Cases Of Feline Infectious Peritonitis Research Articles

Feline infectious peritonitis: A comprehensive evaluation of clinical manifestations, laboratory diagnosis, and therapeutic approaches.

This study aimed to investigate the clinical and laboratory characteristics of naturally occurring feline infectious peritonitis (FIP) and estimate the median survival time of FIP cats treated with prednisolone to guide further therapeutic planning. In this retrospective study, data from a total of 116 cats with effusion were fully recorded. Forty-five FIP-diagnosed cats were enrolled for analysis. The study findings indicate that FIP was a disease affecting cats aged 1-2 years and was highly prevalent among male cats. Clinical manifestations of FIP affected the digestive (60%), hematological (53.3%), respiratory (33.3%), neurological (6.7%), and ocular (4.4%) systems. Blood profiles revealed mild anemia, lymphopenia, thrombocytopenia, hypoalbuminemia, hyperglobulinemia, and an albumin to globulin ratio of 0.4. Fluid analysis and cytology of FIP cats demonstrated a transparent yellow fluid with a protein content of 6 gm/dl and a total nucleated cell count of approximately 5,000-10,000 cells. During the observation period, FIP cats treated with prednisolone exhibited a median survival time of 31 days. Confirming FIP cases can be challenging; therefore, a tentative diagnosis of FIP must be made with care. This study provided practical diagnostic tools to diagnose FIP based on clinical signs and multiple abnormalities, which allowed for more efficient and rapid detection.

Assessing the feasibility of applying machine learning to diagnosing non-effusive feline infectious peritonitis

Feline infectious peritonitis (FIP) is a severe feline coronavirus-associated syndrome in cats, which is invariably fatal without anti-viral treatment. In the majority of non-effusive FIP cases encountered in practice, confirmatory diagnostic testing is not undertaken and reliance is given to the interpretation of valuable, but essentially non-specific, clinical signs and laboratory markers. We hypothesised that it may be feasible to develop a machine learning (ML) approach which may be applied to the analysis of clinical data to aid in the diagnosis of disease. A dataset encompassing 1939 suspected FIP cases was scored for clinical suspicion of FIP on the basis of history, signalment, clinical signs and laboratory results, using published guidelines, comprising 683 FIP (35.2%), and 1256 non-FIP (64.8%) cases. This dataset was used to train, validate and evaluate two diagnostic machine learning ensemble models. These models, which analysed signalment and laboratory data alone, allowed the accurate discrimination of FIP and non-FIP cases in line with expert opinion. To evaluate whether these models may have value as a diagnostic tool, they were applied to a collection of 80 cases for which the FIP status had been confirmed (FIP: n = 58 (72.5%), non–FIP: n = 22 (27.5%)). Both ensemble models detected FIP with an accuracy of 97.5%, an area under the curve (AUC) of 0.969, sensitivity of 95.45% and specificity of 98.28%. This work demonstrates that, in principle, ML can be usefully applied to the diagnosis of non-effusive FIP. Further work is required before ML may be deployed in the laboratory as a diagnostic tool, such as training models on datasets of confirmed cases and accounting for inter-laboratory variation. Nevertheless, these results illustrate the potential benefit of applying ML to standardising and accelerating the interpretation of clinical pathology data, thereby improving the diagnostic utility of existing laboratory tests.

Cross-sectional and histopathological studies of Feline Coronavirus infections in stray cats in Kuwait.

Feline Coronavirus (FCoV) is a worldwide viral infection of felids. The disease is usually asymptomatic, but it can cause mild diarrhoea; however, few numbers of cases may develop a severe systemic disease known as feline infectious peritonitis (FIP). This study aims to determine the prevalence of FCoV shedding in the faeces of stray cats in Kuwait and detect antibodies against FCoV in their serum. Histopathological analyses and RT‑PCR were used to prove cases of FIP. A total of 178 cats were examined for the presence of FCoV in their faeces using a rapid immunochromatography (IC) test. Anti‑FCoV Antibody (Anti‑FCoV Ab) was detected in their serum using ELISA. Eleven samples were tested using RT‑PCR to confirm positive cases. The prevalence of FCoV faecal antigen in stray cats was 32.6%. The overall detection rate of Anti‑FCoV Ab in stray cats was 44.9%. Nine cats tested positive using the RT‑PCR test. Six out of those nine were confirmed to be FIP positive through gross and histopathological examination. The characteristic uveitis and discoloration of the irises were seen. The present study is the first report confirming FCoV infection in stray cats in Kuwait. Postmortem and histopathological lesions in cases of FIP were recorded.

