Risk factors for feline infectious peritonitis in Australian cats

Molecular epidemiology and risk analysis for asymptomatic infection with feline enteric coronavirus in domestic and stray cats in Japan

Feline enteric coronavirus (FECoV) causes subclinical infection; therefore, asymptomatic cats can act as transmitters of FECoV. However, there have been few studies on the prevalence of FECoV in asymptomatic cats in Japan. In this study, we used a nested RT-PCR assay targeting the S gene of FECoV to test 319 normal fecal samples from stray cats and domestic cats in Japan between 2019 and 2020. Seventy-five samples tested positive, and the presence of FECoV in domestic cats was significantly associated with age (p < 0.01), but not with gender, breed, or living in a multi-cat household. The results provide insights into the current prevalence of FECoV in asymptomatic cats in Japan.

Prevalence and Risk Factors Associated with Feline Infectious Peritonitis (FIP) in Mainland China between 2008 and 2023: A Systematic Review and Meta-Analysis

To evaluate the overall prevalence of FIP infection in cats in mainland China and associated risk factors, studies on the prevalence of FIP conducted from 1 January 2008 to 20 December 2023 were retrieved from five databases-CNKI, Wanfang, PubMed, Web of Science, and ScienceDirect-and comprehensively reviewed. The 21 studies selected, with a total of 181,014 samples, underwent a rigorous meta-analysis after quality assessment. The results revealed a 2% prevalence of FIP (95% CI: 1-2%) through the random-effects model, showing considerable heterogeneity (I2 = 95.2%). The subsequent subgroup analysis revealed that the age and gender of cats are significant risk factors for FIP infection in mainland China. In order to effectively reduce and control the prevalence of FIP on the Chinese mainland, we suggest improving the immunity of cats, with special attention given to health management in kittens and intact cats, and continuously monitoring FIPV.

Pathological findings and patterns of feline infectious peritonitis in the respiratory tract of cats

Feline infectious peritonitis (FIP) is an important cause of death in cats. Thoracic manifestations are less common than abdominal manifestations, and FIP-associated respiratory disease is poorly documented. This study aimed to investigate pathological findings in the respiratory tract of cats with FIP and the occurrence and distribution of feline coronavirus antigen in the respiratory tract using immunohistochemistry. A retrospective study was carried out on 112 cats with FIP, of which 66 had inflammatory histological lesions in the respiratory tract (58.9%) and were included in this study. Three major gross patterns were defined: marked fibrin deposition in the thoracic cavity with lung atelectasis; marked fibrin deposition in the thoracic cavity with lung pyogranulomas; and lung pyogranulomas without thoracic effusion. Histological analysis revealed primary lesions in the visceral pleura and lung parenchyma at a similar frequency, with multifocal to diffuse presentations. Marked lesions were commonly observed. Five major histological patterns were defined: pleuritis; pleuritis and vasculitis/perivascular injury in the lung parenchyma; pleuritis and pneumonia; perivascular injury in the parenchyma without pleuritis; and pneumonia without pleuritis. In the pleura and pulmonary parenchyma, FIP virus antigen was detected in perivascular and peribronchial macrophages and in macrophages within bronchial-associated lymphoid tissue and foci of necrosis and inflammation in the pleura and lung parenchyma. Co-infections with retroviruses were detected in 47 cats (71.2%), mainly with feline leukemia virus (62.2%). Although FIP is a systemic disease, some cats developed significant lesions in the thoracic cavity, including involvement of the upper respiratory tract and presenting respiratory signs, without other classic signs of FIP. This work advances our knowledge of FIP in the respiratory system, helping veterinarians to recognize the various presentations of this disease.

Retrospective study and outcome of 307 cats with feline infectious peritonitis treated with legally sourced veterinary compounded preparations of remdesivir and GS-441524 (2020-2022)

OBJECTIVES

Feline infectious peritonitis (FIP) is a serious disease that arises due to feline coronavirus infection. The nucleoside analogues remdesivir and GS-441524 can be effective in its treatment, but most studies have used unregulated products of unknown composition. The aim of the present study was to describe the treatment of FIP using legally sourced veterinary-prescribed regulated veterinary compounded products containing known amounts of remdesivir (injectable) or GS-441524 (oral tablets).

METHODS

Cats were recruited via email advice services, product sales contacts and study publicity. Cats were excluded if they were deemed unlikely to have FIP, were not treated exclusively with the veterinary compounded products, or if there was a lack of cat and/or treatment (including response) data. Extensive cat and treatment data were collected.

RESULTS

Among the 307 cats recruited, the predominant type of FIP was most commonly abdominal effusive (49.5%) and then neurological (14.3%). Three treatment protocols were used; remdesivir alone (33.9%), remdesivir followed by GS-441524 (55.7%) and GS-441524 alone (10.4%). The median (range) initial treatment period duration and longest follow-up time point after starting treatment were 84 (1-330) days and 248 (1-814) days, respectively. The most common side effect was injection pain (in 47.8% of those given subcutaneous remdesivir). Of the 307 cats, 33 (10.8%) relapsed, 15 (45.5%) during and 18 (54.5%) after the initial treatment period. At the longest follow-up time point after completion of the initial treatment period, 84.4% of cats were alive. The cats achieving a complete response within 30 days of starting treatment were significantly more likely to be alive at the end of the initial treatment period than those cats that did not.

CONCLUSIONS AND RELEVANCE

Legally sourced remdesivir and GS-441524 products, either alone or used sequentially, were very effective in the treatment of FIP in this group of cats. Variable protocols precluded statistical comparison of treatment regimens.

Outcomes of treatment of cats with feline infectious peritonitis using parenterally administered remdesivir, with or without transition to orally administered GS-441524

BACKGROUND

Nucleoside analog GS-441524 is effective in treating cats with feline infectious peritonitis (FIP). Investigation into the use of parent nucleotide analog remdesivir (GS-5734) is needed.

OBJECTIVES

To assess efficacy and tolerability of remdesivir with or without transition to GS-441524 in cats with FIP and document clinical and clinicopathologic progression over 6 months.

ANIMALS

Twenty-eight client-owned cats with FIP.

METHODS

Cats were prospectively recruited between May 2021 and May 2022. An induction dosage of remdesivir 10 to 15 mg/kg intravenously or subcutaneously q24h was utilized for 4 doses, with a maintenance dosage of remdesivir (6-15 mg/kg SC) or GS-441524 (10-15 mg/kg per os) every 24 hours continued for at least 84 days. Laboratory testing, veterinary, and owner assessments were recorded.

RESULTS

Twenty-four cats survived to 6 months (86%). Three cats died within 48 hours. Excluding these, survival from 48 hours to 6 months was 96% (24/25). Remission was achieved by day 84 in 56% (14/25). Three cats required secondary treatment for re-emergent FIP. Remission was achieved in all 3 after higher dosing (15-20 mg/kg). Adverse reactions were occasional site discomfort and skin irritation with remdesivir injection. Markers of treatment success included resolution of pyrexia, effusions, and presenting signs of FIP in the first half of treatment and normalization of globulin concentration, and continued body weight gains in the latter half of the treatment period.

