Clinical and Molecular Characteristics of Pyometra in Female Dogs

Pyometra is a common disease of female dogs. In Sweden, where approximately 90% of the dog population is intact (not neutered), nearly 25% of all female dogs are diagnosed with the disease before 10 years of age. In certain high-risk breeds, this risk of developing pyometra exceeds 50%. Various clinical signs associated with the genital tract as well as with systemic disease are present in dogs with pyometra. A frequent and serious consequence of the uterine infection is endotoxaemia and progression into the systemic inflammatory response syndrome (SIRS), or sepsis, and the disease is then regarded as a medical emergency. Acute phase proteins and inflammatory markers associated with SIRS and with the outcome as measured by length of hospitalization have been identified in blood samples. Recently, the inflammatory response in infected uterine tissue during pyometra has been more closely explored. The expression of many genes associated with chemokines, cytokines, inflammatory cell extravasation, anti-bacterial action, the complement system and innate immune responses and also a large panel of proteases are upregulated in the uterine tissue in pyometra. Products of certain upregulated genes may be detected systemically and used for diagnostic or prognostic purposes provided that tests are developed in the future. More knowledge of the complex local and systemic inflammatory response in pyometra may allow identification of novel disease biomarkers or future targets for treatment. In this article, clinical as well as molecular characteristics of the disease are reviewed.