Feline respiratory disease: what is the role of Mycoplasma species?

Isolation and characterization of Chlamydia felis and its pathogenesis in cats

Feline upper respiratory tract disease (URTD) is a common but complicated disease that occurs in domestic cats, worldwide. 396 cats in Guangxi Province, China were screened for URTD-associated pathogens from March 2022 to August 2023. Mycoplasma felis was found to be the most prevalent infectious agent with a positivity rate of 24.75 %, followed by feline calicivirus (FCV), Chlamydia felis, feline herpesvirus 1 (FHV-1) and feline influenza A virus (FeIAV) with rates of 15.91, 11.62, 5.56 and 1.52 %, respectively. In particular, C. felis and M. felis were found in 13 of 55 co-infected cats. Of the 46 C. felis-positive samples, one strain, named as GXNN36, was successfully isolated using chicken embryos and it was characterized both in vivo and in vitro. For the cat studies, both high- and low-dose challenged groups showed severe conjunctivitis, accompanied by transient fever and respiratory symptoms. C. felis replicated well in turbinate, trachea and lung tissues with high copy numbers and the infection subsequently spread to the livers, spleens, pancreas, kidneys, hearts and intestines. These findings will help our understanding of the role of C. felis in feline URTD and provide a valuable model to evaluate the efficacy of vaccines and therapeutic remedies in the future.

Epidemiological Surveillance of Respiratory Diseases in Urban Stray Cats in Shanghai

Urban stray cats are cats without owners that survive in the wild for extended periods of time. They are one of the most common stray animals in cities, and as such, monitoring the pathogens carried by urban stray cats is an important component of urban epidemiological surveillance. In order to understand the prevalence of respiratory diseases in urban stray cats in Shanghai and provide scientific evidence for the development of targeted prevention and control strategies for respiratory diseases in stray cats, we collected 374 ocular, nasal, and oropharyngeal swabs from urban stray cats in Shanghai from January 2022 to December 2022. After RNA extraction, we used real-time PCR to detect six respiratory pathogens, including influenza A virus, feline calicivirus, feline herpesvirus type 1, Mycoplasma, Chlamydia, and Bordetella bronchiseptica. The results showed that among the 374 samples, 146 tested positive, with a positivity rate of 39.04%. The highest positivity rate was observed for Mycoplasma felis at 18.72% (70/374), followed by Chlamydia felis at 11.76% (44/374), feline calicivirus at 3.74% (14/374), feline herpesvirus 1 at 3.48% (13/374), Bordetella bronchiseptica at 1.34% (5/374), and influenza A virus was not detected. The highest positivity rate for Mycoplasma felis was in Minhang District at 31.94% (23/72), while Chlamydia felis and Bordetella bronchiseptica had the highest positivity rates in Jiading District at 23.53% (8/34) and 5.88% (2/34), respectively. The highest positivity rates for feline calicivirus and feline herpesvirus 1 were both observed in Qingpu District, at 14.46% (12/83) and 9.64% (8/83), respectively. A total of 36 samples showed mixed infections with two or more pathogens, with Mycoplasma felis being involved in 32 of these mixed infections, with the highest number of mixed infections being with Chlamydia felis at 25 samples. Respiratory pathogen positivity was detected throughout the year, with peak detection rates in summer and winter. The positivity rates of cat respiratory pathogens in different seasons showed statistical differences (χ2 = 27.73, p < 0.01). There was no statistical difference in the positivity rates of respiratory pathogens between cats of different genders (χ2 = 0.92, p > 0.05). The positivity rates of respiratory pathogens in cats of different age groups showed statistical differences (χ2 = 44.41, p < 0.01). Mycoplasma felis and Chlamydia felis were the main pathogens causing respiratory infections in stray cats, with Mycoplasma felis showing a much higher positivity rate than other respiratory pathogens and often co-infecting with Chlamydia felis and feline calicivirus. The positivity rate of Mycoplasma felis was high in summer, autumn, and winter, with no statistical difference between seasons. These results indicate a serious overall prevalence of respiratory pathogens in urban stray cats in the Shanghai area, showing seasonal trends and mixed infections with other pathogens. These findings suggest the need for comprehensive prevention and control measures to address respiratory pathogen infections in urban stray cats in the Shanghai area.

