TLDR Hair cortisol can reliably indicate chronic stress in cats and dogs.
The study investigated the feasibility of using hair cortisol assays as a non-invasive method to monitor the hypothalamic–pituitary–adrenal (HPA) axis activity in domestic cats and dogs. It involved 56 new hair growth samples and 870 faecal samples from 27 cats and 29 dogs. The results showed a significant positive correlation between cortisol levels in hair and faeces for both species, suggesting that hair cortisol could be a reliable indicator of chronic stress. This method offered a long-term endocrine profile without the stress associated with blood sampling, although it required further validation and understanding of steroid incorporation into hair.
489 citations
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June 2005 in “The FASEB Journal” Human hair follicles can produce cortisol like the body's stress response system.
61 citations
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March 2003 in “American Journal Of Pathology” Stress can cause hair loss and skin issues by affecting hair growth cycles.
31 citations
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January 2003 in “Dermatology” Steroidogenic isoenzymes may help improve treatments for common hair loss.
89 citations
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December 1998 in “The Journal of Steroid Biochemistry and Molecular Biology” Human hair can be used to measure reproductive hormones.
416 citations
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September 1997 in “Journal of Investigative Dermatology” People with hair loss have more androgen receptors and enzymes in certain follicles, with men and women showing different patterns.
154 citations
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October 1996 in “Proceedings of the National Academy of Sciences of the United States of America” Estrogen affects hair growth and skin cell multiplication.
May 2023 in “Animal Reproduction Update” High levels of cortisol in hair show long-term stress which can lower fertility in animals.
September 2025 in “Cosmoderma” Pandemic stress worsens hair loss and skin issues, suggesting combined mental and skin care treatments.
January 2023 in “Research Square (Research Square)” Hair cortisol may be a good indicator of recent mood in people with bipolar disorder.
5 citations
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May 2021 in “Veterinary medicine and science” Injecting cosyntropin into grizzly bears increases blood cortisol but doesn't change hair cortisol levels.
5 citations
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May 2017 in “Journal of the European Academy of Dermatology and Venereology” The study found no significant difference in stress hormone levels between people with alopecia areata and healthy individuals, suggesting that the disease is not caused by an overactive stress response system.
