Detection of respiratory viruses and Bordetella bronchiseptica in dogs with acute respiratory tract infections

Genomic analysis of canine pneumoviruses and canine respiratory coronavirus from New Zealand

AIMS

To isolate canine respiratory coronavirus (CRCoV) and canine pneumovirus (CnPnV) in cell culture and to compare partial genomic sequences of CRCoV and CnPnV from New Zealand with those from other countries.

METHODS

Oropharyngeal swab samples from dogs affected by canine infectious respiratory disease syndrome that were positive for CnPnV (n = 15) or CRCoV (n = 1) by virus-specific reverse transcriptase quantitative PCR (RT-qPCR) in a previous study comprised the starting material. Virus isolation was performed in HRT-18 cells for CRCoV and RAW 264.7 and Vero cells for CnPnV. The entire sequence of CnPnV G protein (1,266 nucleotides) and most (8,063/9,707 nucleotides) of the 3' region of CRCoV that codes for 10 structural and accessory proteins were amplified and sequenced. The sequences were analysed and compared with other sequences available in GenBank using standard molecular tools including phylogenetic analysis.

RESULTS

Virus isolation was unsuccessful for both CRCoV and CnPnV. Pneumovirus G protein was amplified from 3/15 (20%) samples that were positive for CnPnV RNA by RT-qPCR. Two of these (NZ-048 and NZ-049) were 100% identical to each other, and 90.9% identical to the third one (NZ-007). Based on phylogenetic analysis of the G protein gene, CnPnV NZ-048 and NZ-049 clustered with sequences from the USA, Thailand and Italy in group A, and CnPnV NZ-007 clustered with sequences from the USA in group B. The characteristics of the predicted genes (length, position) and their putative protein products (size, predicted structure, presence of N- and O-glycosylation sites) of the New Zealand CRCoV sequence were consistent with those reported previously, except for the region located between open reading frame (ORF)3 (coding for S protein) and ORF6 (coding for E protein). The New Zealand virus was predicted to encode 5.9 kDa, 27 kDa and 12.7 kDa proteins, which differed from the putative coding capacity of this region reported for CRCoV from other countries.

CONCLUSIONS

This report represents the first characterisation of partial genomic sequences of CRCoV and CnPnV from New Zealand. Our results suggest that the population of CnPnV circulating in New Zealand is not homogeneous, and that the viruses from two clades described overseas are also present here. Limited conclusions can be made based on only one CRCoV sequence, but the putative differences in the coding capacity of New Zealand CRCoV support the previously reported variability of this region. The reasons for such variability and its biological implications need to be further elucidated.

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.

Comparative structural and immunological analysis of outer membrane proteins and dermonecrotic toxin in Bordetella bronchiseptica canine isolate

Bordetella bronchiseptica is a pathogen causing respiratory infections in mammals. With the improving understanding of companion animals' welfare, addressing the side effects of bordetella vaccine gains importance in dogs. Studies on diverse subunit vaccines are actively pursued in humans to safely and effectively control bordetellosis. Therefore, our objective was to develop a canine bordetella vaccine inspired by human vaccine development. We evaluated the immunogenicity of the two bacterial components: the outer membrane proteins (OMPs) and the dermonecrotic toxin (DNT) from a canine isolate of B. bronchiseptica. In-silico analysis identified eight domains of DNT, and Domain 3 was selected as the most promising antigen candidate. Additionally, the OMPs were extracted and examined using SDS-PAGE and Western blot analysis. The distinct immunological characteristic of OMPs and DNT-3 were examined individually and in combination. Gene expression and cytokine production were also evaluated in DH82 cells after stimulation with those antigens. Treatment with OMPs resulted in higher level of Th1 related cytokines, while DNT-3 induced a predominant response associated with Th17 and Th2 in the cytokine production. Synergistic effects were observed exclusively on IL-23, indicating increase of a potential risk of side effects when OMPs and DNT act together. These findings provide valuable insights into the reactogenicity of conventional Bordetella vaccines. Further, the presented preclinical data in this study offer an alternative method of the development for an optimal next-generation Bordetella vaccine for companion animals and humans, replacing the acellular vaccines containing both toxin and protein components.

Effect of carbohydrates on the adhesion of Bordetella bronchiseptica to the respiratory epithelium in rabbits

This study proposes an ecological approach for preventing respiratory tract infections caused by Bordetella bronchiseptica in mammals using a mixture of carbohydrates. In an in vivo study, 51-day-old New Zealand rabbits were treated with a solution containing 1 × 107 CFUs of B. bronchiseptica and 250 μg of one of the following carbohydrates: N acetylglucosamine (GlcNAc), N acetylgalactosamine (GalNAc), alpha methyl mannose (AmeMan), alpha methyl glucose (AmeGlc) and sialic acid (Neu5AC). Positive (B. bronchiseptica) and negative (Physiological Saline Solution (PSS)) controls were included. Animals treated with GlcNAc or AmeGlc showed no clinical signs of infection and exhibited a significant reduction (p < 0.05) in the severity of microscopic lesions evaluated in the nasal cavity and lung compared with the positive controls. Additionally, the presence of bacteria was not detected through microbiological isolation or PCR in the lungs of animals treated with these sugars. Use of a mixture of GlcNAc and AmeGlc resulted in greater inhibition of microscopic lesions, with a significant reduction (p < 0.05) in the severity of these lesions compared to the results obtained using individual sugars. Furthermore, the bacterium was not detected through microbiological isolation, Polymerase Chain Reaction (PCR) or indirect immunoperoxidase (IIP) in this group.

Investigation of circulating infectious agents in experimental Beagle dogs of a production colony and three research facilities in China from June 2021 to May 2022

To understand the epizootiologic characteristics of pathogens and opportunistic infections in one Beagle dog production colony and three research facilities, viruses and mycoplasma were detected in 1777 samples collected from Beagle dogs in China by polymerase chain reaction/reverse transcription polymerase chain reaction, and bacteria were isolated and identified by 16S rRNA sequence analysis. In addition, genotyping of the major circulating viruses was carried out by amplification of gene fragments and homology analysis. Canine coronavirus (CCoV), Escherichia coli, canine parvovirus (CPV), Bordetella bronchiseptica, Clostridium perfringens, Mycoplasma cynos, Klebsiella pneumoniae, Streptococcus canis, canine astrovirus (CaAstV), canine kobuvirus (CaKV), Pseudomonas aeruginosa, Proteus mirabilis, Macrococcus canis, Pasteurella canis, canine bocavirus (CBoV) and canine adenovirus (CAdV) were detected in the samples. Single, double, triple and quadruple infections accounted for 6.6%, 1.4%, 1.2% and 0.96% of samples, respectively. CCoV strains in 81 samples included three genotypes, CCoV-I, CCoV-IIa and CCoV-IIb, by analysis of S gene. The rate of single infection of CCoV-I, CCoV-IIa or CCoV-IIb was 19%, 38% or 7.4% respectively. The double and triple infection rates of CCoV were 32.8% and 2.5% respectively. All CPV strains in 36 samples belonged to CPV-2c. There were three amino acid differences in the Fiber protein of CAdV-positive sample QD2022, compared with the reference strain Toronto A26/61 and the vaccine strain YCA-18. These results suggest that CCoV and CPV are primary infectious agents, and that these two viruses were often identified in mixed infections, or coinfections alongside mycoplasma or other bacteria. These results will provide the basis for improvements in prevention and control of naturally occurring infectious diseases in Beagle dog production colonies and research facilities.

