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Home / Equine Research Bank / Front Vet Sci / Sex and Age Don’t Matter, but Breed Type Does-Factors ...
Frontiers in veterinary science2019; 6; 154; doi: 10.3389/fvets.2019.00154

Sex and Age Don’t Matter, but Breed Type Does-Factors Influencing Eye Wrinkle Expression in Horses.

Abstract: Identifying valid indicators to assess animals' emotional states is a critical objective of animal welfare science. In horses, eye wrinkles above the eyeball have been shown to be affected by pain and other emotional states. From other species we know that individual characteristics, e.g., age in humans, affect facial wrinkles, but it has not yet been investigated whether eye wrinkle expression in horses is systematically affected by such characteristics. Therefore, the aim of this study was to assess how age, sex, breed type, body condition, and coat colour affect the expression and/or the assessment of eye wrinkles in horses. To this end, we adapted the eye wrinkle assessment scale from Hintze et al. (1) and assessed eye wrinkle expression in pictures taken from the left and the right eye of 181 horses in a presumably neutral situation, using five outcome measures: a qualitative first impression reflecting how worried the horse is perceived by humans, the extent to which the brow is raised, the number of wrinkles, their markedness and the angle between a line through both corners of the eye and the topmost wrinkle. All measures could be assessed highly reliable with respect to intra- and inter-observer agreement. Breed type affected the width of the angle [ = 8.20, 0.05). In conclusion, horses' eye wrinkle expression and its assessment in neutral situations was not systematically affected by the investigated characteristics, except for "breed type", which accounted for some variation in "angle"; how much eye wrinkle expression is affected by emotion or perhaps mood needs further investigation and validation.
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Publication Date: 2019-05-29 PubMed ID: 31192235PubMed Central: PMC6549476DOI: 10.3389/fvets.2019.00154Google Scholar: Lookup
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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.

The research study investigates various factors that might influence the expression of eye wrinkles in horses, a potential emotional state indicator, and finds that breed type is a significant contributor.

Research Objectives

  • The study aimed to identify any individual characteristics or factors that could systematically impact the expression of eye wrinkles in horses. The potential indicators considered were age, sex, breed type, body condition, and coat colour.

Methodology

  • The researchers adapted the eye wrinkle assessment scale and evaluated eye wrinkle expressions using images of 181 horses in a supposedly neutral situation.
  • They examined five outcome measures: a qualitative first impression of how worried the horse appears to humans, the degree to which the brow is lifted, the number of wrinkles, their markedness, and the angle between a line through both corners of the eye and the highest wrinkle.
  • Both intra- and inter-observer agreement were evaluated for reliability.

Results

  • Breed type significantly influenced the angle width, with thoroughbreds having the narrowest angle, followed by warmbloods and coldbloods.
  • No impact on any of the five outcome measures was found based on the other assessed characteristics.
  • No difference in eye wrinkle expression between the left and right eye area was observed.

Conclusion

  • Apart from breed type which accounted for some variation in the eye wrinkle angle, none of the investigated characteristics including age, sex, body condition, coat colour, and side of the face systematically affected eye wrinkle expression in a neutral setting.
  • The influence of emotion or mood on eye wrinkle expression in horses requires further investigation and validation.

Cite This Article

APA
Schanz L, Krueger K, Hintze S. (2019). Sex and Age Don’t Matter, but Breed Type Does-Factors Influencing Eye Wrinkle Expression in Horses. Front Vet Sci, 6, 154. https://doi.org/10.3389/fvets.2019.00154

Publication

Frontiers in veterinary science
ISSN: 2297-1769
NlmUniqueID: 101666658
Country: Switzerland
Language: English
Volume: 6
Pages: 154
PII: 154

Researcher Affiliations

Schanz, Lisa
  • Division of Livestock Sciences, Department of Sustainable Agricultural Systems, University of Natural Resources and Life Sciences, Vienna, Austria.
  • Department of Equine Economics, Nuertingen-Geislingen University of Applied Sciences, Nürtingen, Germany.
Krueger, Konstanze
  • Department of Equine Economics, Nuertingen-Geislingen University of Applied Sciences, Nürtingen, Germany.
  • Biology I, University of Regensburg, Regensburg, Germany.
Hintze, Sara
  • Division of Livestock Sciences, Department of Sustainable Agricultural Systems, University of Natural Resources and Life Sciences, Vienna, Austria.

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Citations

This article has been cited 11 times.
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