CONCLUSIONS AND CLINICAL IMPORTANCE

Parenteral administration of remdesivir and oral administration of GS-441524 are effective and well-tolerated treatments for FIP. Early emphasis on clinical, and later emphasis on clinicopathologic response, appears prudent when monitoring treatment efficacy.

Feline Infectious Peritonitis: European Advisory Board on Cat Diseases Guidelines

Feline coronavirus (FCoV) is a ubiquitous RNA virus of cats, which is transmitted faeco-orally. In these guidelines, the European Advisory Board on Cat Diseases (ABCD) presents a comprehensive review of feline infectious peritonitis (FIP). FCoV is primarily an enteric virus and most infections do not cause clinical signs, or result in only enteritis, but a small proportion of FCoV-infected cats develop FIP. The pathology in FIP comprises a perivascular phlebitis that can affect any organ. Cats under two years old are most frequently affected by FIP. Most cats present with fever, anorexia, and weight loss; many have effusions, and some have ocular and/or neurological signs. Making a diagnosis is complex and ABCD FIP Diagnostic Approach Tools are available to aid veterinarians. Sampling an effusion, when present, for cytology, biochemistry, and FCoV RNA or FCoV antigen detection is very useful diagnostically. In the absence of an effusion, fine-needle aspirates from affected organs for cytology and FCoV RNA or FCoV antigen detection are helpful. Definitive diagnosis usually requires histopathology with FCoV antigen detection. Antiviral treatments now enable recovery in many cases from this previously fatal disease; nucleoside analogues (e.g., oral GS-441524) are very effective, although they are not available in all countries.

Patterns of Feline Coronavirus Shedding and Associated Factors in Cats from Breeding Catteries

(1) Background: In households in which feline coronavirus (FCoV) is present, three patterns of FCoV shedding are described: non-shedders, intermittent (low-intensity) shedders, or persistent (high-intensity) shedders. It was the aim of this study to describe FCoV shedding patterns in cats from catteries in which FCoV infection is endemic. Additionally, risk factors for high-intensity FCoV shedding or non-shedding were analyzed. (2) Methods: Four fecal samples of 222 purebred cats from 37 breeding catteries were examined for FCoV RNA by quantitative reverse transcription polymerase chain reaction (RT-qPCR). High-intensity shedders were defined as cats positive for FCoV RNA in at least 3/4 fecal samples; non-shedding cats were defined as cats negative in all four fecal samples. Risk factor analysis was performed using information obtained by questionnaire. (3) Results: Of the 222 cats, 125 (56.3%) were considered high-intensity shedders, while 54/222 cats (24.3%) were FCoV non-shedders. The Persian breed was associated with a higher risk of high-intensity shedding in multivariable analysis, while Birman and Norwegian Forest Cats were more likely to be FCoV non-shedders. Cats living together with other cats were more likely to be FCoV shedders. (4) Conclusions: The proportion of both high-intensity shedders and non-shedding cats was higher than previously reported, which possibly can be explained by housing conditions, different genetic susceptibility, or differences in the study period. The risk of high-intensity shedding is higher in certain breeds. However, it cannot be excluded that the individual hygiene procedure of each breeder influenced FCoV-shedding frequency. A smaller group size is a protective factor against FCoV shedding.

An updated review of feline coronavirus: mind the two biotypes

Feline coronavirus (FCoV) includes two biotypes: feline infectious peritonitis virus (FIPV) and feline enteric coronavirus (FECV). Although both biotypes can infect cats, their pathogenicities differ. The FIPV biotype is more virulent than the FECV biotype and can cause peritonitis or even death in cats, while most FECV biotypes do not cause lesions. Even pathogenic strains of the FECV biotype can cause only mild enteritis because of their very low virulence. This article reviews recent progress in FCoV research with regard to FCoV etiological characteristics; epidemiology; clinical symptoms and pathological changes; pathogenesis; and current diagnosis, prevention and treatment methods. It is hoped that this review will provide a reference for further research on FCoV and other coronaviruses.

Serological Investigation on the Presence of Feline Coronavirus (FCoV) and Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in Domestic Cats Living with COVID-19 Positive Owners in the UAE, 2022

Feline coronavirus (FCoV) is widely circulating among domestic cats (Felis catus). The zoonotic origin of the emerged severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and the biological characteristics of CoVs, including the ability to cross interspecies barriers, facilitate its emergence in different animals, including cats' populations. The current study is the first to report the serological investigation on the presence of FCoV and SARS-CoV-2 in domestic cats living with COVID-19-positive owners in the UAE. A total of 83 sera were collected from domestic cats living with COVID-19-positive owners (by RT-qPCR). The cats were sampled during the period between February and May 2022 in Al-Ain and Abu Dhabi Cities, UAE. Detection of FCoV and SARS-CoV-2 was carried out by enzyme-linked immunosorbent assay (ELISA). FCoV antibodies were detected in 54 samples (65%). The frequencies of FCoV were significantly higher in purebred cats (48%; 40/83) and in the cat group with outdoor access (49.4%; 41/83). SARS-CoV-2 seroprevalence in collected sera revealed 8 samples (9.6%) with positive results. Four samples (4.8%) showed positive results for both FCoV and SARS-CoV-2 antibodies. In conclusion, FCoV is widely circulating within cats' populations involved in the study. The antibodies for SARS-CoV-2 were detected in cats' populations but at a low prevalence rate. COVID-19-positive people should avoid close contact with their cats. Future serological testing of large cats' populations is crucial for providing a good understanding of COVID-19 dynamics in cats.

Life expectancy tables for dogs and cats derived from clinical data

There are few recent and methodologically robust life expectancy (LE) tables for dogs or cats. This study aimed to generate LE tables for these species with clinical records from >1,000 Banfield Pet hospitals in the USA. Using Sullivan's method, LE tables were generated across survey years 2013-2019, by survey year, and for subpopulations defined by sex, adult body size group (purebred dogs only: toy, small, medium, large and giant), and median body condition score (BCS) over life. The deceased population for each survey year comprised animals with a recorded date of death in that year; survivors had no death date in that year and were confirmed living by a veterinary visit in a subsequent year. The dataset totaled 13,292,929 unique dogs and 2,390,078 unique cats. LE at birth (LE_birth) was 12.69 years (95% CI: 12.68-12.70) for all dogs, 12.71 years (12.67-12.76) for mixed-breed dogs, 11.18 years (11.16-11.20) for cats, and 11.12 (11.09-11.14) for mixed-breed cats. LE_birth increased with decreasing dog size group and increasing survey year 2013 to 2018 for all dog size groups and cats. Female dogs and cats had significantly higher LE_birth than males: 12.76 years (12.75-12.77) vs. 12.63 years (12.62-12.64), and 11.68 years (11.65-11.71) vs. 10.72 years (10.68-10.75), respectively. Obese dogs (BCS 5/5) had a significantly lower LE_birth [11.71 years (11.66-11.77)] than overweight dogs (BCS 4/5) [13.14 years (13.12-13.16)] and dogs with ideal BCS 3/5 [13.18 years (13.16-13.19)]. The LE_birth of cats with BCS 4/5 [13.67 years (13.62-13.71)] was significantly higher than cats with BCS 5/5 [12.56 years (12.45-12.66)] or BCS 3/5 [12.18 years (12.14-12.21)]. These LE tables provide valuable information for veterinarians and pet owners and a foundation for research hypotheses, as well as being a stepping-stone to disease-associated LE tables.