Predominance of Canine Parainfluenza Virus and Mycoplasma in Canine Infectious Respiratory Disease Complex in Dogs

Canine infectious respiratory disease complex (CIRDC) is caused by different viruses and bacteria. Viruses associated with CIRDC include canine adenovirus type 2 (CAV-2), canine distemper virus (CDV), canine influenza virus (CIV), canine herpesvirus type 1 (CHV-1), canine respiratory coronavirus (CRCoV), and canine parainfluenza virus (CPIV). Bacteria associated with CIRDC include Bordetella bronchiseptica, Streptococcus equi subspecies zooepidemicus (S. zooepidemicus), and Mycoplasma spp. The present study examined the prevalence of CIRDC pathogens in specimens received by a Veterinary Diagnostic Laboratory in Georgia, USA., from 2018 to 2022. Out of 459 cases, viral agents were detected in 34% of cases and bacterial agents were detected in 58% of cases. A single pathogen was detected in 31% of cases, while two or more pathogens were identified in 24% of cases. The percentages of viral agents identified were CAV-2 (4%), CDV (3%), CPIV (16%), CRCoV (7%), and CIV (2%). The percentages of bacterial agents were B. bronchiseptica (10%), Mycoplasma canis (24%), Mycoplasma cynos (21%), and S. zooepidemicus (2%). Over the five-year period, the positive cases ranged from 2-4% for CAV-2, 1-7% for CDV, 1-4% for CHV-1, 9-22% for CPIV, 4-13% for CRCoV, and 1-4% for CIV. Overall, the most prevalent pathogens associated with CIRDC were CPIV, M. canis, and M. cynos.

Bordetella bronchiseptica and Bordetella pertussis: Similarities and Differences in Infection, Immuno-Modulation, and Vaccine Considerations

Bordetella pertussis and Bordetella bronchiseptica belong to the genus Bordetella, which comprises 14 other species. B. pertussis is responsible for whooping cough in humans, a severe infection in children and less severe or chronic in adults. These infections are restricted to humans and currently increasing worldwide. B. bronchiseptica is involved in diverse respiratory infections in a wide range of mammals. For instance, the canine infectious respiratory disease complex (CIRDC), characterized by a chronic cough in dogs. At the same time, it is increasingly implicated in human infections, while remaining an important pathogen in the veterinary field. Both Bordetella can evade and modulate host immune responses to support their persistence, although it is more pronounced in B. bronchiseptica infection. The protective immune responses elicited by both pathogens are comparable, while there are important characteristics in the mechanisms that differ. However, B. pertussis pathogenesis is more difficult to decipher in animal models than those of B. bronchiseptica because of its restriction to humans. Nevertheless, the licensed vaccines for each Bordetella are different in terms of formulation, route of administration and immune responses induced, with no known cross-reaction between them. Moreover, the target of the mucosal tissues and the induction of long-lasting cellular and humoral responses are required to control and eliminate Bordetella. In addition, the interaction between both veterinary and human fields are essential for the control of this genus, by preventing the infections in animals and the subsequent zoonotic transmission to humans.

In Vitro Characteristics of Canine Primary Tracheal Epithelial Cells Maintained at an Air-Liquid Interface Compared to In Vivo Morphology

Culturing respiratory epithelial cells at an air-liquid interface (ALI) represents an established method for studies on infection or toxicology by the generation of an in vivo-like respiratory tract epithelial cellular layer. Although primary respiratory cells from a variety of animals have been cultured, an in-depth characterization of canine tracheal ALI cultures is lacking despite the fact that canines are a highly relevant animal species susceptible to various respiratory agents, including zoonotic pathogens such as severe acute respiratory coronavirus 2 (SARS-CoV-2). In this study, canine primary tracheal epithelial cells were cultured under ALI conditions for four weeks, and their development was characterized during the entire culture period. Light and electron microscopy were performed to evaluate cell morphology in correlation with the immunohistological expression profile. The formation of tight junctions was confirmed using transepithelial electrical resistance (TEER) measurements and immunofluorescence staining for the junctional protein ZO-1. After 21 days of culture at the ALI, a columnar epithelium containing basal, ciliated and goblet cells was seen, resembling native canine tracheal samples. However, cilia formation, goblet cell distribution and epithelial thickness differed significantly from the native tissue. Despite this limitation, tracheal ALI cultures could be used to investigate the pathomorphological interactions of canine respiratory diseases and zoonotic agents.

Gastrointestinal helminths increase Bordetella bronchiseptica shedding and host variation in supershedding

Co-infected hosts, individuals that carry more than one infectious agent at any one time, have been suggested to facilitate pathogen transmission, including the emergence of supershedding events. However, how the host immune response mediates the interactions between co-infecting pathogens and how these affect the dynamics of shedding remains largely unclear. We used laboratory experiments and a modeling approach to examine temporal changes in the shedding of the respiratory bacterium Bordetella bronchiseptica in rabbits with one or two gastrointestinal helminth species. Experimental data showed that rabbits co-infected with one or both helminths shed significantly more B. bronchiseptica, by direct contact with an agar petri dish, than rabbits with bacteria alone. Co-infected hosts generated supershedding events of higher intensity and more frequently than hosts with no helminths. To explain this variation in shedding an infection-immune model was developed and fitted to rabbits of each group. Simulations suggested that differences in the magnitude and duration of shedding could be explained by the effect of the two helminths on the relative contribution of neutrophils and specific IgA and IgG to B. bronchiseptica neutralization in the respiratory tract. However, the interactions between infection and immune response at the scale of analysis that we used could not capture the rapid variation in the intensity of shedding of every rabbit. We suggest that fast and local changes at the level of respiratory tissue probably played a more important role. This study indicates that co-infected hosts are important source of variation in shedding, and provides a quantitative explanation into the role of helminths to the dynamics of respiratory bacterial infections.

