Behavior Genetics of the Horse (Equus caballus) - Genetics and the Behavior of Domestic Animals - page 273

horse to make sure they were looking at him using both eyes, then quickly
walked toward each horse while suddenly opening an umbrella. Sam quickly
turned and escaped to the left, Bobbi quickly turned and escaped to the right.
There was no difference in the immediate response, and both horses ran
about 10 m before stopping and turning to look back. After opening the
umbrella in front of each horse, the first author moved out of the paddock
and noted the time it took for each horse to return to the feed bucket. Bobbi
returned to the bucket and resumed feeding within 3 minutes. After 10 min-
utes Sam had not returned to feed, and for roughly 5 minutes after the
umbrella, she snorted, displayed a raised tail, and pranced. Horses snort
when startled, in pain, or when frightened ( McGreevy, 2004 ). Prancing, vigi-
lance, and a raised tail are attributed to high levels of emotional arousal
( Waring, 1983; Wolff et al., 1997 ). None of these signs of emotional arousal
were shown by Bobbi, and in the following days behavior towards the first
author was unchanged. However, Sam was reluctant to approach the first
author for several days following this experience. This suggests a strong neg-
ative memory of the experience associated with the first author. The escape
turning preference of each horse is also the same as their turning preference
when lunged in a circle, but only when the horses are nervous. For example,
when they have not been lunged for weeks, the first time lunging after time
off they get slightly nervous and directional preference is expressed.
However, after a few minutes on the lunge line they relax and directional
preference disappears.
This preliminary experiment is merely anecdotal, but a controlled experi-
ment conducted using right- and left-side hair whorl horses may provide evi-
dence of cognitive bias. The tests most likely to cause emotional reactions
are exposure to sudden novelty, or social isolation in a novel arena. It would
be interesting to study heart-rate variables and stress hormone levels follow-
ing response to novelty in horses with right- or left-side hair whorls.

Hair Whorl Patterns and Lateralization
Murphy and Arkin (2008) found a significant association between hair whorl
rotation (direction) and motor asymmetry in horses. The study recorded rota-
tion of single hair whorls in 219 horses (males

94), between
4 and 6 years old. The distribution of whorl patterns were 114 counter-
clockwise, 82 clockwise, and 23 radial (no rotation). Experienced trainers
rode and jumped each horse to determine motor laterality. Results showed
that right-lateralized horses had significantly more clockwise hair whorls,
and left-lateralized horses had more counter-clockwise hair whorls. More
recently, Ovando (2010) found no association between hair whorl rotation
and motor asymmetry. The study recorded rotation of single whorls in 50
Thoroughbred foals (males

125, females

5 5

21) all under 1 year of age. The
distribution of whorl patterns was 16 counter-clockwise, 10 clockwise, and

29, females

5 5