Though sleep is rarely considered as part of a horse’s management plan, horses that don’t receive adequate sleep are at risk of serious injury. A sleep-deprived horse is one that doesn’t receive adequate rapid eye movement (REM), which occurs when a horse lies down. Though horses require just 30 minutes of REM sleep a night, it’s physiologically imperative that they get it to function properly.
When a horse is in in REM sleep, he is temporarily unconscious and will not respond to external stimuli. A horse that is sleep deprived may enter REM sleep while standing, which relaxes his muscles and causes him to collapse and potentially injure himself.
A team of researchers from the Ludwig-Maximilian-University of Munich, Germany, led by Dr. Christine Fuchs, used an online questionnaire to recruit owners of horses that had collapsed or that had shown signs of collapsing. The scientists narrowed the pool to 36 horses that had collapsed at their home; they also used seven healthy horses as controls.
All horses were examined and then observed for 24 hours. Their stabling, management and medical histories were recorded. Each horse was fitted with a mobile sleep laboratory that measured physiological functions during sleep, including brain activity, eye movement and muscle tone. Taken together, these functions can be used to determine depth and quality of sleep.
Results of the study showed that:
- The main cause of lack of REM sleep was the horse’s management or pain, which prevented him from lying down
- One-third of the horses did not have enough room in their stalls to lie down comfortably
- The onset of collapse was directly related to an event such as a management change or physical issue in half the horses
- Over 90 percent of the horses that collapsed were injured, mainly in the knees and fetlocks; other injured areas included the head and hocks
- The horses collapsed between four and 199 times during the 24-hour examination period.
Read more at Horse Journals.
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