Comparison of sensitization patterns to dust mite allergens between atopic dermatitis patients and dogs, and non-specific reactivity of canine IgE to the storage mite Tyrophagus putrescentiae

House dust mite is a common cause of atopic dermatitis (AD) both in humans and dogs. Detection of serum IgE to allergens is commonly used to diagnose allergic diseases. However, false-positive reactions due to cross-reactivity and non-specific reactivity may lead to misdiagnosis. We compared human and canine IgE reactivities to mite component allergens. Canine IgE-reactive components of Dermatophagoides farinae and Tyrophagus putrescentiae were identified by tandem mass spectrometry. Recombinant proteins were produced and IgE reactivities to component allergens were assessed by ELISA and inhibition assays using sera from AD patients and dogs. Canine IgE-reactive proteins (Der f 1, Der f 11, Tyr p 4, Tyr p 8, Tyr p 11, Tyr p 28) were identified by proteome analysis. Most patients were sensitized to Der f 1 (93.3%) and Der f 2 (86.7%). Dogs showed high sensitization to Der f 2 (94.1%) and Der f 18 (84.6%). Both patients and dogs showed low IgE binding frequency to Tyr p 8, 43.3% and 4%, respectively. The ELISA inhibition study indicated that canine IgE reactivity to T. putrescentiae is mostly due to non-specific reaction and cross-reaction with D. farinae. Different IgE sensitization patterns were shown between allergic humans and dogs with AD, especially to Der f 18, for the first time in Korea. Furthermore, non-specific canine IgE reactivity to storage mite indicates the possibility of misdiagnoses. Standardizations focused on the major canine allergen content of extracts should be developed. This will allow precision diagnosis and individuated treatments for each patient and atopic dog.

Canine Parainfluenza Virus Infection in a Dog with Acute Respiratory Disease

Simple Summary

A one-day history of dry paroxysmal cough, associated with retching, induced by canine parainfluenza virus without the simultaneous presence of other pathogens, has been reported in a vaccinated household dog. The dog did not show nasal discharge or fever, but it was possible to evoke a dry cough through the palpation of the trachea. Radiographic findings of the thorax showed a diffuse unstructured interstitial pattern with the involvement of multiple lung lobes. Trachea-bronchoscopy and broncho-alveolar lavage were carried out. Edema without exudate and congested mucosa from the larynx to bronchi were observed. Cytological evaluation was negative for the presence of inflammatory or infectious processes. Nucleic acids were extracted from the collected specimens; biomolecular investigations tested positive only for canine parainfluenza virus and negative for all other pathogens associated with “kennel cough”. At first, the afebrile onset and the coughing fits suggested the presence of a foreign body, a common occurrence in Southern Italy during summer. The clinical signs and the absence of findings by cytology have directed the clinicians towards the correct diagnosis, with the support of biomolecular assays, which are fundamental to avoid underestimating the circulation of this virus, even in owned dogs.

Abstract

The canine infectious respiratory disease complex (CIRDC) is an endemic respiratory syndrome caused by different bacterial and viral pathogens. This report describes a case of canine parainfluenza virus infection in a vaccinated household dog with an acute respiratory symptom (dry cough), who underwent clinical and endoscopic investigations for a suspected foreign body. Cytological investigations carried out on the broncho-alveolar lavage fluid (BALF) tested negative for the presence of inflammatory or infectious processes and could have been misleading the clinicians. By the molecular analyses (PCR) carried out on the BALF, canine parainfluenza virus was exclusively detected without the simultaneous presence of other respiratory pathogens associated to CIRDC. This case report emphasizes the role of molecular diagnostics in the differential diagnosis of respiratory diseases, in order to avoid underestimating the circulation of the parainfluenza virus in the canine population.

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.

[Role of systemic infections in canine kidney diseases]

Kidney diseases represent a common problem as well as a frequent cause of death in dogs. Infectious agents may be responsible for glomerulopathies and acute kidney injuries. Many infections commonly associated with the development of immune complex glomerulonephritis in central and southern Europe are important as travel-associated diseases in Germany. These include leishmaniosis, dirofilariosis, and ehrlichiosis. Rarely, anaplasmosis, hepatozoonosis, Lyme disease as well as babesiosis caused by small Babesia spp. are detected as cause of canine immune complex glomerulonephritis in Germany. Leptospirosis, canine infectious hepatitis, and babesiosis caused by large Babesia spp. may be responsible for the development of acute kidney injuries associated with tubulointerstitial nephritis. Therefore, further diagnostics aiming at identifying potentially causative infectious agents in dogs with renal disease is important for both prognosis and therapy of the patient.

Identification of Bordetella bronchiseptica in the throat and nose of dogs and cats by PCR

B.bronchiseptica is pathogenic for some domestic and wild animals. Due to the importance of this bacterium, its presence in dogs and cats has been investigated using PCR. Pharyngeal and nasal swabs were taken from 135 dogs and 42 cats. Based on the PCR performed on the dogs' samples, in 25/63 (39.68%) pharyngeal samples and 20/59 (33.89%) nasal samples DNA of B. bronchiseptica detected. On the other hand, according to the PCR performed on the cats' samples, in 9/23 (39.13%) pharyngeal samples and 319 (15.78%) nasal samples DNA of B. bronchiseptica was existed. According to the present study, the rate of B. bronchiseptica infection is high among dogs and cats in Iran. Also, due to the fact that the prevalence of this bacterium among pets animals is not exactly known in Iran, necessary measures should be taken for rapid diagnosis and treatment and proper control of the infection.

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.

A multipronged next-generation sequencing metabarcoding approach unearths hyperdiverse and abundant dog pathogen communities in Cambodia

Recent surveys in Southeast Asia, including Cambodia, have identified canine vector-borne pathogens (VBPs), including those with zoonotic potential, as highly prevalent. The lack of veterinary care alongside the close association semidomesticated dogs have with humans in the region exacerbates these zoonotic risks. Nonetheless, the number of studies investigating such pathogens and the threats they pose to dog and human health is limited. Here, we utilize a next-generation sequencing (NGS)-based metabarcoding protocol to conduct an assumption-free characterization of the bacterial, apicomplexan, and kinetoplastid blood-borne pathogens of free-roaming dogs from across Cambodia. From 467 dogs at five field sites, 62% were infected with one of eight confirmed pathogens, comprising Anaplasma platys (32%), Ehrlichia canis (20%), Hepatozoon canis (18%), Babesia vogeli (14%), Mycoplasma haemocanis (13%), the zoonotic pathogen Bartonella clarridgeiae (3%), Candidatus Mycoplasma haematoparvum (0.2%), and Trypanosoma evansi (0.2%). Coinfections of between two and four VBPs were common with 28% of dogs found to have a mixed infection. Moreover, DNA from putatively infectious agents belonging to the bacterial family and genera Coxiella, Mycobacterium, Neisseria, Rickettsiaceae, Treponema, and two uncharacterized Mycoplasma species were identified, in addition to protozoan genera Colpodella, Parabodo, and Bodo. Using a multiple logistic regression model, the presence of ectoparasites, abnormal mucous membranes, anemia, and total protein were found as predictors of canine VBP exposure. This study represents the first time an NGS metabarcoding technique has been used to holistically detect the bacterial and protozoan hemoparasites communities of dogs through an in-depth survey, highlighting the power of such methods to unearth a wide spectrum of pathogenic organisms in an unbiased manner.

