When cats' ways of life interact with their viruses: a study in 15 natural populations of owned and unowned cats (Felis silvestris catus)

High prevalence of antibodies against feline calicivirus in Australian feral and stray cat (Felis catus) populations

INTRODUCTION

Feline calicivirus (FCV) commonly causes upper respiratory tract, oral and ocular infections in species of the family Felidae, with high prevalence amongst domestic cat (Felis catus) populations worldwide. Detection of FCV-specific antibodies in serum provides evidence of previous infection with FCV and an indication of whether a cat may be protected against clinical FCV disease. This study describes the most extensive sampling for anti-FCV antibodies in feral and stray cat populations in Australia, and examines variation in prevalence associated with cat age, sex and location.

METHODS

Blood samples were opportunistically collected from 669 feral, stray or Indigenous community cats from the Northern Territory, South Australia, Victoria, south-east Tasmania and south-west New South Wales. The sera were harvested and tested for antibodies capable of neutralising the FCV vaccine strain F9 by serum-virus neutralisation assay.

RESULTS

Of the 669 cats tested, 69.7% had detectable FCV-F9-neutralising antibodies (titres ≥5). Maturity was significantly associated with higher seroprevalence and higher antibody titres, with adult cats being more than twice as likely to have detectable FCV-neutralising antibodies than subadults. Male cats had a higher seroprevalence and slightly higher antibody titres than females. Cats living in closer proximity to humans had significantly higher seroprevalences and higher FCV-neutralising antibody titres than feral cats from more remote regions of Australia.

CONCLUSION

Australian feral and stray cats have a high risk of natural exposure to and infection with FCV, with the prevalence and levels of pre-existing immunity to FCV being highest amongst adult cats living in highly modified urban, peri-urban and agricultural environments.

Prospective Investigation of Feline Leukemia Virus Infection in Stray Cats Subjected to a Trap-Neuter-Return Program in Switzerland

Feline leukemia virus (FeLV) remains a serious concern in some countries despite advances in diagnostics and vaccines. FeLV-infected cats often have reduced lifespans due to FeLV-associated diseases. The infection is transmitted through social interactions. While Northern European countries have reported a decrease in FeLV among pet cats, Switzerland's rates remain stagnant at 2.7% (2016/17: 95% CI 1.4-5.2%). Research on FeLV in Swiss stray cats has been lacking, even though these animals could serve as a virus reservoir. Sampling stray cats that do not receive regular veterinary care can be challenging. Collaboration with the Swiss Network for Animal Protection (NetAP) allowed for the prospective collection of saliva samples from 1711 stray cats during a trap-neuter-return program from 2019 to 2023. These samples were tested for FeLV RNA using RT-qPCR as a measure for antigenemia. Viral RNA was detected in 4.0% (95% CI 3.1-5.0%) of the samples, with 7.7% (95% CI 4.9-11.3%) in sick cats and 3.3% (95% CI 2.4-4.4%) in healthy ones. We identified three geographically independent hotspots with alarmingly high FeLV infection rates in stray cats (up to 70%). Overall, including the previous data of privately owned cats, FeLV-positive cats were scattered throughout Switzerland in 24/26 cantons. Our findings underscore welfare concerns for FeLV infections among stray cats lacking veterinary attention, highlighting the potential risk of infection to other free-roaming cats, including those privately owned. This emphasizes the critical significance of vaccinating all cats with outdoor access against FeLV and developing programs to protect cats from FeLV infections.

Prevalence of Serum Antibody Titers against Core Vaccine Antigens in Italian Cats

Feline core vaccines strongly recommended for all cats are against Feline panleukopenia virus (FPV), Felid herpesvirus type 1 (FeHV-1), and Feline calicivirus (FCV), but cats can be classified as low- and high-risk based on their lifestyle. The aim of this study was to determine the actual seroprotection against FPV, FeHV-1, and FCV in a large cohort of Italian cats by using the VacciCheck test. A total of 740 cats (567 owned and 173 stray cats; 435 vaccinated and 305 unvaccinated) were analyzed for Protective Antibody Titers (PATs). Differences related to origin, sex, age, breed, FIV/FeLV status, health status, and time elapsed since last vaccination were evaluated. Less than half of the entire cohort (36.4%) had PATs for all three diseases simultaneously, increasing to 48.6% if weak positive values were also considered and 50.3% when considering only the 435 vaccinated cats. Particularly, antibodies were detected against FCV, FPV, and FeHV-1 at protective titers (PATs) in 78.6%, 68.1, and 49.1% of the cats, respectively. In general, owned, neutered, and adult FIV- and/or FeLV-negative cats were the most protected categories, even if not always for the three viruses. Most cats maintained high PATs for 3 years or longer after vaccination against FPV and FCV but not FeHV-1. Long-lasting protective immunity persisted for many years after the last vaccination (more than 18 years in the oldest cats). Nevertheless, since not all cats were protected after so many years and for all pathogens, checking protection via antibody titration could be the best choice to prevent immunity breakdowns. The discussion also focuses on the reliability of antibody titration for the two URTD (upper respiratory tract disease) viruses which, unlike for FPV, is not widely accepted as a valid index of protection.

Epididymectomy as a novel surgical procedure; application in the domestic cat

Feline overpopulation raises issues concerning health, ecology, economy, and ethics. Procedures to limit overpopulation should carefully address animal welfare, efficiency, costs, and feasibility. Vasectomy in unowned cats is suggested as preferable to standard neutering as it maintains male sexual behaviour which may induce ovulation and pseudopregnancy in intact females and may prevent immigration of other males. Vasectomy is not performed routinely because it is fastidious, time consuming and requires more material than standard neutering. We describe epididymectomy as an alternative. In a first experiment, we analysed semen, testosterone, behaviour and pain in six experimental cats before and after epididymectomy, and after castration two months later. Excised tissues were analysed histologically. Testosterone concentrations did not differ significantly between intact and epididymectomised animals but were significantly different after castration. Sexual behaviour and testicular spermatogenesis persisted after epididymectomy, but with a marked drop in the semen count after 7 days. The Glasgow pain scores did not differ significantly after epididymectomy and castration. In a subsequent experiment, 20 privately owned cats were epididymectomised and castrated immediately afterwards, to analyse the learning curve and perioperative complications. The time required for an epididymectomy was significantly shorter than for castration. The study confirms that epididymectomy is quicker and less invasive than castration, it is associated with minimal risks and post-operative pain while easy to learn and inexpensive. Further field studies are required to test its efficiency for feline feral population control or in other species such as in bears, lions or deer, where infertility is required and castration not wanted.

