Seasonal variation in serum metabolites of northern European dogs.

Abstract

BACKGROUND: Metabolic profiling identifies seasonal variance of serum metabolites in humans. Despite the presence of seasonal disease patterns, no studies have assessed whether serum metabolites vary seasonally in dogs. HYPOTHESIS: There is seasonal variation in the serum metabolite profiles of healthy dogs. ANIMALS: Eighteen healthy, client-owned dogs. METHODS: A prospective cohort study. Serum metabolomic profiles were assessed monthly in 18 healthy dogs over a 12-month period. Metabolic profiling was conducted using a canine-specific proton nuclear magnetic resonance spectroscopy platform, and the effects of seasonality were studied for 98 metabolites using a cosinor model. Seasonal component was calculated, which describes the seasonal variation of each metabolite. RESULTS: We found no evidence of seasonal variation in 93 of 98 metabolites. Six metabolites had statistically significant seasonal variance, including cholesterol (mean 249&#x2009;mg/dL [6.47&#x2009;mmol/L] with a seasonal component amplitude of 9&#x2009;mg/dL [0.23&#x2009;mmol/L]; 95% confidence interval [CI] 6-13&#x2009;mg/dL [0.14-0.33&#x2009;mmol/L], P&#xa0;<&#x2009;.008), with a peak concentration of 264&#x2009;mg/dL (6.83&#x2009;mmol/L) in June and trough concentration of 236&#x2009;mg/dL (6.12&#x2009;mmol/L) in December. In contrast, there was a significantly lower concentration of lactate (mean 20&#x2009;mg/dL [2.27&#x2009;mmol/L] with a seasonal component amplitude of 4&#x2009;mg/dL [0.42&#x2009;mmol/L]; 95% CI 2-6&#x2009;mg/dL [0.22-0.62&#x2009;mmol/L], P&#xa0;<&#x2009;.001) during the summer months compared to the winter months, with a peak concentration of 26&#x2009;mg/dL (2.9&#x2009;mmol/L) in February and trough concentration of 14&#x2009;mg/dL (1.57&#x2009;mmol/L) in July. CONCLUSIONS AND CLINICAL IMPORTANCE: We found no clear evidence that seasonal reference ranges need to be established for serum metabolites of dogs.