Prevalence and risk factors for gingivitis in a cohort of UK companion cats aged up to 6 years.

OBJECTIVES: Prospectively collected data were used to estimate the prevalence of gingivitis in a cohort of companion cats aged up to 6 years and to investigate factors associated with the risk of gingivitis in cats aged 3 to 4 years. MATERIALS AND METHODS: Data were obtained from a longitudinal study of domestic cats (the Bristol Cats Study), using owner-completed questionnaires and veterinary surgeon-completed oral health scores. Prevalence estimates of veterinary-reported gingivitis for cats aged up to 6 years old (n = 1534) were calculated for different age groups. Cat signalment, diet and dental care were assessed for association with gingivitis in cats aged 3 to 4 years (n = 317) using univariable and multiple logistic regression. RESULTS: The prevalence of gingivitis increased with age and ranged from 24.5% (<12 months old) to 56.3% (5 to 6 years old). Odds of gingivitis in cats aged 3 to 4 years were higher in cats fed a wet only or mixed wet/dry diet compared to dry only (odds ratio: 2.7; 95% confidence interval: 1.4 to 5.1), cats not reported to hunt compared to reported hunters (odds ratio: 2.1; 95% confidence interval: 1.0 to 4.2), cats reported to dribble whilst being stroked at age 6 months compared to reported non-dribblers (odds ratio: 3.2; 95% confidence interval: 1.3 to 8.4) and cats with orange variants in their coat colour compared to non-orange cats (odds ratio: 2.3; 95% confidence interval: 1.0 to 5.3). CLINICAL SIGNIFICANCE: These results will help veterinary surgeons identify cats that may be at a greater risk of gingivitis and provide an evidence base to inform dietary and oral healthcare recommendations aimed at promoting gingival health in cats.

Early-life risk factors identified for owner-reported feline overweight and obesity at around two years of age.

Obesity is considered the second most common health problem in pet cats in developed countries. This study used prospective data from a longitudinal study of pet cats ('C.L.A.W.S.', www.bristol.ac.uk/vetscience/claws) to identify early-life risk factors for feline overweight/obesity occurring at around two years of age. Data were collected via five owner-completed questionnaires (for cats aged two-six months, six months, 12 months, 18 months and two years respectively) completed between May 2011 and April 2015. Owner-reported body condition scores (BCS) of cats at age two years, assessed using images from the 9-point BCS system (Laflamme, 1997), were categorised into a dichotomous variable: overweight/obese (BCS 6-9) and not overweight (BCS 1-5) and used as the dependent variable. Of the 375 cats with owner-reported BCS, 25.3% were overweight or obese at two years of age. Multivariable logistic regression models were built using stepwise forward-selection. To account for potential hierarchical clustering due to multi-cat households two-level random intercept models were considered but clustering had no impact on the analysis. Models were compared using Wald tests. Six factors were significantly associated with overweight/obesity at two years of age: being overweight or obese at one year of age (OR=10.6, 95%CI 4.4-25.3); owner belief that BCS 7 was the ideal weight (OR=33.2, 95%CI 8.5-129.4), or that BCS represented overweight cats but they would not be concerned if their cat were classified in this category (OR=2.7, 95%CI 1.2-6.2), at questionnaire five completion; vets advising owners that the cat should lose weight, or making no comment on their weight, between one and two years of age (OR=12.1, 95%CI 3.2-44.9 and OR=3.9, 95%CI 1.5-10.3 respectively); owners giving their cat treats when they "felt happy" with them at 18 months of age (OR=2.7, 95%CI 1.0 - 7.3); feeding ≥250g wet food daily between two and six months of age (OR=2.7, 95%CI 1.2-5.9), and feeding dry food as the only or major part (>50%) of the diet at two years of age (OR=2.1, 95%CI 1.0-4.2). These findings have the potential to reduce the current high prevalence of a widespread problem by informing preventive advice, and as such improving the health and welfare of pet cats.

Risk factors for road traffic accidents in cats up to age 12†months that were registered between 2010 and 2013 with the UK pet cat cohort ('Bristol Cats').

