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

Development and validation of nanoplate-based RT-dPCR assay for canine respiratory coronavirus detection in various clinical samples

BACKGROUND

Canine respiratory coronavirus (CRCoV) is a major contributor to the canine infectious respiratory disease complex (CIRDC). Despite its widespread prevalence, molecular assays for CRCoV detection remain limited. Additionally, the efficiency and accuracy of detection can vary depending on the type of clinical sample used, such as nasal swabs (NS), oropharyngeal swabs (OS), and rectal swabs (RS). To address these challenges, we developed a nanoplate-based reverse transcription digital polymerase chain reaction (RT-dPCR) method for detecting the spike gene of CRCoV in various clinical samples.

RESULTS

The RT-dPCR assay demonstrated consistent repeatability and reproducibility, ensuring reliable results. With a detection limit of 1.83 copies/µL, the RT-dPCR assay exhibited 100-fold greater sensitivity than probe-based reverse transcription quantitative polymerase chain reaction (RT-qPCR). It showed no cross-reactivity with other common CIRDC-associated viruses or coronaviruses, confirming its high specificity for CRCoV. The assay was further validated using 162 clinical swab samples (NS, OS, and RS) collected from both healthy dogs and those with respiratory distress. The RT-dPCR assay showed a higher overall positivity rate for CRCoV compared to RT-qPCR, with the most notable difference observed in rectal swabs (P < 0.05), where RT-dPCR detected CRCoV in 53.7% of samples compared to 22.22% by RT-qPCR.

CONCLUSIONS

This study demonstrated that the RT-dPCR assay provided high sensitivity for detecting low viral loads across various sample types, making it a valuable tool for precise CRCoV detection. In contrast, RT-qPCR remains valuable for its broader detection range and suitability in initial screening. Both techniques proved to be versatile tools that can contribute to advancing CRCoV research and improving clinical diagnostics.

Efficacy and safety of anemoside B4 in canine pneumonia treatment: a prospective, randomized controlled trial

Background

Canine pneumonia is a serious respiratory disease often associated with Canine Infectious Respiratory Disease (CIRD). Current treatment strategies primarily rely on antibiotics and corticosteroids; however, the emergence of antibiotic resistance and potential side effects from prolonged corticosteroid use limit the effectiveness of these therapies in clinical practice. These challenges highlight the urgent need for alternative treatments. Anemoside B4 (AB4), derived from the traditional Chinese medicine Pulsatilla, has shown promise in preclinical studies for modulating inflammatory responses and improving clinical symptoms of pneumonia. Therefore, AB4 may offer a valuable alternative treatment option for canine pneumonia in veterinary medicine.

Methods

A prospective, randomized controlled trial was conducted at the Veterinary Drug Research and Evaluation Center of South China Agricultural University. Seventy-two dogs with mild-to-moderate pneumonia were randomly assigned to one of three groups: AB4, placebo, or Chuanxinlian injection (CXL). The primary outcome was the effect of AB4 on comprehensive clinical scoring of canine pneumonia; secondary outcomes included recovery times for primary symptoms and efficacy assessments. Additionally, AB4's safety in clinical applications was evaluated.

Results

The AB4 group demonstrated significantly lower composite clinical scores on Days 7 and 14 compared to the placebo group (p = 0.033 and p = 0.000, respectively). Significant differences in recovery times for fever and dyspnea were observed between the AB4 and placebo groups (p = 0.041 and p = 0.024, respectively). Moreover, the cure rate and overall efficacy on Day 14 were significantly higher in the AB4 group than those in the placebo group (p = 0.001 and p = 0.009, respectively).

Conclusion

These findings suggest that AB4 may be a promising treatment option for canine pneumonia, potentially serving as an alternative to traditional therapies. Further research is needed to explore its clinical potential in veterinary medicine.

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.

