Co-infections with respiratory viruses in dogs with bacterial pneumonia

Immunogenicity of a novel inactivated canine adenovirus type 2 variant vaccine for dogs

Purpose

The immunogenicity of vaccines containing the canine adenovirus (CAdV) type 2 (CAdV-2) variant has not yet been reported. We prepared a novel inactivated CAdV-2 variant vaccine using the CAV2232-41 strain, and evaluated its safety and immunogenicity in raccoon dogs.

Materials and Methods

The growth kinetics of CAV2232-41 were determined using Madin-Darby Canine Kidney (MDCK) cells. The nucleotide sequences of CAV2232 and CAV2232-41 were determined by next-generation sequencing. To generate the CAdV-2 variant vaccine, CAV2232-41 propagated in the MDCK cells was inactivated with 0.1% formaldehyde. Two vaccines were prepared by blending inactivated CAV2232-41 with Cabopol and Rehydragel adjuvants. Safety and immunogenicity of the CAV2232C and CAV2232R vaccines were evaluated in guinea pigs. Safety and immunogenicity of the CAV2232C vaccine were also evaluated in raccoon dogs. The virus neutralizing antibody (VNA) titer against CAV2232-41 was measured in sera collected from immunized guinea pigs and raccoon dogs.

Results

CAV2232-41 showed the highest viral titer on days 4-6 post-inoculation and had a deletion in the E3 gene, which was confirmed as a CAdV-2 variant. Guinea pigs inoculated with CAV2232C showed slightly higher VNA titers than those inoculated with CAV2232R 2 weeks after booster vaccination. Raccoon dogs immunized with the CAV2232C vaccine developed high mean VNA titers, while non-vaccinated raccoon dogs were antibody-negative.

Conclusion

The CAV2232C vaccine is safe and induces a protective VNA titer in raccoon dogs.

Rapid diagnosis of canine respiratory coronavirus, canine influenza virus, canine distemper virus and canine parainfluenza virus with a Taqman probe-based multiplex real-time PCR

Canine Infectious Respiratory Disease Complex (CIRDC) is a highly infectious diseases. Canine respiratory coronavirus (CRCoV), Canine influenza virus (CIV), Canine distemper virus (CDV), and Canine parainfluenza virus (CPiV) are crucial pathogens causing CIRDC. Due to the similar clinical symptoms induced by these viruses, differential diagnosis based solely on symptoms can be challenging. In this study, a multiplex real-time PCR assay was developed for detecting the four RNA viruses of CIRDC. Specific primers and probes were designed to target M gene of CRCoV, M gene of CIV, N gene of CDV and NP gene of CPiV. The detection limit is 10 copies/μL for CIV or CRCoV, while the detection limit of CDV or CPiV is 100 copies/μL. Intra-group and inter-group repeatability coefficient of variation (CV) were both less than 2 %. A total of 341 clinical canine samples were analyzed, and the results indicated that the method developed in our study owns a good consistency and better specificity compared with the conventional reverse transcription PCR. This study provides a new method to enable the simultaneous detection of all four pathogens in a single reaction, improving the efficiency for monitoring the prevalence of four viruses in CIRDC, which benefits the control of CIRDC.

Recognition and Diagnosis of Underlying Disease Processes in Bacterial Pneumonia

Bacterial pneumonia can present in both dogs and cats as either acute or chronic disease, and clinical signs may suggest respiratory or systemic impairment. Aspiration pneumonia, a common form of disease, can be caused by esophageal or laryngeal disease, vomiting, or altered mentation, such as with CNS disease or general anesthesia. Bacterial pneumonia can also develop due to inhaled airway foreign bodies, reduced local immune function, or impaired clearance of respiratory secretions. Rapid identification of the etiology and associated risk factors for pneumonia can help veterinarians develop a targeted therapeutic plan and prevent recurrence of disease.

Proposed protocol for utilising high-flow nasal oxygen therapy in treatment of dogs hospitalised due to pneumonia

BACKGROUND

High-flow nasal oxygen (HFNO) therapy is a non-invasive respiratory support method that provides oxygen-enriched, warmed, and humidified air to respiratory-compromised patients. It is widely used in human medical care, but in veterinary medicine it is still a relatively new method. No practical guidelines exist for its use in canine pneumonia patients, although they could potentially benefit from HFNO therapy. This study aims to provide a new, safe, non-invasive, and effective treatment protocol for oxygen supplementation of non-sedated dogs with pneumonia.

METHODS

Twenty privately owned dogs with pneumonia will receive HFNO therapy at a flow rate of 1-2 L/kg, and the fraction of inspired oxygen will be determined individually (ranging from 21% to 100%). HFNO therapy will continue as long as oxygen support is needed based on clinical evaluation. Patients will be assessed thrice daily during their hospitalisation, with measured primary outcomes including partial pressure of oxygen, oxygen saturation, respiratory rate and type, days in hospital, and survival to discharge.

DISCUSSION

The proposed protocol aims to provide a practical guideline for applying HFNO to dogs hospitalised due to pneumonia. The protocol could enable more efficient and well-tolerated oxygenation than traditional methods, thus hastening recovery and improving survival of pneumonia patients.

