Pyometra is a common diestrus disease in adult bitches characterized by genital and systemic illness with a variety of clinical signs, pathological findings, and inflammatory uterine accumulation [1]. Even though the etiopathology of the pyometra has been studied for decades, it is still not yet fully understood but impaired immune function, including the reduced activity of lymphocytes, has a relationship with this problem [2]. Pyometra is also known to be the reason for systemic inflammation which potentially affects multiple organs, specifically the kidney, liver, and heart [3].

Systemic inflammatory response syndrome (SIRS) is the manifestation of the systemic response to an infectious or non-infectious disease associated with a massive release of inflammatory mediators. Criteria for the SIRS diagnosis in dogs have been previously reported and include abnormalities in body temperature, heart and respiratory rate, and leukocyte count [4]. Determination of the SIRS status can be helpful for the diagnosis and treatment for the patient. There are some markers that could be useful tools for evaluation of the SIRS status in dogs, as C-reactive protein, procalcitonin, and lactate. Unfortunately, these parameters may not be readily available or are expensive in veterinary medicine. On the other hand, there are some new indices for veterinary medicine that combined inflammatory markers that can be obtained from hemogram and biochemistry such as neutrophil-lymphocyte ratio (NLR), neutrophil percentage-albumin ratio (NPAR) and monocyte-lymphocyte ratio (MLR) were suggested. These indices have been studied in many cases, especially in oncological and cardiopathic patients, and have been found to be associated with mortality rates [[5], [6], [7]]. The systemic immune-inflammation index (SII) and platelet-lymphocyte ratio (PLR), together with other indices, may be useful for the evaluation of the SIRS status in pyometra cases to predict prognosis.

Determination of the pyometra-induced SIRS could be a useful tool for the evaluation of the disease severity. The early evaluation of the SIRS and prognosis is still imprecise for patients that suffer from the pyometra, and significant research is needed. To our knowledge, there is no study evaluating all these indices in dogs that develop the SIRS only due to the pyometra cases. It was hypothesized that hemato-biochemical differences might be observed in bitches suffering from pyometra with and without the SIRS and that fluctuations might be used as a diagnostic biomarker for evaluating the degree of inflammation, and these indices might be a useful tool for diagnosis of pyometra in bitches. This study aimed to establish a cut-off point by evaluating the usability of the hemato-biochemical indices to determine the severity of inflammation caused by pyometra, and to determine the practical usage of the indices as a diagnostic biomarker in cases of pyometra in bitches.