Road traffic accidents (RTAs) are a common cause of death and injury in domestic cats, and a concern to many owners. This study assessed potential risk factors for RTAs in cats up to 12 months of age within a UK cat cohort known as 'The Bristol Cats study'. Data were obtained from three questionnaires, completed by cat owners when their cats were approximately 8-16 weeks old, 6 months old and 12 months old. Information was gathered regarding environmental conditions, cat characteristics and owner management factors. Univariable and multivariable logistic regression models were used to assess associations between these factors and RTAs. Of 1264 eligible study cats, 49 (3.9 per cent) had been involved in an RTA, of which 71.4 per cent (35/49) were known to result in fatal injuries. Rural locations were associated with a higher odds of RTAs than towns, cities or suburban locations. An increased odds of an RTA was also associated with cats that were reported by their owners to hunt at the roadside, as well as cats whose owners classified the road by their house as being a 'long straight section of road'. No significant associations were found between coat colour, breed, sex or neuter status and the odds of an RTA.

Assessing changes in the UK pet cat and dog populations: numbers and household ownership.

The main aim of this study was to replicate methodology used to estimate the size of the UK pet cat and dog populations in 2006 and the proportion of households owning cats/dogs in 2007, to produce updated data to compare trends in ownership and population sizes. A cross-sectional study design was used to collect telephone interview data from 3155 households in the UK. 2011 UK human census data were used to predict the size of the cat and dog populations owned by households in the UK in 2011. Of the households, 23 per cent (714/3155) owned one or more cats and 30 per cent (940/3155) owned one or more dogs. There was some overlap in pet ownership with 7 per cent (210/3155) of households owning both one or more cats and one or more dogs. There was a small but significant decrease in the proportion of households that owned one or more cats in 2011 compared with 2007, with no change in the proportion owning dogs. However, overall, the total number of cats and dogs that were estimated to be owned by UK households did not change significantly between 2006 and 2011. The estimated size (and 95% CIs) of the pet cat and dog populations in the UK in 2011 was 10,114,764 cats (9,138,603-11,090,924) and 11,599,824 dogs (10,708,070-12,491,578).

Poor owner knowledge of feline reproduction contributes to the high proportion of accidental litters born to UK pet cats.

'Accidental' litters contribute to population growth and the number of unwanted animals entering animal welfare organisations. Assessing the problem's extent and determining risk factors enables identification of education targets. Data were obtained from 715 cat-owning households in a cross-sectional telephone survey. Demographic and lifestyle factors were assessed for their association with accidental litters and with owner knowledge of cat reproduction. A total of 128 litters were reported from 552 female cats, and the proportion of accidental litters reported by owners was 80 per cent. Multivariable analysis identified that respondents were more likely to report an accidental litter of kittens if they believed a female cat should have a litter prior to being neutered, if they had more than one cat and if they rented rather than owned their home. Misconceptions relating to cat reproduction were common. The opinion that the youngest age a cat could get pregnant was five months of age (or older) was held by 83.5 per cent of cat-owning respondents, with over a quarter (26.4 per cent; 174/659) believing a queen is unable to conceive until at least a year of age. Almost half the respondents (49.0 per cent; 334/682) believed a female cat should have a litter before being neutered or were not sure; 38.8 per cent (264/681) thought that un-neutered, related cats would not mate or were not sure. This study suggests that improving cat-owner knowledge of the reproductive capacity of cats is likely to have a significant impact on the numbers of accidental litters born.

Measurement of IL-12 (p40, p35), IL-23p19, and IFN-γ mRNA in duodenal biopsies of cats with inflammatory enteropathy.

BACKGROUND: Dietary hypersensitivity and inflammatory bowel disease (IBD) are important causes of chronic vomiting and diarrhea in cats. IL-23 has been recently found to be a key factor in the immunopathogenesis of IBD in humans but the involvement in IBD has not been investigated in cats. HYPOTHESIS/OBJECTIVES: Expression of genes encoding Il-12p35 and p40, IL-23p19, and IFN-γ may be up-regulated in duodenal biopsy specimens taken from cats with histologic evidence of inflammation. ANIMALS AND METHODS: Duodenal biopsy specimens were collected from control cats (n = 21) and cats with inflammatory enteropathy (n = 13). Routine histopathology, immunohistochemistry (IHC), and qRT-PCR were used to assess expression of MHC class II and to measure gene transcripts encoding the p35, p40, and p19 subunits of the IL-12 family of cytokines and IFN-γ. RESULTS: There were significant differences in expression of mRNA encoding IL-12p35 and IL-23p19 between healthy cats and cats with inflammatory enteropathy. IL-12p35 mRNA was lower in the duodenal mucosa of cats with inflammatory enteropathy compared with the mucosa of healthy cats (P = .001). In contrast, IL-23p19 mRNA expression was higher in duodenal biopsy specimens from cats with inflammatory enteropathy than in those from healthy controls (P = .001). There was no difference in expression of IL-12p40 and IFN-γ mRNA (P > .05). The majority of cats with inflammatory enteropathy had histologic evidence of moderate to severe colitis (score 2). CONCLUSIONS AND CLINICAL IMPORTANCE: The results of this preliminary study suggest that IL-23 plays a role in the pathogenesis of feline inflammatory enteropathy.

