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Home / Equine Research Bank / Front Vet Sci / How facial expressions reveal acute pain in domestic animals...
Frontiers in veterinary science2025; 12; 1546719; doi: 10.3389/fvets.2025.1546719

How facial expressions reveal acute pain in domestic animals with facial pain scales as a diagnostic tool.

Abstract: The growing interest in managing and recognizing pain in animals has led to the search for more sensitive methods to evaluate it, especially because some species conceal any visible changes associated with pain or are not easily assessed. Research has shown that an animal's facial expression changes when exposed to painful stimuli. Thus, developing several pain scales (grimace scales) in species such as horses, cattle, pigs, sheep, donkeys, rabbits, rats, mice, and cats has helped to improve the study of pain in veterinary medicine. The possibility of using facial expression as an indicator of pain is due to the direct relationship between the activation of different regions of the Central Nervous System such as the somatosensory cortex, prefrontal cortex, amygdala, hippocampus, and hypothalamus, and their connections with the motor cortex to elicit motor responses including the movement of facial muscles. The present review aims to discuss the neurobiological association between acute pain and facial expressions in animals. It will analyze the importance of facial expression characterization and the use of grimace scales in farm, companion, and laboratory species.
Copyright © 2025 Mota-Rojas, Whittaker, Coria-Avila, Martínez-Burnes, Mora-Medina, Domínguez-Oliva, Hernández-Avalos, Olmos-Hernández, Verduzco-Mendoza, Casas-Alvarado and Grandin.
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Publication Date: 2025-03-04 PubMed ID: 40104548PubMed Central: PMC11913824DOI: 10.3389/fvets.2025.1546719Google 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 article discusses the use of facial expressions in domestic animals as an indicator of acute pain, and the development and use of various ‘grimace scales’ as diagnostic tools in veterinary medicine.

Interest in Pain Management in Animals

  • The research article starts with the recognition of the growing interest in managing and recognizing pain in animals.
  • There is a need for more sensitive methods to evaluate pain in animals, especially because some species conceal any visible changes associated with pain, or are difficult to assess.

Facial Expressions and Pain

  • The researchers found that an animal’s facial expression changes when exposed to painful stimuli.
  • This has led to the development of various ‘grimace scales’ in a range of species including horses, cattle, pigs, sheep, donkeys, rabbits, rats, mice, and cats.
  • These scales have greatly improved the study of pain in veterinary medicine.

Neurobiological Association Between Facial Expression and Pain

  • The potential use of facial expressions as an indicator of pain is linked to the activation of different regions of the Central Nervous System (CNS).
  • These regions include the somatosensory cortex, prefrontal cortex, amygdala, hippocampus, and hypothalamus.
  • These CNS areas have connections with the motor cortex which controls the movement of facial muscles.

The Purpose of the Review

  • The purpose of this review is to discuss the relationship between acute pain and facial expressions in animals.
  • It also intends to examine the importance of characterizing facial expressions and using the grimace scales across various species.
  • Said species come from different contexts, including farms, companions (pets), and laboratory animals.

Cite This Article

APA
Mota-Rojas D, Whittaker AL, Coria-Avila GA, Martínez-Burnes J, Mora-Medina P, Domínguez-Oliva A, Hernández-Avalos I, Olmos-Hernández A, Verduzco-Mendoza A, Casas-Alvarado A, Grandin T. (2025). How facial expressions reveal acute pain in domestic animals with facial pain scales as a diagnostic tool. Front Vet Sci, 12, 1546719. https://doi.org/10.3389/fvets.2025.1546719

Publication

Frontiers in veterinary science
ISSN: 2297-1769
NlmUniqueID: 101666658
Country: Switzerland
Language: English
Volume: 12
Pages: 1546719

Researcher Affiliations

Mota-Rojas, Daniel
  • Neurophysiology, Behavior and Animal Welfare Assessment, DPAA, Universidad Autónoma Metropolitana (UAM), Mexico City, Mexico.
Whittaker, Alexandra L
  • School of Animal and Veterinary Sciences, Roseworthy Campus, University of Adelaide, Roseworthy, SA, Australia.
Coria-Avila, Genaro A
  • Instituto de Investigaciones Cerebrales, Universidad Veracruzana, Xalapa, Mexico.
Martínez-Burnes, Julio
  • Instituto de Ecología Aplicada, Facultad de Medicina Veterinaria y Zootecnia, Universidad Autónoma de Tamaulipas, Victoria City, Mexico.
Mora-Medina, Patricia
  • Facultad de Estudios Superiores Cuautitlán, Universidad Nacional Autónoma de México (UNAM), Cuautitlán, Mexico.
Domínguez-Oliva, Adriana
  • Neurophysiology, Behavior and Animal Welfare Assessment, DPAA, Universidad Autónoma Metropolitana (UAM), Mexico City, Mexico.
Hernández-Avalos, Ismael
  • Facultad de Estudios Superiores Cuautitlán, Universidad Nacional Autónoma de México (UNAM), Cuautitlán, Mexico.
Olmos-Hernández, Adriana
  • Division of Biotechnology-Bioterio and Experimental Surgery, Instituto Nacional de Rehabilitación Luis Guillermo Ibarra Ibarra (INR-LGII), Mexico City, Mexico.
Verduzco-Mendoza, Antonio
  • Division of Biotechnology-Bioterio and Experimental Surgery, Instituto Nacional de Rehabilitación Luis Guillermo Ibarra Ibarra (INR-LGII), Mexico City, Mexico.
Casas-Alvarado, Alejandro
  • Neurophysiology, Behavior and Animal Welfare Assessment, DPAA, Universidad Autónoma Metropolitana (UAM), Mexico City, Mexico.
Grandin, Temple
  • Department of Animal Science, Colorado State University, Fort Collins, CO, United States.

Conflict of Interest Statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision.

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