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.

Prevalence of Neutralizing Antibodies to Canine Distemper Virus and Response to Vaccination in Client-Owned Adult Healthy Dogs

Re-vaccinations against canine distemper virus (CDV) are commonly performed in 3-year intervals. The study's aims were to determine anti-CDV antibodies in healthy adult dogs within 28 days of vaccination against CDV, and to evaluate factors associated with the presence of pre-vaccination antibodies and with the antibody response to vaccination. Ninety-seven dogs, not vaccinated within 1 year before enrollment, were vaccinated with a modified live CDV vaccine. A measurement of the antibodies was performed before vaccination (day 0), on day 7, and 28 after the vaccination by virus neutralization. A response to vaccination was defined as a ≥4-fold titer increase by day 28. Fisher's exact test was used to determine factors associated with a lack of antibodies and vaccination response. In total, 94.8% of the dogs (92/97; CI 95%: 88.2-98.1) had antibodies (≥10) prior to vaccination. A response to vaccination was not observed in any dog. Five dogs were considered humoral non-responders; these dogs neither had detectable antibodies before, nor developed antibodies after vaccination. Young age (<2 years) was significantly associated with a lack of pre-vaccination antibodies (p = 0.018; OR: 26.825; 95% CI: 1.216-1763.417). In conclusion, necessity of re-vaccination in adult healthy dogs should be debated and regular vaccinations should be replaced by antibody detection.

Molecular characterization of canine adenovirus type 2 in dogs from India

A total of 26 nasal swab samples were collected from dogs with gastroenteritis and respiratory tract infections in and around Chennai, India during 2019–20. All the samples were subjected to PCR using common primers for rapid diagnosis and differentiation of CAV1 and CAV2. Only one sample produced an amplicon of 1030 bp indicating the presence of CAV2 which was confirmed by further sequencing. The analysis of the sequence revealed 100 per cent identity with other CAV type 2 isolates from Brazilian, Canadian and USA strains and 95.9 per cent identity with other Indian CAV2 strains. The phylogenetic analysis of E3 gene reveal two distinct clusters (Asian and America-Europe subgroup) in which our strain (ABT/MVC/CAV2/001) grouped with CAV2 of America-Europe subgroup instead of Asian continent subgroup.This study confirms a novel CAV2 strain using molecular techniques which are genetically distinct in nature from other Indian CAV2 strains that is currently circulating in India.

Comparison of C-reactive protein concentrations in dogs with Bordetella bronchiseptica infection and aspiration bronchopneumonia

BACKGROUND

C-reactive protein (CRP) is a well-known acute-phase protein in dogs that may discriminate bacterial bronchopneumonia from other pulmonary conditions. Bronchopneumonia caused by Bordetella bronchiseptica (Bb) is common but the associated increase in CRP concentration in naturally infected dogs has not been fully explored.

OBJECTIVE

To compare CRP concentrations of dogs with Bb infection, with or without radiographic pulmonary lesions, to dogs with aspiration bronchopneumonia (ABP).

ANIMALS

Sixteen dogs with Bb infection and 36 dogs with ABP.

METHODS

Retrospective study. C-reactive protein concentrations and thoracic radiographs were available for each dog.

RESULTS

Eleven dogs with Bb infection had alveolar lesions. In all dogs, CRP concentration was mildly increased (14-38 mg/L). In the 5 dogs without alveolar lesions, CRP concentration was within the reference range in all but 1 dog, in which it was slightly increased. Median CRP concentration was significantly higher in dogs with alveolar lesions (20 mg/L) compared with dogs without alveolar lesions (5 mg/L; p < .002). In dogs with Bb infection, median duration of clinical signs was not different between dogs with normal CRP concentration and dogs with increased concentration. In dogs with Bb infection either with or without alveolar lessions, median CRP concentration was significantly lower (20 mg/L) than in dogs with ABP (118 mg/L; p < .001).

CONCLUSIONS AND CLINICAL IMPORTANCE

In contrast to dogs with APB, CRP was not a good marker for the diagnosis of dogs suspected to have bordetellosis. Confirmation of Bb infection still requires lower airway sampling.

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.

Evaluation of a Point-of-Care Test for Pre-Vaccination Testing to Detect Antibodies against Canine Adenoviruses in Dogs

(1) Background: Antibody testing is commonly used to assess a dog's immune status. For detection of antibodies against canine adenoviruses (CAVs), one point-of-care (POC) test is available. This study assessed the POC test´s performance. (2) Methods: Sera of 198 privately owned dogs and 40 specific pathogen-free (SPF) dogs were included. The reference standard for detection of anti-CAV antibodies was virus neutralization (VN) using CAV-1 and CAV-2 antigens. Specificity, sensitivity, positive predictive value (PPV), negative predictive value (NPV), and overall accuracy (OA) of the POC test were assessed. Specificity was considered most important. (3) Results: Prevalence of CAV-1 neutralizing antibodies (≥10) was 76% (182/238) in all dogs, 92% (182/198) in the subgroup of privately owned dogs, and 0% (0/40) in SPF dogs. Prevalence of CAV-2 neutralizing antibodies (≥10) was 76% (181/238) in all dogs, 91% (181/198) in privately owned dogs, and 0% (0/40) in SPF dogs. Specificity for detection of CAV-1 antibodies was lower (overall dogs, 88%; privately owned dogs, 56%; SPF dogs, 100%) compared with specificity for detection of CAV-2 antibodies (overall dogs, 90%; privately owned dogs, 65%; SPF dogs, 100%). (4) Conclusions: Since false positive results will lead to potentially unprotected dogs not being vaccinated, specificity should be improved to reliably detect anti-CAV antibodies that prevent infectious canine hepatitis in dogs.

Serum 25-hydroxyvitamin D concentration and infectious respiratory disease complex in shelter dogs

Background

Hypovitaminosis D is a risk factor for the development of respiratory infections in humans and repletion can be protective.

Objectives

Determine if serum 25‐hydroxyvitamin (OH)D concentrations are lower in shelter dogs and if 25(OH)D concentrations are associated with clinical signs of canine infectious respiratory disease complex (CIRDC) or with time in the shelter.

Animals

One hundred forty‐six shelter dogs (clinically ill n = 36, apparently healthy n = 110) and 23 nonshelter control dogs.