The neuter status of cats at four and six months of age is strongly associated with the owners' intended age of neutering.

The recommended neutering age of client-owned cats reduced recently from six to four months of age. This study assessed the proportion of cats neutered at these ages. Data were obtained from owner-completed questionnaires at recruitment (8-16-week-old kittens) and 6.5-7 months of age. Demographic and lifestyle factors were assessed for potential association with neuter status using univariable and multivariable logistic regression models. Of 751 study cats, 14.1 per cent and 73.5 per cent had been neutered at (or before) four and six months of age, respectively. Multivariable analysis showed that being neutered at four months was significantly more likely for cats whose owners intended to have their cat neutered by this age, cats with a microchip, and from households in deprived regions. The likelihood of being neutered at six months of age was significantly increased for cats that were insured, obtained from an animal welfare organisation, given their second vaccination, from a household with an annual income of ≥£10 000, and owned by people intending to have their cat neutered by this age. This study suggests that while neutering rates were high at six months of age, they were low at four months of age, and that further work is required to disseminate the recommended neutering age of four months.

Phylogenetic analysis of feline coronavirus strains in an epizootic outbreak of feline infectious peritonitis.

BACKGROUND: Feline coronavirus (FCoV) infection is common. In a small percentage of cats, FCoV infection is associated with the fatal disease feline infectious peritonitis (FIP). Genetically distinct virulent and avirulent strains of FCoV might coexist within a cat population. OBJECTIVES: To determine whether the strains of FCoV in FIP-affected cats are closely related or genetically distinct from the fecally derived strains of FCoV in contemporary-asymptomatic cats during an epizootic outbreak of FIP. ANIMALS: Four cats euthanized because of FIP and 16 asymptomatic cats. METHODS: This prospective outbreak investigation was initiated during an outbreak of FIP in cats within or rehomed from a rescue/rehoming center. Postmortem samples were collected from cats with FIP and contemporaneous fecal samples from asymptomatic cats. RNA was purified from tissue and fecal samples, FCoV gene fragments were reverse transcribed, PCR-amplified using novel primers, and sequenced. Sequences were aligned with ClustalW and compared with published FCoV sequences. RESULTS: FCoV RNA was detected in all 4 FIP cat postmortem samples and in 9 of the 16 fecal samples from contemporary-asymptomatic cats. Novel primers successfully amplified fragments from 4 regions of the genome for all FCoV-positive samples. Phylogenetic analysis showed that the FIP-associated strains of FCoV from the outbreak were very closely related to the fecally derived strains of FCoV from contemporary-asymptomatic cats. CONCLUSIONS AND CLINICAL IMPORTANCE: Sequence analysis provided no evidence that genetically distinct virulent and avirulent strains of FCoV were present during this FIP outbreak.

Immunohistochemical characterization of oral mucosal lesions in cats with chronic gingivostomatitis.