Development and Validation of a Panel of One-Step Four-Plex qPCR/RT-qPCR Assays for Simultaneous Detection of SARS-CoV-2 and Other Pathogens Associated with Canine Infectious Respiratory Disease Complex

Canine infectious respiratory disease complex (CIRDC) is the primary cause of respiratory disease in the canine population and is caused by a wide array of viruses and bacterial pathogens with coinfections being common. Since its recognition in late 2019, Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) has been reported to cause respiratory disease in dogs. Therefore, the rapid detection and differentiation of SARS-CoV-2 from other common viral and bacterial agents is critical from a public health standpoint. Here, we developed and validated a panel of four one-step multiplex qPCR/RT-qPCR assays for the detection and identification of twelve pathogens associated with CIRDC (canine adenovirus-2, canine distemper virus, canine herpesvirus-1, canine influenza A virus, canine parainfluenza virus, canine pneumovirus, canine respiratory coronavirus, SARS-CoV-2, Bordetella bronchiseptica, Streptococcus equi subsp. zooepidemicus, Mycoplasma cynos, and M. canis), as well as the identification of three main CIV subtypes (i.e., H3N2, H3N8, and H1N1). All developed assays demonstrated high specificity and analytical sensitivity. This panel was used to test clinical specimens (n = 76) from CIRDC-suspected dogs. M. canis, M. cynos, and CRCoV were the most frequently identified pathogens (30.3%, 25.0%, and 19.7% of samples, respectively). The newly emerging pathogens CPnV and SARS-CoV-2 were detected in 5.3% of samples and coinfections were identified in 30.3%. This new multiplex qPCR/RT-qPCR panel is the most comprehensive panel developed thus far for identifying CIRDC pathogens, along with SARS-CoV-2.

The respiratory microbiota and its impact on health and disease in dogs and cats: A One Health perspective

Healthy lungs were long thought of as sterile, with presence of bacteria identified by culture representing contamination. Recent advances in metagenomics have refuted this belief by detecting rich, diverse, and complex microbial communities in the healthy lower airways of many species, albeit at low concentrations. Although research has only begun to investigate causality and potential mechanisms, alterations in these microbial communities (known as dysbiosis) have been described in association with inflammatory, infectious, and neoplastic respiratory diseases in humans. Similar studies in dogs and cats are scarce. The microbial communities in the respiratory tract are linked to distant microbial communities such as in the gut (ie, the gut-lung axis), allowing interplay of microbes and microbial products in health and disease. This review summarizes considerations for studying local microbial communities, key features of the respiratory microbiota and its role in the gut-lung axis, current understanding of the healthy respiratory microbiota, and examples of dysbiosis in selected respiratory diseases of dogs and cats.

Development of a three-panel multiplex real-time PCR assay for simultaneous detection of nine canine respiratory pathogens

Infectious respiratory disease is one of the most common diseases in dogs worldwide. Several bacterial and viral pathogens can serve as causative agents of canine infectious respiratory disease (CIRD), including Mycoplasma cynos, Mycoplasma canis, Bordetella bronchiseptica, canine adenovirus type 2 (CAdV-2), canine herpesvirus 1 (CHV-1), canine parainfluenza virus (CPIV), canine distemper virus (CDV), canine influenza virus (CIA) and canine respiratory coronavirus (CRCoV). Since these organisms cause similar clinical symptoms, disease diagnosis based on symptoms alone can be difficult. Therefore, a quick and accurate test is necessary to rapidly identify the presence and relative concentrations of causative CIRD agents. In this study, a multiplex real-time PCR panel assay was developed and composed of three subpanels for detection of the aforementioned pathogens. Correlation coefficients (R²) were >0.993 for all singleplex and multiplex real-time PCR assays with the exception of one that was 0.988; PCR amplification efficiencies (E) were between 92.1% and 107.8% for plasmid DNA, and 90.6-103.9% for RNA templates. In comparing singular and multiplex PCR assays, the three multiplex reactions generated similar R² and E values to those by corresponding singular reactions, suggesting that multiplexing did not interfere with the detection sensitivities. The limit of detection (LOD) of the multiplex real-time PCR for DNA templates was 5, 2, 3, 1, 1, 1, 4, 24 and 10 copies per microliter for M. cynos, M. canis, B. brochiseptica, CAdV-2, CHV-1, CPIV, CDV, CIA and CRCoV, respectively; and 3, 2, 6, 17, 4 and 8 copies per microliter for CAdV-2, CHV-1, CPIV, CDV, CIA and CRCoV, respectively, when RNA templates were used for the four RNA viruses. No cross-detection was observed among the nine pathogens. For the 740 clinical samples tested, the newly designed PCR assay showed higher diagnostic sensitivity compared to an older panel assay; pathogen identities from selected samples positive by the new assay but undetected by the older assay were confirmed by Sanger sequencing. Our data showed that the new assay has higher diagnostic sensitivity while maintaining the assay's specificity, as compared to the older version of the panel assay.

Are Bordetella bronchiseptica Siphoviruses (Genus Vojvodinavirus) Appropriate for Phage Therapy-Bacterial Allies or Foes?