Complete genome sequences of Mycoplasma cynos and Mycoplasma felis isolated from dogs and cats with infectious respiratory disease

Mycoplasma cynos is a primary agent of pneumonia in dogs, and Mycoplasma felis is associated with upper respiratory tract disease in cats. We present complete genome sequences of 26 isolates from clinically affected dogs and cats. These genome sequences will facilitate new molecular and epidemiological analyses.

Unveiling genome plasticity and a novel phage in Mycoplasma felis: Genomic investigations of four feline isolates

Mycoplasma felis has been isolated from diseased cats and horses, but to date only a single fully assembled genome of this species, of an isolate from a horse, has been characterized. This study aimed to characterize and compare the completely assembled genomes of four clinical isolates of M. felis from three domestic cats, assembled with the aid of short- and long-read sequencing methods. The completed genomes encoded a median of 759 ORFs (range 743-777) and had a median average nucleotide identity of 98.2 % with the genome of the available equid origin reference strain. Comparative genomic analysis revealed the occurrence of multiple horizontal gene transfer events and significant genome reassortment. This had resulted in the acquisition or loss of numerous genes within the Australian felid isolate genomes, encoding putative proteins involved in DNA transfer, metabolism, DNA replication, host cell interaction and restriction modification systems. Additionally, a novel mycoplasma phage was detected in one Australian felid M. felis isolate by genomic analysis and visualized using cryo-transmission electron microscopy. This study has highlighted the complex genomic dynamics in different host environments. Furthermore, the sequences obtained in this work will enable the development of new diagnostic tools, and identification of future infection control and treatment options for the respiratory disease complex in cats.

[Evaluierung der Langzeittherapie bei Katzen mit felinem Asthma und chronischer Bronchitis]

GEGENSTAND UND ZIEL

Felines Asthma (FA) und chronische Bronchitis (CB) sind häufige entzündliche Erkrankungen der Atemwege der Katze. Obwohl beide Krankheitsbilder durch eine Infiltration mit unterschiedlichen Entzündungszelltypen gekennzeichnet sind, sind die therapeutischen Maßnahmen oft ähnlich. Über mögliche Unterschiede im therapeutischen Management dieser beiden Atemwegserkrankungen ist wenig bekannt. Ziel der Studie war es daher, bei Katzen mit FA und CB die Erst- und Langzeitbehandlung, Therapieerfolg, Nebenwirkungen und Besitzerzufriedenheit zu vergleichen.

MATERIAL UND METHODEN

35 Katzen mit FA und 11 Katzen mit CB wurden in die retrospektive Querschnittstudie eingeschlossen. Einschlusskriterien waren kompatible klinische und radiologische Befunde sowie der zytologische Nachweis einer eosinophilen Entzündung (FA) oder einer sterilen neutrophilen Entzündung (CB) in der bronchoalveolären Lavage-Flüssigkeit (BALF). Katzen mit CB wurden ausgeschlossen, wenn Hinweise auf pathologische Bakterien vorlagen. Besitzer wurden gebeten einen standardisierten Fragebogen zum therapeutischen Management und Ansprechen auf die Behandlung auszufüllen.