Clinico-epidemiological survey of feline parvovirus circulating in three Egyptian provinces from 2020 to 2021

Feline parvovirus infection, caused by feline parvovirus and canine parvovirus 2, is a highly contagious, life-threatening disease affecting cats. The available epidemiological data on parvovirus infection in cats in Egypt is limited. Therefore, the aim of the current study was to provide data concerning the epidemiological profile of cats infected with parvovirus, including the prevalence of parvovirus infection in cats in three Egyptian provinces (Sohag, Assiut, and Cairo) and the associated risk factors. Using rapid antigen tests of fecal samples and conventional PCR, the overall prevalence of parvovirus infection in cats was found to be 35% (35/100) and 43% (43/100), respectively. Anorexia, bloody diarrhea, severe dehydration, hypothermia, and vomiting were the most common clinical findings significantly associated with parvovirus-infected cats. The geographical location (Sohag) and the season (winter) were both statistically significant risk factors for parvovirus infection. These findings indicate that parvoviruses are circulating in different regions of Egypt. Our study provides baseline epidemiological data for future preventive and control measures against parvovirus infection, as well as highlighting the need for future genomic surveillance studies involving a large study population from various parts of Egypt in order to better shape the epidemiological picture of parvovirus infection.

Evaluation of Platelet-Rich Plasma by means of PRGF®-Endoret® protocol in leukemia cats: PDGF-BB and TGF-ß1 valuation

Introduction

Feline leukemia virus (FeLV) is a chronic disease that leads to the weakening of a cat's immune system. Platelet-rich plasma (PRP) offers therapeutic effects for multiple diseases, the use of PRP and growth factors (GFs) determination could be an alternative treatment to improve the quality of life in these patients. The objectives of this study were to determine and compare the concentration of platelets (PLTs), red blood cells (RBCs) and white blood cells (WBCs) between samples of whole blood (WB), PRP and platelet-poor plasma (PPP) fractions, and to evaluate the concentration of platelet-derived growth factor BB (PDGF-BB) and transforming growth factor β1 (TGF-β1) in both fractions in FeLV cats using a PRGF^®-Endoret^® protocol previously standardized in this species.

Methods

WB was collected from 11 asymptomatic FeLV-positive cats. PRP and PPP was obtained following PRGF^®-Endoret^® technology according to centrifugation at 265 g for 10 min. Cellular components, RBCs, WBCs, PLTs, and the PDGF-BB and TGF-β1 concentrations in PRP and PPP fractions were determined.

Results

PLT in the PRP fraction was statistically higher than WB and PPP fraction, with no statistical differences between WB and PPP. PLT concentration increased 1.4 times in PRP fraction compared to WB. Mean platelet volume (MPV) did not differ significantly between the WB, PRP, and PPP fractions. Compared to WB, the absolute numbers of RBCs and WBCs were decreased by 99% and more than 95% in the PRP and PPP fractions, respectively. TGF-ß1 concentrations increased in PRP vs. PPP, with no changes in PDGF-BB.

Discussion

Based on the degree of PLT enrichment and the absence of RBCs and WBCs, this blood product could be classified as a Pure Platelet-Rich Plasma (P-PRP). The presence of GFs in PRP and PPP samples suggests that the PRGF^®-Endoret^® methodology is suitable for obtaining PRP in FeLV cats, despite future studies are necessary to optimize the technique, standardize the results and assess clinical efficacy.

Feral Cat Populations and Feline Retrovirus Prevalence in San Mateo County, California in Three Time Periods between 2001 and 2016

This study was initiated in 2004 because the prevalence of feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) infections in feral cats in San Mateo County (SMC) was not known. The cities attributed to the feral cat population presented to the Peninsula Humane Society & SPCA’s Spay/Neuter Clinic and to the Shelter itself were analyzed to examine potential geographic concentrations of feral cats with positive retroviral status. Trends in FIV and FeLV status were examined in three 3-year periods (2001−2003, 2005−2007, and 2014−2016). Population trends over the 15 years of this study for feral cats admitted to the Shelter were also examined. In each study period, more female feral cats were presented to the S/N Clinic (54.06%, 57.37%, 54.89%). FIV prevalence increased from 5.52% to 6.41% (p = 0.29) from the first to third period; FeLV prevalence decreased significantly from 1.73% to 0.29% (p = 0.01). Significantly more FIV-positive males than females were identified each year and for each period (p < 0.01). The four largest SMC cities were the major source of feral cats to the Shelter, S/N Clinic, and of FIV- and FeLV-positive cats in the first two periods; in the third period, 50% of feral cats to the Shelter and of FeLV-positive cats were from these cities. Despite a 61.63% reduction in feral cat admissions to the S/N Clinic, the FIV prevalence for males remained similar and increased for females. The retrovirus prevalence suggests the need for continued testing and surveillance of FIV among SMC free-living cats.

