Systemic Inflammatory Response in Canine Pyometra The Response to Bacterial Uterine Infection

Fransson, B. 2003. Systemic inflammatory response in canine pyometra; the response to uterine bacterial infection. Doctor’s dissertation. ISSN 1401-6257, ISBN 91-576-6393-9. Research efforts have focused mainly on the hormonal aspects of canine pyometra for more than 6 decades. However, this disease is often manifested as systemic illness in response to the bacterial uterine infection. Studies I-II were undertaken to clarify bacteriological aspects of canine pyometra; i.e. the origin of the infecting bacteria, the infecting bacteria’s impact on severity of the systemic illness and the presence of bacterial endotoxin in the systemic circulation. Study I, a bacterio-epidemiologic study, investigated the predominant bacteria, Escherichia coli, using biochemical fingerprinting. The homogeneity among E. coli populations, isolated from various sites in bitches with pyometra and from faeces of healthy dogs, was determined. Study II, a clinical study of bitches with pyometra, determined uterine bacterial species, haematology, blood biochemical parameters and plasma endotoxin levels. The impact of infecting bacteria on blood parameters and clinical status was studied. Study III investigated if bitches with pyometra display the Systemic Inflammatory Response syndrome (SIRS) and if SIRS relates to outcome. Systemic levels of interleukin-6 (IL-6), C reactive protein (CRP) and tumor necrosis factor α (TNFα) were determined, investigating a possible correlation between these inflammatory markers and SIRS or outcome. Study IV used clinical parameters, haematology, blood biochemical parameters, CRP and TNFα to clinically differentiate pyometra from the often preceding uterine condition cystic endometrial hyperplasia (CEH). Study I revealed that E. coli isolated from bitches with pyometra show high level of homogeneity indicating that E. coli associated with pyometra may have properties, yet undetermined, in common. Identical clones of E. coli were found in the faeces and uterus of bitches with pyometra, indicating an ascending infection route. Study II failed to show systemic endotoxemia in bitches with pyometra, but showed many other signs of systemic affection in blood parameters. Study III showed that 57 % of pyometra cases fulfil clinical criteria for SIRS and that SIRS criteria are correlated to increased length of hospitalization. Body temperature, heart rate and CRP correlated to SIRS and CRP correlated to outcome. Study IV revealed that clinical signs and levels of percent band neutrophils and CRP aid in the differentiation of CEH from pyometra.