ERGEBNISSE

Im Gruppenvergleich wurden keine statistisch signifikanten Unterschiede der Therapie festgestellt. Die meisten Katzen wurden anfänglich mit Kortikosteroiden mittels einer oralen (FA 63%/CB 64%, p=1), inhalativen (FA 34%/CB 55%, p=0,296) oder injizierbaren Applikationsform (FA 20%/CB 0%, p=0,171) behandelt. Zusätzlich wurden in einigen Fällen orale Bronchodilatatoren (FA 43%/CB 45%, p=1) und Antibiotika (FA 20%/CB 27%, p=0,682) verabreicht. In der Langzeittherapie erhielten 43% der Katzen mit FA und 36% der Katzen mit CB inhalative Kortikosteroide (p=1), orale Kortikosteroide (FA 17%/CB 36%, p=0,220) und orale Bronchodilatatoren (FA 6%/CB 27%, p=0,084) sowie phasenweise Antibiotika (FA 6%/CB 18%, p=0,238). Behandlungsbedingte Nebenwirkungen (Polyurie/Polydipsie, Pilzinfektion im Gesicht und Diabetes mellitus) wurden bei 4 Katzen mit FA und 2 Katzen mit CB registriert. Die Mehrheit der Besitzer gab an, mit dem Ansprechen auf die Behandlung äußerst oder sehr zufrieden zu sein (FA 57%/CB 64%, p=1).

SCHLUSSFOLGERUNG

Signifikante Unterschiede hinsichtlich des Managements und des Therapieansprechens konnten bei beiden Erkrankungen laut Besitzerbefragung nicht festgestellt werden.

KLINISCHE RELEVANZ

Laut Besitzerumfrage können chronische Bronchialerkrankungen der Katze wie Asthma und chronische Bronchitis können mit einer ähnlichen Behandlungsstrategie erfolgreich therapiert werden.

Comparison of the respiratory bacterial microbiome in cats with feline asthma and chronic bronchitis

Objectives

While feline chronic bronchitis (CB) is known as neutrophilic bronchial inflammation (NI), feline asthma (FA) is defined as an eosinophilic airway inflammation (EI). Feline chronic bronchial disease refers to both syndromes, with similar clinical presentations and applied treatment strategies. Recent studies described alterations of the microbiota composition in cats with FA, but little is known about the comparison of the lung microbiota between different types of feline bronchial disease. The study aimed to describe the bacterial microbiota of the lower respiratory tracts of cats with FA and CB and to identify potential differences.

Methods

Twenty-two client-owned cats with FA (n = 15) or CB (n = 7) confirmed via bronchoalveolar-lavage (BALF)-cytology were included. Next-generation sequencing analysis of 16S rRNA genes was performed on bacterial DNA derived from BALF samples. QIIME was used to compare microbial composition and diversity between groups.

Results

Evenness and alpha-diversity-indices did not significantly differ between cats with FA and CB (Shannon p = 0.084, Chao 1 p = 0.698, observed ASVs p = 0.944). Based on a PERMANOVA analysis, no significant differences were observed in microbial composition between animals of both groups (Bray-Curtis metric, R-value 0.086, p = 0.785; unweighted UniFrac metric, R-value −0.089, p = 0.799; weighted Unifrac metric, R-value −0.072, p = 0.823). Regarding taxonomic composition, significant differences were detected for Actinobacteria on the phylum level (p = 0.026), Mycoplasma spp. (p = 0.048), and Acinetobacteria (p = 0.049) on the genus level between cats with FA and CB, with generally strong interindividual differences seen. There was a significant difference in the duration of clinical signs before diagnosis in animals dominated by Bacteriodetes (median 12 months, range 2–58 months) compared to animals dominated by Proteobacteria (median 1 month, range 1 day to 18 months; p = 0.003).

Conclusions and relevance

Lung microbiota composition is very similar in cat populations with spontaneous FA and CB besides small differences in some bacterial groups. However, with disease progression, the lung microbiome of cats with both diseases appears to shift away from dominantly Proteobacteria to a pattern more dominated by Bacteriodetes. A substantial proportion of cats tested positive for Mycoplasma spp. via sequencing, while none of them tested positive using classical PCR.

