NL Journal of Veterinary and Animal Nutrition

---

Stress Biomarkers in Companion Animals: An Integrative Review

Author(s) : Mousumi Hazorika*, Abhijit Deka, Pallabi Devi, Utpal Barman, Manjyoti Bhuyan, Mohua Das Gupta, Mridusmrita Buragohain, Mamata Joysowal.

---

Abstract

Stress in companion animals is a multifaceted physiological and behavioural response driven primarily by activation of the hypothalamic–pituitary–adrenal (HPA) axis and sympathetic–adrenal–medullary (SAM) system, often resulting in compromised welfare, disrupted homeostasis, reduced fitness, and impaired alignment with owner and societal expectations. This review provides current knowledge on recognising different signs of stress and diverse biomarkers used to assess acute and chronic stress in companion animals—highlighting long-term endocrine measures such as cortisol accumulation in hair and nails during dog maternity, neuromodulators including prolactin and serotonin for evaluating stress-associated behavioural and lifestyle influences, oxytocin linked to sociality despite lower circulating levels in assistance dogs, metabolic indicators from neonatal blood gas changes reflecting intrapartum hypoxia or asphyxia risk, non-invasive skin temperature shifts measured via infrared thermography, facial expression–based tools like FACS adaptations and Grimace/Grimace-type scales for emotional and welfare evaluation, and oxidative-stress biomarker panels combined with enzymatic and non-enzymatic antioxidant defences (SOD, CAT, GPx, TAC, GSH, vitamins, trace-element ratios, and oxidative damage products such as MDA, 8-OHdG, protein carbonyls, isoprostanes, and myeloperoxidase). Evidence across studies remains heterogeneous due to influences of diet, age, sex, breed, lifestyle, environment, and pre-analytical sampling variability, reinforcing that no single biomarker can comprehensively define stress across contexts, and that integrative multi-biomarker frameworks, standardized sampling protocols, and longitudinal validation are critical to improve diagnostic reliability and advance clinical and welfare-centric stress assessment in dogs and other companion species. Keywords: Stress, Companion animals, Biomarkers, Animal welfare.

This article licensed under the Creative Commons Attribution 4.0 International License CC-BY 4.0., which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.