PS7-9. Increase in Markers of Systemic Inflammation in Canines and Subsequent Mortality Risk.

Abstract Systemic inflammatory blood biomarkers involving lymphocytes are reliable indicators of changes in immune function. In this study, we evaluated the Neutrophil-to-Lymphocyte Ratio (NLR), Platelet-to-Lymphocyte Ratio (PLR), and Systemic Immune-Inflammation Index (SII) from standard CBC in canines. These ratios are indicators of chronic inflammation and an increase in values have been associated with inflammation and poor prognosis in selected adverse health conditions. Chronic low-grade inflammation is a key feature in aging dogs. In this study we analyzed a minimum of eight years of complete blood count (CBC) data from 107 aging dogs housed at the Hill’s Pet Nutrition Center. Ratios were calculated longitudinally based on time-to-mortality or natural end-of-life intervals (0–6 months, >6 months–1.5 years, >1.5–3 years, and >3 years preceding death). Furthermore, the data were evaluated by binning the subjects into three age groups: 1–6 years, 6–11 years, and >11 years. Data are presented as Mean + SEM and Tukey’s post-hoc test for multiple comparisons. Mean age at death was 14.1+1.5 years. NLR, PLR and SII all increased as dogs neared the end-of-life (EOL). NLR was significantly increased in dogs that were 11 years or older (3.5+0.1) when compared to dogs in age groups of 1-6 years (2.7+0.1) and 6-11 years (2.9+0.1, both p < 0.05). When compared across age groups, there was a progressive increase in PLR as the animals aged: 1-6 years (180+5.40); 6-11 years (235+4.5), and >11 years (324+7.4; all p < 0.05 between groups). The increase in SII was more pronounced within 6 months of EOL when compared to 3 years from EOL (1959+102, vs 756+14.2, p < 0.05). In summary, NLR, PLR, and SII are accessible biomarkers of age-related systemic inflammation. SII and PLR increased significantly as dogs aged and approached the natural EOL. Together, these markers offer clinical insights for monitoring systemic inflammation in aging. Establishing reference intervals will be useful for prognosis as well as developing targeted nutritional strategies for chronic low-grade inflammation in selected health conditions in canines.