Clinicopathological and Radiological Features of Cats Presented with Infectious Respiratory Disease Signs: A Focus on Rhodococcus equi and Klebsiella pneumoniae

The objective of this study was to evaluate the prevalence of involvement of common viral organisms R. equi and K. pneumoniae and their clinicopathological and radiological features in respiratory disease of Malaysian domestic cats. A total of 34 feline cases with acute/chronic infectious respiratory disease signs were followed prospectively to investigate respiratory disease due to R. equi and K. pneumoniae and their relationship with concurrent viral infections in disease manifestation. All sampled cats (n = 27) were positive for FCoV antibodies and negative for FeLV. A significantly high antibody titer for FCV in n = 26 cases was also noticed. A single sample of pyothorax from a 3-months-old, non-vaccinated kitten was positive for R. equi. Bronchopneumonia with severe infiltration of the polymorphs and mononuclear inflammatory cells were prominent features of lungs histopathology from the kitten positive for R. equi. K. pneumoniae subsp. pneumoniae was confirmed from tracheal swabs of two cats. Histologically, the tracheal tissues of the two cats positive for K. pneumoniae were normal. In diagnostic imaging, epicenter of the infectious URT disease was nasal conchae rostrally and nasal turbinates caudally, however for infectious LRT disease was bronchial tree. Conclusively, infectious respiratory disease is a complex illness in cats, predominantly for unvaccinated kittens and young adult cats, especially those kept in multi-cat household or shelter environments because of the involvement of multiple bacterial and viral organisms as primary or secondary invaders. Clinicians should not preclude feline rhodococcosis from differentials, especially in kittens with pyothorax and less than one year of age. Unlike R. equi, K. pneumoniae has the potential to colonize URT of cats which might be disseminating further to cause LRT disease.

Development of a long-read next generation sequencing workflow for improved characterization of fastidious respiratory mycoplasmas

Mycoplasma cynos and Mycoplasma felis are often associated with canine and feline infectious respiratory disease in dogs and cats, respectively. Mycoplasmas have a reduced genome and dearth of many biosynthetic pathways, making them dependent on rich medium for growth. Due to this fastidious nature, mycoplasmas have been historically underdiagnosed. The aim of this study was to develop a cost-effective and accurate sequencing workflow for genotypic characterization of clinical isolates of M. cynos and M. felis using a rapid long-read sequencing platform. We explored the following critical aspects of bacterial whole genome sequencing, including: (i) five solid and liquid-based culture approaches based on a specialized media formulation for Mycoplasma culture, (ii) three DNA extraction methods modified for long-read sequencing purposes, and (iii) two de novo assembly platforms, Flye and Canu, as key components of a bioinformatics pipeline. DNA extraction method 1, a solid-phase and column-based kit with enzymatic lysis, provided the best DNA quality and concentration followed by high coverage and sequencing contiguity. This was obtained with a culture volume of 45 ml in modified Hayflick's broth incubated for 48 h. DNA extracted directly from colonies on agar or from small broth volumes (6 ml) did not meet the criteria required for long-read sequencing. Overall, Flye generated more contiguous assemblies than the Canu assembler and was more time efficient. This 4-5 day sample-to-sequence workflow provides the scientific and clinical communities with a more comprehensive tool than laborious conventional methods for complete genomic characterization of M. cynos and M. felis clinical isolates.

Respiratory dysbiosis in cats with spontaneous allergic asthma

Deviations from a core airway microbiota have been associated with the development and progression of asthma as well as disease severity. Pet cats represent a large animal model for allergic asthma, as they spontaneously develop a disease similar to atopic childhood asthma. This study aimed to describe the lower airway microbiota of asthmatic pet cats and compare it to healthy cats to document respiratory dysbiosis occurring with airway inflammation. We hypothesized that asthmatic cats would have lower airway dysbiosis characterized by a decrease in richness, diversity, and alterations in microbial community composition including identification of possible pathobionts. In the current study, a significant difference in airway microbiota composition was documented between spontaneously asthmatic pet cats and healthy research cats mirroring the finding of dysbiosis in asthmatic humans. Filobacterium and Acinetobacter spp. were identified as predominant taxa in asthmatic cats without documented infection based on standard culture and could represent pathobionts in the lower airways of cats. Mycoplasma felis, a known lower airway pathogen of cats, was identified in 35% of asthmatic but not healthy cats. This article has been published alongside "Temporal changes of the respiratory microbiota as cats transition from health to experimental acute and chronic allergic asthma" (1).