Bordetella bronchiseptica is a respiratory animal pathogen that shows growing resistance to commonly used antibiotics, which has necessitated the examination of new antimicrobials, including bacteriophages. In this study, we examined the previously isolated and partially characterized B. bronchiseptica siphoviruses of the genus Vojvodinavirus (LK3, CN1, CN2, FP1 and MW2) for their ability to inhibit bacterial growth and biofilm, and we examined other therapeutically important properties through genomic analysis and lysogeny experiments. The phages inhibited bacterial growth at a low multiplicity of infection (MOI = 0.001) of up to 85% and at MOI = 1 for >99%. Similarly, depending on the phages and MOIs, biofilm formation inhibition ranged from 65 to 95%. The removal of biofilm by the phages was less efficient but still considerably high (40–75%). Complete genomic sequencing of Bordetella phage LK3 (59,831 bp; G + C 64.01%; 79 ORFs) showed integrase and repressor protein presence, indicating phage potential to lysogenize bacteria. Lysogeny experiments confirmed the presence of phage DNA in bacterial DNA upon infection using PCR, which showed that the LK3 phage forms more or less stable lysogens depending on the bacterial host. Bacterial infection with the LK3 phage enhanced biofilm production, sheep blood hemolysis, flagellar motility, and beta-lactam resistance. The examined phages showed considerable anti-B. bronchiseptica activity, but they are inappropriate for therapy because of their temperate nature and lysogenic conversion of the host bacterium.

A molecular survey of canine respiratory viruses in New Zealand

AIMS

The aim of this study was to identify viruses associated with canine infectious respiratory disease syndrome (CIRDS) among a population of New Zealand dogs.

METHODS

Convenience samples of oropharyngeal swabs were collected from 116 dogs, including 56 CIRDS-affected and 60 healthy dogs from various locations in New Zealand between March 2014 and February 2016. Pooled samples from CIRDS-affected (n = 50) and from healthy (n = 50) dogs were tested for the presence of canine respiratory viruses using next generation sequencing (NGS). Individual samples (n = 116) were then tested by quantitative PCR (qPCR) and reverse transcriptase qPCR (RT-qPCR) for specific viruses. Groups were compared using Fisher's exact or χ² tests. The effect of explanatory variables (age, sex, type of household, presence of viral infection) on the response variable (CIRDS-affected or not) was tested using RR.

RESULTS

Canine pneumovirus (CnPnV), canine respiratory coronavirus (CRCoV), canine herpesvirus-1 (CHV-1), canine picornavirus and influenza C virus sequences were identified by NGS in the pooled sample from CIRDS-affected but not healthy dogs. At least one virus was detected by qPCR/RT-qPCR in 20/56 (36%) samples from CIRDS dogs and in 23/60 (38%) samples from healthy dogs (p = 0.84). CIRDS-affected dogs were most commonly positive for CnPnV (14/56, 25%) followed by canine adenovirus-2 (CAdV-2, 5/56, 9%), canine parainfluenza virus (CpiV) and CHV-1 (2/56, 4% each), and CRCoV (1/56, 2%). Only CnPnV (17/60, 28%) and CAdV-2 (14/60, 23%) were identified in samples from healthy dogs, and CAdV-2 was more likely to be detected healthy than diseased dogs (RR 0.38; 95% CI = 0.15-0.99; p = 0.045).

CONCLUSIONS

The frequency of detection of viruses traditionally linked to CIRDS (CAdV-2 and CPiV) among diseased dogs was low. This suggests that other pathogens are likely to have contributed to development of CIRDS among sampled dogs. Our data represent the first detection of CnPnV in New Zealand, but the role of this virus in CIRDS remains unclear. On-going monitoring of canine respiratory pathogens by NGS would be beneficial, as it allows rapid detection of novel viruses that may be introduced to the New Zealand canine population in the future. Such monitoring could be done using pooled samples to minimise costs.

CLINICAL RELEVANCE

Testing for novel respiratory viruses such as CnPnV and CRCoV should be considered in all routine laboratory investigations of CIRDS cases, particularly in dogs vaccinated with currently available kennel cough vaccines.

Asymptomatic carriage of canine infectious respiratory disease complex pathogens among healthy dogs

OBJECTIVES

The objectives of this study were to determine the prevalence of canine infectious respiratory disease pathogens among asymptomatic client-owned dogs, and to compare the risks of asymptomatic pathogen carriage between client-owned dogs and dogs in an animal shelter.

MATERIALS AND METHODS

Pooled tonsillar, conjunctival and nasal cavity swabs from asymptomatic client-owned dogs (n=133) were tested using a real-time polymerase chain reaction canine respiratory panel. Identical samples from asymptomatic dogs in an animal shelter (n=295) were similarly tested for selected pathogens. Risk differences were calculated between client-owned dogs and shelter dogs for each of the respiratory pathogens included in the analyses.

RESULTS

A total of 15 of 133 (11.3%) asymptomatic client-owned dogs were positive for at least one pathogen in the complex. Seven dogs (6.1%) were positive for M. cynos, six (5.2%) were positive for B. bronchiseptica, two (1.7%) were positive for canine herpesvirus type 1 and two (1.7%) were positive for canine respiratory coronavirus. For all eight pathogens tested in both groups, the proportion of positive cases was higher among shelter dogs than among client-owned dogs. Shelter dogs had a higher risk for M. cynos (0.18, 95% confidence interval: 0.12 to 0.25), canine respiratory coronavirus (0.15, 95% confidence interval: 0.10 to 0.19), canine distemper virus (0.06, 95% confidence interval: 0.03 to 0.09), and canine pneumovirus (0.05, 95% confidence interval: 0.03 to 0.08) than client-owned dogs. Odds ratios for M. cynos (0.31, 95% confidence interval: 0.08 to 0.92) and canine respiratory coronavirus (0.05, 95% confidence interval: 0.01 to 0.18) were significantly different between client-owned and shelter dogs. In all cases except for canine herpesvirus type 1, dogs within the shelter population were observed to be at higher risk of exhibiting asymptomatic carriage of a respiratory pathogen as compared to client-owned dogs. The strength of this association was strongest for M. cynos and canine respiratory coronavirus.

