Behavior Genetics of the Horse (Equus caballus) - Genetics and the Behavior of Domestic Animals - page 255

stress hormone levels. Mares had higher stress hormone levels than stallions,
and mounting by a rider caused the most pronounced stress reaction. Leiner
and Fendt (2011) measured heart rate and behavioral reactions to novel
objects on 18 Warmblood stallions. The results show correlations between
behavioral and physiological fear responses. Furthermore, after habituation
to an object occurs, the fear response to the object is reduced, whereas the
fear response to another totally different novel object remains. Habituation to
a stationary blue and white umbrella does not transfer to an orange tarp
( Leiner and Fendt, 2011 ). Heart rate increases are a reliable measure of fear
intensity in horses, although responses to the novel stimuli differed between
individuals.
The purpose of this review was to show some of the methods used to
study individual differences in temperament. Many of these tests are compli-
cated and take a considerable amount of time to perform. In addition, a few
are not easy to perform and difficult to standardize. For lay persons, it may
be difficult to make decisions about a horse based on these results. However,
the consistency of responses to sudden novelty, novel objects, and behavior
in novel environments, all indicate a core dimension of temperament. As we
discussed earlier, fearfulness is probably the most important factor influenc-
ing the suitability of horses for any type of work. In the next section we dis-
cuss evidence collected by the first author that may provide an easy and
practical method for assessing temperament that anyone can use.
THE RELATIONSHIP BETWEEN HAIR WHORLS AND
BEHAVIOR
In early 1993, the first author approached me (Temple Grandin) in my office
at Colorado State University to discuss some observations he had made while
working as a farrier and horse trainer. The anecdotal evidence he collected
suggested a possible relationship between hair whorls on horses' foreheads
and temperament. I was of course skeptical; however, the story he told was
compelling. All my years of working in the industry had taught me that peo-
ple who work around cattle or horses daily often make valid observations
that scientists working in the laboratory often miss. Before we met, Mark
approached others in academia. Most said his ideas were too far-fetched to
be worth consideration. We began by searching the literature for any evi-
dence to support his observations. At the time, the only reference to horse
hair whorls was a questionnaire survey of 1500 horse collected in 1965 by
Tellington-Jones and Taylor (1995) ; however, the conclusions of the authors
offered no statistical evidence.
What follows is the anecdotal evidence Mark discussed with me about
hair whorls collected over a 15-year period and involving over 10,000
horses. He noticed hair whorls located high on the forehead predicted a
flighty temperament. Whorls located below the center of the eyes predicted a