Animal science journal = Nihon chikusan Gakkaiho2026; 97(1); e70251; doi: 10.1111/asj.70251

New Noninvasive Long-Term Stress indicator in Horses: Analysis of Cortisol Levels in the Hoof of Foals.

Ojima, Y
·
Kimura, Y
·
Maeda, Y
·
Matsuura, A

Abstract: Noninvasive sampling methods are recommended in animals as far as possible. However, there has been no way to safely measure long-term stress in all horses including foals and stallions. Currently, nail cortisol in humans has been reported to be a promising noninvasive long-term stress indicator. This study aimed to evaluate the usefulness of a horse's hoof as a noninvasive long-term stress indicator by determining whether hoof cortisol levels varied similarly to hair cortisol levels noted in a previous study. All hooves were sampled by one farrier after a foal's birth. They were divided into three groups: (1) hooves reflecting cortisol levels 1 month prior to birth of fetuses (n = 18), (2) the 1 month-period immediately after birth (n = 11), and (3) the 1 month-period more than 1 month after birth (n = 9). Cortisol levels in the fetal period markedly exceeded those of the other two periods (p < 0.05). Moreover, the changes of cortisol levels in this study were consistent with those of similar periods in previous studies. Therefore, the hoof would be useful to obtain noninvasive long-term stress indicators in the horse.

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Publication Date: 2026-10-16 PubMed ID: 42886070DOI: 10.1111/asj.70251Google Scholar: Lookup

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Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

Overview

This study explores a new, noninvasive method of assessing long-term stress levels in horses by measuring cortisol in their hooves, with a focus on foals.
The research aims to determine if hoof cortisol levels reflect stress in a similar way to hair cortisol levels, which have been previously studied.

Background and Rationale

Stress assessment in animals is important for welfare monitoring, and noninvasive methods are preferred to minimize the impact on the animals.
Currently, no safe and effective method exists for measuring long-term stress in horses, including foals and stallions.
In humans, cortisol measured in nails has emerged as a promising noninvasive biomarker for long-term stress.
The researchers hypothesized that the horse’s hooves, which are analogous in structure to human nails, could similarly reflect long-term cortisol levels and thus stress.

Study Design and Methods

Samples of hooves were collected from foals by a single farrier to ensure consistency.
The study divided hoof samples into three time-based groups based on periods relative to the foal’s birth:
- (1) Hooves representing cortisol levels from 1 month before birth (n = 18)
- (2) Hooves representing cortisol levels from the first month after birth (n = 11)
- (3) Hooves representing cortisol levels from more than 1 month after birth (n = 9)
Cortisol concentrations were measured in these hoof samples and compared across the three groups.

Key Findings

Cortisol levels were significantly higher in hooves corresponding to the fetal period (1 month prior to birth) compared to the postnatal periods (p < 0.05).
The pattern of cortisol variation in hooves was consistent with previous findings on hair cortisol levels over similar time frames, supporting the validity of hoof cortisol as a stress biomarker.
This suggests that the hoof can serve as an indicator of long-term stress, capturing retrospective cortisol levels related to different developmental stages.

Conclusions and Implications

The study demonstrates that horse hooves can be used as a noninvasive and practical sample source for assessing long-term stress through cortisol analysis.
This approach could be especially useful for foals and stallions where traditional sampling might be difficult or stressful.
Using hoof cortisol analysis may improve animal welfare by allowing better monitoring of physical and psychological stress over time without invasive procedures.
Future work could expand this method to larger populations and different breeds and verify its application in various stress-related research and clinical scenarios.

Cite This Article

APA

Ojima Y, Kimura Y, Maeda Y, Matsuura A. (2026). New Noninvasive Long-Term Stress indicator in Horses: Analysis of Cortisol Levels in the Hoof of Foals. Anim Sci J, 97(1), e70251. https://doi.org/10.1111/asj.70251

Publication

Animal science journal = Nihon chikusan Gakkaiho

ISSN: 1740-0929

NlmUniqueID: 100956805

Country: Australia

Language: English

Volume: 97

Issue: 1

Pages: e70251

Researcher Affiliations

Ojima, Yuki

Department of Animal Science School of Veterinary Medicine, Kitasato University, Aomori, Japan.

Kimura, Yuya

Department of Animal Health Technology, Yamazaki University of Animal Health Technology, Tokyo, Japan.

Maeda, Yosuke

Department of Animal Science School of Veterinary Medicine, Kitasato University, Aomori, Japan.

Matsuura, Akihiro

Department of Animal Science School of Veterinary Medicine, Kitasato University, Aomori, Japan.

MeSH Terms

Animals
Hydrocortisone / analysis
Hydrocortisone / metabolism
Horses / physiology
Horses / metabolism
Hoof and Claw / metabolism
Hoof and Claw / chemistry
Stress, Physiological / physiology
Female
Time Factors
Hair / metabolism
Biomarkers / analysis
Animals, Newborn

References

This article includes 26 references

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