Methods

Prospective cohort study. Shelter dogs were grouped as clinically ill or apparently healthy based on the presence or absence, respectively, of clinical signs associated with CIRDC. Serum 25(OH)D concentrations were measured with a competitive chemiluminesence immunoassay. Nucleic acids of agents associated with the CIRDC were amplified by polymerase chain reaction assays.

Results

The concentration of 25(OH)D was 7.3 ng/mL (4.5‐9.9, 95% confidence interval [CI]) lower in dogs with signs of CIRDC than apparently healthy shelter dogs (t(142) = 2.0, P = .04). Dogs positive for DNA of canine herpesvirus (CHV)‐1 had serum 25(OH)D concentrations 14.9 ng/mL (−3.7 to 29.6, 95% CI) lower than dogs that were negative (t(137) = 2.0, P = .04). Serum 25(OH)D concentrations in shelter dogs were not different from control dogs (t(45) = −1.4, P = .17). Serum 25(OH)D concentration was not associated with duration of time in the shelter (F(1, 140) = 1.7, P = .2, R² = 0.01).

Conclusion and Clinical Importance

Vitamin D could have a role in acute respiratory tract infections in shelter dogs.

Antibody Response to Canine Adenovirus-2 Virus Vaccination in Healthy Adult Dogs

BACKGROUND

Re-vaccination against canine adenovirus (CAV) is performed in ≤3-year-intervals but their necessity is unknown. The study determined anti-CAV antibodies within 28 days of re-vaccination and factors associated with the absence of antibodies and vaccination response.

METHODS

Ninety-seven healthy adult dogs (last vaccination ≥12 months) were re-vaccinated with a modified live CAV-2 vaccine. Anti-CAV antibodies were measured before vaccination (day 0), and after re-vaccination (day 7, 28) by virus neutralization. A ≥4-fold titer increase was defined as vaccination response. Fisher's exact test and multivariate regression analysis were performed to determine factors associated with the absence of antibodies and vaccination response.

RESULTS

Totally, 87% of dogs (90/97; 95% CI: 85.61-96.70) had anti-CAV antibodies (≥10) before re-vaccination. Vaccination response was observed in 6% of dogs (6/97; 95% CI: 2.60-13.11). Time since last vaccination (>3-5 years, OR = 9.375, p = 0.020; >5 years, OR= 25.000, p = 0.006) was associated with a lack of antibodies. Dogs from urban areas were more likely to respond to vaccination (p = 0.037).

CONCLUSION

Many dogs had anti-CAV pre-vaccination antibodies, even those with an incomplete vaccination series. Most dogs did not respond to re-vaccination. Based on this study, dogs should be re-vaccinated every 3 years or antibodies should be determined.

Biologic Immunomodulatory Drugs and Infection in the Respiratory Tract of Nonhuman Primates

Though rare due to measures and practices to control the risk, infections can occur in research and toxicology studies, especially in nonhuman primates (NHPs) exposed to xenobiotics, particularly immunomodulatory drugs. With such xenobiotics, immunocompromised or immunosuppressed animals will not be able to mount a protective response to infection by an opportunistic pathogen (bacteria, virus, parasite, or fungus) that might otherwise be nonpathogenic and remain clinically asymptomatic in immunocompetent animals. The respiratory tract is one of the most commonly affected systems in clinic, but also in toxicology studies. Pulmonary inflammation will be the main finding associated with opportunistic infections and may cause overt clinical disease with even early sacrifice or death, and may compromise or complicate the pathology evaluation. It is important to properly differentiate the various features of infection, to be aware of the range of possible opportunistic pathogens and how they may impact the interpretation of pathology findings. This review will present the most common bacterial, viral, parasitic, and fungal infections observed in the respiratory tract in NHPs during research and/or toxicology studies.

Clinical response to 2 protocols of aerosolized gentamicin in 46 dogs with Bordetella bronchiseptica infection (2012-2018)

Background

Bordetella bronchiseptica (Bb) infection commonly causes respiratory disease in dogs. Gentamicin delivered by aerosol maximizes local drug delivery without systemic absorption but clinical response to protocols remains undetermined.

Objectives

To compare the clinical response to 2 protocols of aerosolized delivery of gentamicin in bordetellosis.

Animals

Forty‐six dogs with Bb infection confirmed by culture or quantitative polymerase chain reaction on bronchoalveolar lavage.

Methods

Retrospective study. Administration of aerosolized gentamicin for ≥10 minutes q12h for ≥3 weeks using 4 mg/kg diluted with saline (group 1) or undiluted 5% solution (group 2). Clinical response firstly assessed after 3‐4 weeks and treatment pursued by 3‐weeks increments if cure not reached. Cure defined as absence of cough persisting at least a week after treatment interruption.

Results

Demographic data were similar between both groups. Clinical cure at 3‐4 weeks was more frequently observed with the use of undiluted solution (19/33 vs 3/13 dogs, P = .03) in association with a shorter median duration of treatment (4 vs 6 weeks, P = .01). Dogs from group 2 having less than 1000 cells/μL in lavage were also more likely to be cured at 3‐4 weeks than dogs with more than 1000 cells/μL [9/9 vs 10/19, P = .006] and median duration of treatment in that subgroup of animals was reduced (3 vs 5 weeks, P = .02).

Conclusion and Clinical Importance

Aerosolized delivery of gentamicin seems effective for inducing clinical cure in Bb infection. Clinical response appears better using undiluted 5% solution, particularly in the subgroup of dogs having less than 1000 cells/μL in lavage.

Molecular detection of canine respiratory pathogens between 2017 and 2018 in Japan

A molecular survey was conducted to understand recent distribution of pathogens associated with canine infectious respiratory disease (CIRD) in Japan. Nasal and/or pharyngeal swabs were collected from asymptomatic dogs and those with CIRD, living in private house or in kennels. PCR-based examination was conducted for detecting nine pathogens. Among private household dogs, 50.8% with CIRD, 11.1% with respiratory disease other than CIRD, and 4.3% asymptomatic were positive for more than one pathogen, whereas in kennel-housed dogs, 42.9% with CIRD and 27.3% asymptomatic were positive. Bordetella bronchiseptica was most frequently detected, followed by canine herpesvirus 1, canine parainfluenza virus, canine pneumovirus, Mycoplasma cynos, and canine adenovirus type 2. In kennel environment, asymptomatic dogs might act as reservoirs carrying the respiratory pathogens.

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.

