Priapism in a castrated cat associated with feline infectious peritonitis

This report describes a case of feline infectious peritonitis (FIP) in a castrated cat which first presented with the unusual sign of priapism. Laboratory examinations showed increased serum protein content and decreased albumin/globulin ratio. Serum electrophoresis revealed increased alpha 2- and gamma-globulin content. One month after the first examination, the cat died. At necropsy, histopathological evaluation of organs showed inflammatory granulomatous lesions compatible with non-effusive FIP and coronavirus-specific polymerase chain reaction confirmed the diagnosis. FIP antigen was demonstrated immunohistochemically in penile tissue.     

Cutaneous lesions associated with coronavirus-induced vasculitis in a cat with feline infectious peritonitis and concurrent feline immunodeficiency virus infection

This report describes a clinical case of feline infectious peritonitis (FIP) with multisystemic involvement, including multiple nodular cutaneous lesions, in a cat that was co-infected with feline coronavirus and feline immunodeficiency virus. The skin lesions were caused by a pyogranulomatous-necrotising dermal phlebitis and periphlebitis. Immunohistology demonstrated the presence of coronavirus antigen in macrophages within these lesions. The pathogenesis of FIP involves a viral associated, disseminated phlebitis and periphlebitis which can arise at many sites. Target organs frequently include the eyes, abdominal organs, pleural and peritoneal membranes, and central nervous tissues, but cutaneous lesions have not previously been reported.     

Cellular composition and interferon-gamma expression of the local inflammatory response in feline infectious peritonitis (FIP)

Feline infectious peritonitis (FIP) is one of the most important viral diseases of cats. International studies estimate that approximately 80% of all purebred cats are infected with the causative agent, feline coronavirus (FCoV). Out of these, 5-12% develop clinical symptoms of FIP. The pathogenesis of the disease is complex with many unresolved issues relating to the role of the immune system. The aim of the present study was to determine the proportions of various inflammatory cell types in FIP lesions by using a panel of cat specific, thoroughly validated, monoclonal antibodies. In addition, the expression of interferon-gamma within the inflammatory lesions was examined by RT-PCR. Our results confirm the mixed nature of the inflammatory reaction in FIP, involving B cells and plasma cells as well as CD4+ and CD8+ T cells. However, one cell type stands out as being the key element in both the "wet" and "dry" forms of FIP: the macrophage. Upregulation of IFN-gamma expression within the inflammatory lesions suggests a local activation of macrophages, which might result in increased viral replication.     

The feline acute phase reaction

The acute phase reaction (APR) is a response to potentially pathogenic stimuli. It begins with the release of interleukin (IL)-1, IL-6 and tumour necrosis factor (TNF)-alpha from inflammatory cells. These cytokines induce fever, leucocytosis and release of serum acute phase proteins (APPs). In this review, the characteristics of the feline APR are described. In cats with inflammatory conditions, fever is a common finding, with leucocytosis due to the release of cells from the marginal pool, followed by activation of myelopoiesis. Because excitement frequently causes leucocytosis in cats, a diagnosis of inflammation should therefore be supported by additional findings such as the presence of toxic neutrophils. The major APPs are serum amyloid A and alpha(1)-acid glycoprotein (AGP), which both increase a few hours after the inflammatory stimulus and remain elevated for as long as the inflammation persists. AGP plays an important role in the diagnosis of feline infectious peritonitis (FIP) and may also be useful also in studies of FIP pathogenesis.     

Tissue distribution of a feline AGP related protein (fAGPrP) in cats with feline infectious peritonitis (FIP)

Feline alpha(1)-acid glycoprotein (fAGP) increases during feline infectious peritonitis (FIP). We have recently identified a 29 kDa protein that we named feline AGP-related protein (fAGPrP) due to its cross-reactivity with an anti-human AGP monoclonal antibody. In this work we describe the tissue distribution of fAGPrP during FIP, and its relationship with feline coronavirus (FCoV) and myeloid cells. Tissues from five control cats and from 15 cats with FIP were examined by immunohistochemistry using monoclonal antibodies against human AGP, FCoV and myeloid antigens. Diffuse fAGPrP positivity within the lesions, likely due to vascular plasma leakage, endothelial and epithelial lining were detectable. Compared to controls, fAGPrP-expressing cells often increased in number and were diffusely distributed in lymph nodes, as usually occurs for IgM-producing plasma cells during early immune responses. These findings did not depend on the presence of FCoVs or of myeloid cells, suggesting that fAGPrP is not directly involved in the pathogenesis of FIP.     