2022 AAFP/EveryCat Feline Infectious Peritonitis Diagnosis Guidelines

CLINICAL IMPORTANCE

Feline infectious peritonitis (FIP) is one of the most important infectious diseases and causes of death in cats; young cats less than 2 years of age are especially vulnerable. FIP is caused by a feline coronavirus (FCoV). It has been estimated that around 0.3% to 1.4% of feline deaths at veterinary institutions are caused by FIP.

SCOPE

This document has been developed by a Task Force of experts in feline clinical medicine as the 2022 AAFP/EveryCat Feline Infectious Peritonitis Diagnosis Guidelines to provide veterinarians with essential information to aid their ability to recognize cats presenting with FIP.

TESTING AND INTERPRETATION

Nearly every small animal veterinary practitioner will see cases. FIP can be challenging to diagnose owing to the lack of pathognomonic clinical signs or laboratory changes, especially when no effusion is present. A good understanding of each diagnostic test's sensitivity, specificity, predictive value, likelihood ratio and diagnostic accuracy is important when building a case for FIP. Before proceeding with any diagnostic test or commercial laboratory profile, the clinician should be able to answer the questions of 'why this test?' and 'what do the results mean?' Ultimately, the approach to diagnosing FIP must be tailored to the specific presentation of the individual cat.

RELEVANCE

Given that the disease is fatal when untreated, the ability to obtain a correct diagnosis is critical. The clinician must consider the individual patient's history, signalment and comprehensive physical examination findings when selecting diagnostic tests and sample types in order to build the index of suspicion 'brick by brick'. Research has demonstrated efficacy of new antivirals in FIP treatment, but these products are not legally available in many countries at this time. The Task Force encourages veterinarians to review the literature and stay informed on clinical trials and new drug approvals.

Feline breeding and pregnancy management: What is normal and when to intervene

Practical relevance:

Cats are common pets worldwide. Successful breeding of cats starts with the selection of suitable breeding animals, and care should be taken to avoid inbreeding. Keeping cats in smaller groups reduces stress and facilitates management.

Clinical challenges:

Breeding cats is challenging in many ways. Group housing is a common scenario, and care should be taken not to have groups that are too large, because of the risk of stress and infectious diseases. Feline pregnancy and parturition both vary in length, which is one reason why it may be challenging to diagnose dystocia. In queens with pyometra, a vaginal discharge may not be evident due to their meticulous cleaning habits.

Audience:

This review is aimed at clinicians in small animal practice, especially those in contact with cat breeders.

Patient group:

Reproductive emergencies occur in both intentionally and unintentionally bred cats, and more often in young or middle-aged queens. Pyometra tends to be a disease of older queens.

Evidence base:

Evidence is poor for many conditions in the breeding queen, and information is extrapolated from the dog or based on case reports and case series.

Molecular epidemiology of type I and II feline coronavirus from cats with suspected feline infectious peritonitis in China between 2019 and 2021

Feline infectious peritonitis (FIP) is one of the deadliest diseases of cats in China. In this study, 120 ascitic fluid samples from FIP-suspected cats were collected from veterinary hospitals in 21 provinces in China between 2019 and 2021. One hundred nine samples were positive for feline coronavirus (FCoV), with no feline immunodeficiency virus infections and one feline leukemia virus infection (1/109, 0.92%). The prevalence of FCoV was significantly associated with age (p < 0.01) and was not highly associated with gender, breed, geographical location, or viral coinfection (p > 0.01). One unique strain, SD/202012/003, contained a six-nucleotide deletion in the spike gene. Sequence analysis showed that 94.68% (89/94) of the isolates had a mutation of methionine to leucine at position 1058 in the spike protein. The epidemiological data obtained of FCoV in this study may be beneficial for clinical monitoring of FCoV in China.

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.

Comparative sequence analysis of the accessory and nucleocapsid genes of feline coronavirus strains isolated from cats diagnosed with effusive feline infectious peritonitis

Feline infectious peritonitis (FIP) is a lethal infectious disease of domestic cats caused by feline coronavirus (FCoV) infection. Feline infectious peritonitis virus (FIPV) is a mutant type of FCoV that is characterized by causing fibrinous serositis with effusions in the pleural and abdominal cavities (wet form) and/or granulomatous-necrotizing inflammatory lesions in several organs (dry form). There have been numerous studies on FIP worldwide, whereas information about this disease in Thailand is still limited. Most studies involving molecular surveillance and evaluation of FCoV field strains have examined the genetic diversity of the spike and accessory ORF3c coding regions. Of these, the S gene is more divergent and is responsible for the two FCoV serotypes, while ORF3c harbors mutations that result either in early termination or destruction of the protein. In this study, we investigated the genetic diversity and genetic relationships among the current Thai and global FCoV strains in the accessory and nucleocapsid genes using a virus-specific PCR method. Comparative sequence analysis suggested that the Thai FCoV isolates were most closely related to strains reported in the Netherlands, the USA, and China. In the ORF3ab sequences, some Thai strains were more than 99% identical to the DF-2 prototype strain. Truncation of the 3a gene product was found in Thai FCoV strains of group 2. Amino acid deletions were observed in the N, ORF3c, and ORF7b proteins of Thai FCoV sequences. The accessory gene sequence divergence may be responsible for driving the periodic emergence and continued persistence of FCoVs in Thai domestic cat populations. Our findings provide updated information about the molecular characteristics of the accessory and nucleocapsid genes of FCoV strains in circulation that were not previously documented in this country.

The Population Diversity of Candidate Genes for Resistance/Susceptibility to Coronavirus Infection in Domestic Cats: An Inter-Breed Comparison

Feline coronavirus (FCoV) is a complex pathogen causing feline infectious peritonitis (FIP). Host genetics represents a factor contributing to the pathogenesis of the disease. Differential susceptibility of various breeds to FIP was reported with controversial results. The objective of this study was to compare the genetic diversity of different breeds on a panel of candidate genes potentially affecting FCoV infection. One hundred thirteen cats of six breeds were genotyped on a panel of sixteen candidate genes. SNP allelic/haplotype frequencies were calculated; pairwise FST and molecular variance analyses were performed. Principal coordinate (PCoA) and STRUCTURE analyses were used to infer population structure. Interbreed differences in allele frequencies were observed. PCoA analysis performed for all genes of the panel indicated no population substructure. In contrast to the full marker set, PCoA of SNP markers associated with FCoV shedding (NCR1 and SLX4IP) showed three clusters containing only alleles associated with susceptibility to FCoV shedding, homozygotes and heterozygotes for the susceptibility alleles, and all three genotypes, respectively. Each cluster contained cats of multiple breeds. Three clusters of haplotypes were identified by PCoA, two clusters by STRUCTURE. Haplotypes of a single gene (SNX5) differed significantly between the PCoA clusters.