Histological and immunohistochemical studies were performed on samples of the glossopalatine mucosa from 30 cats with feline chronic gingivostomatitis (FCGS). Immunohistochemical labelling and computer-assisted morphometric analysis were used to identify expression of CD3, CD4, CD8, CD79a, IgG, IgM, IgA, leucocyte antigen 1 (L1) and class II molecules of the major histocompatibility complex (MHC) in tissue sections. Mast cells were detected by toluidine blue staining. The microscopical lesions were graded by severity of inflammation and although this grading correlated significantly with the severity of mucosal inflammation assessed at clinical examination, sites assessed as clinically normal or mildly inflamed were poorly predictive of the histopathological grade in the corresponding tissue sample. The number of CD79a+ cells (mostly plasma cells), L1+ cells (mostly neutrophils) and CD3+ T cells, and the level of MHC class II expression, tended to correlate with the severity of the inflammation. In general, CD8+ T cells were more numerous than CD4+ T cells. The majority of the plasma cells were of the IgG isotype and fewer IgA+ and IgM+ plasma cells were present. In some cases MHC class II expression by mucosal epithelium, salivary duct epithelium or skeletal muscle fibres was observed. Relative to equivalent oral mucosal samples from healthy cats, the number of cells labelled for CD3, CD4, CD8, CD79a, IgG, IgM, IgA or L1, and the number of mast cells, within the lamina propria/submucosa were significantly increased. Limited analysis of the epithelial compartment also found more CD3+ T cells compared with healthy cats. These findings indicate that the glossopalatine mucosal lesions in FCGS represent a complex, chronic and destructive inflammatory process affecting the epithelium and lamina propria, with frequent extension into submucosal tissues. The predominance of CD8+ cells over CD4+ cells suggests the induction of an underlying cytotoxic cell-mediated immune response, which could be consistent with a viral aetiology.

Number and ownership profiles of cats and dogs in the UK.

A random sample of 2980 households in the UK in 2007 showed that 26 per cent and 31 per cent of households owned cats and dogs, respectively. Households with gardens were more likely to own cats and dogs than households without gardens. Households in which someone was qualified to degree level were more likely to own cats and less likely to own dogs than other households. Cats were more likely to be owned by semi-urban/rural households and by female respondents. Dog ownership significantly decreased the likelihood of cat ownership, and respondents aged 65 years or more were less likely to report that their household owned a cat than younger respondents. Households with one or more dogs and children aged 11 to 15 years were more likely to own a cat than other households. The likelihood of dog ownership increased as household size increased. Dogs were more likely to be owned by rural households, and less likely to be owned by households with cats or children aged 10 years or younger. Female respondents and those aged less than 55 years were more likely to report dog ownership than other respondents. The estimated size (and 95 per cent confidence intervals) of the owned cat and dog populations in the UK in 2006 was 10,332,955 (9,395,642 to 11,270,269) cats and 10,522,186 (9,623,618 to 11,420,755) dogs.

Survey of the characteristics of cats owned by households in the UK and factors affecting their neutered status.

Data were collected on 1260 cats owned by a random sample of UK households in 2007, by means of telephone questionnaires, which were completed by 33 per cent of the households contacted. Cats were owned by 26 per cent of these households, 42 per cent of which owned more than one cat. The owners of 622 female cats reported a total of 110 unplanned litters of kittens. Excluding cats with an unknown neutered status 92 per cent of the cats aged six months or more were neutered, but only 66 per cent of the cats aged six to 12 months were neutered. Multivariable logistic regression, based on data collected for one randomly selected cat aged four months or more in each cat-owning household, was used to identify factors affecting the cats' neutered status. Analysis of 48 sexually entire cats and 501 neutered cats showed that cats aged 10 months or more, with indoor access, that had been vaccinated within the last year or were currently registered with a veterinary practice, were more likely to be neutered than cats aged less than 10 months, without indoor access, that had been vaccinated more than one year ago or were not registered with a veterinary practice.

Opinions of veterinarians about the age at which kittens should be neutered.

The mean age recommended by veterinary practices for neutering kittens is 22.6 weeks, with only 28 per cent of veterinarians considering it appropriate to neuter 12- to 16-week-old kittens. Multivariable logistic regression was used to identify variables associated with veterinarians' opinion that 12 to 16 weeks is an appropriate age at which to neuter kittens. Significant risk factors included time since graduation, perception of the problem of there being too many unwanted domestic cats and their practice's policy on the recommended neutering age. Veterinarians who thought that neutering eight- to 11-week-old rescue kittens before homing was justified and veterinarians who had neutered 12- to 16-week-old domestic kittens within the previous year were more likely to consider that neutering 12- to 16-week-old kittens was appropriate. Veterinarians who thought that surgical complications, anaesthetic complications and lower urinary tract disease were, or might be, more likely to occur in kittens neutered at 12 to 16 weeks than in those neutered at six months of age, were significantly less likely to think that neutering 12- to 16-week-old kittens was appropriate.

Is feline foamy virus really apathogenic?