A Retrospective Study of Viral Molecular Prevalences in Cats in Southern Italy (Campania Region)

From 2019 to 2021, a retrospective molecular study was conducted in the Campania region (southern Italy) to determine the prevalence of viral diseases in domestic cats. A total of 328 dead animals were analyzed by Real-Time PCR for the presence of feline panleukopenia virus (FPV), feline leukemia virus (FeLV), feline enteric coronavirus (FCoV), rotavirus (RVA), feline herpesvirus type 1 (FHV-1), and feline calicivirus (FCV). The possible presence of SARS-CoV-2 was also investigated by Real-Time PCR. The cats included in this study were specifically sourced and referred by local veterinarians and local authorities to the Zooprofilactic Experimental Institute of Southern Italy (IZSM) for pathological evaluation. The samples consisted of owners, catteries, and stray cats. Results revealed: 73.5% positive cats for FPV (189/257), 23.6% for FeLV (21/89), 21.5% for FCoV (56/266), 11.4% for RVA (16/140), 9.05% for FeHV-1 (21/232), and 7.04 for FCV (15/213). In contrast, SARS-CoV-2 was never detected. FPV was more prevalent in winter (p = 0.0027). FCoV FHV-1, FCV, and RVA predominated in autumn, whereas FeLV predominated in summer. As expected, viral infections were found more frequently in outdoor and shelter cats than in indoor ones, although no statistical association was found between animal lifestyle and viral presence. The study showed a high prevalence of FPV, FeLV, and FCoV and a moderate prevalence of RVA, FHV-1, and FCV. Moreover, the prevalence of these pathogens varied among the cat populations investigated.

Feline immunodeficiency virus (FIV) infection in domestic pet cats in Australia and New Zealand: Guidelines for diagnosis, prevention and management

Despite the passage of over 30 years since its discovery, the importance of feline immunodeficiency virus (FIV) on the health and longevity of infected domestic cats is hotly debated amongst feline experts. Notwithstanding the absence of good quality information, Australian and New Zealand (NZ) veterinarians should aim to minimise the exposure of cats to FIV. The most reliable way to achieve this goal is to recommend that all pet cats are kept exclusively indoors, or with secure outdoor access (e.g., cat enclosures, secure gardens), with FIV testing of any in‐contact cats. All animal holding facilities should aim to individually house adult cats to limit the spread of FIV infection in groups of animals that are stressed and do not have established social hierarchies. Point‐of‐care (PoC) FIV antibody tests are available in Australia and NZ that can distinguish FIV‐infected and uninfected FIV‐vaccinated cats (Witness™ and Anigen Rapid™). Although testing of whole blood, serum or plasma remains the gold standard for FIV diagnosis, PoC testing using saliva may offer a welfare‐friendly alternative in the future. PCR testing to detect FIV infection is not recommended as a screening procedure since a negative PCR result does not rule out FIV infection and is only recommended in specific scenarios. Australia and NZ are two of three countries where a dual subtype FIV vaccine (Fel‐O‐Vax® FIV) is available and offers a further avenue for disease prevention. Since FIV vaccination only has a reported field effectiveness of 56% in Australia, and possibly lower in NZ, FIV‐vaccinated cats should undergo annual FIV testing prior to annual FIV re‐vaccination using a suitable PoC kit to check infection has not occurred in the preceding year. With FIV‐infected cats, clinicians should strive to be even more thorough than usual at detecting early signs of disease. The most effective way to enhance the quality of life and life expectancy of FIV‐infected cats is to optimise basic husbandry and to treat any concurrent conditions early in the disease course. Currently, no available drugs are registered for the treatment of FIV infection. Critically, the euthanasia of healthy FIV‐infected cats, and sick FIV‐infected cats without appropriate clinical investigations, should not occur.

Calicivirus Infection in Cats

Feline calicivirus (FCV) is a common pathogen in domestic cats that is highly contagious, resistant to many disinfectants and demonstrates a high genetic variability. FCV infection can lead to serious or even fatal diseases. In this review, the European Advisory Board on Cat Diseases (ABCD), a scientifically independent board of experts in feline medicine from 11 European countries, presents the current knowledge of FCV infection and fills gaps with expert opinions. FCV infections are particularly problematic in multicat environments. FCV-infected cats often show painful erosions in the mouth and mild upper respiratory disease and, particularly in kittens, even fatal pneumonia. However, infection can be associated with chronic gingivostomatitis. Rarely, highly virulent FCV variants can induce severe systemic disease with epizootic spread and high mortality. FCV can best be detected by reverse-transcriptase PCR. However, a negative result does not rule out FCV infection and healthy cats can test positive. All cats should be vaccinated against FCV (core vaccine); however, vaccination protects cats from disease but not from infection. Considering the high variability of FCV, changing to different vaccine strain(s) may be of benefit if disease occurs in fully vaccinated cats. Infection-induced immunity is not life-long and does not protect against all strains; therefore, vaccination of cats that have recovered from caliciviral disease is recommended.

How Serious Are Health-Related Welfare Problems in Unowned Unsocialised Domestic Cats? A Study from Denmark Based on 598 Necropsies

Free ranging unsocialised domestic cats are widely believed to suffer from a high load of welfare problems. We assessed the validity of this belief by performing necropsies on the corpses of 598 unsocialised cats, originating from all parts of Denmark, that had been euthanised by two Danish cat welfare organisations. We selected a number of variables for health-related cat welfare that could be assessed through necropsy (e.g., gross lesions, ectoparasites and body condition) or by laboratory analysis (e.g., infection with feline immunodeficiency virus (FIV), and by feline leukaemia virus (FeLV)). Each finding was classified as having either a major or minor welfare impact on the cat. More than 83% of the cats had no major finding, and 54% had no finding indicating a welfare issue at all. More than 83% of the cats had a body condition within normal range. Only 0.3% were emaciated. The most common finding was infestation with ectoparasites, with 15.9% infected with lice, 12.3% with fleas, 4.7% with ticks, and 6.7% with ear mites. FIV and FeLV were detected in 9.2% and 1.2% of the cases, respectively. The most common lesion related to the cats’ teeth. Overall, unsocialised cats in Denmark have a moderate level of health-related welfare problems.

