Study finds dog hair stress biomarkers vary by sampling site

A newly published paper in Veterinary Sciences takes on a deceptively simple question with real implications for canine welfare research: does it matter where hair is collected when measuring chronic stress biomarkers in dogs? In 30 neutered Anatolian shelter dogs, the authors compared hair cortisol, DHEA, and the cortisol-to-DHEA ratio from the shoulder, neck, and rump, and found that sampling site affects the results. That gives clinicians and researchers a useful caution flag at a time when hair-based hormone testing is gaining traction as a non-invasive way to assess chronic stress. (pmc.ncbi.nlm.nih.gov)

The interest in hair biomarkers comes from their potential to reflect longer-term hormone exposure, unlike serum or saliva cortisol, which can shift rapidly with handling, transport, or the veterinary visit itself. That has made hair especially attractive in shelter medicine and welfare work, where repeated low-stress sampling is a major advantage. Earlier canine studies have linked hair cortisol to chronic stress physiology, shelter experience, and behavioral reactivity, while reviews have described hair cortisol as promising, but methodologically sensitive. (pmc.ncbi.nlm.nih.gov)

What this new paper adds is a direct comparison of three commonly accessible body sites in a controlled group of dogs: 30 shelter-housed Anatolians, all neutered, ages 2 to 3 years, evenly split by sex. That kind of relatively uniform study population helps reduce some biological noise, but it also means the findings should be applied carefully outside similar dogs or settings. Even so, the core message is broadly relevant: anatomical site is not just a collection detail. It may shape the biomarker value itself. (mdpi.com)

That fits with the wider literature. Reviews of hair cortisol methods in domestic animals have already identified body region as one of several variables that can alter results, alongside age, sex, season, hair color, and collection technique. A recent methodological review of endogenous steroids in hair and fur also found that reporting on harvest and preparation methods is often incomplete, which makes comparison across papers harder than it should be. And in companion dogs, even the tool used to collect hair can matter: one preliminary Dog Aging Project study reported that clippers outperformed scissors for chemical analysis samples. (pmc.ncbi.nlm.nih.gov)

There doesn’t appear to be substantial outside commentary yet on this specific paper, but the broader expert view is fairly consistent. Reviews in canine and animal welfare research describe hair cortisol as useful, while also emphasizing that it’s vulnerable to confounding from biology, environment, and technique. Separate commentary on DHEA in animal welfare research has argued that pairing cortisol with DHEA, and looking at the ratio, may give a more nuanced picture of allostatic load than cortisol alone. That makes the present study especially relevant, because it addresses not just one analyte, but three related readouts that could each be altered by inconsistent sampling. (pmc.ncbi.nlm.nih.gov)

Why it matters: For veterinary professionals, especially those in shelter medicine, behavior, and clinical research, the study sharpens an operational point: if hair hormones are going to inform welfare assessment, longitudinal monitoring, or clinical investigation, sampling protocols need to be rigid. A neck sample at one visit and a rump sample at the next may not be interchangeable. The same goes for comparing published reference values if the collection sites differ. This doesn’t diminish the promise of hair-based testing, but it does reinforce that standardization is essential before these biomarkers can support confident benchmarking across populations or settings. (pmc.ncbi.nlm.nih.gov)

The findings also land in a shelter context, where chronic stress measurement is especially important and especially difficult. Prior work has shown that shelter dogs can have elevated hair cortisol, and that hair measures may rise over time in shelter housing. At the same time, newer shelter studies suggest behavior may sometimes be a more reliable real-world stress indicator than hormones alone. Taken together, that suggests hair biomarkers are best viewed as one tool in a larger welfare assessment framework, not a standalone answer. (mdpi.com)

What to watch: Watch for replication in other breeds, coat types, and living conditions, and for future welfare or clinical research protocols to converge on one recommended body site for canine hair hormone collection. If that happens, this study may end up being less about Anatolian shelter dogs specifically, and more about helping the field standardize a promising, but still variable, biomarker method. (pmc.ncbi.nlm.nih.gov)