Glucocorticoid assessment in the domestic horse: The impacts of time and climatic variables on sample integrity.

Summary

# Editorial Summary: Glucocorticoid assessment in the domestic horse Faecal glucocorticoid metabolite (FGM) analysis provides a valuable non-invasive window into equine adrenal function and stress responses, yet its reliability depends critically on sample handling conditions that field practitioners rarely control. Yarnell and Walker (2018) investigated how time elapsed since defaecation and exposure to environmental variables—temperature, humidity, and precipitation—affect FGM concentration stability in equine faeces, recognising that opportunistic field sampling often means samples sit unrefrigerated for hours or days before laboratory analysis. Their findings demonstrated significant degradation of measurable FGM concentrations under common field conditions, with temperature and moisture exposure emerging as the primary drivers of sample integrity loss. For practitioners relying on FGM testing to assess stress, training load, or metabolic dysfunction, these results underscore the importance of documenting collection time precisely, refrigerating samples immediately, and standardising protocols between sampling and analysis; failure to do so risks both false negatives (underestimating actual stress levels) and compromised longitudinal comparisons within individual animals. This work reinforces that non-invasive endocrine monitoring is only as robust as the sample handling that precedes it.

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Key Findings

• •Faecal glucocorticoid metabolite (FGM) analysis provides noninvasive monitoring of adrenal activity in horses
• •Sample integrity is compromised by time elapsed since collection and exposure to environmental/climatic conditions
• •Fresh samples or those not exposed to elements are required for accurate FGM concentration reflection

Conditions Studied

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