RNA in-situ hybridization for pathology-based diagnosis of feline infectious peritonitis (FIP): current diagnostics for FIP and comparison to the current gold standard

Feline infectious peritonitis (FIP) is a systemic disease of cats caused by a highly pathogenic variant of feline coronavirus, or FCoV. Two distinct genotypes of FCoV exist (also referred to as serotypes): Type 1 viruses constitute the vast majority of FIP cases, while type 2 viruses are responsible for the remaining infections. Immunohistochemistry (IHC) currently serves as the gold standard for diagnosis of FIP; however, IHC is limited by variations in sensitivity. RNA in situ hybridization (RNA ISH) has an established foothold in infectious disease diagnostics and presents a potentially improved method for detection of FIP. This proof-of-concept study evaluated the efficacy of RNA ISH probes targeted to FCoV, as compared to IHC using monoclonal antibody FIP 3-70. Formalin-fixed paraffin-embedded tissues from FIP-positive cats were used for ISH, with the presence of RNA determined chromogenically. ISH tissue slides were then compared to their IHC counterparts, with efficacy determined based on metrics including staining intensity and abundance. Positive ISH staining on tissue was found to be both more intense and abundant than for IHC, suggesting that ISH serves as a highly sensitive method for the detection of FCoV/FIP in comparison to IHC - a finding that awaits further validation.

RNA in-situ hybridization for pathology-based diagnosis of feline infectious peritonitis (FIP): current diagnostics for FIP and comparison to the current gold standard

Feline infectious peritonitis (FIP) is a systemic disease of cats caused by a highly pathogenic variant of feline coronavirus, or FCoV. Two distinct genotypes of FCoV exist (also referred to as serotypes): Type 1 viruses constitute the vast majority of FIP cases, while type 2 viruses are responsible for the remaining infections. Immunohistochemistry (IHC) currently serves as the gold standard for diagnosis of FIP; however, IHC is limited by variations in sensitivity. RNA in situ hybridization (RNA ISH) has an established foothold in infectious disease diagnostics and presents a potentially improved method for detection of FIP. This proof-of-concept study evaluated the efficacy of RNA ISH probes targeted to FCoV, as compared to IHC using monoclonal antibody FIP 3-70. Formalin-fixed paraffin-embedded tissues from FIP-positive cats were used for ISH, with the presence of RNA determined chromogenically. ISH tissue slides were then compared to their IHC counterparts, with efficacy determined based on metrics including staining intensity and abundance. Positive ISH staining on tissue was found to be both more intense and abundant than for IHC, suggesting that ISH serves as a highly sensitive method for the detection of FCoV/FIP in comparison to IHC - a finding that awaits further validation.

Molecular Detection of Feline Coronavirus in Captive Non-Domestic Felids from Zoological Facilities.

Simple SummaryNon-domestic felids are well-known threatened species, and are susceptible to several diseases that also affect domestic cats. Among viral infections, fatal outbreaks of feline infectious peritonitis, caused by a feline coronavirus, have been reported in captive settings. Considering the devastating effects that this pathogen could have in non-domestic felids, the aim of this study was to assess the prevalence of feline coronavirus in captive non-domestic felids from Northern Italy, since in the literature, this information is not currently available. The overall prevalence of feline coronavirus in captive non-domestic felids from Northern Italy was 7.9%. Results of the present study highlight the need of control programs for feline coronavirus infection to prevent pathogen introduction into a naïve group of animals, which may lead to devastating effects on animal welfare and conservation programs.Cases of feline infectious peritonitis (FIP), a disease with a high mortality rate caused by the feline coronavirus (FCoV), have been reported in non-domestic felids, highlighting the need for surveys of FCoV in these endangered species. With the aim of adding information on FCoV prevalence in captive non-domestic felids, samples (feces or rectal swabs and, when available, oral swabs, blood, and abdominal effusion) collected between 2019 and 2021 from 38 non-domestic felids from three different zoological facilities of Northern Italy were tested for evidence of FCoV infection via RT-qPCR. Three animals were found to be FCoV positive, showing an overall 7.9% FCoV prevalence ranging from 0% to 60%, according to the zoological facility. FCoV infection was detected in tiger cubs of the same litter, and all of them showed FCoV-positive oral swabs, with low viral loads, whereas in one animal, FCoV presence was also detected in rectal swabs at low FCoV copy numbers. Future studies should be carried out, including samplings from a higher number of captive non-domestic felids, in order to gain a deeper knowledge of FCoV epidemiology within these populations.