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.

Current status on treatment options for feline infectious peritonitis and SARS-CoV-2 positive cats

Feline infectious peritonitis (FIP) is a viral-induced, immune-mediated disease of cats caused by virulent biotypes of feline coronaviruses (FCoV), known as the feline infectious peritonitis virus (FIPV). Historically, three major pharmacological approaches have been employed to treat FIP: (1) immunomodulators to stimulate the patient’s immune system non-specifically to reduce the clinical effects of the virus through a robust immune response, (2) immunosuppressive agents to dampen clinical signs temporarily, and (3) re-purposed human antiviral drugs, all of which have been unsuccessful to date in providing reliable efficacious treatment options for FIPV. Recently, antiviral studies investigating the broad-spectrum coronavirus protease inhibitor, GC376, and the adenosine nucleoside analogue GS-441524, have resulted in increased survival rates and clinical cure in many patients. However, prescriber access to these antiviral therapies is currently problematic as they have not yet obtained registration for veterinary use. Consequently, FIP remains challenging to treat. The purpose of this review is to provide an update on the current status of therapeutics for FIP. Additionally, due to interest in coronaviruses resulting from the current human pandemic, this review provides information on domesticated cats identified as SARS-CoV-2 positive.

Coronavirus Infections in Companion Animals: Virology, Epidemiology, Clinical and Pathologic Features

Coronaviruses are enveloped RNA viruses capable of causing respiratory, enteric, or systemic diseases in a variety of mammalian hosts that vary in clinical severity from subclinical to fatal. The host range and tissue tropism are largely determined by the coronaviral spike protein, which initiates cellular infection by promoting fusion of the viral and host cell membranes. Companion animal coronaviruses responsible for causing enteric infection include feline enteric coronavirus, ferret enteric coronavirus, canine enteric coronavirus, equine coronavirus, and alpaca enteric coronavirus, while canine respiratory coronavirus and alpaca respiratory coronavirus result in respiratory infection. Ferret systemic coronavirus and feline infectious peritonitis virus, a mutated feline enteric coronavirus, can lead to lethal immuno-inflammatory systemic disease. Recent human viral pandemics, including severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS), and most recently, COVID-19, all thought to originate from bat coronaviruses, demonstrate the zoonotic potential of coronaviruses and their potential to have devastating impacts. A better understanding of the coronaviruses of companion animals, their capacity for cross-species transmission, and the sharing of genetic information may facilitate improved prevention and control strategies for future emerging zoonotic coronaviruses. This article reviews the clinical, epidemiologic, virologic, and pathologic characteristics of nine important coronaviruses of companion animals.

Detection of Feline Coronavirus in Feline Effusions by Immunofluorescence Staining and Reverse Transcription Polymerase Chain Reaction

Feline coronavirus (FCoV), the pathogen for feline infectious peritonitis, is a lethal infectious agent that can cause effusions in the pleural and abdominal cavities in domestic cats. To study the epidemiology of FCoV in Taiwan, 81 FIP-suspected sick cats with effusive specimens were recruited to test for FCoV infection using immunofluorescence staining and reverse transcription-polymerase chain reaction as detection methods, and viral RNAs were recovered from the specimens to conduct genotyping and phylogenetic analysis based on the spike (S) protein gene. The results revealed that a total of 47 (47/81, 58%) of the sick cats were positive for FCoV in the effusion samples, of which 39 were successfully sequenced and comprised of 21 type I strains, 9 type II strains, and 9 co-infections. The signalment analysis of these sick cats revealed that only the sex of cats showed a significant association (odds ratio = 2.74, 95% confidence interval = 1.06–7.07, p = 0.03) with the infection of FCoV, while age and breed showed no association. FCoV-positive cats demonstrated a significantly lower albumin to globulin ratio than negative individuals (p = 0.0004). The partial S gene-based phylogenetic analysis revealed that the type I strains demonstrated genetic diversity forming several clades, while the type II strains were more conserved. This study demonstrates the latest epidemiological status of FCoV infection in the northern part of Taiwan among sick cats and presents comparisons of Taiwan and other countries.

Assay validation and determination of in vitro binding of mefloquine to plasma proteins from clinically normal and FIP-affected cats

The antimalarial agent mefloquine is currently being investigated for its potential to inhibit feline coronavirus and feline calicivirus infections. A simple, high pressure liquid chromatography assay was developed to detect mefloquine plasma concentrations in feline plasma. The assay’s lower limit of quantification was 250 ng/mL. The mean ± standard deviation intra- and inter-day precision expressed as coefficients of variation were 6.83 ± 1.75 and 5.33 ± 1.37%, respectively, whereas intra- and inter-day accuracy expressed as a percentage of the bias were 11.40 ± 3.73 and 10.59 ± 3.88%, respectively. Accordingly, this validated assay should prove valuable for future in vivo clinical trials of mefloquine as an antiviral agent against feline coronavirus and feline calicivirus. However, the proportion of mefloquine binding to feline plasma proteins has not been reported. The proportion of drug bound to plasma protein binding is an important concept when developing drug dosing regimens. As cats with feline infectious peritonitis (FIP) demonstrate altered concentrations of plasma proteins, the proportion of mefloquine binding to plasma proteins in both clinically normal cats and FIP-affected cats was also investigated. An in vitro method using rapid equilibrium dialysis demonstrated that mefloquine was highly plasma protein bound in both populations (on average > 99%).

Evaluation of Interferon-Gamma Polymorphisms as a Risk Factor in Feline Infectious Peritonitis Development in Non-Pedigree Cats-A Large Cohort Study

Feline infectious peritonitis (FIP) is a common infectious cause of death in cats, with heritable host factors associated with altered risk of disease. To assess the role of feline interferon-gamma gene (fIFNG) variants in this risk, the allele frequencies of two single nucleotide polymorphisms (SNPs) (g.401 and g.408) were determined for non-pedigree cats either with confirmed FIP (n = 59) or from the general population (cats enrolled in a large lifetime longitudinal study; n = 264). DNA was extracted from buccal swabs or tissue samples. A pyrosequencing assay to characterize the fIFNG SNPs was designed, optimized and subsequently performed on all samples. Genotype and allele frequency were calculated for each population. Characterization of the target SNPs was possible for 56 of the cats with FIP and 263 of the cats from the general population. The SNPs were in complete linkage disequilibrium with each other. There was an association between FIP status and genotype (χ²; p = 0.028), with a reduced risk of developing FIP (χ²; p = 0.0077) associated with the genotype TT at both positions. These results indicate that, although fIFNG variants may be associated with altered risk of disease, the prevalence of individual variants within both populations limits application of their characterization to breeding purposes.