Clinicopathologic features of a systemic coronavirus-associated disease resembling feline infectious peritonitis in the domestic ferret (Mustela putorius)

From 2002 to 2007, 23 ferrets from Europe and the United States were diagnosed with systemic pyogranulomatous inflammation resembling feline infectious peritonitis (FIP). The average age at the time of diagnosis was 11 months. The disease was progressive in all cases, and average duration of clinical illness was 67 days. Common clinical findings were anorexia, weight loss, diarrhea, and large, palpable intra-abdominal masses; less frequent findings included hind limb paresis, central nervous system signs, vomiting, and dyspnea. Frequent hematologic findings were mild anemia, thrombocytopenia, and hypergammaglobulinemia. Grossly, whitish nodules were found in numerous tissues, most frequently the mesenteric adipose tissue and lymph nodes, visceral peritoneum, liver, kidneys, spleen, and lungs. One ferret had a serous abdominal effusion. Microscopically, pyogranulomatous inflammation involved especially the visceral peritoneum, mesenteric adipose tissue, liver, lungs, kidneys, lymph nodes, spleen, pancreas, adrenal glands, and/or blood vessels. Immunohistochemically, all cases were positive for coronavirus antigen using monoclonal antibody FIPV3-70. Electron microscopic examination of inflammatory lesions identified particles with coronavirus morphology in the cytoplasm of macrophages. Partial sequencing of the coronavirus spike gene obtained from frozen tissue indicates that the virus is related to ferret enteric coronavirus.     

Sensitivity of Tru-cut and fine needle aspiration biopsies of liver and kidney for diagnosis of feline infectious peritonitis

BACKGROUND: The detection of typical lesions and feline coronavirus (FCoV) antigen in tissues is the only conclusive method for making a diagnosis of feline infectious peritonitis (FIP). A positive result using Tru-cut biopsy (TCB) and fine-needle aspiration biopsy (FNAB) has high diagnostic specificity, but information about the capacity of these techniques to correctly identify cats with FIP lesions is not available. OBJECTIVES: The diagnostic sensitivity of TCB and FNAB for detecting liver and kidney histologic lesions caused by FIP was evaluated. METHODS: TCB and FNAB specimens collected mainly at necropsy from 25 cats with FIP were analyzed. Diagnostic sensitivity was calculated on the basis of the number of false-negative and true-positive specimens, compared with the number of organs bearing histologic lesions of FIP. RESULTS: Diagnostic sensitivity was higher for hepatic TCB (64%) and FNAB (82%) than for renal (39% and 42%, respectively) procedures. A high percentage of renal cytologic and TCB specimens were inadequate. Combined analysis of TCB and FNAB specimens collected from the same organ increased the diagnostic sensitivity for liver (86%) and kidney (48%). The sensitivity of immunohistochemical/cytochemical analysis was low (11-38% depending on the technique), probably due to variable distribution of feline coronavirus in the lesions. CONCLUSION: Biopsy of liver and kidney can correctly identify FIP lesions. However, false-negative results or inadequate samples occur with moderate frequency, especially for immunochemical analysis. Diagnostic sensitivity may be increased when both TCB and FNAB specimens from the same organ are examined.     

A comparison between immunofluorescence staining on smears from Membrana nictitans (M3 test), immunohistopathology and routine pathology in cats with suspected feline infectious peritonitis (FIP).

An indirect immunofluorescence method using smears from membrana nictitans (M3 test) to diagnose feline corona virus (FCV) infection was compared with immunohistopathology (using indirect immunofluorescence assay (IFFA) performed on organs (IFO], and routine pathology (RP) in cats with suspected feline infectious peritonitis (FIP). A close correlation between the 2 immunofluorescence methods (IFO and M3) was observed. Although the M3 test requires samples from only 1 organ per animal, both the sensitivity and specificity were high (80%), when compared to IFO (using samples from an average of 5 organs per animal). In 21% of the cats with suspected FIP typical pathological lesions were found. As the M3 test is relatively easy to perform, it could reduce work-load of pathology laboratories and provide valuable data for clinical and epidemiological use.     