RNA in-situ hybridization for pathology-based diagnosis of feline infectious peritonitis (FIP): current diagnostics for FIP and comparison to the current gold standard

Feline infectious peritonitis (FIP) is a systemic disease of cats caused by a highly pathogenic variant of feline coronavirus, or FCoV (termed FIPV). Two serotypes of FCoV exist: type 1 viruses constitute 85% to 95% of FIP cases, while type 2 viruses are responsible for the remaining 5% to 15% of infections. Immunohistochemistry (IHC) currently serves as the gold standard for diagnosis of FIPV; however, IHC is limited by its wide variations in sensitivity. RNA in situ hybridization (RNA ISH) has an established foothold in infectious disease diagnostics and presents a potentially improved method for detection of FIPV. This study evaluated the efficacy of RNA ISH probes targeted to FIPV, as compared to IHC using monoclonal antibody FIP 3-70. Formalin-fixed paraffin-embedded tissues from FIP-positive cats were used for ISH, with RNA presence determined chromogenically. ISH tissue slides were then compared to their IHC counterparts, with efficacy determined based on metrics including staining intensity and abundance. Positive ISH staining on tissue was found to be both more intense and abundant than for IHC—suggesting that ISH serves as a highly sensitive method for the detection of FCoV/FIPV, in comparison to IHC.

Epidemiology and Comparative Analyses of the S Gene on Feline Coronavirus in Central China.

Feline coronavirus (FCoV) infections present as one of two forms: a mild or symptom-less enteric infection (FEC) and a fatal systemic disease termed feline infectious peritonitis (FIP). The lack of epidemiology of FCoV in central China and the reason why different symptoms are caused by viruses of the same serotype have motivated this investigation. Clinical data of 81 suspected FIP cases, 116 diarrhea cases and 174 healthy cases were collected from veterinary hospitals using body cavity effusion or fecal samples. Risk factors, sequence comparison and phylogenetic studies were performed. The results indicated that FIPV was distinguished from FECV in the average hydrophobicity of amino acids among the cleavage sites of furin, as well as the mutation sites 23,531 and 23,537. FIPV included a higher minimal R-X-X-R recognition motif of furin (41.94%) than did FECV (9.1%). The serotype of FCoV was insignificantly correlated with FIP, and the clade 1 and clade 2 strains that appeared were unique to central China. Thus, it is hypothesized that this, along with the latent variables of an antigenic epitope at positions 1058 and 1060, as well as mutations at the S1/S2 sites, are important factors affecting FCoV transmission and pathogenicity.

Alpha-1 Acid Glycoprotein Reduction Differentiated Recovery from Remission in a Small Cohort of Cats Treated for Feline Infectious Peritonitis.