Positive attitudes towards feline obesity are strongly associated with ownership of obese cats

Overweight and obesity (O&O) is a risk factor for several health conditions and can result in a shorter lifespan for cats. The objectives of this study were to investigate (a) cat owners’ attitudes towards feline O&O and their associations with O&O in their cats; and (b) the risk factors for feline O&O and underweight, particularly those involving owner practice. An online survey comprising questions related to cat owners’ attitudes towards feline O&O, owner-reported body weight and body condition of their cat, and potential risk factors for feline O&O was conducted. Primarily targeting the Australian population, the survey attracted 1,390 valid responses. In response to ten attitude-related questions, more participants (percentage range among the ten questions: 39.1–76.6%) held a disapproving attitude towards feline O&O than a neutral (17.1–31.9%) or approving attitude (3.9–27.7%). A greater proportion of participants had a more disapproving attitude towards obesity than towards overweight. Cats belonging to owners with an approving attitude towards O&O were more likely to be overweight or obese than cats belonging to owners with a disapproving attitude towards O&O. The cats had particularly high odds of overweight or obesity if their owner agreed that ‘being chubby says that the cat has a quality life’ (OR: 3.75, 95% CI: 2.41–5.82) and ‘being fat says that the cat has a quality life’ (OR: 4.98, 95%CI: 2.79–8.91). This study revealed, for the first time, that begging for food was a risk factor for O&O in cats. Other important feline risk factors for O&O identified included being middle-aged, being mixed-breed, dry food as the major diet, the amount of feed not being quantified, and frequently spending time indoors. Being over 11 years, receiving no dry food and receiving measured amounts of feed were associated with an increased odds of underweight in cats. As specific attitudes often lead to certain behaviours, reducing approving attitudes towards feline O&O may potentially reduce the frequency of O&O and the risks of O&O-related disorders in cats.

The Role of Host Genetic Factors in Coronavirus Susceptibility: Review of Animal and Systematic Review of Human Literature

BACKGROUND

The recent SARS-CoV-2 pandemic raises many scientific and clinical questions. One set of questions involves host genetic factors that may affect disease susceptibility and pathogenesis. New work is emerging related to SARS-CoV-2; previous work has been conducted on other coronaviruses that affect different species.

OBJECTIVES

We aimed to review the literature on host genetic factors related to coronaviruses, with a systematic focus on human studies.

METHODS

We conducted a PubMed-based search and analysis for articles relevant to host genetic factors in coronavirus. We categorized articles, summarized themes related to animal studies, and extracted data from human studies for analyses.

RESULTS

We identified 1,187 articles of potential relevance. Forty-five studies were related to human host genetic factors related to coronavirus, of which 35 involved analysis of specific genes or loci; aside from one meta-analysis on respiratory infections, all were candidate-driven studies, typically investigating small number of research subjects and loci. Multiple significant loci were identified, including 16 related to susceptibility to coronavirus (of which 7 identified protective alleles), and 16 related to outcomes or clinical variables (of which 3 identified protective alleles). The types of cases and controls used varied considerably; four studies used traditional replication/validation cohorts. Of the other studies, 28 involved both human and non-human host genetic factors related to coronavirus, 174 involved study of non-human (animal) host genetic factors related to coronavirus, 584 involved study of non-genetic host factors related to coronavirus, including involving immunopathogenesis, 16 involved study of other pathogens (not coronavirus), 321 involved other studies of coronavirus, and 18 studies were assigned to the other categories and removed.

KEY FINDINGS

We have outlined key genes and loci from animal and human host genetic studies that may bear investigation in the nascent host genetic factor studies of COVID-19. Previous human studies to date have been limited by issues that may be less impactful on current endeavors, including relatively low numbers of eligible participants and limited availability of advanced genomic methods.

Evaluation of polymorphisms in inflammatory mediator and cellular adhesion genes as risk factors for feline infectious peritonitis

OBJECTIVES

Feline infectious peritonitis (FIP) is a high mortality infectious disease. Single nucleotide polymorphisms (SNPs) in the genes encoding interferon gamma (IFNG), tumour necrosis factor alpha (TNFA) and dendritic cell-specific intercellular adhesion molecule-grabbing non-integrin (DC-SIGN; CD209) have been associated with increased and decreased risk of developing FIP. This study was designed to determine whether these associations were present in a UK population of pedigree cats using samples from cats euthanased with a confirmed diagnosis (FIP, n = 22; non-FIP, n = 10) or clinically healthy cats over 11 years of age (n = 3).

METHODS

DNA was extracted from tissue (n = 32) or blood (n = 3) and PCR performed for regions of IFNG, TNFA and CD209. PCR amplicons were sequenced, each SNP genotype was determined, and genotype/allele frequency for each SNP and FIP status were compared.

RESULTS

No significant association was found between the genotype and FIP status for any SNP analysed. There was a trend for the heterozygous CT genotype at both IFNG g.401 and IFNG g.408 to be associated with FIP (P = 0.13), but this genotype was also found in a substantial proportion of non-FIP cats. There was also a trend for the heterozygous CT genotype at IFNG g.428 to be associated with FIP (P = 0.06), although most cats with FIP had the CC genotype at this locus. No associations were found between any allele at TNFA g.-421, CD209 g.1900, CD209 g.2276, CD209 g.2392 and CD209 g.2713 and FIP.

CONCLUSIONS AND RELEVANCE

The use of the IFNG, TNFA and CD209 SNPs described to predict the risk of FIP cannot currently be recommended.

Feline infectious peritonitis: answers to frequently asked questions concerning FIP and coronavirus

Feline infectious peritonitis (FIP) is caused by infection with feline coronavirus (FCoV), a highly infectious virus transmitted mostly indirectly, by sharing litter trays with a FCoV excretor, or by fomites. The majority of FCoV-infected cats remain healthy, with up to 12% developing FIP. While any age or breed of cat can develop FIP, FIP disproportionately affects pedigree kittens: most studies found that around 70% of FIP cases occurred in pure-bred cats under 2 years of age. In this paper, some questions about FCoV and FIP that are likely to be asked of, and by, a veterinary nurse will be addressed.

Breed-specific variations in the coding region of toll-like receptor 4 in the domestic cat

Specific point mutations in the human toll-like receptor 4 (TLR4) confer altered risk for diverse diseases including sepsis, aspergillosis and inflammatory bowel disease. Some of these TLR4 polymorphisms are racially specific. We hypothesised that feline TLR4 polymorphisms might underlie an observed increased risk to infectious and inflammatory diseases in some cat breeds. The aim of this study was to identify breed-specific variations in the coding region of feline TLR4 and to model the effect of mutations on protein structure and function in silico. The entire coding region of TLR4 was sequenced in 8 groups (7 pure-bred, 1 crossbred) of domestic cats (Felis catus) comprising 158 individuals. Twenty-two single nucleotide polymorphisms (SNPs) were identified in TLR4, with 16 located in the coding region (11 non-synonymous) and four in the 3′UTR. Comparison of breed specific allelic frequencies indicated that Burmese and British shorthairs most commonly differed from other breeds. In silico analyses to predict the impact of the 11 non-synonymous variants indicated a deleterious effect on protein structure for one SNP (c.869 G > A), which was not associated with a specific breed. Overall, findings from this study do not support a role of TLR4 dysfunction in breed-predispositions to infectious diseases in domestic cats in Australia.