Feline foamy virus (FFV) is a retrovirus commonly found in cats. It is generally thought to be apathogenic, making it a suitable candidate as a gene therapy vector. However, there have been reports of association of FFV with chronic progressive arthritis and a cofactor effect with feline immunodeficiency virus. This study investigated experimental FFV infection and whether this was associated with signs of disease. Eight young specific pathogen free cats were inoculated intramuscularly with FFV. The cats were examined twice weekly and blood and pharyngeal samples were taken. Haematology, biochemistry and FFV quantitative polymerase chain reaction (qPCR) were performed. Tissue samples were also collected throughout the six month period. FFV was initially detected by qPCR in the blood within the first two weeks of infection and viraemia persisted throughout the study. Two peaks of viraemia were observed, at day 20 (80-170FFU/ml blood) and day 155 (332-415FFU/ml blood). FFV was also consistently detected in oropharyngeal samples after day 36. Anti-FFV IgG was detected in all cats by ELISA; antibody levels had an early peak around day 35 and then increased again following the second rise in circulating viral load. All cats remained clinically normal, except for one cat with an unrelated gingivitis. None of the cats developed pyrexia. The biochemical profile and blood cell counts remained within normal limits except for one cat with a persistent eosinophilia. Initial fluctuations in white cell counts settled within three weeks and did not deviate outside of the normal ranges. All tissue samples contained FFV DNA; lymphoreticular tissues, salivary gland and lung had the highest viral loads. Although there were no gross pathological lesions on post mortem examination, histologically a mild glomerulonephritis and a moderate interstitial pneumonia were observed in all cats. We conclude that during the six month period of infection, although cats appeared clinically normal, histopathological changes were observed in the lungs and kidneys. Further investigation of the significance of these changes is warranted before FFV is developed as a vector for gene delivery.

A kinetic study of histopathological changes in the subcutis of cats injected with non-adjuvanted and adjuvanted multi-component vaccines.

The aim of this study was to investigate the subcutaneous tissue response to administration of a single dose of multi-component vaccine in the cat. Three groups of 15 cats were injected with one of three vaccine products with saline as a negative control. Cats in group A received non-adjuvanted vaccine; cats in group B received vaccine with a lipid-based adjuvant; whilst those in group C were vaccinated with a product adjuvanted with an alum-Quil A mixture. The vaccine and saline injection sites were sampled on days 7, 21 and 62 post-vaccination. Biopsies of these vaccine sites were examined qualitatively and scored semi-quantitatively for a series of parameters related to aspects of the inflammatory and tissue repair responses. These data were analysed statistically, including by principal component analysis. At all three time points of the experiment, there was significantly less inflammation associated with administration of non-adjuvanted vaccine (p=0.000). Although there was evidence of tissue repair by day 62 in all groups, those cats receiving adjuvanted vaccines had evidence of residual adjuvant material accumulated within macrophages at this late time point. The severity of tissue reactions may vary significantly in response to vaccines which include adjuvants or are non-adjuvanted.

Measurement of cytokine mRNA expression in intestinal biopsies of cats with inflammatory enteropathy using quantitative real-time RT-PCR.

Inflammatory bowel disease (IBD) is a common condition in cats characterised by infiltration of inflammatory cells into the intestinal mucosa. In this study, real-time reverse transcriptase polymerase chain reaction (RT-PCR) was used to quantify cytokine messenger RNA (mRNA) expression in intestinal biopsies from cats. Biopsies were collected from seven cats with chronic diarrhoea and histologically confirmed IBD, five cats with chronic diarrhoea due to non-IBD gastrointestinal (GI) disease, and nine clinically normal cats with or without subclinical inflammatory changes in small intestine. Real-time RT-PCR was developed for quantification of mRNA encoding interleukin (IL)-2, IL-4, IL-5, IL-6, IL-10, IL-12 (p35 and p40), IL-18, tumour necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma) and transforming growth factor-beta (TGF-beta). Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was used as a 'housekeeper' gene. All real-time PCR efficiencies were>90% (range 90.4-102%) with correlation coefficients >0.99 (range 0.998-1). The results of the study were analyzed on the basis of either clinical presentation or histopathological evidence of intestinal inflammation. The former analysis showed that mRNA encoding IL-10 and TGF-beta (immunoregulatory cytokines), and IL-6, IL-18, TNF-alpha and IL-12 p40 (Th1 and pro-inflammatory cytokines) was significantly higher in clinically normal cats and cats with IBD when compared to cats with other GI diseases. IL-5 mRNA was significantly higher in cats with IBD compared to clinically normal cats. IL-2 mRNA was significantly lower in cats with non-IBD GI disease than in clinically normal cats. Analysis on the basis of histopathological change revealed that cats with intestinal inflammation had significantly more transcription of genes encoding IL-6, IL-10, IL-12p40, TNF-alpha and TGF-beta than those with normal intestinal morphology. The results suggest that immune dysregulation plays a role in feline IBD and that IBD in cats has a complicated pathogenesis with both pro-inflammatory and immunoregulatory features.

