Canine bacterial pneumonia - role of acute phase proteins and viral co-infections

Research output: ThesisDoctoral Thesis

Abstract

Bacterial pneumonia (BP) is an acquired inflammation of the lower airways and lung parenchyma secondary to bacterial infection. BP is difficult to induce experimentally in healthy dogs; the pathogenesis is therefore considered complex, involving several underlying mechanisms. BP was first described in dogs decades ago, but it is still one of the most common systemic bacterial infections in dogs, with a significant morbidity and mortality. Several aspects of BP, including the applicability of inflammatory biomarkers in its diagnosis and follow-up as well as the role of respiratory viruses in its clinical picture and development, warrant further studies. This thesis aimed to describe clinical findings during the disease and recovery periods in dogs with BP and to evaluate the applicability of acute-phase proteins as diagnostic and follow-up markers in BP. The prevalence and role of viral co-infections in dogs with BP were also investigated. We evaluated the diagnostic applicability of serum C-reactive protein (CRP) and noted that CRP is significantly elevated in BP relative to dogs with other lower respiratory tract diseases, such as chronic bronchitis, bacterial tracheobronchitis, canine idiopathic pulmonary fibrosis, and eosinophilic bronchopneumopathy, as well as in cardiogenic pulmonary edema. Our results indicate that serum CRP concentration may be used as an additional biomarker in the diagnosis of canine BP. Serum CRP, serum amyloid A (SAA), and haptoglobin (Hp) were followed during the disease and recovery periods. The follow-up study showed that serum CRP and SAA reflected well the recovery process and declined rapidly after initiation of successful therapy and could therefore be used as markers of treatment response in dogs with BP. Currently, markedly longer antibiotic courses are recommended in dogs with BP than in humans with pneumonia. Since serum CRP is a sensitive inflammatory biomarker, it was hypothesized that normalization of serum CRP could be used as an indicator for the cessation of antimicrobial therapy. In our study, we treated a group of dogs according to conventional recommendations. In another group, antimicrobial therapy was ended 5-7 days after CRP normalization. When the normalization of CRP was used to guide antimicrobial therapy, treatment length was significantly reduced without increasing the number of relapses. According to these results, normalization of serum CRP may be applied to guide the length of antimicrobial therapy in dogs with BP. Respiratory viruses, primarily canine parainfluenza virus, were found frequently in lower respiratory tract samples in dogs with BP. This indicates that viruses may play an important role in the etiology and pathogenesis of BP. Viral co-infections did not affect disease severity or clinical variables. Our findings add new knowledge about the natural course of BP as well as about the possible applications of acute phase protein measurements in the diagnosis and follow-up of BP. The utilization of acute phase protein measurements may allow a more precise diagnosis of BP, enable the early identification of patients with a poor response to treatment, and diminish the use of antimicrobial drugs.
Original languageEnglish
Awarding Institution
  • University of Helsinki
Supervisors/Advisors
  • Rajamäki, Minna, Supervisor
  • Sankari, Satu, Supervisor
Award date13 Jan 2017
Place of PublicationHelsinki
Publisher
Print ISBNs978-951-51-2467-8
Electronic ISBNs978-951-51-2468-5
Publication statusPublished - 13 Jan 2017
MoE publication typeG5 Doctoral dissertation (article)

Fields of Science

  • 413 Veterinary science

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