Circulation and genetic diversity of Feline coronavirus type I and II from clinically healthy and FIP-suspected cats in China

Feline infectious peritonitis (FIP) is a fatal infectious disease of wild and domestic cats, and the occurrence of FIP is frequently reported in China. To trace the evolution of type I and II feline coronavirus in China, 115 samples of ascetic fluid from FIP-suspected cats and 54 fecal samples from clinically healthy cats were collected from veterinary hospitals in China. The presence of FCoV in the samples was detected by RT-PCR targeting the 6b gene. The results revealed that a total of 126 (74.6%, 126/169) samples were positive for FCoV: 75.7% (87/115) of the FIP-suspected samples were positive for FCoV, and 72.2% (39/54) of the clinically healthy samples were positive for FCoV. Of the 126 FCoV-positive samples, 95 partial S genes were successfully sequenced. The partial S gene-based genotyping indicated that type I FCoV and type II FCoV accounted for 95.8% (91/95) and 4.2% (4/95), respectively. The partial S gene-based phylogenetic analyses showed that the 91 type I FCoV strains exhibited genetic diversity; the four type II FCoV strains exhibited a close relationship with type II FCoV strains from Taiwan. Three type I FCoV strains, HLJ/HRB/2016/10, HLJ/HRB/2016/11 and HLJ/HRB/2016/13, formed one potential new clade in the nearly complete genome-based phylogenetic trees. Further analysis revealed that FCoV infection appeared to be significantly correlated with a multi-cat environment (p < 0.01) and with age (p < 0.01). The S gene of the three type I FCoV strains identified in China, BJ/2017/27, BJ/2018/22 and XM/2018/04, exhibited a six nucleotide deletion (C⁴⁰³⁵ AGCTC⁴⁰⁴⁰ ). Our data provide evidence that type I and type II FCoV strains co-circulate in the FIP-affected cats in China. Type I FCoV strains exhibited high prevalence and genetic diversity in both FIP-affected cats and clinically healthy cats, and a multi-cat environment and age (<6 months) were significantly associated with FCoV infection.

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 real-time reporting system of causes of death or reasons for euthanasia: A model for monitoring mortality in domesticated cats in Taiwan

A novel, real-time mortality recording system was designed to collect mortality data in companion animals from veterinary hospitals in Taiwan. This retrospective study aims to introduce the system, and to utilize the data collected for further investigation of the lifespan and mortality of the domesticated cat population stratified by demographic variables. Our data revealed that 1325 domesticated cats were acquired between 2012 and 2014. The median age of the study population was 8.0 years (IQR 3.0–13.0; range 0.0–22.7). Neutered and purebred cats lived longer. The most common causes of death were renal and urologic disorders, followed by neoplasia, infection, cardiovascular disorders, and trauma. Independent factors for common causes were surveyed. Advanced age and neutering was found to be associated with death due to renal and urologic disorders as well as with neoplasia. In contrast, younger age was found to be associated with death due to trauma and infection; being unneutered and living in the capital city were found to be associated with death due to trauma. Being male or purebred was found to be associated with death due to cardiovascular disorders.

Feline Coronaviruses: Pathogenesis of Feline Infectious Peritonitis

Feline infectious peritonitis (FIP) belongs to the few animal virus diseases in which, in the course of a generally harmless persistent infection, a virus acquires a small number of mutations that fundamentally change its pathogenicity, invariably resulting in a fatal outcome. The causative agent of this deadly disease, feline infectious peritonitis virus (FIPV), arises from feline enteric coronavirus (FECV). The review summarizes our current knowledge of the genome and proteome of feline coronaviruses (FCoVs), focusing on the viral surface (spike) protein S and the five accessory proteins. We also review the current classification of FCoVs into distinct serotypes and biotypes, cellular receptors of FCoVs and their presumed role in viral virulence, and discuss other aspects of FIPV-induced pathogenesis. Our current knowledge of genetic differences between FECVs and FIPVs has been mainly based on comparative sequence analyses that revealed “discriminatory” mutations that are present in FIPVs but not in FECVs. Most of these mutations result in amino acid substitutions in the S protein and these may have a critical role in the switch from FECV to FIPV. In most cases, the precise roles of these mutations in the molecular pathogenesis of FIP have not been tested experimentally in the natural host, mainly due to the lack of suitable experimental tools including genetically engineered virus mutants. We discuss the recent progress in the development of FCoV reverse genetics systems suitable to generate recombinant field viruses containing appropriate mutations for in vivo studies.

Health and Behavioral Survey of over 8000 Finnish Cats

A comprehensive feline health survey was conducted to reveal breed-specific inheritable diseases in Finnish pedigree cats for genetic research. Prevalence of 19 disease categories and 227 feline diseases were defined in a study population of 8175 cats belonging to 30 breeds. Dental and oral diseases, with a prevalence of 28%, and dental calculus and gingivitis (21 and 8%, respectively) were the most prevalent disease category and diseases among all cats and in most of the breeds. An exception was Korats, which were more often affected by the diseases of the respiratory tract (23%) and asthma (19%). Other prevalent disease categories affected various organ systems, such as the skin (12%), the urinary system (12%), the digestive tract (11%), eyes (10%), the musculoskeletal system (10%), and genitals of female cats (17%). Prevalent health or developmental issues included repetitive vomiting (4%), tail kink (4%), feline odontoclastic resorption lesion (4%), urinary tract infections (4%), as well as cesarean section (6%) and stillborn kittens (6%) among female cats. We found 57 breed-specific conditions by Fisher’s exact tests and logistic regression analyses, including 32 previously described and 19 new breed-specific diseases. The genetic defect has already been found in six of them: polycystic kidney disease, progressive retinal atrophy, hypertrophic cardiomyopathy, and three types of tail malformations. Behavioral profiling revealed breed-specific traits, such as an increased human avoidance in British Short and Longhairs and a higher level of aggression in Turkish vans. Our epidemiological study reveals the overall health profile in Finnish pure and mixed breed cats and identifies many breed-specific conditions without molecular identity for genetic research.

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

OBJECTIVES

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS AND RELEVANCE

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.

Natural resistance to experimental feline infectious peritonitis virus infection is decreased rather than increased by positive genetic selection

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Laboratory cats resistant to primary FIPV infection were purposely inbred.

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P, F1 and F1/P backcross cats were tested for resistance to primary and secondary FIPV exposures.

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Resistance to primary and secondary FIPV infection decreased as a result of inbreeding.

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Loss of heterozygosity is a risk factor for FIP.

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Resistance to FIPV infection is genetically complex.