CLINICAL SIGNIFICANCE

The risk of canine infectious respiratory disease pathogen exposure posed by asymptomatic client-owned dogs is poorly defined. This study also corroborates previous reports of high canine infectious respiratory disease prevalence among clinically healthy shelter dogs, and further determined that the overall prevalence of canine infectious respiratory disease pathogen carriage among clinically healthy client-owned dogs is low but is highest for the traditional pathogen B. bronchiseptica and the emerging pathogen M. cynos.

Molecular detection and whole genome characterization of Canine Parainfluenza type 5 in Thailand

Parainfluenza virus type 5 (PIV-5) causes respiratory infection in several animal species and humans. Canine parainfluenza virus type 5 (CPIV-5) causes respiratory disease in domestic dogs worldwide. In this study, we conducted a cross-sectional survey of CPIV-5 in dogs with respiratory symptoms from small animal hospitals in Thailand from November 2015 to December 2018. Our results showed that 32 out of 571 nasal swab samples (5.6%) were positive for CPIV-5 by RT-PCR specific to the NP gene. To characterize the viruses, three representative CPIV-5 were subjected to whole genome sequencing, and an additional ten CPIV-5 were subjected to HN, F, SH and V/P gene sequencing. Pairwise sequence comparison and phylogenetic analysis showed that Thai CPIV-5 was closely related to the CPIV-5 isolated from China and Korea. In conclusion, this study constitutes a whole genome characterization of CPIV-5 from dogs in Thailand. The surveillance of CPIV-5 should be further investigated at a larger scale to determine the dynamics, distribution and potential zoonotic transmission of CPIV-5.

Factors associated with clinical interpretation of tracheal wash fluid from dogs with respiratory disease: 281 cases (2012-2017)

Background

Clinicians face several dilemmas regarding tracheal washes (TWs) for the diagnosis of respiratory disease, including method and prediction of bacterial growth from cytology results.

Objective

To compare cytology and culture of endotracheal and transtracheal washes and identify factors associated with discordancy and bacterial growth.

Animals

Two hundred forty‐five dogs with respiratory disease.

Methods

Retrospective study. Tracheal wash submissions were included if cellularity was sufficient for cytologic interpretation and aerobic cultures were performed. Collection technique, cytology, bacterial growth, and antibiotic history were analyzed.

Results

Fewer transtracheal specimens (9/144, 6.3%) were excluded for hypocellularity than endotracheal (28/174, 16.1%); otherwise, results were similar and were combined. Of 281 specimens with cellularity sufficient for interpretation, 97 (34.5%) had bacteria on cytology and 191 (68.0%) had bacterial growth. Cytology positive/culture negative discordancy was uncommon (8/97, 8%). Cytology negative/culture positive discordancy was frequent (102/184, 55.4%), but occurred less often (28/184, 14.2%) when only 1+ growth or greater was considered positive. Oropharyngeal contamination was associated with bacterial growth, but not discordancy. No association was found between antibiotic administration and bacterial growth.

Conclusions and Clinical Importance

Endotracheal wash fluid, in particular, should be screened for gross mucus or turbidity to maximize the likelihood of an adequate specimen. Otherwise, endotracheal and transtracheal specimens were similar. Presence of bacteria on cytology was a good predictor of any growth, while their absence was a good predictor of the absence of growth of 1+ or more. Recent antibiotic usage should not discourage TW culture if there is compelling reason to avoid delay.

Occurrence and Predictors of Bacterial Respiratory Tract Infections and Antimicrobial Resistance Among Isolates From Dogs Presented With Lower Respiratory Tract Infections at a Referral Veterinary Hospital in South Africa

Background: Respiratory tract infections (RTIs) associated with Pasteurella multocida, Bordetella bronchiseptica, Streptococci, Staphylococci, and Pseudomonas species have been reported in dogs. The objective of this study was to investigate the occurrence and predictors of bacterial RTIs and antimicrobial resistance among samples from dogs with lower RTIs at a referral veterinary teaching hospital in South Africa.

Methods: Records of 157 dogs with lower RTIs presented to the veterinary teaching hospital between 2007 and 2013 were included in the study. Crude and factor-specific proportions of RTIs and antimicrobial resistance by breed, season, year, sex, age category, and specimen type were computed. Chi-square or Fisher's exact tests were used to compare proportions of RTIs and antimicrobial resistant isolates across categorical variables. Associations between breed, season, year, sex, age, specimen, and odds of RTIs or multidrug resistance were assessed using Generalized Estimating Equations.

Results: There was only one sample per clinical case and bacterial RTIs were observed in 53.5% of the samples tested. Pasteurella species (23.5%) were more common than other species. Almost all (99.5%) isolates were resistant to at least one antimicrobial, while 64.7% were multidrug resistant (MDR). Additionally, 17.0% and 3.3% showed evidence of extensive drug resistance (XDR) and pan-drug resistance (PDR), respectively. The majority of MDR isolates were resistant to penicillin-G (90.9%), lincomycin (100%), tylosine (75.8%), lincospectin (73.7%), ampicillin (72.5%), and kanamycin (68.4%). None of the investigated predictors had significant association with RTIs or antimicrobial resistance.