Prevalence and Risk Factors of Feline Immunodeficiency Virus and Feline Leukemia Virus Infection in Healthy Cats in Thailand

Infections with feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) occur worldwide and are among the most important infectious diseases in cats. The aim of the present study was to determine the prevalence of FIV and FeLV infection in healthy outdoor cats in North, Northeast and Central Thailand. So far, a study on retrovirus prevalence of healthy cats in Thailand in a larger geographic area has not been published yet. In addition, risk factors for FIV and FeLV infections were evaluated. Two hundred sixty healthy cats were prospectively recruited. They originated from 13 locations in North, Northeast, and Central Thailand and were presented for either preventive health care and/or neutering. In each cat, a physical examination was performed to confirm health status. FIV and FeLV status was determined using a commercial rapid enzyme-linked immunosorbent assay (ELISA) (SNAP Combo Plus FeLV/FIV, IDEXX). Risk factors were analyzed by binary logistic regression analysis. Samples of 15/260 (5.8%) cats were positive for FIV antibodies, and 11/260 (4.2%) samples were positive for FeLV antigen. One of the 260 (0.4%) cats was positive for both, FIV and FeLV infection. In binary logistic regression analysis, no parameter was associated with a higher risk for FeLV infection. However, cats had a significantly (p = 0.025) higher risk for FIV infection when they were 2 years or older. FIV and FeLV infections occur in healthy cats in North, Northeast and Central Thailand, but prevalence was lower than expected. No risk factors for FeLV infection were detected, but risk for FIV infection increases with age.

Methods of Assessment of the Welfare of Shelter Cats: A Review

At any moment, there are millions of cats housed in foster care facilities for abandoned and stray animals for various reasons worldwide. Care, management and regulation among these facilities differ. Moreover, shelters can never substitute the full comfort of a good home for the animal, and the welfare of cats in shelters is a subject of discussion in many respects. Cats are animals sensitive to changes; for most of them, placement in a shelter is a stressful experience because of changes in routine, environment and the presence of other animals. Stress is reflected in changes in behaviour, causes fluctuations in physiological values and disrupts the immune system, which is a predisposition to the development or reactivation of disease. Evaluation of the presence and intensity of negative impacts is possible through the use of evaluation tools based on indicators that help set the environment and management of keeping so as to disrupt the quality of life as little as possible. Although a comprehensive and valid welfare tool that would evaluate animal-based and at the same time resource-based (or management-based) indicators of cats in shelters is not currently available, it is possible to use partial evaluation of individual welfare indicators to assess welfare. This review aims to provide the readers with an insight into current options of assessment of the welfare of cats in shelters with an emphasis on behavioural, physiological and health indicators with an application in both practical and scientific contexts.

What's New in Feline Leukemia Virus Infection

Feline leukemia virus (FeLV) is a retrovirus with global impact on the health of domestic cats that causes tumors (mainly lymphoma), bone marrow disorders, and immunosuppression. The importance of FeLV is underestimated due to complacency associated with previous decline in prevalence. However, with this comes lowered vigilance, which, along with potential for regressively infected cats to reactivate viremia and shed the virus or develop clinical signs, can pose a risk to feline health. This article summarizes knowledge on FeLV pathogenesis, courses of infection, and factors affecting prevalance, infection outcome, and development of FeLV-associated diseases, with special focus on regressive FeLV infection.

Subsidised by junk foods: factors influencing body condition in stray cats (Felis catus)

Domestic cats (Felis catus) are one of the most widely distributed and successful carnivores globally. While cats are popular pets, many unowned, ‘stray’ cats live freely in anthropogenic environments at high densities where they make use of anthropogenic resources. These stray cats present a management challenge due to concerns about wildlife predation, pathogen transmission, public nuisance and threats to cat welfare (e.g. vehicle collisions). In Australia, there are few studies of strays compared with pet cats or feral cats (free-roaming cats in rural areas that are independent of resources provided by humans). To contribute original data about stray cat biology, the carcasses of 188 euthanised stray cats were collected from Perth, Western Australia. Cats were assessed for general health, age, reproduction, diet and gastrointestinal parasite biomass. The influence of cat demographics, collection location, season, parasite biomass, diet and history of supplemental feeding by people were tested against body condition. Overall, strays were physically healthy and reproductive, with few life-threatening injuries or macroscopic evidence of disease; however, helminths were extremely common (95% of cats) and pose a threat. Nearly 40% of strays consumed wildlife, including two species of endemic marsupial. Alarmingly, 57.5% of strays were scavenging vast amounts of refuse, including life-threatening items in volumes that blocked their gastrointestinal tracts. These findings illustrate that strays need to be removed from anthropogenic environments for their own health and welfare and to prevent continued breeding. Targeted control programmes should prioritise removal of cats from areas where refuse is common and where valued native fauna exist.

Feline Parvovirus Seroprevalence Is High in Domestic Cats from Disease Outbreak and Non-Outbreak Regions in Australia

Multiple, epizootic outbreaks of feline panleukopenia (FPL) caused by feline parvovirus (FPV) occurred in eastern Australia between 2014 and 2018. Most affected cats were unvaccinated. We hypothesised that low population immunity was a major driver of re-emergent FPL. The aim of this study was to (i) determine the prevalence and predictors of seroprotective titres to FPV among shelter-housed and owned cats, and (ii) compare the prevalence of seroprotection between a region affected and unaffected by FPL outbreaks. FPV antibodies were detected by haemagglutination inhibition assay on sera from 523 cats and titres ≥1:40 were considered protective. Socioeconomic indices based on postcode and census data were included in the risk factor analysis. The prevalence of protective FPV antibody titres was high overall (94.3%), even though only 42% of cats were known to be vaccinated, and was not significantly different between outbreak and non-outbreak regions. On multivariable logistic regression analysis vaccinated cats were 29.94 times more likely to have protective FPV titres than cats not known to be vaccinated. Cats from postcodes of relatively less socioeconomic disadvantage were 5.93 times more likely to have protective FPV titres. The predictors identified for FPV seroprotective titres indicate targeted vaccination strategies in regions of socioeconomic disadvantage would be beneficial to increase population immunity. The critical level of vaccine coverage required to halt FPV transmission and prevent FPL outbreaks should be determined.

