The brain of the horse: weight and cephalization quotients.
Abstract: The horse is a common domestic animal whose anatomy has been studied since the XVI century. However, a modern neuroanatomy of this species does not exist and most of the data utilized in textbooks and reviews derive from single specimens or relatively old literature. Here, we report information on the brain of Equus caballus obtained by sampling 131 horses, including brain weight (as a whole and subdivided into its constituents), encephalization quotient (EQ), and cerebellar quotient (CQ), and comparisons with what is known about other relevant species. The mean weight of the fresh brains in our experimental series was 598.63 g (SEM ± 7.65), with a mean body weight of 514.12 kg (SEM ± 15.42). The EQ was 0.78 and the CQ was 0.841. The data we obtained indicate that the horse possesses a large, convoluted brain, with a weight similar to that of other hoofed species of like mass. However, the shape of the brain, the noteworthy folding of the neocortex, and the peculiar longitudinal distribution of the gyri suggest an evolutionary specificity at least partially separate from that of the Cetartiodactyla (even-toed mammals and cetaceans) with whom Perissodactyla (odd-toed mammals) are often grouped.
Publication Date: 2013-12-04 PubMed ID: 24335261DOI: 10.1159/000356527Google Scholar: Lookup
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- Comparative Study
- Journal Article
Summary
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The research article presents data obtained from studying the brains of 131 horses to provide a contemporary understanding of the horse’s brain anatomy. The study measured brain weight, encephalization quotient (existing brain size compared to expected brain size for particular body size) and cerebellar quotient and compares these findings with other relevant species.
Research Method
- The authors focused on the anatomy of the brain of the horse (Equus caballus). To obtain modern findings, 131 horses’ brains were studied, examining both the total brain weight and subdivided constituents.
- Significant focus was given on measuring the encephalization quotient (EQ), which illustrates the existing brain size in comparison to the expected brain size for a specific body mass. The cerebellar quotient (CQ), denoting the proportional size of the cerebellum compared to the brain, was also evaluated.
Key Findings
- The researchers found that the fresh brains under examination weighed on average 598.63 g, with the corresponding average body weight of the horses being 514.12 kg.
- They noted an EQ of 0.78 and a CQ of 0.841 for the horses’ brains, indicating that the horse’s brain is large and convoluted, handling the control of advanced motor control and cognitive functions.
- From this analysis, the brain weight of these horses is found to be relatively similar to other hoofed species of comparable body mass.
Implications
- This study provides an updated view on the horse’s neuroanatomy, providing stuffed gaps in existing literature that typically draws from single specimens or old research.
- The researchers also observed distinctive characteristics in the horse’s brain. They noted its shape, the noteworthy folding of the neocortex (the outer layer of the brain), and an unusual distribution of gyri (ridges on the surface of the brain) spread lengthwise. These findings suggest a unique evolutionary path for the horse, somewhat separable from the path of even-toed mammals and cetaceans, with whom odd-toed mammals, such as horses, are often grouped.
Cite This Article
APA
Cozzi B, Povinelli M, Ballarin C, Granato A.
(2013).
The brain of the horse: weight and cephalization quotients.
Brain Behav Evol, 83(1), 9-16.
https://doi.org/10.1159/000356527 Publication
Researcher Affiliations
- Department of Comparative Biomedicine and Food Science, University of Padova, Legnaro, Italy.
MeSH Terms
- Animals
- Brain / anatomy & histology
- Cerebral Cortex / anatomy & histology
- Female
- Horses / anatomy & histology
- Male
Citations
This article has been cited 15 times.- Graïc JM, Peruffo A, Corain L, Finos L, Grisan E, Cozzi B. The primary visual cortex of Cetartiodactyls: organization, cytoarchitectonics and comparison with perissodactyls and primates. Brain Struct Funct 2022 May;227(4):1195-1225.
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- Bitschi ML, Bagó Z, Rosati M, Reese S, Goehring LS, Matiasek K. A Systematic Approach to Dissection of the Equine Brain-Evaluation of a Species-Adapted Protocol for Beginners and Experts. Front Neuroanat 2020;14:614929.
- Johnson PJ, Janvier V, Luh WM, FitzMaurice M, Southard T, Barry EF. Equine Stereotaxtic Population Average Brain Atlas With Neuroanatomic Correlation. Front Neuroanat 2019;13:89.
- Triarhou LC. The Comparative Neurology of Neocortical Gyration and the Quest for Functional Specialization. Front Syst Neurosci 2017;11:96.
- Bhagwandin A, Haagensen M, Manger PR. The Brain of the Black (Diceros bicornis) and White (Ceratotherium simum) African Rhinoceroses: Morphology and Volumetrics from Magnetic Resonance Imaging. Front Neuroanat 2017;11:74.
- Steinhausen C, Zehl L, Haas-Rioth M, Morcinek K, Walkowiak W, Huggenberger S. Multivariate Meta-Analysis of Brain-Mass Correlations in Eutherian Mammals. Front Neuroanat 2016;10:91.
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- Ballarin C, Povinelli M, Granato A, Panin M, Corain L, Peruffo A, Cozzi B. The Brain of the Domestic Bos taurus: Weight, Encephalization and Cerebellar Quotients, and Comparison with Other Domestic and Wild Cetartiodactyla. PLoS One 2016;11(4):e0154580.
- Davis NE, Forsyth DM, Triggs B, Pascoe C, Benshemesh J, Robley A, Lawrence J, Ritchie EG, Nimmo DG, Lumsden LF. Interspecific and geographic variation in the diets of sympatric carnivores: dingoes/wild dogs and red foxes in south-eastern Australia. PLoS One 2015;10(3):e0120975.
- Valenchon M, Reigner F, Lefort G, Adriaensen H, Gesbert A, Barrière P, Gaude Y, Elleboudt F, Lévy I, Ducluzeau C, Dupont J, Lainé AL, Uszynski I, Dardente H, Poupon C, Lansade L, Calandreau L, Keller M, Barrière DA. Affiliative behaviours regulate allostasis development and shape biobehavioural trajectories in horses. Nat Commun 2026 Jan 13;17(1):47.
- Fletcher KA, Benedetti B, Limon G, Grist A, Padalino B, Hernández-Gil M, Gibson TJ. Pathophysiology of penetrating captive-bolt stunning of horses. Anim Welf 2025;34:e51.
- Pattaro A, Ghibaudi M, Corrente C, Telitsyn N, Graic JM, Aresu L, Sherwood CC, Bonfanti L. Phylogenetic variation of layer II cortical immature neurons in dog and horse confirms covariance with brain size and neocortical surface. Brain Struct Funct 2025 Jul 7;230(6):115.
- Fletcher KA, Padalino B, Felici M, Bigi D, Limon-Vega G, Grist A, Gibson TJ. Assessment of ante mortem welfare indicators and the pathophysiology of captive-bolt trauma in equids at slaughter. Anim Welf 2024;33:e65.
- Al Aiyan A, Balan R, Gebreigziabiher S, Zerom S, Mihreteab Y, Ghebrehiwot E, AlDarwich A, Willingham AL, Kishore U. Comprehensive mapping of the exterior architecture of the dromedary camel brain. Sci Rep 2024 Feb 5;14(1):2971.
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