Feline infectious peritonitis (FIP) is a systemic immune-mediated inflammatory perivasculitis that occurs in a minority of cats infected with feline coronavirus (FCoV). Various therapies have been employed to treat this condition, which was previously usually fatal, though no parameters for differentiating FIP recovery from remission have been defined to enable clinicians to decide when it is safe to discontinue treatment. This retrospective observational study shows that a consistent reduction of the acute phase protein alpha-1 acid glycoprotein (AGP) to within normal limits (WNL, i.e., 500 μg/mL or below), as opposed to duration of survival, distinguishes recovery from remission. Forty-two cats were diagnosed with FIP: 75% (12/16) of effusive and 54% (14/26) of non-effusive FIP cases recovered. Presenting with the effusive or non-effusive form did not affect whether or not a cat fully recovered (p = 0.2). AGP consistently reduced to WNL in 26 recovered cats but remained elevated in 16 cats in remission, dipping to normal once in two of the latter. Anaemia was present in 77% (23/30) of the cats and resolved more quickly than AGP in six recovered cats. The presence of anaemia did not affect the cat’s chances of recovery (p = 0.1). Lymphopenia was observed in 43% (16/37) of the cats and reversed in nine recovered cats but did not reverse in seven lymphopenic cats in the remission group. Fewer recovered cats (9/24: 37%) than remission cats (7/13: 54%) were lymphopenic, but the difference was not statistically different (p = 0.5). Hyperglobulinaemia was slower than AGP to return to WNL in the recovered cats. FCoV antibody titre was high in all 42 cats at the outset. It decreased significantly in 7 recovered cats but too slowly to be a useful parameter to determine discontinuation of antiviral treatments. Conclusion: a sustained return to normal levels of AGP was the most rapid and consistent indicator for differentiating recovery from remission following treatment for FIP. This study provides a useful model for differentiating recovery from chronic coronavirus disease using acute phase protein monitoring.

Feline Coronaviruses Identified in Feline Effusions in Suspected Cases of Feline Infectious Peritonitis.

Ninety-five effusion samples were collected from cats with suspected feline infectious peritonitis in northern Taiwan; these samples showed a 47.4% (45/95) feline coronavirus (FCoV) positivity rate on immunofluorescence staining and RT-PCR. Young cats (≤24 months old) were found to have a significantly higher risk than cats >24 months old (odds ratio (OR) = 6.19, 95% confidence interval (CI) 2.54–16.00). No significant association was found between the positive rates and sex or breed. The A/G ratio in positive cases was significantly lower than the A/G ratio in negative cases. Genotyping and sequencing of the positive cases revealed 71.9% single infection with type I strains and 28.1% coinfection with types I and II. No single infections with type II strains were noted. The type I sequences had high diversity, while the type II sequences had high internal sequence identity and were more similar to CoVs from other species, such as dogs, pigs, and various small mammals. This study demonstrates the latest analysis of FCoV infection cases in northern Taiwan.

FELINE CORONAVIRUS AND FELINE INFECTIOUS PERITONITIS IN NONDOMESTIC FELID SPECIES.

Feline coronavirus (FCoV) is reported worldwide and known to cause disease in domestic and nondomestic felid species. Although FCoV often results in mild to inapparent disease, a small subset of cats succumb to the fatal, systemic disease feline infectious peritonitis (FIP). An outbreak of FIP in Cheetahs (Acinonyx jubatus) in a zoological collection demonstrated the devastating effect of FCoV introduction into a naïve group of animals. In addition to cheetahs, FIP has been described in European wildcats (Felis silvestris), a tiger (Panthera tigris), a mountain lion (Puma concolor), and lion (Panthera leo). This paper reviews the reported cases of FIP in nondomestic felid species and highlights the surveys of FCoV in populations of nondomestic felids.

A retrospective study of clinical and laboratory features and treatment on cats highly suspected of feline infectious peritonitis in Wuhan, China

Feline infectious peritonitis (FIP) is a systemic, potentially fatal viral disease. The objectives of this study were to review clinical and laboratory features and treatment of cats highly suspected of FIP in Wuhan, China. The clinical records of 127 cats highly suspected of FIP were reviewed for history, clinical signs, physical findings, and diagnostic test results. Sex, neutering status, breed, age, and month of onset of disease were compared with the characteristics of the clinic population. Age and neutering status were significantly correlated with FIP-suspicion. Sex, breed and onset month were not associated with FIP. There were many more FIP-suspected cases in cats in young cats or male intact cats. Effusion was observed in 85.8% of the FIP-suspected cats. Increased serum amyloid A (SAA) and lymphopenia were common laboratory abnormalities in the FIP cases. Furthermore, 91.7% of the cats highly suspected of FIP had an albumin/globulin (A/G) ratio < 0.6, while 85.3% had an A/G ratio < 0.5. The mortality rate for FIP-suspected cats was 67%, and six submitted cases were confirmed by FIP-specific immunohistochemistry. Of the 30 cats treated with GS-441524 and/or GC376, 29 were clinically cured. The study highlights the diverse range of clinical manifestations by clinicians in diagnosing this potentially fatal disease. A/G ratio and SAA were of higher diagnostic value. GS-441524 and GC376 were efficient for the treatment of FIP-suspected cats.