Feline upper respiratory tract disease – Computed tomography and laboratory diagnostic

Background and Aim: Upper respiratory tract disease (URTD) is prevalent in cats, and diagnosis can be challenging. This study aimed to determine the most common causes of cat URTD in Latvia and describe computed tomography (CT) and laboratory diagnostic findings. Materials and Methods: The present retrospective study included a total of 94 cats who were diagnosed with URTD. All cats underwent CT, and 50 of them had additional diagnostic tests, such as histology and respiratory infection polymerase chain reaction (PCR) testing. Results: The most common CT finding was rhinosinusitis (55.32%) followed by nasal neoplasia (26.6%) and nasopharyngeal polyp (14.89%), but in three cats, a cause of respiratory symptoms was larynx neoplasia, nasal dermoid cyst, and an oronasal fistula. PCR test showed that the most cause of rhinosinusitis was Mycoplasma felis. Nasopharyngeal polyp as the primary diagnosis was identified in 14 cats from 3 months to 6 years, with an average age of 1.85 ± 1.915 years, and 54% of cats were female. Nasal neoplasia as a primary CT diagnosis was determined in 25 cats at the age of 5–18 years, with an average age of 10.56 ± 3.416 years. Histology diagnosis included four types of neoplasia – squamous cell carcinoma, sarcoma, adenocarcinoma, and aplastic carcinoma. Conclusion: This study describes the most common CT and laboratory findings in cats with URTD. Included information will be helpful for general veterinary practitioners and researchers and will update their knowledge on feline URTD.

Investigation of Bacterial Isolations and Antimicrobial Susceptibility of Chronic Rhinitis in Cats

Chronic rhinitis is a quite common upper respiratory tract (URT) disease in cats. As a result of unclear etiology, frequently, multidrug-resistant bacteria are identified. This study investigated bacterial isolations and an antimicrobial susceptibility test (AST) in chronic rhinitis in cats. The medical records of 395 cats with chronic URT signs were reviewed at the Kasetsart University Veterinary Teaching Hospital (KUVTH) between 2016 and 2021 to survey the underlying causes of URT. Then, apart from rhinitis, other causes were excluded to identify the bacterial species and antimicrobial susceptibility. The results indicated that the most frequent finding was neoplasia, followed by rhinitis and anatomical defects. Furthermore, the only significant association was between the age range and disease group, with gender, FIV, or FeLV infection not being significant. Rhinitis was 4.7 times more likely to occur than neoplasia in younger and young adult cats in the age range < 1−3 years compared to the group > 10 years. The main bacterial species was the Pseudomonas species. Antimicrobials with a susceptibility rate of more than 90% were amikacin, gentamicin, ciprofloxacin, norfloxacin, marbofloxacin, imipenem, and meropenem. In conclusion, rhinitis was the second most common chronic URT disease in cats and was more common in younger and young adult cats. The predominant bacteria with AST in this study reflect the antimicrobial resistance situation. Thus, antimicrobial usage should follow antimicrobial use guidelines first.

Frequency of respiratory pathogens and SARS-CoV-2 in canine and feline samples submitted for respiratory testing in early 2020

Objectives

The emergence of the 2019 novel coronavirus (SARS‐CoV‐2) has necessitated evaluation of the potential for SARS‐CoV‐2 infection in dogs and cats. Using a large data set, we evaluated the frequency of SARS‐CoV‐2 and other respiratory pathogens in samples submitted for respiratory testing from mid‐February to mid‐April 2020.

Materials and Methods

A SARS‐CoV‐2 real‐time PCR was developed and validated. A subset of canine and feline samples submitted for respiratory pathogen panel testing to reference laboratories in Asia, Europe, and North America were also tested for SARS‐CoV‐2. The frequency of respiratory pathogens was compared for the February–April period of 2020 and 2019.