Antibody Response to Feline Calicivirus Vaccination in Healthy Adult Cats

This study evaluated the prevalence of feline calicivirus (FCV) antibodies and response to vaccination in healthy adult cats. Cats >1 year (n = 111) that had not been vaccinated within 12 months of enrollment in the study received a vaccine containing inactivated FCV antigen strains 431 and G1. Antibodies were determined on Days 0, 7, and 28 by virus neutralization (VN) using FCV isolate KS20, and by broad spectrum blocking FCV enzyme-linked immunosorbent assay (ELISA). Factors associated with the presence of antibodies and vaccine response were determined by uni- and multivariate analysis. Pre-vaccination antibodies were detected in 62.2% of cats (CI_95%: 52.9-70.1) by VN and in 77.2% (CI_95%: 67.5-84.6) by ELISA. A ≥4-fold titer increase after vaccination was observed in 13.6% (CI_95%: 8.3-21.4) of cats with VN and 33.7% (CI_95%: 24.5-44.5) with ELISA. Factors associated with the presence of pre-vaccination VN antibodies were age (≥2 years; OR: 7.091; p = 0.022) and lack of previous vaccination (OR: 3.472; p = 0.014). The presence of pre-vaccination ELISA antibodies was associated with time since last vaccination (OR: 5.672; p = 0.043). Outdoor cats were more likely to have a ≥4-fold ELISA titer increase (OR: 5.556; p = 0.005). Many cats had pre-vaccination FCV antibodies, and their presence depended on previous vaccinations and increases with age. A ≥4-fold titer increase was rarely observed and was influenced by the lifestyle of the cat.

Feline Panleukopenia: A Re-emergent Disease

Feline panleukopenia (FPL) is caused by a Carnivore protoparvovirus infection. Feline parvovirus (FPV) causes most cases. When Canine parvovirus 2 (CPV-2) first emerged, it could not replicate in cats. All current CPV variants (CPV-2a-c) can infect cats to cause subclinical disease or FPL. Feline panleukopenia has re-emerged in Australia in shelter cats associated with failure to vaccinate. Parvoviruses can remain latent in mononuclear cells post-infection. Molecular methods such as polymerase chain reaction are used to determine the infecting strain. Current perspectives on causes, epidemiology, diagnosis, treatment, prognostic indicators, and management of outbreaks in shelters are reviewed.

Prevalence of serum antibody titres against feline panleukopenia, herpesvirus and calicivirus infections in stray cats of Milan, Italy

The aim of the study was to determine the seroprevalence of feline panleukopenia virus (FPV), feline herpesvirus type 1 (FHV-1) and feline calicivirus (FCV) in stray colony cats from Milan, Italy. Cats were divided in groups based on age, gender, reproductive status, health status and colony of origin. Blood samples were tested with an in-clinic ELISA test. The possible presence of a link between the antibody titre or the presence of seropositive results and the independent variables (age, gender, reproductive status, health status and colony location) was assessed by means of multinomial and univariate logistic regression models, respectively. Seroprevalence of 85.4% was reported for FCV. The diffusion of the other two pathogens in the cat population was much lower compared to FCV, with 45.7% and 37.1% seroprevalence observed for FPV and FHV-1, respectively. An increase of antibody titres from kitten to senior was generally observed for the three pathogens. Age was a statistically significant variable for FHV-1, with senior cats significantly associated with higher antibody titres and higher percentages of seropositive animals compared to younger age groups. Neutered cats had significantly higher antibody titres and showed significantly higher FHV-1 seroprevalences compared to sexually intact cats. Colonies from two of the nine administrative districts of Milan showed significantly higher FPV seroprevalences compared to the others. No other significant differences were observed. Our results, based on cats belonging to 70 different colonies located in urban areas far from each other, suggest that the three viruses circulate in the feline population of stray cats in Milan. The feline calicivirus represents the most common circulating pathogen, as observed also in other studies worldwide. Finally, our results suggest that stray cats may be not adequately protected against FPV, FHV-1 and FCV and vaccination could be a possible strategic solution, especially for FPV.

Antibody response to feline panleukopenia virus vaccination in healthy adult cats

OBJECTIVES

According to prior studies, between 25.0% and 92.8% of adult cats have antibodies against feline panleukopenia virus (FPV) and thus are likely protected against FPV infection. It is, however, unknown how healthy adult cats with different antibody titres react to FPV vaccination in the field. Therefore, the aim of the study was to measure antibody titres in healthy adult cats within a period of 28 days after vaccination against FPV and to evaluate factors that are associated with a lack of adequate response to vaccination.

METHODS

One hundred and twelve healthy adult cats were vaccinated with a vaccine against FPV, feline herpesvirus and feline calicivirus. Antibodies against FPV were determined before vaccination (day 0), on day 7 and day 28 after vaccination by haemagglutination inhibition (HI). A HI titre ⩾1:40 was defined as protective. An adequate response to vaccination was defined as a four-fold titre increase. Uni- and multivariate statistical analysis was used to determine factors associated with an adequate response.

RESULTS

Pre-vaccination antibody titres of ⩾1:40 were present in 64.3% (72/112; 95% confidence interval [CI] 55.1-72.6). Only 47.3% (53/112; 95% CI 37.8-57.0) of cats had an adequate response to vaccination. Factors associated with an adequate response to vaccination were lack of previous vaccination (odds ratio [OR] 15.58; 95% CI 1.4-179.1; P = 0.035), lack of antibodies (⩾1:40) prior to vaccination (OR 23.10; 95% CI 5.4-98.8; P <0.001) and breed (domestic shorthair cats; OR 7.40; 95% CI 1.4-38.4; P = 0.017).

CONCLUSIONS AND RELEVANCE

As none of the cats with high pre-vaccination antibody titres (⩾1:160) had an at least four-fold increase in FPV antibody titres, measurement of antibodies rather than regular revaccinations should be performed. Thus, evaluation of FPV antibody titre in cats with previous vaccinations against FPV are recommended prior to revaccination.

Prevalence of feline immunodeficiency virus and feline leukaemia virus infection in Malaysia: a retrospective study

Objectives

Feline ownership is popular and represents the largest segment of the pet population in Malaysia. Most feline owners own, on average, 2–3 cats, with some having >10 cats per household. Feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV) are two clinically important viral infections in cats. Documenting the prevalence of these diseases in the feline population is important for both veterinarians and the public.

Methods

This was a retrospective study, using data collected from the domestic cat population seen at a 24 h private veterinary hospital in Malaysia, to determine the prevalence of FIV and FeLV in an urban area and risk factors associated with these infections. Between 2010 and 2016, 2230 blood samples were collected and tested for FIV antibodies and FeLV antigen using commercially available ELISA test kits.