Conclusion:Pasturella species were the most common causes of RTIs. The high levels of MDR and the presence of both XDR and PDR isolates raise the question of the effectiveness of the current antimicrobial therapy used in patients with RTIs in referral hospitals. Given the high level of resistance observed in this study, it is advisable that the choice of antimicrobials for treatment of RTIs be based on antibiograms. This will ensure use of the most efficacious antimicrobials and will minimize treatment failures among cases presented with RTIs.

Analysis of the lung microbiota in dogs with Bordetella bronchiseptica infection and correlation with culture and quantitative polymerase chain reaction

Infection with Bordetella bronchiseptica (Bb), a pathogen involved in canine infectious respiratory disease complex, can be confirmed using culture or qPCR. Studies about the canine lung microbiota (LM) are recent, sparse, and only one paper has been published in canine lung infection. In this study, we aimed to compare the LM between Bb infected and healthy dogs, and to correlate sequencing with culture and qPCR results. Twenty Bb infected dogs diagnosed either by qPCR and/or culture and 4 healthy dogs were included. qPCR for Mycoplasma cynos (Mc) were also available in 18 diseased and all healthy dogs. Sequencing results, obtained from bronchoalveolar lavage fluid after DNA extraction, PCR targeting the V1–V3 region of the 16S rDNA and sequencing, showed the presence of Bb in all diseased dogs, about half being co-infected with Mc. In diseased compared with healthy dogs, the β-diversity changed (P = 0.0024); bacterial richness and α-diversity were lower (P = 0.012 and 0.0061), and bacterial load higher (P = 0.004). Bb qPCR classes and culture results correlated with the abundance of Bb (r = 0.71, P < 0.001 and r = 0.70, P = 0.0022). Mc qPCR classes also correlated with the abundance of Mc (r = 0.73, P < 0.001). Bb infection induced lung dysbiosis, characterized by high bacterial load, low richness and diversity and increased abundance of Bb, compared with healthy dogs. Sequencing results highly correlate with qPCR and culture results showing that sequencing can be reliable to identify microorganisms involved in lung infectious diseases.

Aetiology of Canine Infectious Respiratory Disease Complex and Prevalence of its Pathogens in Europe

The canine infectious respiratory disease complex (CIRDC) is an endemic worldwide syndrome involving multiple viral and bacterial pathogens. Traditionally, Bordetella bronchiseptica (Bb), canine adenovirus type 2 (CAV-2), canine distemper virus (CDV), canine herpesvirus (CHV) and canine parainfluenza virus (CPiV) were considered the major causative agents. Lately, new pathogens have been implicated in the development of CIRDC, namely canine influenza virus (CIV), canine respiratory coronavirus (CRCoV), canine pneumovirus (CnPnV), Mycoplasma cynos and Streptococcus equi subspecies zooepidemicus. To better understand the role of the different pathogens in the development of CIRDC and their epidemiological relevance in Europe, prevalence data were collected from peer-reviewed publications and summarized. Evidence of exposure to Bb is frequently found in healthy and diseased dogs and client-owned dogs are as likely to be infected as kennelled dogs. Co-infections with viral pathogens are common. The findings confirm that Bb is an important cause of CIRDC in Europe. CAV-2 and CDV recovery rates from healthy and diseased dogs are low and the most likely explanation for this is control through vaccination. Seroconversion to CHV can be demonstrated following CIRDC outbreaks and CHV has been detected in the lower respiratory tract of diseased dogs. There is some evidence that CHV is not a primary cause of CIRDC, but opportunistically re-activates at the time of infection and exacerbates the disease. The currently available data suggest that CIV is, at present, neither a prevalent nor a significant pathogen in Europe. CPiV remains an important pathogen in CIRDC and facilitates co-infection with other viral and bacterial pathogens. CnPnV and CRCoV are important new elements in the aetiology of CIRDC and spread particularly well in multi-dog establishments. M. cynos is common in Europe and is more likely to occur in younger and kennelled dogs. This organism is frequently found together with other CIRDC pathogens and is significantly associated with more severe respiratory signs. S. zooepidemicus infection is not common and appears to be a particular problem in kennels. Protective immunity against respiratory diseases is rarely complete, and generally only a reduction in clinical signs and excretion of pathogen can be achieved through vaccination. However, even vaccines that only reduce and do not prevent infection carry epidemiological advantages. They reduce spread, increase herd immunity and decrease usage of antimicrobials. Recommending vaccination of dogs against pathogens of CIRDC will directly provide epidemiological advantages to the population and the individual dog.