Morphologic features and development of granulomatous vasculitis in feline infectious peritonitis

Feline infectious peritonitis (FIP) is a fatal, coronavirus (CoV)-induced systemic disease in cats, characterized by granulomas in organs and granulomatous vasculitis. This study describes the morphologic features of granulomatous vasculitis in FIP as well as its development in the course of monocyte-associated feline CoV (FCoV) viremia in five naturally infected Domestic Shorthair cats with FIP. Monocyte-associated FCoV viremia was demonstrated by immunohistology, RNA in situ hybridization, and electron micropscopy. Granulomatous phlebitis at different stages of development was observed. Vasculitic processes ranged from attachment and emigration of FCoV-infected monocytes to vascular/perivascular granulomatous infiltrates with destruction of the vascular basal lamina. Monocytes as well as perivascular macrophages were activated because they were strongly positive for CD18 and expressed cytokines (tumor necrosis factor-alpha and interleukin-1beta) and matrix metalloproteinase-9. In addition, general activation of endothelial cells, represented by major histocompatibility complex II upregulation, was observed in all cases. These results confirm FIP as a monocyte-triggered systemic disease and demonstrate the central role of activated monocytes in FIP vasculitis.     

Cytokine mRNA expression in experimental porcine pneumonia

A porcine Pasteurella multocida (P. m.) infection model was established to study the spatial distribution of cytokine mRNA-expressing cells in lung tissue during acute pneumonia. The mRNA detection was performed by non-radioactive, formamide-free in situ hybridization (ISH) using oligonucleotides against the porcine interleukins (IL): IL-1 beta, IL-2, IL-4, IL-6, IL-8, TNF alpha and TGF beta. Cytokine mRNA-expressing macrophages were demonstrated by a double staining procedure combining immunohistochemistry (IH) using the primary antibody 2G6 with IL-1 beta, IL-6 and TGF beta ISH. With the exception of some stained TNF alpha-expressing cells, no IL mRNA was detectable in the lung of unaffected animals. The experimental P. m. pneumonia was characterized by a predominant, exudative and an additional proliferative interstitial component as well as abscess formation in the lung. Many cells of the region between the abscess membrane and the affected lung area showed high IL-6, IL-1 beta, IL-4 as well as TGF beta and few cells low IL-8 mRNA expression with characteristic distribution patterns. The ISH/IH double staining procedure revealed that at least some of the IL-6 or TGF beta-producing cells belonged to the 2G6-positive macrophages.     

Decreased sialylation of the acute phase protein alpha1-acid glycoprotein in feline infectious peritonitis (FIP)

Feline infectious peritonitis (FIP) is an immune-mediated disease of domestic and exotic felides infected with feline coronavirus. FIP is characterized by the overexpression of an acute phase protein, the alpha1-acid glycoprotein (AGP). In humans, AGP is a heavily glycosylated protein that undergoes several modifications of its glycan moiety during acute and chronic inflammatory pathologies. We studied the changes in AGP glycosylation in the course of FIP. Specifically, we focussed our attention on the degree of sialylation, fucosylation and branching. This study presents a purification method for feline AGP (fAGP) from serum, using an ion exchange chromatography strategy. The glycosylation pattern was analyzed in detail by means of interaction of purified fAGP with specific lectins. In particular, Sambucus nigra agglutinin I and Maackia amurensis agglutinin lectins were used to detect sialic acid residues, Aleuria aurantia lectin was used to detect L-fucose residues and Concanavalin A was used to evaluate the branching degree. By this method we showed that fAGP did not present any L-fucose residues on its surface, and that its branching degree was very low, both in normal and in pathological conditions. In contrast, during FIP disease, fAGP underwent several modifications in the sialic acid content, including decreased expression of both alpha(2-6)-linked and alpha(2-3)-linked sialic acid (76 and 44%, respectively when compared to non-pathological feline AGP).     

Flow cytometric detection of alpha-1-acid glycoprotein on feline circulating leucocytes

To assess whether alpha‐1‐acid glycoprotein (AGP) can be detected on the membrane of feline circulating leucocytes. Design The presence of AGP on circulating leucocytes was investigated in both clinically healthy cats and cats with different diseases. A group of feline coronavirus (FCoV)‐positive cats, comprising cats with feline infectious peritonitis (FIP) and cats not affected by FIP but seropositive for FCoV, were included in this study because the serum concentration of AGP increases during FCoV infection. Procedure Flow cytometry (using an anti‐feline AGP antibody), serum protein electrophoresis, routine haematology and measurement of the serum AGP concentration were performed using blood samples from 32 healthy cats (19 FCoV‐seropositive), 13 cats with FIP and 12 with other diseases (6 FCoV‐seropositive). The proportion of cats with AGP‐positive leucocytes in the different groups (e.g. controls vs sick; FIP vs other diseases, etc.) or in cats with different intensities of inflammatory response was compared using a Chi‐square test. Results AGP‐positive leucocytes were found in 23% of cats. Compared with controls, the proportion of patients with positive granulocytes and monocytes was higher among sick cats (especially cats with diseases other than FIP) and cats with high serum AGP concentration, but not in cats with leucocytosis or that were FCoV‐seropositive. Conclusion AGP‐positive leucocytes can be found in feline blood, especially during inflammation. Conversely, no association between AGP‐positive leucocytes and FIP was found. Further studies are needed to elucidate the mechanism responsible for this finding and its diagnostic role in cats with inflammation.     