Results

In total, 10.0% (n = 224; 95% confidence interval [CI] 8.80–11.26) were seropositive for FIV; 12.0% (n = 267; 95% CI 10.62–13.32) were seropositive for FeLV; and 2.6% (n = 58; 95% CI 2.01–3.17) were seropositive for both.

Conclusions and relevance

The prevalence of FIV is lower and FeLV higher than previously documented for this region. Because of the immunosuppressive potential of both viruses, client education and use of appropriate control strategies such as routine screening, vaccination and eradication should be considered.

Epidemiology and clinical outcomes of feline immunodeficiency virus and feline leukaemia virus in client-owned cats in New Zealand

Objectives

The objectives were to collect baseline data on the occurrence, testing and vaccination practices, and clinical outcomes of feline leukaemia virus (FeLV) and feline immunodeficiency virus (FIV) in New Zealand

Methods

A cross-sectional survey of 423 veterinary practices in New Zealand was performed to collect data on FeLV and FIV testing and vaccination during the 2015 calendar year. Clinical records from 572 cats tested using a point-of-care ELISA at a first-opinion veterinary practice between 7 April 2010 and 23 June 2016 were also obtained and multivariable logistic regression models were constructed to identify risk factors for test positivity. Survival times were estimated using Kaplan–Meier methods.

Results

The survey was completed by 112 clinics (26.4%) of which 72 performed in-house testing. Of the 2125 tests performed, 56 (2.6%) were positive for FeLV and 393 (18.5%) were positive for FIV. Fewer than 1% of cats were vaccinated for FeLV, with veterinarians citing low perceived prevalence as the primary reason for not vaccinating. Being male compared with being female and having clinical evidence of immunosuppression were significant risk factors for both FeLV and FIV test positivity. The median survival times of FeLV and FIV test-positive cats were 10 days (95% confidence interval [CI] 0–16) and 650 days (95% CI 431–993), respectively.

Conclusions and relevance

Testing and vaccination for FeLV and FIV in New Zealand appears targeted towards high-risk animals, which may bias prevalence estimates. Baseline data should be monitored for changes in FeLV epidemiology now commercial vaccines are no longer available.

Prevalence of and risk factors for FIV and FeLV infection in two shelters in the United Kingdom (2011-2012)

The aims of this study were to determine the prevalence of feline leukaemia virus (FeLV) and feline immunodeficiency virus (FIV) infections in cats presented to two RSPCA (Royal Society for the Prevention of Cruelty to Animals) animal rehoming centres and to identify risk factors for infection. All cats presented at each centre between August 2011 and August 2012 were subjected to a patient-side test for FeLV/FIV on entry. Kittens under three months and cats euthanased within a short time of presentation were excluded from the study. Univariable and multivariable logistic regression were used to separately determine risk factors for FeLV and FIV infections. At shelter A, the prevalence of FIV infection was 11.4 per cent (54/474) and FeLV infection was 3 per cent (14/473), with two FIV/FeLV coinfections identified. At shelter B, the prevalence of FIV infection was 3 per cent (4/135) and FeLV infection was 0 per cent (0/135). Cats at shelter A were significantly more likely than those at shelter B to test positive for FIV (p=0.0024) and FeLV (p=0.048). Male cats were more likely to be infected with FIV (odds ratio 27.1, p=0.001), and thin body condition and musculoskeletal disease were associated with risk of FeLV. Overall, FIV-positive and FeLV-positive cats were significantly older (median ages 5.1 and 4.75 years, respectively) than the uninfected populations (median ages 3.4 and 3.5 years, respectively). This study shows that the prevalence of these diseases varies between shelter populations. Local knowledge combined with the risk factors identified may be useful in focusing resources for population testing strategies.

Ability of vaccine strain induced antibodies to neutralize field isolates of caliciviruses from Swedish cats

Background

Feline calicivirus (FCV) is a common cause of upper respiratory tract disease in cats worldwide. Its characteristically high mutation rate leads to escape from the humoral immune response induced by natural infection and/or vaccination and consequently vaccines are not always effective against field isolates. Thus, there is a need to continuously investigate the ability of FCV vaccine strain-induced antibodies to neutralize field isolates.

Methods

Seventy-eight field isolates of FCV isolated during the years 2008–2012 from Swedish cats displaying clinical signs of upper respiratory tract disease were examined in this study. The field isolates were tested for cross-neutralization using a panel of eight anti-sera raised in four pairs of cats following infection with four vaccine strains (F9, 255, G1 and 431).

Results

The anti-sera raised against F9 and 255 neutralised 20.5 and 11.5 %, and 47.4 and 64.1 % of field isolates tested, respectively. The anti-sera against the more recently introduced vaccine strains G1 and 431 neutralized 33.3 and 70.5 % and 69.2 and 89.7 %, respectively. Dual vaccine strains displayed a higher cross-neutralization.

Conclusions

This study confirms previous observations that more recently introduced vaccine strains induce antibodies with a higher neutralizing capacity compared to vaccine strains that have been used extensively over a long period of time. This study also suggests that dual FCV vaccine strains might neutralize more field isolates compared to single vaccine strains. Vaccine strains should ideally be selected based on updated knowledge on the antigenic properties of field isolates in the local setting, and there is thus a need for continuously studying the evolution of FCV together with the neutralizing capacity of vaccine strain induced antibodies against field isolates at a national and/or regional level.

Electronic supplementary material

The online version of this article (doi:10.1186/s13028-015-0178-z) contains supplementary material, which is available to authorized users.