Canine bufavirus (Carnivore protoparvovirus-3) infection in dogs with respiratory disease

Canine bufavirus (CBuV) or Carnivore protoparvovirus-3, a nonenveloped DNA virus belonging to the genus Protoparvovirus, family Parvoviridae, has been identified in dogs with respiratory and enteric diseases. Although CBuV detection has been reported in multiple countries, descriptions of pathologic findings associated with infection have not yet been provided. In this study, the authors necropsied 14 dogs (12 puppies and 2 adult dogs) from a breeding colony that died during multiple outbreaks of respiratory diseases. Postmortem investigations revealed extensive bronchointerstitial pneumonia with segmental type II pneumocyte hyperplasia in all necropsied puppies but less severe lesions in adults. With negative results of common pathogen detection by ancillary testing, CBuV DNA was identified in all investigated dogs using a polymerase chain reaction (PCR). Quantitative PCR demonstrated CBuV DNA in several tissues, and in situ hybridization (ISH) indicated CBuV tissue localization in the lung, tracheobronchial lymph node, and spinal cord, suggesting hematogenous spread. Dual CBuV ISH and cellular-specific immunohistochemistry were used to determine the cellular tropism of the virus in the lung and tracheobronchial lymph node, demonstrating viral localization in various cell types, including B-cells, macrophages, and type II pneumocytes, but not T-cells. Three complete CBuV sequences were successfully characterized and revealed that they clustered with the CBuV sequences obtained from dogs with respiratory disease in Hungary. No additional cases were identified in small numbers of healthy dogs. Although association of the bufavirus with enteric disease remains to be determined, a contributory role of CBuV in canine respiratory disease is possible.

Basic triage in dogs and cats: Part I

Background

Emergency cases can present at any time of the day or night. All small animal practitioners need to have the skills to triage and stabilize common emergency cases even if they ultimately aim to refer the patient to another facility.

Objectives and procedures

The first part of this 3-part review article series covers respiratory distress and seizures. A stepwise approach to categorize and stabilize these cases is outlined, along with helpful tips to optimize the referral experience, if indicated.

Results

Having a strong methodical approach to animals in respiratory distress optimizes treatment. Similarly, achieving cessation of seizures, along with having a good understanding of the causes of seizures, allows for patient stabilization.

Conclusion and clinical relevance

Do NOT refer emergent cases before completing basic stabilization. Many emergency cases do not require emergent referral and can be worked up by the primary veterinarian or sent to a referral clinic on an appointment basis after appropriate stabilization steps are completed.

Development of a Large-Scale Pathogen Screening Test for the Biosafety Evaluation of Canine Mesenchymal Stem Cells

BACKGROUND

The action of mesenchymal stem cells (MSCs) is the subject of intense research in the field of regenerative medicine, including their potential use in companion animals, such as dogs. To ensure the safety of canine MSC batches for their application in regenerative medicine, a quality control test must be conducted in accordance with Good Manufacturing Practices (GMP). Based on guidance provided by the European Medicines Agency, this study aimed to develop and validate a highly sensitive and robust, nucleic acid-based test panel for the detection of various canine pathogens. Analytical sensitivity, specificity, amplification efficiency, and linearity were evaluated to ensure robust assessment. Additionally, viable spike-in controls were used to control for optimal nucleic acid extraction. The conventional PCR-based and real-time PCR-based pathogen assays were evaluated in a real-life setting, by direct testing MSC batches.

RESULTS

The established nucleic acid-based assays displayed remarkable sensitivity, detecting 100-1 copies/reaction of template DNA. They also exhibited high specificity and efficiency. Moreover, highly effective nucleic acid isolation was confirmed by the sensitive detection of spike-in controls. The detection capacity of our optimized and validated methods was determined by direct pathogen testing of nine MSC batches that displayed unusual phenotypes, such as reduced cell division or other deviating characteristics. Among these MCS batches of uncertain purity, only one tested negative for all pathogens. The direct testing of these samples yielded positive results for important canine pathogens, including tick-borne disease-associated species and viral members of the canine infectious respiratory disease complex (CIRDC). Notably, samples positive for the etiological agents responsible for enteritis (CPV), leptospirosis (Leptospira interrogans), and neosporosis (Neospora caninum) were also identified. Furthermore, we conducted biosafety evaluation of 12 MSC batches intended for therapeutic application. Eleven MSC batches were found to be free of extraneous agents, and only one tested positive for a specific pathogen, namely, canine parvovirus.

CONCLUSION

In this study, we established and validated reliable, highly sensitive, and accurate nucleic acid-based testing methods for a broad spectrum of canine pathogens.