Cross-sectional investigation and risk factor analysis of community-acquired and hospital-associated canine viral infectious respiratory disease complex

Canine infectious respiratory disease complex (CIRDC) is associated with multiple factors. The possible transmission source can be via community-acquired infection (CAI) or hospital-associated infection (HAI), but the variable factors within these two routes are not well described. This study aimed to (i) investigate a cross-sectional incidence of canine respiratory viruses, including influenza (CIV), parainfluenza, distemper (CDV), respiratory coronavirus (CRCoV), adenovirus-2, and herpesvirus, in respiratory-diseased dogs, and (ii) analyze the possibly related risk factors. In total 209 dogs with respiratory illness, consisting of 133 CAI and 76 HAI dogs, were studied. Both nasal and oropharyngeal swabs were sampled from each dog and subjected for CIRDC virus detection using multiplex PCRs. Common six viruses associated with CIRDC were detected in both groups with CIV and CRCoV being predominantly found. Only CDV was significantly more prevalent in CAI than HAI dogs. Multiple virus detections were found in 81.2% and 78.9% of CAI and HAI dogs, respectively. Co-detection of CIV and CRCoV was represented the highest proportion and most often found with other CIRD viruses. Moreover, the clinical severity level was notably related to the age of infected dogs, but not to the vaccination status, sex and transmission route. Since healthy or control dogs were not included in this study, the prevalence of the CIRD virus infections could not be assessed.

Phylogenetic evidence of a novel lineage of canine pneumovirus and a naturally recombinant strain isolated from dogs with respiratory illness in Thailand

BACKGROUND

Canine pneumovirus (CPV) is a pathogen that causes respiratory disease in dogs, and recent outbreaks in shelters in America and Europe have been reported. However, based on published data and documents, the identification of CPV and its variant in clinically symptomatic individual dogs in Thailand through Asia is limited. Therefore, the aims of this study were to determine the emergence of CPV and to consequently establish the genetic characterization and phylogenetic analysis of the CPV strains from 209 dogs showing respiratory distress in Thailand.

RESULTS

This study identified and described the full-length CPV genome from three strains, designated herein as CPV_CP13 TH/2015, CPV_CP82 TH/2016 and CPV_SR1 TH/2016, that were isolated from six dogs out of 209 dogs (2.9%) with respiratory illness in Thailand. Phylogenetic analysis suggested that these three Thai CPV strains (CPV TH strains) belong to the CPV subgroup A and form a novel lineage; proposed as the Asian prototype. Specific mutations in the deduced amino acids of these CPV TH strains were found in the G/glycoprotein sequence, suggesting potential substitution sites for subtype classification. Results of intragenic recombination analysis revealed that CPV_CP82 TH/2016 is a recombinant strain, where the recombination event occurred in the L gene with the Italian prototype CPV Bari/100-12 as the putative major parent. Selective pressure analysis demonstrated that the majority of the nucleotides in the G/glycoprotein were under purifying selection with evidence of positive selection sites.

CONCLUSIONS

This collective information on the CPV TH strains is the first evidence of CPV emergence with genetic characterization in Thailand and as first report in Asia, where homologous recombination acts as a potential force driving the genetic diversity and shaping the evolution of canine pneumovirus.

Detection of selected viral pathogens in dogs with canine infectious respiratory disease in Austria

Objectives

To assess the prevalence of canine parainfluenza virus, canine adenovirus type 2, canine distemper virus, canine respiratory coronavirus and influenza virus A infections in: (1) privately‐owned or, (2) kennelled dogs showing signs consistent with canine infectious respiratory disease and, (3) clinically healthy dogs in Vienna, Austria.

Materials and Methods

Prospectively, nasal and tonsillar swabs from 214 dogs affected with infectious respiratory disease, and 50 healthy control dogs were tested for nucleic acids specific to the various viral infections. Concurrent bronchoalveolar lavage fluid from 31 dogs with chronic respiratory disease was investigated for the same viral pathogens. Additionally, anti‐canine respiratory coronavirus antibody concentrations were measured in paired blood samples from 30 acutely diseased dogs.

Results

Canine respiratory coronavirus (7.5%) and canine parainfluenza virus (6.5%) were the most commonly detected viruses in samples from the upper airways of dogs with respiratory infections. Serological results showed a significant seroconversion in response to coronavirus in 50% of the examined cases. None of the samples was positive for influenza virus A‐specific nucleic acid. Canine coronavirus‐specific nucleic acid was detected in 4.0% of healthy dogs.

Clinical Significance

Canine coronavirus should be considered as a clinically relevant cause of infectious respiratory disease in crowded dog populations. For sample collection, the nasal mucosa can be recommended as the favoured site. Analysis of paired serum samples aids verification of canine coronavirus infection in respiratory disease.

Bronchoalveolar lavage fluid lymphocytosis in 104 dogs (2006-2016)

BACKGROUND

Bronchoalveolar lavage (BAL) fluid cytology and culture are used to characterize respiratory diseases in dogs. Little is known about disorders associated with increased numbers of lymphocytes in BAL fluid.

OBJECTIVE

To evaluate duration of clinical signs and detection of specific respiratory diagnoses in dogs with BAL lymphocytosis.

ANIMALS

One-hundred four client-owned dogs evaluated for respiratory signs.

METHODS

Medical records of dogs that had >300 cells/μL and >20% lymphocytes on a differential cell count of BAL fluid between January 1, 2006, and January 1, 2016, were reviewed retrospectively. Cases were evaluated for the duration of clinical signs and respiratory diagnoses, including aspiration injury, infectious or inflammatory respiratory disease, and airway collapse.