Results

Samples from 4616 patients were included in the study and 44% of canine and 69% of feline samples were PCR positive with Mycoplasma cynos and Bordetella bronchiseptica and Mycoplasma felis and feline calicivirus, respectively. No SARS‐CoV‐2 infections were identified. Positive results for respiratory samples were similar between years.

Clinical Significance

The data in this study suggest that during the emergence of the SARS‐CoV‐2 pandemic in early 2020, respiratory diseases in tested pet cats and dogs were caused by common veterinary pathogens and that SARS‐CoV‐2 infections in dogs and cats are rare.

A retrospective study on the presence of selected infectious agents in lung samples of cats with pneumonia

The causative role of some infectious agents found in cases of feline pneumonia is under debate, because they are also part of the physiological microbiota of the respiratory tract of healthy animals. In this retrospective study, archived formalin-fixed and paraffin-wax-embedded lung samples of 69 severe and lethal cases of pneumonia in cats were examined by immunohistochemistry (IHC) for the detection of nine selected infectious agents: Pasteurella multocida, Bordetella bronchiseptica, Mycoplasma felis, M. gateae, Chlamydia felis, feline herpesvirus type 1, feline coronavirus, canine distemper virus, and Toxoplasma gondii. The intention was to elucidate their immediate involvement in pneumonia formation. Due to the cross-reactivity of the applied antibodies, a species-specific polymerase chain reaction (PCR) for both targeted Mycoplasma species was applied additionally. In the 42 cases (60.9%) positive for at least one pathogen, several agents were present in a high proportion of the samples (P. multocida - 34.8%, B. bronchiseptica - 29.0%), while others were present in a moderate (feline herpesvirus type 1 - 18.8%, M. gateae - 13.0%, M. felis - 10.1%) or low percentage (T. gondii - 1.4%). All samples were negative for C. felis, feline coronavirus and canine distemper virus. Mixed infections of up to four pathogens were more frequent than single infections. Mycoplasma preferably colonised lung tissue damaged by other pathogens because they never occurred as single infections. Pasteurella multocida, B. bronchiseptica, M. felis, feline herpesvirus type 1 and T. gondii showed abundant replication within lung lesions, thus suggesting a prominent role in pneumonia formation.

Comparison of signalment, clinical, laboratory and radiographic parameters in cats with feline asthma and chronic bronchitis

OBJECTIVES

Feline asthma (FA) and feline chronic bronchitis (CB) are common respiratory conditions in cats, frequently referred to as 'feline lower airway disease'. However, the aetiologies of both inflammatory airway diseases are probably different. Little is known about the differences in signalment, clinical signs, laboratory abnormalities and radiographic features between cats with these two airway diseases. The aim of the study was to investigate whether certain parameters can help in differentiating between both diseases, as distinguished by airway cytology.

METHODS

Seventy-three cats with FA and 24 cats with CB were included in the retrospective study. Inclusion criteria were compatible clinical signs and a cytological evaluation of bronchoalveolar lavage fluid indicating either FA (eosinophilic inflammation) or CB (neutrophilic inflammation) without cytological or microbiological evidence of bacterial infection. Parameters of signalment, physical examination, haematology and thoracic radiographs of both disease groups were compared statistically (P <0.05).

RESULTS

The median age of cats with FA was 6 years, and was 7.5 years in cats with CB (P = 0.640). The most commonly reported clinical signs in both groups were a cough (95% FA/96% CB; P = 1.000), pathological pulmonary auscultatory sounds (82% FA/79% CB; P = 0.766) and dyspnoea (73% FA/79% CB; P = 0.601). Abnormal radiographic lung patterns were detected in 94% of cats with FA and 91% with CB (P = 0.629), respectively. Blood eosinophilia was significantly more common in cats with FA (40%) compared with CB (27%) (P = 0.026).

CONCLUSIONS AND RELEVANCE

The study indicates that a differentiation of FA and CB by means of signalment, a single clinical sign, and haematological and radiographic findings is not possible.

