Age-related presence of selected viral and bacterial pathogens in paraffin-embedded lung samples of dogs with pneumonia

Abstract

The aim of this retrospective study was to detect selected pathogens in pneumonic lung tissue of dogs of different age groups by immunohistochemistry (IHC), in situ hybridisation (ISH) or polymerase chain reaction (PCR) in order to get information about their involvement in pneumonia formation. In archived formalin-fixed and paraffin wax-embedded lung samples from 68 cases with the clinical and histologic diagnosis of pneumonia the histological pattern of pneumonia was re-evaluated and the samples were further investigated for the following infectious agents: canine distemper virus (CDV), canine adenovirus type 2 (CAV-2), canine respiratory coronavirus (CRCoV), Bordetella (B.) bronchiseptica, Pasteurella (P.) multocida, Mycoplasma spp., and Pneumocystis spp. In 47.1% of the samples at least one of the featured respiratory pathogens was detected. In 31.3% of these positive samples more than one pathogen could be found. The correct detection of CDV had been achieved in ten out of eleven positive cases (90.9%) upon initial investigation, but the presence of bacterial pathogens, like B. bronchiseptica (10 cases) and P. multocida (17 cases) had been missed in all but one case. While CDV and CRCoV infections were exclusively found in dogs younger than one year, the vast majority of infections with P. multocida and B. bronchiseptica were both common either in dogs younger than 4 months or older than one year. Thus, this retrospective approach yielded valuable data on the presence, absence and prevalence of certain respiratory pathogens in dogs with pneumonia.

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

“…Furthermore, CRCoV is frequently detected in the respiratory tract of dogs with respiratory disease. Woehrer et al (2016) found 15.5% of pathological samples from dogs with pneumonia contained CRCoV. Some of the positive samples were co-infected with Bb and/or bacterial pathogens.…”

“…In Germany (Schulz et al, 2014b) and Finland (Viitanen et al, 2015) neither healthy dogs nor dogs with CIRDC were infected with CDV. Woehrer et al (2016) found CDV in 16.2% of Austrian dogs with pneumonia when investigating historical samples by immunohistochemistry. All CDV-positive dogs were #12 months of age and many had concurrent neurological and/or gastrointestinal signs.…”

“…Reasons for this may have been the small animal number in this study and antibiotic pre-treatment of diseased dogs, which may have reduced the number of positive dogs. Woehrer et al (2016) found mycoplasma in 2.9% of dogs with pneumonia in a retrospective study of histopathological samples. Considerably higher detection rates were achieved using BALF samples of dogs with bacterial pneumonia (40%; Viitanen et al, In two studies investigating dogs with Bb infections, Mycoplasma spp.…”

“…Bb was detected in dogs with pneumonia (14.7%, Woehrer et al, 2016), eosinophilic bronchopneumonia (25%) and chronic bronchitis (10%) (Canonne et al, 2018). Woehrer et al (2016) found Bb together with Pasteurella multocida in five puppies: in one of these puppies concurrently with CRCoV and in another puppy concurrently with CRCoV and M. canis. Bb was also detected in five adult dogs, two of which showed concurrent infection with P. multocida.…”

Diagnosis of pneumocystis pneumonia in a 2‐year‐old King Charles Cavalier Spaniel using the polymerase chain reaction

“…Diagnosis involves direct visualization of the organism on cytologic or histopathologic preparations or via PCR. Most canine pneumocystis infections reported in the literature are diagnosed postmortem from lung tissue specimens, although many use PCR or DNA analysis for confirmation . Antemortem diagnosis can be performed via lung biopsies; however, these are invasive and may be risky in a compromised respiratory patient with diseased lungs.…”