RESULTS

Dogs ranged in age from 0.5 to 16 years (median, 7.9 years) and had a median body weight of 11.4 kg (range, 2.0-42.7 kg). Eosinophilic lung disease was documented in 13 of 104 dogs (Group 1) and airway neutrophilia associated with infectious or inflammatory disease was found in 59 of 104 dogs (Group 2). Lymphocytosis alone in BAL fluid was described in 32 dogs (Group 3). Duration of cough did not differ among groups, but airway collapse was significantly more common in dogs with solitary lymphocytosis than in those with other types of inflammation.

CONCLUSIONS AND CLINICAL IMPORTANCE

Lymphocytosis in BAL fluid is common in dogs and, in many cases, likely represents a common response to airway injury, independent of the type or duration of insult. It is unknown whether airway collapse leads to lymphocytosis or if the inflammatory process causes airway collapse.

Recurrent bacterial pneumonia in Irish Wolfhounds: Clinical findings and etiological studies

BACKGROUND

Increased incidence of bacterial pneumonia (BP) has been reported in Irish Wolfhounds (IWHs), and recurrence of BP is common. The etiology of recurrent pneumonia in IWHs is largely unknown.

OBJECTIVES

To describe clinical findings in IWHs with recurrent BP and investigate possible etiologies.

ANIMALS

Eleven affected IWHs, 25 healthy IWHs, 28 healthy dogs of other Sighthound breeds, and 16 healthy dogs of other breeds.

METHODS

Prospective cross-sectional observational study. All affected IWHs underwent thorough clinical examinations including thoracic radiographs, thoracic computed tomography, electron microscopic evaluation of ciliary structure, and bronchoscopy and bronchoalveolar lavage fluid (BALF) cytology and culture. Serum and BALF immunoglobulin concentrations were measured using an ELISA method, and peripheral blood lymphocyte subpopulations were analyzed using flow cytometry. Esophageal function was assessed by fluoroscopy (n = 2).

RESULTS

Median age of onset was 5.0 years (range, 0.4-6.5 years), and when presented for study, dogs had experienced a median of 5 previous episodes of BP (range, 2-6). The following predisposing factors to BP were detected: focal bronchiectasis (10/11), unilateral (2/9) and bilateral (1/9) laryngeal paralysis, and esophageal hypomotility (2/2). Local or systemic immunoglobulin deficiencies or primary ciliary defects were not detected.

CONCLUSIONS AND CLINICAL IMPORTANCE

Recurrent BP affects mostly middle-aged and older IWHs without any evident immune deficit or primary ciliary defects. Focal BE was a frequent finding in affected dogs and likely contributed to the development of recurrent respiratory infections. Laryngeal and esophageal dysfunction identified in a minority of dogs may contribute to recurrent BP.

Quantitative PCR and Cytology of Bronchoalveolar Lavage Fluid in Dogs with Bordetella bronchiseptica Infection

Background

The use of quantitative PCR (qPCR) for detection of Bordetella bronchiseptica in bronchoalveolar lavage fluid (BALF) and demonstration of bacteria adhering to ciliated epithelial cells in BALF or bronchial brushing fluid (BBF) has not been assessed in a series of affected dogs. Coinfections can worsen the clinical severity in bordetellosis, but the specific association with Mycoplasma cynos has not been evaluated.

Objectives

To assess the utility of culture, qPCR and cytologic examination of cytospin preparations in the diagnosis of bordetellosis in dogs and the influence of coinfection by M. cynos on disease severity.

Animals

Twenty‐four referred dogs with B. bronchiseptica infection and 10 healthy dogs.

Methods

Retrospective case series. qPCR (B. bronchiseptica and M. cynos) and culture results from BALF were recorded. Cytospin preparations from BALF and BBF were reviewed. qPCR on BALF from 10 healthy dogs were used as negative control.

Results

The BALF culture and qPCR detected B. bronchiseptica in 14/24 and 18/18 dogs, respectively. Coccobacilli were found adhering to ciliated epithelial cells in 20 of the 21 BALF cytologic preparations where epithelial cells were found, and 2/3 BBF cytologic preparations. Quantitative PCR detected a low level of B. bronchiseptica in one healthy dog. The frequency of detection of M. cynos was not significantly different in B. bronchiseptica (9/17 dogs) compared with healthy dogs (2/10 dogs) (P = .09).

Conclusion and Clinical Importance

Quantitative PCR detection of B. bronchiseptica in BALF appears to be a useful diagnostic tool. Cytologic examination of BALF or BBF, when positive, allows a rapid and reliable diagnosis.

Antimicrobial use Guidelines for Treatment of Respiratory Tract Disease in Dogs and Cats: Antimicrobial Guidelines Working Group of the International Society for Companion Animal Infectious Diseases

Respiratory tract disease can be associated with primary or secondary bacterial infections in dogs and cats and is a common reason for use and potential misuse, improper use, and overuse of antimicrobials. There is a lack of comprehensive treatment guidelines such as those that are available for human medicine. Accordingly, the International Society for Companion Animal Infectious Diseases convened a Working Group of clinical microbiologists, pharmacologists, and internists to share experiences, examine scientific data, review clinical trials, and develop these guidelines to assist veterinarians in making antimicrobial treatment choices for use in the management of bacterial respiratory diseases in dogs and cats.