Update on feline infectious peritonitis

Background: Feline coronavirus (FCoV) infection in cats is common, usually only causing mild intestinal signs, such as diarrhoea. It is highly infectious and found worldwide. A sequela of FCoV infection,...

Immunocytochemistry of mesenteric lymph node fine-needle aspirates in the diagnosis of feline infectious peritonitis.

Immunohistochemistry (IHC) of tissue samples is considered the gold standard for diagnosing feline infectious peritonitis (FIP), and, in cats without body cavity effusion, IHC is the only method available to establish definitive antemortem diagnosis. However, IHC requires invasive tissue sample collection. We evaluated sensitivity and specificity of an immunocytochemical assay of fine-needle aspirates (FNAs) of mesenteric lymph nodes that can be obtained noninvasively by ultrasound-guided aspiration to diagnose FIP. FNAs of mesenteric lymph nodes were obtained postmortem from 41 cats suspected of having FIP based on clinical and/or laboratory findings. FIP was confirmed immunohistochemically in 30 cats. In the other 11 cats, a disease other than FIP, which explained the clinical signs, was diagnosed histopathologically. Immunocytochemistry (ICC) was performed as an avidin-biotin complex method using a monoclonal anti-FCoV IgG 2A. Sensitivity, specificity, negative and positive predictive values (NPV, PPV, respectively) including 95% confidence intervals (95% CIs) were determined. ICC was positive in 17 of 30 cats with FIP, but also in 1 of 11 control cats that was diagnosed with lymphoma. Sensitivity of ICC was 53% (95% CI: 34-72); specificity 91% (95% CI: 59-100); NPV 42% (95% CI: 22-63); and PPV 94% (95% CI: 71-100). In a lethal disease such as FIP, specificity is most important in order to avoid euthanasia of unaffected cats. Given that a false-positive result occurred and FIP was correctly detected in only approximately half of the cases of FIP, ICC of mesenteric lymph node FNA alone cannot reliably confirm or exclude FIP, but can be a helpful test in conjunction with other diagnostic measures.

Diagnosis of non-effusive feline infectious peritonitis by reverse transcriptase quantitative PCR from mesenteric lymph node fine-needle aspirates.

The aim of this study was to evaluate a feline coronavirus (FCoV) reverse transcriptase quantitative PCR (RT-qPCR) on fine-needle aspirates (FNAs) from mesenteric lymph nodes (MLNs) collected in sterile saline for the purpose of diagnosing non-effusive feline infectious peritonitis (FIP) in cats. First, the ability of the assay to detect viral RNA in MLN FNA preparations compared with MLN biopsy preparations was assessed in matched samples from eight cats. Second, a panel of MLN FNA samples was collected from a series of cats representing non-effusive FIP cases (n = 20), FCoV-seropositive individuals (n = 8) and FCoV-seronegative individuals (n = 18). Disease status of the animals was determined using a combination of gross pathology, histopathology and/or 'FIP profile', consisting of serology, clinical pathology and clinical signs. Viral RNA was detected in 18/20 non-effusive FIP cases; it was not detected in two cases that presented with neurological FIP. Samples from 18 seronegative non-FIP control cats and 7/8 samples from seropositive non-FIP control cats contained no detectable viral RNA. Thus, as a method for diagnosing non-effusive FIP, MLN FNA RT-qPCR had an overall sensitivity of 90.0% and specificity of 96.1%. In cases with a high index of suspicion of disease, RT-qPCR targeting FCoV in MLN FNA can provide important information to support the ante-mortem diagnosis of non-effusive FIP. Importantly, viral RNA can be reliably detected in MLN FNA samples in saline submitted via the national mail service. When applied in combination with biochemistry, haematology and serological tests in cases with a high index of suspicion of disease, the results of this assay may be used to support a diagnosis of non-effusive FIP.

