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STRESS AND THE THOROUGHBRED
Thoroughbred
frequency of aggression in equine society because of the effects of resource restriction. Horses are not, by nature, aggressive animals. It is our management that results in the exaggerated aggression we see in many individuals. A change in routine is commonly said to result in horses showing signs of exposure to stress. For this reason, it is often said that horses are ‘creatures of habit’ that ‘thrive on routine.’ This notion is debatable. Horses do indeed appear to react badly when established routine is changed, for reasons I shall discuss shortly. However, it is important to note that horses are not inherently predisposed to a life organized around routine.
Let us consider the horse in its natural environment, that for which it evolved. The horse’s time budget, the amount of time allocated to different activities, varies with features of the environment it finds itself in, the time of year, and age and gender of the individual (Boyd and Keiper, 2005). As an example of the flexibility of the division of the horse’s time, we find considerable variation in the proportion of the time budget spent grazing, primarily related to the availability of forage. Horses living in areas with sparse vegetation such as deserts or alpine forests spend about 18 hours per day grazing; those living in more lush areas such as marshes can spend as little as 13 hours per day grazing (Boyd and Keiper, 2005).
There is a certain degree of rhythm to the organization of these activities; bouts of intense grazing alternate with resting, with particularly heavy grazing just after sunrise and around sunset. In the summer a major resting period coincides with the hottest part of the day, with horses often moving to areas of minimum exposure to insect nuisance. Another major resting period occurs between midnight and four in the morning (Boyd and Keiper, 2005). There is, however, no strict routine such as we find in the majority of stables. In reality, horses are not ‘creatures of habit’ by nature, but we impose a routine upon them for our convenience. It suits us to feed horses at set mealtimes, to exercise them at particular
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