The assessment of haematologic and serum chemistry parameters in canine pyometra: a systematic review and meta-analysis

Abstract

Objectives: Pyometra is common in non-spayed adult female dogs requiring early diagnosis and treatment to increase the survival rate. The diagnosis of pyometra is mainly based on clinical examination and anamnesis. Radiography, ultrasonography and laboratory analyses are recommended to support a diagnosis. The aim of this study was to assess blood parameters associated with pyometra by performing a systematic review and meta-analysis.

Materials and methods: The review was conducted in accordance with PRISMA guidelines. A search of three databases (PubMed, Google Scholar and CAB abstracts) was performed in July 2022. Studies providing information about laboratory parameters for both the pyometra group and healthy control group dogs were eligible for inclusion. Data extraction included the first author's name, publication year, country, number of participants in both groups, mean values of selected studies, standard deviation values, and blood parameters. The risk of bias for each study was evaluated, and a random-effects meta-analysis was performed.

Results: We included 44 studies which investigated 12 blood parameters. High heterogeneity was detected in all parameters in these meta-analyses. The following blood parameters were increased in dogs with pyometra: white blood cell (mean=27.75×10⁹ L^-1 , mean difference (MD)=17.16, 95% confidence interval (CI) 14.85 to 19.47), monocytes (mean=2.06×10¹² /L, MD=1.37, 95% CI 0.99 to 1.74), blood urea nitrogen (mean=41.42 mg/dL MD=18.06, 95% CI 12.26 to 23.85), alkaline phosphatase (mean=212.78 IU/L, MD=137.51, 95% CI 81.81 to 88.62), and aspartate aminotransferase (mean=48.31 IU/L, MD=16.96, 95% CI 10.61 to 23.30). The following parameters were reduced: red blood cell (mean=5.42 10¹² /L, MD=-1.37, 95% CI -1.68 to -1.05), haemoglobin (mean=121.20 g/L, MD=-30.57, 95% CI -39.70 to 21.45), albumin (mean=23.71 g/L, MD = -8.16, 95% CI -11.46 to -4.86). Lymphocyte, creatinine, urea, and alanine transaminase parameters were increased in some studies and decreased in others.

Clinical significance: In canine pyometra, some blood parameters are consistently increased, some consistently decreased, and some increased or decreased depending on the study.