Detection of antigenic heterogeneity in feline coronavirus nucleocapsid in feline pyogranulomatous meningoencephalitis

A new monoclonal antibody (mAb), CCV2-2, was compared with the widely used FIPV3-70 mAb, both directed against canine coronavirus (CCoV), as a diagnostic and research tool. Western blot showed that both anti-CCoV mAbs only reacted with a protein of 50 kD, a weight consistent with the feline coronavirus (FCoV) viral nucleocapsid. A competitive inhibition enzyme-linked immunosorbent assay showed that the 2 recognized epitopes are distinct. Preincubation of CCV2-2 mAb with FCoV antigen suppressed the immunostaining. Formalin-fixed, paraffin-embedded sections from brains of 15 cats with the dry form of feline infectious peritonitis (FIP) were examined by immunohistochemistry. Immunohistochemistry was performed with both anti-CCoV mAbs, either on consecutive or on the same sections. A myeloid-histiocytic marker, MAC 387, was also used to identify FIP virus-infected cells. In all regions where MAC 387-positive cells were present, positive staining with the CCV2-2 mAb was systematically detected, except at some levels in 1 cat. In contrast, none or only a few cells were positive for the FIPV3-70 mAb. Double immunostaining showed macrophages that were immunopositive for either CCV2-2 alone or alternatively for CCV2-2 and FIPV3-70 mAbs. This reveals the coexistence of 2 cohorts of phagocytes whose FIP viral contents differed by the presence or absence of the FIPV3-70-recognized epitope. These findings provide evidence for antigenic heterogeneity in coronavirus nucleocapsid protein in FIP lesions, a result that is in line with molecular observations. In addition, we provide for the first time morphologic depiction of viral variants distribution in these lesions.     

Changes in some acute phase protein and immunoglobulin concentrations in cats affected by feline infectious peritonitis or exposed to feline coronavirus infection

The possible role of some acute phase proteins (APPs) and immunoglobulins in both the pathogenesis and diagnosis of feline infectious peritonitis (FIP) has been investigated. Serum protein electrophoresis and the concentration of haptoglobin (Hp), serum amyloid A (SAA), alpha(1)-acid glycoprotein (AGP), IgG and IgM were evaluated in cats exposed to feline coronavirus (FCoV) and in cats with FIP. The highest concentration of APPs was detected in affected cats, confirming the role of these proteins in supporting a clinical diagnosis of FIP. Repeated samplings from both FIP affected and FCoV-exposed cats showed that when FIP appeared in the group, all the cats had increased APP levels. This increase persisted only in cats that developed FIP (in spite of a decrease in alpha(2)-globulins) but it was only transient in FCoV-exposed cats, in which a long lasting increase in alpha(2)-globulins was observed. These results suggest that changes in the electrophoretic motility of APPs or APPs other than Hp, SAA and AGP might be involved in the pathogenesis of FIP or in protecting cats from the disease.     

Skin fragility syndrome in a cat with feline infectious peritonitis and hepatic lipidosis

A 6-year-old spayed female domestic shorthair cat with a 3-week history of inappetence, weight loss, and hiding was examined. A palpable abdominal fluid wave, dehydration, and a small tear on the left flank were noted during initial examination. When the cat was gently restrained for blood sampling, the skin on the dorsal neck tore, leaving a 15 cm x 7 cm flap of skin. Clinicopathological abnormalities included nonregenerative anaemia, hypoalbuminaemia, increased globulin concentration, and mildly elevated aspartate aminotransferase and alkaline phosphatase activities. Abdominal fluid was viscous and had a total protein of 5.3 g dL(-1) with 316 cells microL(-1), consistent with a modified transudate. Cytology of the abdominal fluid revealed 86% nondegenerate neutrophils, 13% macrophages, and 1% small lymphocytes. Histopathological evaluation and indirect immunohistochemistry confirmed a diagnosis of feline infectious peritonitis, hepatic lipidosis and feline skin fragility syndrome. Feline skin fragility syndrome has not previously been reported in association with feline infectious peritonitis (FIP). Its inclusion as a clinical sign associated with FIP may facilitate a diagnosis.     