Born to roam? Surveying cat owners in Tasmania, Australia, to identify the drivers and barriers to cat containment

Free-roaming domestic cats, Felis catus, are a major public nuisance in neighbourhoods across the world, and have been linked to biodiversity loss and a host of community health problems. Owners who let their cats roam, also place their cats at risk of serious injury. One management strategy that is gaining considerable support involves encouraging cat owners to contain their pets within their property. Contemporary behaviour change models highlight the importance of identifying drivers and barriers that encourage and discourage target behaviours such as cat containment. Results from a random dial phone survey of 356 cat owners in northern Tasmania identified four distinct cat containment profiles: owners who contained their cat all the time, owners who only contained their cat at night, owners who sporadically contained their cat with no set routine, and owners who made no attempt to contain their pet. Our results indicated that cat-owners' decisions to contain or not contain their cats were guided by a range of factors including owners' beliefs about their ability to implement an effective containment strategy and their views about the physical and psychological needs of their cats. The results are discussed in terms of improving the behavioural effectiveness of cat containment interventions by selecting appropriate behavioural change tools for the identified drivers and barriers, and developing targeted engagement strategies and messaging.

Patterns of seroprevalence of feline viruses among domestic cats (Felis catus) and Pallas’ cats (Otocolobus manul) in Daursky Reserve, Russia

Few data are available on the prevalence of feline viruses in the wild and little is known about natural sources of infections. The aim of this study was to estimate patterns of seroprevalence to feline viruses (feline immunodeficiency virus (FIV), feline calicivirus (FCV), feline panleukopenia virus (FPV), feline herpesvirus (FHV), and feline leukemia virus (FeLV)) in two cat species, domestic cats (Felis catus L., 1758) (n = 61) and Pallas’ cats (Otocolobus manul (Pallas, 1776)) (n = 24), living in the same area, in Daursky Reserve, Russia. Our results indicate that four of five viruses are circulating in the study area, with the exception of FHV. The pattern of FCV and FPV prevalence differed from FIV and FeLV. FCV and FPV seroprevalence did not depend on the sex and predominated in the group of cats living in the village (76% and 55%, respectively). No Pallas’ cats were seropositive to these viruses. The prevalence of FIV and FeLV were similar in areas with different cat densities (at the stations (16% for both viruses) and in the village (16% for both viruses)). The patterns of seroprevalence between species testify to the low rate of interspecific contacts. In Pallas’ cats, we found the presence of antibodies to FIV to be 5% and antigens of FeLV to be 5%, pathogens for which transmission demand close direct contacts between animals (mainly aggressive and (or) sexual contact), which is typical in the breeding season. Arid climate may also reduce patterns of viral prevalence in the study area, decreasing the risk of infection for both cat species.

Unknown age in health disorders: A method to account for its cumulative effect and an application to feline viruses interactions

Parasite interactions have been widely evidenced experimentally but field studies remain rare. Such studies are essential to detect interactions of interest and access (co)infection probabilities but face methodological obstacles. Confounding factors can create statistical associations, i.e. false parasite interactions. Among them, host age is a crucial covariate. It influences host exposition and susceptibility to many infections, and has a mechanical effect, older individuals being more at risk because of a longer exposure time. However, age is difficult to estimate in natural populations. Hence, one should be able to deal at least with its cumulative effect. Using a SI type dynamic model, we showed that the cumulative effect of age can generate false interactions theoretically (deterministic modeling) and with a real dataset of feline viruses (stochastic modeling). The risk to wrongly conclude to an association was maximal when parasites induced long-lasting antibodies and had similar forces of infection. We then proposed a method to correct for this effect (and for other potentially confounding shared risk factors) and made it available in a new R package, Interatrix. We also applied the correction to the feline viruses. It offers a way to account for an often neglected confounding factor and should help identifying parasite interactions in the field, a necessary step towards a better understanding of their mechanisms and consequences.

Feline parvovirus infection and associated diseases

Feline panleukopenia, caused by the single-stranded DNA virus feline parvovirus (FPV), is a highly contagious and often lethal disease of cats and other Felidae. FPV, but also canine parvovirus (CPV) can be isolated from both healthy and diseased cats. In Germany, CPV was detected in only approximately 10% of feline samples, but in Southeast Asia, reports estimated that up to approximately 80% of diseased cats were infected with CPV. Infection spreads rapidly, especially in cells with high mitotic activity, such as bone marrow, lymphoid tissue and intestinal crypt cells. Anorexia, vomiting, diarrhoea, neutropenia and lymphopenia are common in clinically affected cases. In utero or neonatal infection can result in cerebellar hypoplasia. Depending on the severity of clinical signs, mortality ranges from 25 to 100%. Effective vaccination and thorough disinfection are of the utmost importance in the prevention of disease transmission in multi-cat households and animal shelters. If clinical signs develop, supportive treatment should be commenced. The efficacy of feline recombinant interferon and FPV antibodies has not been clearly demonstrated. Commercially available vaccines should induce protective immunity when administered according to current guidelines. Recent studies suggest that in some kittens, maternally derived antibodies (MDA) can persist for much longer than has been previously recognised. FPV serum antibody tests are available, but protection status needs to be interpreted with caution in kittens with MDA and a negative titre in adult cats does not necessarily denote lack of protection.

Case series of feline panleukopenia virus in an animal shelter

The aim of this study was to describe a series of confirmed and suspected cases of feline panleukopenia virus (FPV) and in-contact cats in an adoption-guarantee shelter in an FPV-endemic area by reviewing shelter records over a 10-month period (January-October 2010). Cats were divided into three groups: in-contact group - asymptomatic cats that were housed with a FPV fecal antigen (Ag)-positive cat/kitten as part of a litter group (n = 66); FPV-survivors group (FPV-infected survivors) - tested FPV fecal Ag-positive and showed clinical signs of FPV, but survived (n = 27); FPV-non-survivors group (FPV-infected non-survivors) - showed clinical signs of FPV and either tested FPV fecal Ag-positive or were housed with an Ag-positive family member, but did not survive (n = 52). Ages ranged from 3 weeks to 3 years, but most were <6 months old (in-contact group: 79%; FPV-survivors group: 70%; FPV-non-survivors group: 85%). A seasonal peak occurred over summer, but cases occurred year-round. Anorexia, dehydration, fever and diarrhea predominated in the FPV-survivors group, and death was preceded by clinical signs of circulatory shock in the FPV-non-survivors group. Housing litters of kittens with their mother was not associated with improved outcome, perhaps because in this population clinical FPV infection was relatively common in queens arriving at the shelter with susceptible litters.