Feline upper respiratory tract infection and disease in Australia

OBJECTIVES

The aim of this study was to conduct a comprehensive assessment of feline infectious upper respiratory tract infection (URTI) and disease (URTD) in Australian cats.

METHODS

Laboratory data demonstrating URTI from feline URTD multiplex PCR panel (feline herpesvirus 1 [FHV-1], feline calicivirus [FCV], Bordetella bronchiseptica, Chlamydophila felis, Mycoplasma felis and H1N1 influenza) submissions in Australia (2013-2015) were obtained. For comparison, reports of feline URTD during the same time period were sourced from a voluntary companion animal disease surveillance system.

RESULTS

A total of 3126 samples were submitted for testing; 1533 (49%) were positive. Of these, the most commonly detected agents were M felis (21.5%) and FCV (16.0%) alone, followed by FCV and M felis (13.4%) together as a respiratory infection complex, then FHV-1 (7.0%) alone. During the study period, there were 262 reports of 320 clinical feline URTD cases. Most cases (69%) were reported from New South Wales, <1 year of age (41%) and equally distributed between the sexes. Infection was more common in entire cats (69%) and most cases (55%) involved domestic shorthair cats. Of the 90 reports that had a known vaccination status, 63 had a vaccination history, 40 of which were recently vaccinated. Most (72%) feline URTD cases recovered from clinical disease. Both feline URTI and URTD were more common during winter months.

CONCLUSIONS AND RELEVANCE

Feline URTI and URTD cause substantial impact in Australia, being most commonly associated with M felis and FCV infection. This information can be used by veterinarians to educate clients about prevention and management of this important infectious disease of cats.

Activation of upper respiratory tract mucosal innate immune responses in cats by liposomal toll-like receptor ligand complexes delivered topically

BACKGROUND

Nonspecific induction of local innate immune responses by mucosally administered immunotherapy is a new approach to protection from upper respiratory tract infections. Therefore, a new liposome-toll-like receptor complex (LTC) immune stimulant was developed and investigated for its ability to activate innate immune responses in cats, both in vitro and in vivo, as part of an initial evaluation of LTC for use as an immunotherapeutic agent in cats.

OBJECTIVES

We hypothesized that LTC could activate innate immune responses in cats after topical application to nasal and oropharyngeal mucosal surfaces.

ANIMALS

Mucosal immune responses to topical administration of LTC were assessed in 7 healthy, purpose-bred cats, and in vitro responses were assessed using blood samples from healthy cats.

METHODS

Cytokine and cellular immune responses to LTC were evaluated in blood samples, nasal lavage specimens, and pharyngeal swabs from cats, using reverse transcriptase polymerase chain reaction assays, ELISA assays, and flow cytometry.

RESULTS

Liposome-TLR complexes rapidly activated leukocytes in vitro, including upregulation of costimulatory molecule expression and cytokine production. Topical administration of LTC in healthy cats triggered rapid recruitment of monocytes to the nasal and oropharyngeal mucosa.

CONCLUSIONS AND CLINICAL IMPORTANCE

Liposome-TLR complexes were found to effectively activate innate immune responses in cats after mucosal administration. These findings suggest that LTC have potential for use as a new mucosally administered immunotherapy for nonspecific protection from viral and bacterial respiratory tract infections.

A systematic review and meta-analysis of the association between Mycoplasma spp and upper and lower respiratory tract disease in cats

