nephritis, as indicated by the heavy infiltration of lymphocytes, plasma cells and some dead neutrophils, together with dilatation and congestion of the interstitial blood vessels. The photograph was kindly provided by Dr. Diane Addie.