Prevalence of respiratory pathogens detected in dogs with kennel cough in Poland

Kennel cough is a multifactorial disease occurring all over the world; however, its epidemiology is still not fully understood. To the authors’ knowledge, no studies monitoring the occurrence of infectious agents responsible for kennel cough have been carried out in Poland. Therefore, the objective of our study was to determine which of the four pathogens most frequently isolated in other countries are predominant in north-eastern Poland. Swabs from the upper respiratory tract and tracheal lavage fluids from dogs (n = 40) exhibiting symptoms of this disease were analysed. Canine herpesvirus, canine parainfluenza virus, canine adenovirus type 2 andBordetella bronchisepticawere identified by polymerase chain reaction. At least one of the above-listed infectious agents was found in all dogs. The predominant pathogen within the area under our study, both in mono- and co-infections, was canine herpesvirus (32/40), whereas canine adenovirus type 2 occurred least frequently (4/40). The effectiveness of detection of selected pathogens from both types of study material was also compared. Tracheal lavage fluid was more suitable for the isolation of canine herpes virus, canine parainfluenza virus, andBordetella bronchiseptica. Swabs from the upper respiratory tract were more suitable for the isolation of canine adenovirus type 2.

The Utility of Acute-Phase Proteins in the Assessment of Treatment Response in Dogs With Bacterial Pneumonia

Background

Acute‐phase proteins (APPs) are sensitive markers of inflammation, and serum C‐reactive protein (CRP) recently has been shown to be a useful diagnostic marker in dogs with bacterial pneumonia (BP). In humans with community‐acquired pneumonia, APPs also have great utility as follow‐up markers aiding in the assessment of treatment response.

Objectives

The aim of our study was to investigate the applicability of APPs as markers of treatment response in dogs with BP.

Animals

Nineteen dogs diagnosed with BP and 64 healthy dogs.

Methods

The study was conducted as a prospective longitudinal observational study. Serum CRP, serum amyloid A (SAA), and haptoglobin concentrations were followed during a natural course of BP. Normalization of serum CRP was used to guide the duration of antibiotic treatment (treatment was stopped 5–7 days after CRP normalized) in 8 of 17 dogs surviving to discharge; 9 of 17 dogs were treated according to conventional recommendations.

Results

All measured APPs initially were significantly increased, but the magnitude of increase was not correlated to disease severity. C‐reactive protein and SAA concentrations decreased rapidly after initiation of antimicrobial treatment. When normalization of serum CRP was used to guide the duration of antibiotic treatment, treatment duration was significantly (P = .015) decreased without increasing the number of relapses.

Conclusions and Clinical Importance

Serum CRP and SAA reflected the recovery process well and therefore may be used as markers of treatment response. According to the results, the normalization of serum CRP may be used to guide the duration of antibiotic treatment in dogs with BP.

THORACIC RADIOGRAPHIC CHARACTERISTICS OF CANINE INFLUENZA VIRUS IN SIX DOGS

Canine influenza virus is an emerging, highly contagious, respiratory pathogen that has not previously been radiographically described. In this retrospective case series study, we describe the thoracic radiographic appearance of confirmed canine influenza virus in six dogs. Radiographic findings varied, but included abnormal unstructured interstitial (one) and unstructured interstitial and alveolar (five) pulmonary patterns, which were distributed cranioventral (four), diffuse (one), and caudodorsal (one). The right middle (five), left cranial (five), and right cranial (four) lung lobes were most commonly affected. Additionally, mild pleural effusion was present in one dog. Intrathoracic lymphadenopathy and cranial mediastinal widening/fluid accumulation were not detected in any dog. Canine influenza virus should be considered as a differential diagnosis for canine patients with respiratory signs and a cranioventral unstructured interstitial to alveolar pulmonary pattern.

Cilia-associated bacteria in fatal Bordetella bronchiseptica pneumonia of dogs and cats

Bordetella bronchiseptica frequently causes nonfatal tracheobronchitis, but its role in fatal pneumonia is less recognized. Our study evaluated histologic identification of cilia-associated bacteria as a method for diagnosis of B. bronchiseptica pneumonia. Cases of fatal bronchopneumonia were studied retrospectively, excluding neonates and cases of aspiration pneumonia, minor lung lesions, or autolysis. The study population comprised 36 canine and 31 feline cases of bronchopneumonia. B. bronchiseptica was identified in 8 of 36 canine and 14 of 31 feline cases based on immunohistochemistry (IHC) using serum from a rabbit hyperimmunized with pertactin, PCR testing (Fla2/Fla12), and/or bacterial culture data when available. Of these, IHC was positive in 4 canine and 7 feline cases, PCR was positive in 8 canine and 14 feline cases, and B. bronchiseptica was isolated in 2 of 5 canine and 3 of 9 feline cases tested. Examination of histologic sections stained with hematoxylin and eosin revealed bronchial cilia-associated bacteria in 4 of 36 canine and 5 of 31 feline cases; these were all positive by IHC and PCR. The presence of cilia-associated bacteria had been noted in the pathology report for only 2 of these 9 cases. Thus, the presence of cilia-associated bacteria seems frequently overlooked by pathologists, but is a diagnostically significant feature of B. bronchiseptica pneumonia. A specific diagnosis of B. bronchiseptica pneumonia is important because it suggests primary or opportunistic bacterial pneumonia rather than aspiration pneumonia, and because of the risk of animal-to-animal transmission of B. bronchiseptica, the availability of vaccines for disease prevention, and the potential zoonotic risk to immunocompromised pet owners.