Evolutionary genetics of canine respiratory coronavirus and recent introduction into Swedish dogs

Canine respiratory coronavirus (CRCoV) has been identified as a causative agent of canine infectious respiratory disease, an upper respiratory infection affecting dogs. The epidemiology is currently opaque, with an unclear understanding of global prevalence, pathology, and genetic characteristics. In this study, Swedish privately-owned dogs with characteristic signs of canine infectious respiratory disease (n = 88) were screened for CRCoV and 13 positive samples (14.7%, 8.4-23.7% [95% confidence interval (CI)]) were further sequenced. Sequenced Swedish CRCoV isolates were highly similar despite being detected in dogs living in geographically distant locations and sampled across 3 years (2013-2015). This is due to a single introduction into Swedish dogs in approximately 2010, as inferred by time structured phylogeny. Unlike other CRCoVs, there was no evidence of recombination in Swedish CRCoV viruses, further supporting a single introduction. Finally, there were low levels of polymorphisms, in the spike genes. Overall, we demonstrate that there is little diversity of CRCoV which is endemic in Swedish dogs.

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.

Parainfluenza Virus 5 Infection in Neurological Disease and Encephalitis of Cattle

The etiology of viral encephalitis in cattle often remains unresolved, posing a potential risk for animal and human health. In metagenomics studies of cattle with bovine non-suppurative encephalitis, parainfluenza virus 5 (PIV5) was identified in three brain samples. Interestingly, in two of these animals, bovine herpesvirus 6 and bovine astrovirus CH13 were additionally found. We investigated the role of PIV5 in bovine non-suppurative encephalitis and further characterized the three cases. With traditional sequencing methods, we completed the three PIV5 genomes, which were compared to one another. However, in comparison to already described PIV5 strains, unique features were revealed, like an 81 nucleotide longer open reading frame encoding the small hydrophobic (SH) protein. With in situ techniques, we demonstrated PIV5 antigen and RNA in one animal and found a broad cell tropism of PIV5 in the brain. Comparative quantitative analyses revealed a high viral load of PIV5 in the in situ positive animal and therefore, we propose that PIV5 was probably the cause of the disease. With this study, we clearly show that PIV5 is capable of naturally infecting different brain cell types in cattle in vivo and therefore it is a probable cause of encephalitis and neurological disease in cattle.

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.

Presumptive Development of Fibrotic Lung Disease From Bordetella bronchiseptica and Post-infectious Bronchiolitis Obliterans in a Dog

A 7-month-old Miniature Poodle acquired from a pet store developed cough and subsequently respiratory distress compatible with Bordetella bronchiseptica infection. Partial but incomplete resolution of clinical signs and thoracic radiographic/computed tomographic imaging lesions were noted with use of susceptibility-guided antimicrobials. Additionally, a concern for an infectious nidus led to left cranial lung lobectomy at 9 months of age. Histopathology predominantly revealed polypoid and constrictive bronchiolitis obliterans (i.e., small airway disease). Intermittent antimicrobial administration over the next 5 years failed to blunt progressive clinical signs. At 8 years, necropsy confirmed severe airway-centered interstitial fibrosis. This pattern of fibrosis was strongly suggestive of underlying small airway disease as the trigger. In retrospect, post-infectious bronchiolitis obliterans (PIBO), a syndrome in young children caused by pulmonary infections but not yet recognized in pet dogs, likely initiated a pathway of fibrosis in this dog. In dogs with risk factors for community-acquired pathogens such as Bordetella bronchiseptica, PIBO is a differential diagnosis with development of severe, persistent respiratory signs incompletely responsive to appropriate antimicrobials. Untreated PIBO may lead to airway-centered interstitial fibrosis. Future study is required to determine if targeted therapy of PIBO could alter the course of end-stage pulmonary fibrosis.

Prevalence and risk factors for the presence of serum antibodies against canine distemper, canine parvovirus, and canine adenovirus in communities in mainland Ecuador

The purpose of this study was to estimate the apparent prevalence and identify risk factors for antibody levels (AL) against canine distemper virus (CDV), canine parvovirus (CPV), and canine adenovirus (CAV) in three communities in the metropolitan area of Quito, Ecuador that have limited access to regular veterinary care. Whole blood samples were collected from 154 dogs presenting to three veterinary field clinics in mainland Ecuador and tested for AL against CDV, CPV, and CAV by a commercially available point-of-care ELISA. Potential risk factors for the presence of AL were analyzed. A majority of dogs had AL against CDV (66%, 95% CI = 58-73%), CPV (95%, 95% CI = 91-98%) and CAV (60%, 95% CI = 52-67%). Dogs had significantly greater odds of AL against CDV if they were >2 years of age, from an urban community, and had previously received veterinary care. Dogs had significantly greater odds of AL against CAV if they were male, >2 years of age, and had previously received veterinary care. Results provide baseline estimates of AL within each community and allow for the targeting of future veterinary services to communities and dogs most at risk.

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.

Canine infectious respiratory disease: New insights into the etiology and epidemiology of associated pathogens

Canine infectious respiratory disease (CIRD) is a syndrome where multiple viral and bacterial pathogens are involved sequentially or synergistically to cause illness. There is limited information regarding the prevalence of pathogens related to CIRD in the United States as well as the role of co-infections in the pathogenesis of the syndrome. We aimed to conduct a comprehensive etiologic and epidemiologic study of multiple CIRD agents in a diverse dog population using molecular methods and statistical modeling analyses. In addition, a novel probe-based multiplex real-time PCR was developed to simultaneously detect and differentiate two species of Mycoplasma (M. canis and M. cynos). Canine adenovirus, canine distemper virus, canine parainfluenza virus, coronavirus, influenza A virus (H3N2 and H3N8), Bordetella bronchiseptica, M. canis, M. cynos and Streptococcus equi subsp. zooepidemicus were investigated in specimens from clinically ill and asymptomatic dogs received at the Athens Veterinary Diagnostic Laboratory. Results showed low occurrence of classical CIRD agents such as B. bronchiseptica, canine adenovirus and distemper virus, while highlighting the potential role of emerging bacteria such as M. canis and M. cynos. Statistical modeling analyses of CIRD pathogens emphasized the impact of co-infections on the severity of clinical presentation, and showed that host factors, such as animal age, are the most important predictors of disease severity. This study provides new insights into the current understanding of the prevalence and role of co-infections with selected viruses and bacteria in the etiology of CIRD, while underscoring the importance of molecular diagnosis and vaccination against this disease.

H3N2 canine influenza virus and Enterococcus faecalis coinfection in dogs in China

BACKGROUND

In May 2017, 17 dogs in a German Shepherd breeding kennel in northern China developed respiratory clinical signs. The owner treated the dogs with an intravenous injection of Shuang-Huang-lian, a traditional Chinese medicine, and azithromycin. The respiratory signs improved 3 days post-treatment, however, cysts were observed in the necks of eight dogs, and three of them died in the following 2 days.