A previous study demonstrated the existence of a natural resistance to feline infectious peritonitis virus (FIPV) among 36% of randomly bred laboratory cats. A genome wide association study (GWAS) on this population suggested that resistance was polygenic but failed to identify any strong specific associations. In order to enhance the power of GWAS or whole genome sequencing to identify strong genetic associations, a decision was made to positively select for resistance over three generations. The inbreeding experiment began with a genetically related parental (P) population consisting of three toms and four queens identified from among the survivors of the earlier study and belonging to a closely related subgroup (B). The subsequent effects of inbreeding were measured using 42 genome-wide STR markers. P generation cats produced 57 first filial (F1) kittens, only five of which (9.0%) demonstrated a natural resistance to FIPV infection. One of these five F1 survivors was then used to produce six F1/P-backcrosses kittens, only one of which proved resistant to FIP. Six of eight of the F1 and F1/P survivors succumbed to a secondary exposure 4–12 months later. Therefore, survival after both primary and secondary infection was decreased rather than increased by positive selection for resistance. The common genetic factor associated with this diminished resistance was a loss of heterozygosity.

Investigation of inherited diseases in cats: genetic and genomic strategies over three decades

PRACTICAL RELEVANCE

The health of the cat mirrors a complex interaction between its environment (nurture) and its genetics (nature). To date, over 70 genetic mutations (variants) have been defined in the cat; many involve diseases, structural anomalies, coat color and texture, including numerous that are clinically relevant. This trend will continue as more of the feline genome is deciphered. Genetic testing, and eventually whole-genome sequencing, should become routine diagnostic tools in feline healthcare within the foreseeable future.

GLOBAL IMPORTANCE

Cat breeds have dispersed around the world. Thus, feline medicine clinicians should be aware of breeds common to their region and common mutations found within those regional populations. Random-bred populations of domestic cats can also have defined genetic characteristics and mutations, which are equally worthy of understanding by feline medicine clinicians.

OUTLINE

This article reviews the chronology and evolution of genetic and genomic tools pertinent to feline medicine. Possible strategies for mapping genetic traits and defects, and how these impact on feline health, are also discussed. The focus is on three historical periods: (1) research conducted before the availability of the cat genome; (2) research performed immediately after the availability of sequences of the cat genome; and (3) current research that goes beyond one cat genome and utilizes the genome sequences of many cats.

EVIDENCE BASE

The data presented are extracted from peer-reviewed publications pertaining to mutation identification, and relevant articles concerning heritable traits and/or diseases. The authors draw upon their personal experience and expertise in feline genetics.

Feline gastrointestinal eosinophilic sclerosing fibroplasia: 13 cases and review of an emerging clinical entity

OBJECTIVE

Feline gastrointestinal eosinophilic sclerosing fibroplasia (FGESF) is a recently described inflammatory disease of cats affecting stomach or intestines and draining regional lymph nodes. This study presents clinical and laboratory data on 13 newly described cases from Australia (11) and the UK (two).

OBSERVATIONS

The disease was most often observed in middle-aged cats (median 7 years of age; interquartile range 5-9 years). Ragdolls (7/13) and males (9/13) were overrepresented. Cats generally had a long history of vomiting and/or diarrhoea. Lesions were typically large, hard, non-painful, easily palpable and most commonly situated near the pylorus or ileocaecocolic junction. Lesions were heterogeneous ultrasonographically and on sectioning at celiotomy or necropsy. Masses were hard and 'gritty' on fine-needle aspiration due to internal trabeculae made up of mature collagen bundles. Bacteria were commonly detected within masses (9/13 cases) using either culture or conventional light microscopy and a panel of special stains, and/or fluorescence in situ hybridisation (FISH), although detection often required a diligent search of multiple tissue sections. A consistent bacterial morphology could not be appreciated among the different cases.

OUTCOME

Patients were treated with a variable combination of cytoreduction (debulking and biopsy, to complete surgical resection), immunosuppressive therapy and antimicrobial agents. Many cats had a poor outcome, which was attributable to late diagnosis combined with suboptimal management. It is hoped that suggestions outlined in the discussion may improve clinical outcomes and long-term survival in future cases.

A retrospective clinical and epidemiological study on feline coronavirus (FCoV) in cats in Istanbul, Turkey

The presence of antibodies to feline coronavirus (FCoV) and feline immunodeficiency virus (FIV), together with feline leukemia virus (FeLV) antigen was investigated in 169 ill household and stray cats attending a veterinary surgery in Istanbul in 2009-14. The estimated FCoV and FIV seroprevalence (95% confidence intervals) were 37% (30-45%) and 11% (6-16%), respectively and FeLV prevalence was 1% (0-3%). FCoV seroprevalence increased until 2 years of age, was highest in 2014 and among household cats living with other cats and with outdoor access, and was lower in FIV seropositive compared to seronegative cats. Symptoms typically associated with wet feline infectious peritonitis (FIP) including ascites, abdominal distention or pleural effusion, coupled in many cases with non-antibiotic responsive fever, were observed in 19% (32/169) of cats, and 75% (24/32) of these cats were FCoV seropositive. FCoV seropositivity was also associated with a high white blood cell count, high plasma globulin, low plasma albumin and low blood urea nitrogen. The percentage of FCoV seropositive and seronegative cats that died in spite of supportive veterinary treatment was 33% (21/63) and 12% (13/106), respectively. These results indicate that FCoV is widespread and has a severe clinical impact in cats from Istanbul. Moreover, the incidence of FCoV infections could be rising, and in the absence of effective vaccination cat owners need to be made aware of ways to minimize the spread of this virus.

Polymorphisms in the feline TNFA and CD209 genes are associated with the outcome of feline coronavirus infection

Feline infectious peritonitis (FIP), caused by feline coronavirus (FCoV) infection, is a highly lethal disease without effective therapy and prevention. With an immune-mediated disease entity, host genetic variant was suggested to influence the occurrence of FIP. This study aimed at evaluating cytokine-associated single nucleotide polymorphisms (SNPs), i.e., tumor necrosis factor alpha (TNF-α), receptor-associated SNPs, i.e., C-type lectin DC-SIGN (CD209), and the five FIP-associated SNPs identified from Birman cats of USA and Denmark origins and their associations with the outcome of FCoV infection in 71 FIP cats and 93 FCoV infected non-FIP cats in a genetically more diverse cat populations. A promoter variant, fTNFA - 421 T, was found to be a disease-resistance allele. One SNP was identified in the extracellular domain (ECD) of fCD209 at position +1900, a G to A substitution, and the A allele was associated with FIP susceptibility. Three SNPs located in the introns of fCD209, at positions +2276, +2392, and +2713, were identified to be associated with the outcome of FCoV infection, with statistical relevance. In contrast, among the five Birman FIP cat-associated SNPs, no genotype or allele showed significant differences between our FIP and non-FIP groups. As disease resistance is multifactorial and several other host genes could involve in the development of FIP, the five genetic traits identified in this study should facilitate in the future breeding of the disease-resistant animal to reduce the occurrence of cats succumbing to FIP.