Canine respiratory coronavirus in Thailand undergoes mutation and evidences a potential putative parent for genetic recombination

Canine respiratory coronavirus (CRCoV) is associated with canine infectious respiratory disease complex. Although its detection has been reported worldwide, the genomic characteristics and evolutionary patterns of this virus remain poorly defined. In this study, 21 CRCoV sequences obtained from dogs in Thailand during two episodes (2013-2015, group A; 2021-2022, group B) were characterized and analyzed. The genomic characteristics of Thai CRCoVs changed from 2013 to 2022 and showed a distinct phylogenetic cluster. Phylogenetic analysis of the spike (S) genes divided the analyzed CRCoV strains into five clades. The full-length genome characterization revealed that all Thai CRCoVs possessed a nonsense mutation within the nonstructural gene located between the S and envelope genes, leading to a truncated putative nonstructural protein. Group B Thai CRCoV strains represented the signature nonsynonymous mutations in the S gene that was not identified in group A Thai CRCoVs, suggesting the ongoing evolutionary process of Thai CRCoVs. Although no evidence of recombination of Thai CRCoV strains was found, our analysis identified one Thai CRCoV strain as a potential parent virus for a CRCoV strain found in the United States. Selective pressure analysis of the hypervariable S region indicated that the CRCoV had undergone purifying selection during evolution. Evolutionary analysis suggested that the CRCoV was emerged in 1992 and was first introduced in Thailand in 2004, sharing a common ancestor with Korean CRCoV strains. These findings regarding the genetic characterization and evolutionary analysis of CRCoVs add to the understanding of CRCoVs. IMPORTANCE Knowledge of genomic characterization of the CRCoV is still limited and its evolution remains poorly investigated. We, therefore, investigated the full-length genome of CRCoV in Thailand for the first time and analyzed the evolutionary dynamic of CRCoV. Genomic characterization of Thai CRCoV strains revealed that they possess unique genome structures and have undergone nonsynonymous mutations, which have not been reported in previously described CRCoV strains. Our work suggests that the Thai CRCoVs were not undergone mutation through genetic recombination for their evolution. However, one Thai CRCoV strain PP158_THA_2015 was found to be a potential parent virus for the CRCoV strains found in the United States. This study provides an understanding of the genomic characterization and highlights the signature mutations and ongoing evolutionary process of CRCoV that could be crucial for monitoring in the future.

Isolation and Genetic Characterization of Emerging H3N2 Canine Influenza Virus in Guangdong Province, Southern China, 2018–2021

H3N2 canine influenza virus (CIV) emerged in dogs in China or Korea around 2005 and was first reported in 2008. In 2015, H3N2 CIV was detected in the United States and caused a huge outbreak. To date, H3N2 CIV is continuously circulating in dog populations in China, Korea, and the United States. For continuous monitoring of H3N2 CIV in China, we collected 180 dog nasal swab samples and 196 cat nasal swabs from veterinary hospitals in Guangdong Province between 2018 and 2021. Six emerging H3N2 CIV strains were isolated. Following full genome sequencing and phylogenetic analyses, we found that A/canine/Guangdong/1-3/2018 and A/canine/Guangdong/1-3/2021 diverged from the reported sequences of the Chinese H3N2 CIV strains. Moreover, we found that these H3N2 CIV strains belong to the group that contains US and northern China CIV strains in 2017 and 2019 and dominate in the dog population until 2021.

Canine bocavirus-2 infection and its possible association with encephalopathy in domestic dogs

Canine bocaviruses (CBoVs) have been recognized as pathogens associated with intestinal diseases. Hematogenous spreading caused by CBoV has been documented and may potentiate the virus entry across the blood-brain barrier to initiate a brain infection. This study focused attention on CBoV detection in cases of encepahlopathy and attempted to determine its viral localization. A total of 107 dog brains that histologically exhibited encephalopathy (ED) were investigated for the presence of CBoVs using polymerase chain reaction (PCR). Thirty-three histologically normal brain samples from dogs were used as a control group (CD). CBoV-2 was detected in 15 ED dogs (14.02%) but not in CD dogs (p = 0.02), while no CBoV-1 and -3 were detected. Among the CBoV-2 positive dogs, brain histological changes were characterized by nonsuppurative encephalitis, with inclusion body-like materials in some brains. In situ hybridization (ISH) and transmission electron microscopy (TEM) confirmed the presence of CBoV-2 viral particles in glial cells, supporting neurotropism of this virus. ISH signals were also detected in the intestines, lymphoid organs, and the heart, suggesting both enteral and parenteral infections of this virus. Whole genome characterization and evolutionary analysis revealed genetic diversity of CBoV-2 sequences and it was varying among the different countries where the virus was detected. This study points to a possible association of CBoV-2 with encephalopathy in dogs. It also highlights the genetic diversity and cellular tropism of this virus.

