Early recognition of excessive inflammation and infectious complications related to the peripartum period, leading to early institution of therapy, reduces postpartum discomfort and facilitates recovery. Because serum amyloid A (SAA) is a highly sensitive marker of inflammation, measurements of SAA and other inflammatory markers in postpartum mares may be valuable in assisting clinical
assessment of periparturient complications. We hypothesized that mares with peripartum complications substantially altered inflammatory responses compared to normal postpartum mares. Aims were to: 1) determine if inflammatory markers (serum amyloid A (SAA), fibrinogen, white blood cell count (WBC), and iron are affected by normal parturition; and 2) investigate if parturition-related complications affect concentrations of WBC, SAA, fibrinogen, and iron. A retrospective case-control study included 118 postpartum mares, 72 clinically healthy (CH) mares accompanying sick foals and 46 mares with periparturient complications (PC) admitted to the University of Copenhagen Large Animal Teaching Hospital from 2008 - 2017. Periparturient complications were divided into 3 groups: metritis (n = 9), dystocia (n = 13) and others (n =24). A multivariate linear regression analysis evaluated the effects of health status of mare (CH or PC), time after foaling (Day PP) and individual mare on blood parameters. Independent-samples Student’s t test analyzed differences in inflammatory parameters between CH and PC mares at different days after foaling. CH mares had SAA, WBC, and iron concentrations within reference intervals for first week postpartum (PP). Mean fibrinogen concentrations increased above upper
reference limit in both CH and PC mares during the first week PP, but PC mares had higher (p < 0.05) concentrations compared to CH mares. Health status of mares had substantial influence on concentrations of SAA (p < 0.0001), fibrinogen (p < 0.0001), and iron (p = 0.009), and day PP had an effect (p = 0.02) on WBC in both CH and PC mares. Fibrinogen concentrations increased (p < 0.05) on days 2, 3, and 7 and SAA concentrations on days 1 - 7 (p < 0.05), and WBC and iron concentrations decreased (p < 0.05) on days 1 - 3 (p < 0.05) in PC mares compared to CH mares. Iron and WBC concentrations were, however, within reference concentrations, for both groups of mares. Mares diagnosed with metritis had lower (p = 0.008) iron concentrations compared to mares with other periparturient complications. Inflammatory markers SAA and WBC were not affected by normal parturition and can be used to monitor inflammation and infection in mares with peripartum complications. Healthy postpartum mares had
increased fibrinogen concentrations within first 7 days after parturition. Periparturient complications elicited, however, substantial higher fibrinogen concentrations compared to concentrations in normal postpartum mare. A major fibrinogen response, therefore, still indicates periparturient complications in a
postpartum mare, and can, together with SAA and WBC, be used to monitor the inflammatory response related to periparturient complications.