CASE PRESENTATION

Quantitative real-time PCR was used to detect canine influenza virus (CIV). All of the dogs in this kennel were positive and the remaining 14 dogs had seroconverted. Two of the dogs were taken to the China Agricultural University Veterinary Teaching Hospital for further examination. Two strains of influenza virus (A/canine/Beijing/0512-133/2017 and A/canine/Beijing/0512-137/2017) isolated from the nasal swabs of these dogs were sequenced and identified as avian-origin H3N2 CIV. For the two dogs admitted to the hospital, hematology showed mild inflammation and radiograph results indicated pneumonia. Cyst fluid was plated for bacterial culture and bacterial 16 s rRNA gene PCR was performed, followed by Sanger sequencing. The results indicated an Enterococcus faecalis infection. Antimicrobial susceptibility tests were performed and dogs were treated with enrofloxacin. All 14 remaining dogs recovered within 16 days.

CONCLUSIONS

Coinfection of H3N2 CIV and Enterococcus faecalis was detected in dogs, which has not been reported previously. Our results highlight that CIV infection might promote the secondary infection of opportunistic bacteria and cause more severe and complicated clinical outcomes.

Novel Parvovirus Related to Primate Bufaviruses in Dogs

A novel protoparvovirus species, related genetically to human bufaviruses, was identified in dogs with respiratory signs. The canine bufavirus was distantly related to the well-known canine protoparvovirus, canine parvovirus type 2, sharing low amino acid identities in the nonstructural protein 1 (40.6%) and in the capsid protein 1 (33.4%). By screening collections of fecal, nasal, and oropharyngeal samples obtained from juvenile dogs (<1 year of age), canine bufavirus DNA appeared as a common component of canine virome. The virus was common in the stool samples of dogs with or without enteric disease and in the nasal and oropharyngeal swab samples of dogs with respiratory signs. However, the virus was not detected in nasal and oropharyngeal swab samples from animals without clinical signs.

Outcomes of and risk factors for presumed canine H3N2 influenza virus infection in a metropolitan outbreak

OBJECTIVE To determine clinical signs, case fatality rate, and factors associated with positive results of PCR testing for canine influenza virus (CIV) in dogs during an H3N2 CIV outbreak in the Atlanta area. DESIGN Cross-sectional study. ANIMALS 220 dogs with a nasal swab specimen submitted to an Atlanta-area diagnostic laboratory between May 1 and July 2, 2015, for PCR assay detection of CIV specifically or CIV and 5 other respiratory pathogens. PROCEDURES Veterinarians of tested dogs were surveyed by various means to collect information regarding clinical signs, survival status at the time of survey completion, vaccination history (≤ 12 months prior to testing), and travel history (≤ 2 months prior to testing). Data were compared between CIV-positive and CIV-negative dogs. RESULTS Surveys for 120 (55%) dogs were completed. Forty (33%) of these dogs had positive results of CIV testing. No significant differences were identified between CIV-positive and CIV-negative dogs regarding breed, sex, reproductive status, duration of clinical signs prior to testing, other dogs in the household, or travel history. When other factors were controlled for, CIV-positive dogs were more likely to be adult (> 1 year of age) than juvenile (≤ 1 year of age) and to be inappetent. Only 1 (3%) CIV-positive dog died during the study period (shortly after it was evaluated because of respiratory signs). CONCLUSIONS AND CLINICAL RELEVANCE From May 1 to July 2, 2015, the reported clinical signs of dogs tested during the Georgia H3N2 CIV outbreak were similar to those reported for dogs with H3N8 CIV infection, and the case fatality rate was low.

An Outbreak of Fatal Bordetella bronchiseptica Bronchopneumonia in Puppies

Twenty-two newborn puppies that did not receive colostrum exhibited acute respiratory signs and died at a breeding facility. Pathological examinations were performed on four of the puppies. At necropsy examination, the lungs were firm and mottled dark red, consistent with acute bronchopneumonia. Histopathologically, there was marked infiltration of neutrophils and macrophages into the bronchi and alveoli, and gram-negative coccobacilli were attached diffusely to the cilia of bronchial mucosa. Immunohistochemistry for Bordetella bronchiseptica antigen revealed positive labelling of the bacterial agents. On electron microscopy, a large number of coccobacilli were observed attaching to the cilia of bronchial epithelial cells. Real-time polymerase chain reaction amplified a B. bronchiseptica gene from the affected lung tissue. Based on these findings, the four puppies were diagnosed with fatal B. bronchiseptica bronchopneumonia.

Bordetella bronchiseptica Colonization Limits Efficacy, but Not Immunogenicity, of Live-Attenuated Influenza Virus Vaccine and Enhances Pathogenesis After Influenza Challenge

Intranasally administered live-attenuated influenza virus (LAIV) vaccines provide significant protection against heterologous influenza A virus (IAV) challenge. However, LAIV administration can modify the bacterial microbiota in the upper respiratory tract, including alterations in species that cause pneumonia. We sought to evaluate the effect of Bordetella bronchiseptica colonization on LAIV immunogenicity and efficacy in swine, and the impact of LAIV and IAV challenge on B. bronchiseptica colonization and disease. LAIV immunogenicity was not significantly impacted by B. bronchiseptica colonization, but protective efficacy against heterologous IAV challenge in the upper respiratory tract was impaired. Titers of IAV in the nose and trachea of pigs that received LAIV were significantly reduced when compared to non-vaccinated, challenged controls, regardless of B. bronchiseptica infection. Pneumonia scores were higher in pigs colonized with B. bronchiseptica and challenged with IAV, but this was regardless of LAIV vaccination status. While LAIV vaccination provided significant protection against heterologous IAV challenge, the protection was not sterilizing and IAV replicated in the respiratory tract of all LAIV vaccinated pig. The interaction between IAV, B. bronchiseptica, and host led to development of acute-type B. bronchiseptica lesions in the lung. Thus, the data presented do not negate the efficacy of LAIV vaccination, but instead indicate that controlling B. bronchiseptica colonization in swine could limit the negative interaction between IAV and Bordetella on swine health.