The influence of age and genetics on natural resistance to experimentally induced feline infectious peritonitis

Naturally occurring feline infectious peritonitis (FIP) is usually fatal, giving the impression that immunity to the FIP virus (FIPV) is extremely poor. This impression may be incorrect, because not all cats experimentally exposed to FIPV develop FIP. There is also a belief that the incidence of FIP may be affected by a number of host, virus, and environmental cofactors. However, the contribution of these cofactors to immunity and disease incidence has not been determined. The present study followed 111 random-bred specific pathogen free (SPF) cats that were obtained from a single research breeding colony and experimentally infected with FIPV. The cats were from several studies conducted over the past 5 years, and as a result, some of them had prior exposure to feline enteric coronavirus (FECV) or avirulent FIPVs. The cats were housed under optimized conditions of nutrition, husbandry, and quarantine to eliminate most of the cofactors implicated in FIPV infection outcome and were uniformly challenge exposed to the same field strain of serotype 1 FIPV. Forty of the 111 (36%) cats survived their initial challenge exposure to a Type I cat-passaged field strains of FIPV. Six of these 40 survivors succumbed to FIP to a second or third challenge exposure, suggesting that immunity was not always sustained. Exposure to non-FIP-inducing feline coronaviruses prior to challenge with virulent FIPV did not significantly affect FIP incidence but did accelerate the disease course in some cats. There were no significant differences in FIP incidence between males and females, but resistance increased significantly between 6 months and 1 or more years of age. Genetic testing was done on 107 of the 111 infected cats. Multidimensional scaling (MDS) segregated the 107 cats into three distinct families based primarily on a common sire(s), and resistant and susceptible cats were equally distributed within each family. Genome-wide association studies (GWAS) on 73 cats that died of FIP after one or more exposures (cases) and 34 cats that survived (controls) demonstrated four significant associations after 100k permutations. When these same cats were analyzed using a sib-pair transmission test, three of the four associations were confirmed although not with genome-wide significance. GWAS was then done on three different age groups of cases to take into account age-related resistance, and different associations were observed. The only common and strong association identified between the various GWAS case configurations was for the 34.7-45.8Mb region of chromosome A3. No obvious candidate genes were present in this region.

Common and emerging infectious diseases in the animal shelter

The beneficial role that animal shelters play is unquestionable. An estimated 3 to 4 million animals are cared for or placed in homes each year, and most shelters promote public health and support responsible pet ownership. It is, nonetheless, inevitable that shelters are prime examples of anthropogenic biological instability: even well-run shelters often house transient, displaced, and mixed populations of animals. Many of these animals have received minimal to no prior health care, and some have a history of scavenging or predation to survive. Overcrowding and poor shelter conditions further magnify these inherent risks to create individual, intraspecies, and interspecies stress and provide an environment conducive to exposure to numerous potentially collaborative pathogens. All of these factors can contribute to the evolution and emergence of new pathogens or to alterations in virulence of endemic pathogens. While it is not possible to effectively anticipate the timing or the pathogen type in emergence events, their sites of origin are less enigmatic, and pathologists and diagnosticians who work with sheltered animal populations have recognized several such events in the past decade. This article first considers the contribution of the shelter environment to canine and feline disease. This is followed by summaries of recent research on the pathogenesis of common shelter pathogens, as well as research that has led to the discovery of novel or emerging diseases and the methods that are used for their diagnosis and discovery. For the infectious agents that commonly affect sheltered dogs and cats, including canine distemper virus, canine influenza virus, Streptococcus spp, parvoviruses, feline herpesvirus, feline caliciviruses, and feline infectious peritonitis virus, we present familiar as well as newly recognized lesions associated with infection. Preliminary studies on recently discovered viruses like canine circovirus, canine bocavirus, and feline norovirus indicate that these pathogens can cause or contribute to canine and feline disease.

Detection of ascitic feline coronavirus RNA from cats with clinically suspected feline infectious peritonitis

Ascitic feline coronavirus (FCoV) RNA was examined in 854 cats with suspected feline infectious peritonitis (FIP) by RT-PCR. The positivity was significantly higher in purebreds (62.2%) than in crossbreds (34.8%) (P<0.0001). Among purebreds, the positivities in the Norwegian forest cat (92.3%) and Scottish fold (77.6%) were significantly higher than the average of purebreds (P=0.0274 and 0.0251, respectively). The positivity was significantly higher in males (51.5%) than in females (35.7%) (P<0.0001), whereas no gender difference has generally been noted in FCoV antibody prevalence, indicating that FIP more frequently develops in males among FCoV-infected cats. Genotyping was performed for 377 gene-positive specimens. Type I (83.3%) was far more predominantly detected than type II (10.6%) (P<0.0001), similar to previous serological and genetic surveys.

Genetic susceptibility to feline infectious peritonitis in Birman cats

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Feline infectious peritonitis (FIP) is caused by a mutant enteric coronavirus.

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Susceptibility to FIP appears to be heritable in pedigreed cats.

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Birman cats suffer a high incidence of FIP and are highly inbred.

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Heritable factors were interrogated in Birman cats by genome wide association study.

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Five relevant candidate genes were strongly associated with FIP susceptibility.

Genetic factors are presumed to influence the incidence of feline infectious peritonitis (FIP), especially among pedigreed cats. However, proof for the existence of such factors has been limited and mainly anecdotal. Therefore, we sought evidence for genetic susceptibility to FIP using feline high density single nucleotide polymorphism (SNP) arrays in a genome-wide association study (GWAS). Birman cats were chosen for GWAS because they are highly inbred and suffer a high incidence of FIP. DNA from 38 Birman cats that died of FIP and 161 healthy cats from breeders in Denmark and USA were selected for genotyping using 63K SNPs distributed across the feline genome. Danish and American Birman cats were closely related and the populations were therefore combined and analyzed in two manners: (1) all cases (FIP) vs. all controls (healthy) regardless of age, and (2) cases 1½ years of age and younger (most susceptible) vs. controls 2 years of age and older (most resistant). GWAS of the second cohort was most productive in identifying significant genome-wide associations between case and control cats. Four peaks of association with FIP susceptibility were identified, with two being identified on both analyses. Five candidate genes ELMO1, RRAGA, TNFSF10, ERAP1 and ERAP2, all relevant to what is known about FIP virus pathogenesis, were identified but no single association was fully concordant with the disease phenotype. Difficulties in doing GWAS in cats and interrogating complex genetic traits were discussed.

Positive predictive value of albumin: globulin ratio for feline infectious peritonitis in a mid-western referral hospital population

Low albumin to globulin ratio has been found previously to have a high positive predictive value for feline infectious peritonitis (FIP) in cats with clinical signs highly suggestive of the disease. However, FIP can have a more vague clinical presentation. This retrospective study found that the positive predictive value of an albumin:globulin (A:G) ratio of <0.8 and <0.6 was only 12.5% and 25%, respectively, in a group of 100 cats with one or more clinical signs consistent with FIP. The negative predictive value was 100% and 99% for an A:G ratio of <0.8 and A:G<0.6%, respectively. Therefore, when the prevalence of FIP is low, the A:G ratio is useful to rule out FIP but is not helpful in making a positive diagnosis of FIP.