Pathogenesis of feline infetious peritonitis: pathologic changes and immunofluorescence

Feline infectious peritonitis (FIP) was experimentally induced in FIP virus (FIPV) antibody-positive and antibody-negative kittens after challenge exposure to live-virus aerosol. Seropositive kittens developed antiviral immunofluorescence and lesions more rapidly after challenge exposure than did seronegative kittens. In seropositive kittens, FIPV antigen was present in macrophages and large mononuclear cells in tracheobronchial lymph nodes, lungs, and trachea on postchallenge-exposure day (PCD) 2; in liver and spleen on PCD 3; in kidneys and omentum on PCD 4; and subsequently in nasal turbinates, thoracic and abdominal lymph nodes, thymus, bone marrow, parotid salivary gland, eyes, and brain. Initial antiviral immunofluorescence on PCD 2 coincided with the onset of viremia and vascular lesions. Systemic lesions characterized by perivascular necrotizing pyogranulomatous inflammation, phlebitis and thrombosis, fibrinous serositis, and generalized lymphoid necrosis developed on PCD 3 and 4. Coronavirus-like particles were observed by electron microscopy in cytoplasmic vacuoles or smooth endoplasmic reticulum of degenerating macrophages in inflammatory lesions. In seronegative kittens, antiviral immunofluorescence in tracheobronchial lymph nodes was first detected on PCD 5, and viremia occurred on PCD 6. Systemic necrotizing lesions, comparable with those observed in seropositive kittens on PCD 3 or 4, did not occur in seronegative kittens until PCD 13 or 16. In both groups of kittens, initial viral infection in regional lymphoreticular tissue was followed by viremia and infection of macrophages in reticuloendothelial organs (liver, spleen, lymph nodes) and perivascular locations. The accelerated onset of infection and lesions indicative of an Arthus-type reaction in challenge-exposed seropositive vs seronegative kittens further supports the immune-mediated pathogenesis of FIP.     

Epidemiology of feline infectious peritonitis among cats examined at veterinary medical teaching hospitals

OBJECTIVE: To determine proportions of cats in which feline infectious peritonitis (FIP) was diagnosed on an annual, monthly, and regional basis and identify unique characteristics of cats with FIP. DESIGN: Case-control study. SAMPLE POPULATION: Records of all feline accessions to veterinary medical teaching hospitals (VMTH) recorded in the Veterinary Medical Data Base between January 1986 and December 1995 and of all feline accessions for necropsy or histologic examination at 4 veterinary diagnostic laboratories. PROCEDURE: Proportions of total and new feline accessions for which a diagnosis of FIP was recorded were calculated. To identify characteristics of cats with FIP, cats with FIP were compared with the next cat examined at the same institution (control cats). RESULTS: Approximately 1 of every 200 new feline and 1 of every 300 total feline accessions at VMTH in North America and approximately 1 of every 100 accessions at the diagnostic laboratories represented cats with FIP. Cats with FIP were significantly more likely to be young, purebred, and sexually intact males and significantly less likely to be spayed females and discharged alive than were control cats. The proportion of new accessions for which a diagnosis of FIP was recorded did not vary significantly among years, months, or regions of the country. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that FIP continues to be a clinically important disease in North America and that sexually intact male cats may be at increased risk, and spayed females at reduced risk, for FIP. The high prevalence of FIP and lack of effective treatment emphasizes the importance of preventive programs, especially in catteries.     

The frequency and pathogenesis of feline infectious peritonitis (FIP)

Between 1980 and 1987 about 10% of the cats which underwent a post mortem examination at the Institute of Veterinary Pathology of the Freie Universit?t Berlin were infected with feline infectious peritonitis (FIP). The exudative, granulomatous or mixed form of the FIP are all symptoms of the same disease whose clinical picture is dependent on the state of the cellular immunity. Statistically there is no significant relationship between the form of the FIP and the age of the cats. A breed or a sex disposition is also not apparent. 42 organs and/or tissue samples were taken from a total of 30 cats and were examined both histologically and immunohistochemically. The antigen is located, above all, in the mesothelium and the cells of the mononuclear phagocyte system, whereas the parenchymatous inflammation foci show little evidence of the FIP-virus-antigen. The antigen is, however, also found in the nerve cells. Within the framework of a second viraemia, occurring after infection of the mesothelium (polyserositis), a perivasculitis non purulenta generalisata occurs. Possible excretory organs of the antigen are the respiratory, digestive and urinary tract.