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

Abstract

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 peerreviewed 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.

Humoral responses to SARS-CoV-2 by healthy and sick dogs during the COVID-19 pandemic in Spain

“…Historically, the most common pathogens associated with complex canine infectious respiratory disease have been CPIV, CAV-2, Bordetella bronchiseptica, Streptococcus equi subsp. zooepidemicus, Mycoplasma cynos, CaHV-1, CDV, CIV, and CRCoV [25]. In our study, we detected eight of 33 analyzed dogs presenting classical primary respiratory pathogens, and we also detected IgM for CCoV in four dogs (3/17 pathological dogs and 1/20 healthy dog).…”

Humoral response to SARS-CoV-2 by healthy and sick dogs during COVID-19 pandemic in Spain

“…Moreover, in veterinary medicine the respiratory disease is rarely lethal in the pet dog population. A mortality rate of 1•2% due to respiratory disease (only 0•3% due to pneumonia) has been reported, 19,20 nevertheless in our study we found a mortality rate of 42•5% during follow-up without a clarified etiology. These dogs, with very aggressive lung diseases, showed a very similar appearance to those described for COVID-19 pneumonia in human medicine.…”

“…zooepidemicus, Mycoplasma cynos, CHV-1, CDV, CIV, and CRCoV. 20 In our study, we detect eight of 33 analyzed dogs presenting classical primary respiratory pathogens, and we also detect IgM for CCoV in four dogs (3/17 pathological dogs and 1/20 healthy dog). In this regard, the presence of CRCoV is detected more frequently in dogs with mild clinical signs than in dogs with moderate or severe clinical signs, 5 therefore, we would rule out that it was the agent responsible for the severe respiratory pathologies in these three dogs.…”

“…levels ranging from 20•7% to 61•9%, 23 but in other study with healthy dogs mycoplasma were isolated from 78% to 93% of throat swabs. 20 Moreover, mycoplasma infections are usually associated with other infections. It is interesting to note that mycoplasma coinfections are very common in COVID-19 human patients 24 and it also has been suggested that a co-infection or activation of latent mycoplasma infections in COVID-19 disease may be important in determining a fatal disease course.…”

Infectious canine hepatitis, not only in the textbooks: a brief review and three case reports

“…Adenoviruses are very resistant in the environment, surviving several days at room temperature and several months at ≤4°C. Canine adenovirus 2 (CAdV-2) causes mild self-limiting infection of the upper respiratory tract and is a contributor to infectious tracheobronchitis (ITB) known as kennel cough (Greene, 2012;Day et al, 2020).…”