Immunohistochemical diagnosis of alimentary lymphomas and severe intestinal inflammation in cats.

Intestinal tissue samples were examined from 32 cats in which a histopathological diagnosis of alimentary lymphoma or multicentric lymphoma affecting the gastrointestinal tract had been made. These samples were re-evaluated histopathologically and serial sections were examined immunohistochemically with antisera specific for the lymphoid markers CD3, CD79a and BLA-36 and for class II molecules of the major histocompatability complex. The cats ranged in age from 4-16 years (median 10.5 years). The main presenting clinical signs were vomiting, diarrhoea and weight loss. The majority of alimentary lymphomas were of the B-cell type (n=15), whereas cases of T-cell lymphoma were fewer in number (n=8). Four cats had lymphoma of a mixed T-and B-cell phenotype. In five of the cats, immunohistochemistry suggested an inflammatory process, in contradiction to the original histopathological diagnosis of lymphoma. Immunolabelling would appear to be a useful adjunct to histopathology in classifying cases of feline alimentary lymphoma, and may help in distinguishing lymphoma from severe intestinal inflammation.

Preliminary study using an indirect ELISA for the detection of serum antibodies to Alternaria in domestic cats.

Alternaria is a saprophytic fungus that is widespread in the environment; it is an opportunistic pathogen and causes disease in human beings and domestic animals. Fungal spores gain entry to the host through skin lesions and cause slow-growing, soft to firm, subcutaneous swellings, either with or without ulcers. An indirect ELISA was developed for the detection of anti-Alternaria immunoglobulin G (IgG) antibodies in serum to determine the prevalence of Alternaria exposure in domestic cats. Fifty-two of 63 cats had detectable levels of anti-Alternaria IgG antibody. There were no correlations between the concentration of antibody and the sex, breed or living environment of the cats, but cats less than two years of age had significantly lower concentrations than older cats. The cats with disease caused by culture-confirmed Alternaria infections did not have significantly higher concentrations of antibody than the healthy cats or cats with other diseases.

Diagnosis of feline haemoplasma infection in Australian cats using a real-time PCR assay.

A total of 147 cats from the Sydney area of Australia that had blood samples submitted to veterinary laboratories were tested using a real-time polymerase chain reaction (PCR) assay able to detect and distinguish the two feline haemoplasma species. This sample number included two cats diagnosed with feline haemoplasma infection by routine blood smear examination. Statistical analysis was performed to evaluate associations between haemoplasma infection, age, sex, breed, haematocrit (HCT) values and anaemia status. One hundred and six cats (72.1%) were negative. Thirty-four cats (23.1%) were positive for 'Candidatus M. haemominutum', six cats (4.1%) were positive for M. haemofelis and one cat (0.7%) was positive for both species. Older, male, non-pedigree cats, with lower HCT values were more likely to be infected with 'Candidatus M. haemominutum'. Significant inverse correlation was found between the amount of M. haemofelis DNA present in the blood and the HCT value. This report documents the existence of, and prevalence of, both haemoplasma species in a sample of cats in Australia and is the first to use quantitative real-time PCR in a prevalence study for haemoplasma infection.

A retrospective study of 286 cases of neurological disorders of the cat.

Archive central nervous tissue from 286 cats with neurological disorders was reviewed for histological evidence of feline spongiform encephalopathy (FSE), which may have occurred before it was first recognized in 1990. The following six categories of disease were identified: congenital; degenerative; inflammatory; neoplastic; FSE; lesion-free. The largest category (inflammatory) contained 92 cats, of which 47 were considered to be consistent with infection by feline infectious peritonitis (FIP) virus. Six cats showed evidence of more than one disease process; thus, one cat with FIP also had toxocara infection of the lateral ventricles and five cats with FSE also showed perivascular cuffing suggestive of concurrent viral infection. In only two cases did the diagnosis on review differ significantly from the original interpretation. There was no evidence of FSE before the original case was recognized in April 1990.