Diagnosis of feline infectious peritonitis: Update on evidence supporting available tests.

Practical relevance: Feline coronavirus (FCoV) infection is very common in cats, usually causing only mild intestinal signs such as diarrhoea. Up to 10% of FCoV infections, however, result in the fatal disease feline infectious peritonitis (FIP). Clinical challenges: Obtaining a definitive diagnosis of FIP based on non-invasive approaches is difficult. Confirmation of the disease relies on finding appropriate cytological or histopathological changes in association with positive immunostaining for FCoV antigen. In FIP cases with effusions, cytology and immunostaining on effusion samples can be relatively easy to perform; otherwise obtaining diagnostic samples is more challenging and collection of biopsies from tissues with gross lesions is necessary. In the absence of a definitive diagnosis, a high index of suspicion of FIP may be obtained from the cat's signalment and history, combined with findings on clinical examination and laboratory test results. If largely consistent with FIP, these can be used as a basis for discussion with the owner about whether additional, more invasive, diagnostic tests are warranted. In some cases it may be that euthanasia is discussed as an alternative to pursuing a definitive diagnosis ante-mortem, especially if financial limitations exist or where there are concerns over a cat's ability to tolerate invasive diagnostic procedures. Ideally, the diagnosis should be confirmed in such patients from samples taken at post-mortem examination. Global importance: FIP occurs wherever FCoV infection is present in cats, which equates to most parts of the world. Evidence base: This review provides a comprehensive overview of how to approach the diagnosis of FIP, focusing on the tests available to the veterinary practitioner and recently published evidence supporting their use.

A retrospective study of the neuropathology and diagnosis of naturally occurring feline infectious peritonitis.

Feline infectious peritonitis (FIP) is one of the most important viral diseases of cats worldwide. Our study describes the neuropathology and the diagnostic features of 26 cases of FIP in domestic cats. The average age of affected individuals was 11.8 mo, and there was no sex or breed predisposition. Clinical neurologic signs were noted in 22 cases, and rabies was clinically suspected in 11 cases. Twenty cats had lesions in multiple organs, and 6 cats had lesions only in the brain. Gross neuropathologic changes occurred in 15 cases and consisted of hydrocephalus (10 cases), cerebellar herniation through the foramen magnum (6 cases), cerebral swelling with flattening of gyri (2 cases), and accumulation of fibrin within ventricles (2 cases) or leptomeninges (1 case). Histologically, 3 main distinct distributions of neuropathologic changes were observed, namely periventricular encephalitis (12 cases), rhombencephalitis (8 cases), and diffuse leptomeningitis with superficial encephalitis (6 cases). Fresh tissue samples were submitted for fluorescent antibody testing (FAT) after autopsy in 17 cases, and positive results were found in only 7 cases. Immunohistochemistry (IHC) for feline coronavirus confirmed the diagnosis in all 26 cases. IHC appears to be a more sensitive and reliable test for confirmation of FIP than is FAT.

Feline Infectious Peritonitis: Immunohistochemical Features of Ocular Inflammation and the Distribution of Viral Antigens in Structures of the Eye.

Feline infectious peritonitis (FIP) is a serious, widely distributed systemic disease caused by feline coronavirus (FCoV), in which ocular disease is common. However, questions remain about the patterns of ocular inflammation and the distribution of viral antigen in the eyes of cats with FIP. This study characterized the ocular lesions of FIP including the expression of glial fibrillary acidic protein and proliferating cell nuclear antigen by Müller cells in the retina in cases of FIP and to what extent macrophages are involved in ocular inflammation in FIP. Immunohistochemistry for FCoV, CD3, CD79a, glial fibrillary acidic protein, calprotectin, and proliferating cell nuclear antigen was performed on paraffin sections from 15 naturally occurring cases of FIP and from controls. Glial fibrillary acidic protein expression was increased in the retina in cases of FIP. Müller cell proliferation was present within lesions of retinal detachment. Macrophages were present in FIP-associated ocular lesions, but they were the most numerous inflammatory cells only within granulomas (2/15 cats, 13%). In cases of severe inflammation of the ciliary body with damage to blood vessel walls and ciliary epithelium (3/15, 20%), some macrophages expressed FCoV antigens, and immunolabeling for calprotectin on consecutive sections suggested that these FCoV-positive macrophages were likely to be recently derived from blood. In cases of severe and massive inflammation of most ocular structures (4/15, 26%), B cells and plasma cells predominated over T cells and macrophages. These results indicate that gliosis can be present in FIP-affected retinas and suggest that breakdown of the blood-ocular barrier can allow FCoV-bearing macrophages to access the eye.