Prevalence of antibodies against feline panleukopenia virus in client-owned cats in Southern Germany

Feline panleukopenia is a frequent and commonly fatal disease of cats. Recent published studies have raised suspicions that some cats fail to develop antibodies after vaccination. The purpose of this study was to assess the prevalence of antibodies against feline panleukopenia virus (FPV) in cats in Southern Germany, and to identify factors that are associated with a lack of antibodies. In total, 350 cats presented to the Clinic of Small Animal Medicine, Ludwig-Maximilians-Universitaet were randomly included in the study. Information regarding signalment, origin, environment, lifestyle, housing conditions, health status, chronic diseases, glucocorticoid therapy, and vaccination status were collected. Antibodies were detected by haemagglutination inhibition test. Asymptomatic chi-squared tests and univariable logistic regression were used to investigate associations between a lack of antibodies and the different variables. Associations determined to be statistically significant at P<0.1 were verified by a multivariable logistic regression analysis. Of the 350 cats, 103 (29.4%) had no antibodies against FPV. Chronic kidney disease, neoplasia, glucocorticoid therapy, and vaccination status were significantly associated with a lack of antibodies. The cats with no antibodies were likely to have inadequate immunity against panleukopenia and those with chronic diseases or receiving glucocorticoids were less likely to be protected.

Differential association between circulating testosterone and infection risk by several viruses in natural cat populations: a behavioural-mediated effect?

Testosterone is involved in the development and expression of physiological, morphological and behavioural traits. High levels are often associated with high infection risk and/or intensity, suggesting a trade-off between sexual traits and immunity. Classically invoked mechanisms are immunological or behavioural, i.e., testosterone increases susceptibility or resistance to parasites via an impact on immunity or modulates behaviours involved in parasite transmission. However, studies report contrasted patterns. Given its modes of action and the diversity of host-parasite interactions, testosterone should not act similarly on all interactions. To reduce host and context diversity, we studied 3 viruses in the same cat population: the aggressively transmitted Feline Immunodeficiency virus (FIV), and the Feline Calicivirus (FCV) and Herpesvirus (FHV) both transmitted during friendly contacts. Testosterone had a strong effect on the probability of being positive to FIV whereas its effect was significantly weaker on FCV and FHV. These findings demonstrate that testosterone can be differentially associated with parasites of the same type (viruses). The difference we observed was consistent with a behavioural-mediated effect (increased aggressiveness), supporting the idea that the testosterone effect on infection risk is at least partially driven by behavioural mechanisms in our system. Further investigations (e.g., individual immunity measures) are required to confirm this hypothesis.

Prevalence and risk factors of feline leukaemia virus and feline immunodeficiency virus in peninsular Malaysia

BACKGROUND

Feline leukaemia virus (FeLV) and feline immunodeficiency virus (FIV) are major causes of morbidity and mortality in domestic and wild felids. Despite the clinical importance of feline retroviruses and the growing interest in cats as pets, information about FeLV and FIV in Malaysia is presently insufficient to properly advise veterinarians and pet owners. A cross-sectional study was carried out from January 2010 to December 2010 to determine the prevalence and risk factors associated with FeLV and FIV among domestic cats in peninsular Malaysia. Plasma samples were harvested from the blood of 368 domestic cats and screened for evidence of FeLV p27 antigen and FIV antibodies, using an immunochromatographic kit. Additionally, data on cat demographics and health were collected using a structured questionnaire, and were evaluated as potential risk factors for FeLV or FIV status.

RESULTS

Of the 368 cats that were evaluated in this study, 12.2% (45/368; 95% CI = 8.88 - 15.58) were positive for FeLV p27 antigen, 31.3%, (115/368; 95% CI = 26.51 - 35.99) were seropositive to FIV antibodies, and 4.3% (16/368; 95% CI = 2.27 - 6.43) had evidence of both viruses. Factors found to significantly increase the risk for FeLV seropositivity include sex, age, behaviour, sickness, and living in a multi-cat household. Seropositive response to FIV was significantly associated with sex, neuter status, age, behaviour, and health status.

CONCLUSIONS

The present study indicates that FeLV and FIV are common among domestic cats in peninsular Malaysia, and that factors related to cat demographics and health such as age, sex, behaviour, health status and type of household are important predictors for seropositive status to FeLV or FIV in peninsular Malaysia. High prevalence of FeLV or FIV observed in our study is of concern, in view of the immunosuppressive potentials of the two pathogens. Specific measures for control and prevention such as screening and routine vaccination are needed to ensure that FeLV and FIV are controlled in the cat population of peninsular Malaysia.

True versus false parasite interactions: a robust method to take risk factors into account and its application to feline viruses

Background

Multiple infections are common in natural host populations and interspecific parasite interactions are therefore likely within a host individual. As they may seriously impact the circulation of certain parasites and the emergence and management of infectious diseases, their study is essential. In the field, detecting parasite interactions is rendered difficult by the fact that a large number of co-infected individuals may also be observed when two parasites share common risk factors. To correct for these “false interactions”, methods accounting for parasite risk factors must be used.

Methodology/Principal Findings

In the present paper we propose such a method for presence-absence data (i.e., serology). Our method enables the calculation of the expected frequencies of single and double infected individuals under the independence hypothesis, before comparing them to the observed ones using the chi-square statistic. The method is termed “the corrected chi-square.” Its robustness was compared to a pre-existing method based on logistic regression and the corrected chi-square proved to be much more robust for small sample sizes. Since the logistic regression approach is easier to implement, we propose as a rule of thumb to use the latter when the ratio between the sample size and the number of parameters is above ten. Applied to serological data for four viruses infecting cats, the approach revealed pairwise interactions between the Feline Herpesvirus, Parvovirus and Calicivirus, whereas the infection by FIV, the feline equivalent of HIV, did not modify the risk of infection by any of these viruses.

Conclusions/Significance

This work therefore points out possible interactions that can be further investigated in experimental conditions and, by providing a user-friendly R program and a tutorial example, offers new opportunities for animal and human epidemiologists to detect interactions of interest in the field, a crucial step in the challenge of multiple infections.