Feline morbillivirus-1 in dogs with respiratory diseases

Feline morbillivirus-1 (FeMV-1) is a viral pathogen associated with kidney disease in domestic cats and wild felids. We initially identified the FeMV-1 from the lung of a necropsied dog with severe pulmonary disease by the reverse transcription polymerase chain reaction (RT-PCR). Thereafter, we investigated FeMV-1 in nasal and oral swab samples from 73 healthy and 113 dogs with respiratory illnesses. We found polymerase chain reaction (PCR)-positive FeMV-1 from only 14/113 (12.39%) dogs with respiratory disease (p = .001). Of these 14 dogs, six were co-infected with other canine respiratory viruses (6/14; 42.86%). Two independent immunohistochemistry procedures, using antibodies against matrix and phosphoprotein of FeMV-1, confirmed the presence of FeMV-1 in lung tissues of two necropsied dogs (out of a total of 22 dogs, 9.09%) that died from respiratory disease. This finding corresponded to transmission electron microscopy findings that paramyxoviral particles exist in lung epithelia. FeMV-1 antigen localization was also evident in the kidney, lymphoid and brain tissues of two deceased dogs. FeMV-1 was successfully isolated from a necropsied dog and from two living dogs, all with respiratory illnesses, which supports FeMV infection in dogs. The detection of FeMV-1 in dog tissues expands the known tropism of this virus to a non-felid host. Our findings indicate that FeMV-1, alone or in co-infection with other viral pathogens, might contribute to respiratory illness and death in dogs.

Natural infection of parvovirus in wild fishing cats (Prionailurus viverrinus) reveals extant viral localization in kidneys

Carnivore protoparvovirus-1 (CPPV-1), a viral species containing feline panleukopenia virus (FPV) and canine parvovirus (CPV) variants, are widely spread among domestic and wild carnivores causing systemic fatal diseases. Wild fishing cats (Prionailurus viverrinus), a globally vulnerable species, have been found dead. Postmortem examination of the carcasses revealed lesions in intestine, spleen and kidney. CPPV-1 antigen identification in these tissues, using polymerase chain reaction (PCR) and immunohistochemistry (IHC), supported the infection by the virus. PCR- and IHC-positivity in kidney tissues revealed atypical localization of the virus while in situ hybridization (ISH) and transmission electron microscopy (TEM) with the pop-off technique confirmed the first description of viral localization in kidneys. Complete genome characterization and deduced amino acid analysis of the obtained CPPV-1 from the fishing cats revealed FPV as a causative agent. The detected FPV sequences showed amino acid mutations at I566M and M569R in the capsid protein. Phylogenetic and evolutionary analyses of complete coding genome sequences revealed that the fishing cat CPPV-1 genomes are genetically clustered to the FPV genomes isolated from domestic cats in Thailand. Since the 1970s, these genomes have also been shown to share a genetic evolution with Chinese FPV strains. This study is the first evidence of CPPV-1 infection in fishing cats and it is the first to show its localization in the kidneys. These findings support the multi-host range of this parvovirus and suggest fatal CPPV-1 infections may result in other vulnerable wild carnivores.

Novel human coronavirus (SARS-CoV-2): A lesson from animal coronaviruses

The recent pandemic caused by the novel human coronavirus, referrred to as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), not only is having a great impact on the health care systems and economies in all continents but it is also causing radical changes of common habits and life styles. The novel coronavirus (CoV) recognises, with high probability, a zoonotic origin but the role of animals in the SARS-CoV-2 epidemiology is still largely unknown. However, CoVs have been known in animals since several decades, so that veterinary coronavirologists have a great expertise on how to face CoV infections in animals, which could represent a model for SARS-CoV-2 infection in humans. In the present paper, we provide an up-to-date review of the literature currently available on animal CoVs, focusing on the molecular mechanisms that are responsible for the emergence of novel CoV strains with different antigenic, biologic and/or pathogenetic features. A full comprehension of the mechanisms driving the evolution of animal CoVs will help better understand the emergence, spreading, and evolution of SARS-CoV-2.