Isometric Scaling in Two Sizes of Equids

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Chris Alford, Holly Lang and Lacy Bach.
Dr. Charlie Apter, Faculty Mentor.

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Allometric scaling is an important biological principle that demonstrates a unity of design across many orders of magnitude of body size. While allometric scaling has been considered in many interspecies comparisons, less is known about intraspecies allometric scaling. In this preliminary study, body weight and six different body dimensions were determined for two size groups of equids (Equus caballus): eight Quarter horse and Paint mares typifying the light stockhorse type, and six Percheron draft mares representing the heavy horse type. Body dimensions were then plotted against body mass and correlation coefficients determined. Results indicate that height at the withers is most closely correlated to mass, with an R2 value of 0.86. A future study is planned that will utilize larger sample sizes and five size categories of equids: the two groups as outlined above and miniature mares, pony mares, and Arabian mares.