OBJECTIVE To critically assess available data from controlled observational studies on the pathogenic role of Mycoplasma spp in the upper respiratory tract (URT) and lower respiratory tract (LRT) of cats. DESIGN Systematic review and meta-analysis. SAMPLE 12 studies. PROCEDURES Seven electronic databases were searched for relevant publications. Risk of bias was assessed via the Newcastle-Ottawa Scale. Meta-analyses, stratified by URT versus LRT disease, were performed to estimate pooled ORs and 95% confidence intervals (CIs) for the association between Mycoplasma isolation and URT or LRT disease. Subanalyses by diagnostic method, sampling site, and environment (shelter vs nonshelter) were planned for studies on URT disease. RESULTS A significant association was found between isolation of mycoplasmal organisms and URT disease (pooled OR, 1.65; 95% CI, 1.14 to 2.40) but not LRT disease (pooled OR, 1.56; 95% CI, 0.51 to 4.76). The association with URT disease was only significant when conjunctival or pharyngeal samples from nonshelter cats were analyzed with a Mycoplasma felis-specific PCR assay. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that M felis may be a primary pathogen in cats with URT disease, warranting treatment in infected cats. The environment was important to consider when interpreting a mycoplasma-positive sample because of aclinical carriage, especially in shelter cats. Further investigations are needed to determine the role, if any, of mycoplasmal organisms in LRT disease of cats.

Bacterial Diversity in Feline Conjunctiva Based on 16S rRNA Gene Sequence Analysis: A Pilot Study

Changes in the microbial populations in the conjunctival sacs of animals have traditionally been evaluated using conventional microbiology techniques. The goal of this study was to examine the suitability of a methodology which may reveal a previously unknown microbiome inhabiting feline conjunctival membranes. In the present study, we determined the microbial diversity in feline conjunctivas based on 16S rRNA gene sequence analysis. Five taxa not described earlier in veterinary ophthalmology (i.e., Staphylococcus caprae, Staphylococcus succinus, Propionibacterium acnes, Psychrobacter faecalis, and Bacillus subtilis) were identified in feline conjunctivas with a high similarity (99-100%). The study demonstrates that the feline conjunctival sacs are inhabited by much more rich and diverse microbial communities than previously thought using culture-based methods. From the clinical perspective, this could suggest that other laboratory procedures (e.g., extended incubation time in the case of Actinobacteria, formerly order Actinomycetales) or a new tool like culture-independent approaches (next-generation DNA sequencing) should be taken into account.

Prevalence of feline herpesvirus-1, feline calicivirus, Chlamydophila felis and Mycoplasma felis DNA and associated risk factors in cats in Spain with upper respiratory tract disease, conjunctivitis and/or gingivostomatitis

Objectives Our objective was to perform the first multicentric study in Spain to evaluate the prevalence of feline herpesvirus-1 (FHV-1), feline calicivirus (FCV), Chlamydophila felis and Mycoplasma felis in cats with upper respiratory tract disease (URTD), conjunctivitis and/or gingivostomatitis (GS) compared with control cats; and to evaluate risk factors for these clinical conditions. Methods Conjunctival and oropharyngeal swabs were collected and a questionnaire regarding signalment, lifestyle, vaccination history and clinical signs was obtained for each cat. Swabs were tested for each pathogen by real-time PCR. Results The study population consisted of 358 cats, including 98 control cats. Among the 260 diseased cats, 127 cats presented with URTD, 149 cats had conjunctivitis, 154 cats were suffering GS; many cats presented more than one clinical condition. The prevalence observed of FHV-1, FCV, C felis and M felis was, respectively, 28.3%, 48.0%, 20.5% and 46.5% in cats with URTD; 24.2%, 43.6%, 19.5% and 38.3% in cats with conjunctivitis; and 15.6%, 58.4%, 9.1% and 37.7% in cats with GS. Prevalences in the control group were 6.1%, 15.3%, 2.0% and 20.4%, respectively. Coinfections were common among all groups of cats. Risk factors were identified for all groups. FHV-1, FCV and C felis were associated with URTD and conjunctivitis. FCV was strongly associated with GS. M felis was present in a high percentage of the population in all groups, but its role in these clinical conditions remains uncertain. Vaccination was protective for URTD and GS but not for conjunctivitis. Conclusions and relevance This epidemiological study describes, for the first time, prevalence for FHV-1, FCV, C felis and M felis in Spain. In general, the prevalences found are similar to those reported in other countries. Factors associated with disease expression were also identified, which are relevant for practitioners.