Glial response in the central nervous system of cats with feline infectious peritonitis.

The aim of the study was to evaluate central nervous system (CNS) lesions in non-effusive and effusive cases of feline infectious peritonitis (FIP) regarding aspects related to astrocytic and microglial reactions. Five necropsied cats that were naturally infected with FIP virus, confirmed by reverse transcriptase polymerase chain reaction and immunohistochemistry, with different intensities of CNS lesions, were studied. Brain and cerebellum were evaluated by light microscopy and immunohistochemistry for glial fibrillary acidic protein (GFAP) and vimentin to assess astrocytic morphology, and lectin histochemistry for Ricinus communis agglutinin-I (RCA-I) to detect microglia was performed to evaluate the glial response in the CNS of cats with FIP. An important astrocytic response in many areas of the CNS of all cats, including the periventricular areas of lateral ventricles and fourth ventricle, the molecular layer of the cerebellum and cerebral cortex, was visualized. This astrocytic reactivity was associated with areas of granulomatous or pyogranulomatous vasculitis/perivasculitis in most cases, and it was characterized by multifocal to coalescing astrocytosis and astrogliosis with an increase in the expression of intermediate filaments, such as GFAP. However, astrocytes exhibited strong vimentin expression in neuroparenchyma with severe inflammatory and necrotic changes, but GFAP expression was mild or absent in these cases. A microglial response was present only in severe lesions, and RCA-I expression was detected primarily in gitter cells and resting microglia. The present study indicates a strong astrocytic response, including the presence of many less differentiated vimentin-positive astrocytes and gitter cells positive for RCA-1 in severe lesions in the CNS of cats with FIP.

Clinical and laboratory features of cats with feline infectious peritonitis--a retrospective study of 231 confirmed cases (2000-2010).

The objectives of this study were to review signalment, clinical signs and laboratory features in a large number of naturally occurring cases of feline infectious peritonitis (FIP), and to evaluate potential changes in diagnostic criteria for FIP and compare findings in cats with and without effusion. The medical records of 231 cats with confirmed FIP that presented to the Clinic of Small Animal Medicine of the Ludwig-Maximilian University of Munich, Germany, were reviewed for signalment, history, and clinical and laboratory parameters. Age, sex and breed distribution of the cats were compared with the clinic population. Male sex and young age were significantly correlated with FIP. Neutering status was not associated with FIP. No breed predisposition was observed and the majority of cats presented were domestic shorthair and mixed breed. Microcytosis of peripheral erythrocytes was found in 35.1% of cats, of which 42.4% did not have concurrent anaemia. Band neutrophilia was documented in 44.3% (81/183), of which 35.8% did not have mature neutrophilia. Lymphopenia, observed significantly more often with effusion, was documented in only 26.8% of cats without effusion. Hyperbilirubinaemia also occurred significantly more often in cats with vs without effusion. While serum total protein was increased in only 17.5% of cats, hyperglobulinaemia was documented in 89.1%. Nearly 85.0% of cats had an albumin-to-globulin (A:G) ratio <0.8, while 67.8% had an A:G ratio <0.6. Microcytosis was common and can increase suspicion of FIP in the presence of other typical clinical and laboratory abnormalities. The low prevalence of lymphopenia in cats without effusion suggests that this is not a useful parameter in non-effusive FIP. The frequent occurrence of a left shift in the absence of a mature neutrophilia complicates the differentiation of effusive FIP and septic peritonitis. Globulins and A:G ratio were of higher diagnostic value than hyperproteinaemia.