Canine morbillivirus (canine distemper virus) with concomitant canine adenovirus, canine parvovirus-2, and Neospora caninum in puppies: a retrospective immunohistochemical study

A retrospective immunohistochemical study was designed to investigate the frequency of concomitant traditional infectious disease pathogens in puppies that died suddenly and review the aspects of associated pathogenesis. Fifteen puppies were evaluated; the pathology reports and histopathologic slides of these animals were reviewed to determine the pattern of histopathologic lesions. The intralesional identification of antigens of canine (distemper) morbillivirus (CDV), canine adenovirus-1 and -2 (CAdV-1 and -2), canine parvovirus-2 (CPV-2), Toxoplasma gondii, and Neospora caninum was evaluated by IHC within the histopathologic patterns observed. All puppies contained CDV nucleic acid by molecular testing. The most frequent histopathologic patterns were intestinal crypt necrosis (n = 8), white matter cerebellar demyelination (n = 7), necrohaemorrhagic hepatitis (n = 7), interstitial pneumonia (n = 7), and gallbladder oedema (n = 5). All puppies contained intralesional antigens of CDV in multiple tissues resulting in singular (n = 3), and concomitant dual (n = 3), triple (n = 5) and quadruple (n = 4) infections by CAdV-1, and -2, CPV-2, and N. caninum; T. gondii was not identified. Concomitant infections by CDV was observed with N. caninum (100%; 1/1), CPV-2 (100%; 8/8), CAdV-1 (100%; 8/8), and CAdV-2 (100%; 8/8). Intralesional antigens of CDV and not CAdV-1 were identified in cases of gallbladder oedema. The “blue eye” phenomenon was histologically characterized by corneal oedema and degenerative lesions to the corneal epithelium, without inflammatory reactions.

A survey of canine respiratory pathogens in New Zealand dogs

AIMS To determine which of the common canine respiratory pathogens circulate among selected populations of healthy and diseased dogs in New Zealand. METHODS Coagulated blood samples for serology and oropharyngeal swabs for virology were collected from healthy dogs (n=47) and from dogs with acute respiratory disease (n=49). For diseased dogs a convalescent blood sample was also collected 3-4 weeks later. Oropharyngeal swabs were subjected to virus isolation and tested for canine parainfluenza virus (CPIV), canine adenovirus (CAdV) 2, canine herpesvirus (CHV), canine respiratory coronavirus (CRCoV), canine influenza virus (CIV), canine distemper virus (CDV), Bordetella bronchiseptica, Streptococcus equi subsp. zooepidemicus, and Mycoplasma cynos nucleic acids by quantitative PCR (qPCR). Sera were tested for CRCoV antibody using competitive ELISA and results expressed as percent of inhibition (POI). RESULTS The mean age of diseased dogs (2.7, min <0.5, max 8.5 years) was lower than the mean age of healthy dogs (5.3, min <0.5, max 17 years) (p<0.001). In total, 20/94 (21%) dogs were positive for at least one agent by qPCR. Diseased dogs were most commonly positive for M. cynos (8/47, 17%), followed by CPIV (3/47, 6%) and B. bronchiseptica (3/47, 6%), while healthy dogs were most commonly positive for CAdV-2 (6/47, 13%), followed by M. cynos (2/47, 4%). All samples were negative for CIV, CRCoV, CDV and S. equi subsp. zooepidemicus. Viruses were not isolated from any of the samples tested. In total, 47/93 (50%) dogs were seropositive for CRCoV on at least one sampling occasion. Samples from diseased dogs were more frequently seropositive for CRCoV, with higher POI, than samples from healthy dogs. CONCLUSIONS AND CLINICAL RELEVANCE We showed that CAdV-2, CPIV, CHV, CRCoV, B. bronchiseptica and M. cynos circulated among sampled dogs. The convenience sampling methodology, with a poor match between the populations of diseased and healthy dogs in terms of age, breed and use, together with the relatively small sample size precluded inference of any causal relationships between infection with a given pathogen and development of disease. None-the-less, our data suggest that further investigation into epidemiology and disease association of CRCoV and M. cynos is warranted. In addition, circulation of novel respiratory pathogens among dogs in New Zealand should be considered in future studies, as 70/94 (74%) diseased dogs were negative for all the pathogens tested.

Detection of specific bacterial agents by quantitative PCR assays in the bronchoalveolar lavage fluid of dogs with eosinophilic bronchopneumopathy vs. dogs with chronic bronchitis and healthy dogs

In humans, Mycoplasma pneumoniae and Bordetella pertussis infections are suggested to trigger or exacerbate asthma. Whether Mycoplasma or Bordetella are associated with chronic inflammatory bronchial diseases in dogs has not been investigated. The aim of this study was to assess detection rates of Mycoplasma canis (M. canis), M. cynos and Bordetella bronchiseptica (Bb), in dogs with eosinophilic bronchopneumopathy (EBP) and chronic bronchitis (CB), compared with healthy dogs. Specific quantitative PCR (qPCR) analysis for M. canis, M. cynos and Bb were retrospectively performed on bronchoalveolar lavage fluid (BALF) collected from 24 dogs with EBP, 21 dogs with CB and 15 healthy dogs. Possible associations between qPCR results and age, BALF cytology or clinical severity scores (CSS) in dogs with EBP were investigated. There was no difference in M. canis, M. cynos and Bb detection rates in dogs with EBP (n=6, n=2 and n=6, respectively) and dogs with CB (n=2, n=2 and n=2, respectively) compared with control dogs (n=4, n=2 and n=2, respectively). In dogs with EBP, the proportion that were qPCR-positive for Bb was higher in dogs with higher CSS (P=0.014) and BALF from Bb-positive dogs had higher percentage of neutrophils (P<0.001). Among dogs that were qPCR-positive for Bb, moderate to high loads were only detected in dogs with EBP. M. canis and M. cynos detection was not associated with EBP or CB; higher Bb loads were only present in dogs with EBP and high CSS. A possible cause and effect relationship between Bb infection or load and EBP remains unclear and requires further investigation.

The Bordetella Bps Polysaccharide Is Required for Biofilm Formation and Enhances Survival in the Lower Respiratory Tract of Swine

Bordetella bronchiseptica is pervasive in swine populations and plays multiple roles in respiratory disease. Additionally, B. bronchiseptica is capable of establishing long-term or chronic infections in swine. Bacterial biofilms are increasingly recognized as important contributors to chronic bacterial infections. Recently the polysaccharide locus bpsABCD has been demonstrated to serve a critical role in the development of mature biofilms formed by the sequenced laboratory strain of B. bronchiseptica We hypothesized that swine isolates would also have the ability to form mature biofilms and the bpsABCD locus would serve a key role in this process. A mutant containing an in-frame deletion of the bpsABCD structural genes was constructed in a wild-type swine isolate and found to be negative for poly-N-acetylglucosamine (PNAG)-like material by immunoblot assay. Further, the bpsABCD locus was found to be required for the development and maintenance of the three-dimensional structures under continuous-flow conditions. To investigate the contribution of the bpsABCD locus to the pathogenesis of B. bronchiseptica in swine, the KM22Δbps mutant was compared to the wild-type swine isolate for the ability to colonize and cause disease in pigs. The bpsABCD locus was found to not be required for persistence in the upper respiratory tract of swine. Additionally, the bpsABCD locus did not affect the development of anti-Bordetella humoral immunity, did not contribute to disease severity, and did not mediate protection from complement-mediated killing. However, the bpsABCD locus was found to enhance survival in the lower respiratory tract of swine.

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.