From — Equine Wellness
IS YOUR HORSE SLEEP DEPRIVED, OR NARCOLEPTIC?
HERE'S WHAT TO WATCH FOR, AND HOW TO MAKE SURE HE GETS PROPER SLEEP
Just as with humans, proper sleep is important for your horse. The average horse will devote approximately three to five hours a day to sleep. Despite anatomy that allows horses to nap standing up, they will lie down for periods of deep sleep every day. If this deep sleep is avoided for a significant period, excessive drowsiness and periodic collapse can occur, and that can be a scary thing to witness!
These horses are often thought to have narcolepsy, a sleep disorder causing abrupt onset of a sleeping episode. Narcolepsy has been described in the horse, but is exceedingly rare and typically breed associated (i.e. Miniature horse). It is much more likely that the majority of horses displaying these symptoms are simply suffering from sleep deprivation. The causes of sleep deprivation vary widely, and can be physical or environmental.
WHY ISN'T YOUR HORSE SLEEPING?
Physical factors that can result in poor sleep for your horse can run the gamut from cardiovascular and respiratory abnormalities to neurologic disorders and metabolic derangements. Pain can also cause excessive wakefulness - no one sleeps well when they are experiencing discomfort. Musculoskeletal pain as well as neurologic conditions may prevent a horse from being able to lie down or get up, resulting in a lack of deep sleep. In these cases, a short course of analgesics or treatment of the underlying neurological condition may result in an improved ability to get up and down. If your horse has another issue that is causing him significant or chronic pain, you will need to work with his health care team to determine the cause and develop a treatment plan.
Environmental factors may prevent sleep in a number of different ways. For example, a dominant horse may not sleep enough because he's constantly on the alert for threats; conversely, a horse that is lower in the pecking order may not sleep enough if his herd mates constantly harass him. Lone horses may also suffer sleep deprivation if they feel too vulnerable to sleep deeply. Excessive noise and a lack of adequate bedding can also contribute to sleep deprivation. Sudden environmental changes such as moving your horse to a different facility or a rigorous show schedule can lead to periods of sleeplessness in your horse.
Thankfully, environmental factors can be much easier to resolve than physical ones, and solutions like separating or moving certain individuals, providing a friend (such as a goat or another horse), providing deeper bedding and eliminating noisy disruptions can allow the affected individual to get some rest, resulting in an alleviation of clinical signs.
Although narcolepsy is extremely rare in the horse, it's important to have an understanding of it when dealing with a horse suffering from periodic collapse.
Narcolepsy is multifactorial, the specifics of which are poorly understood. It is usually associated with cataplexy - loss of motor control often resulting in collapse, and preceded by a period of excitement. This excitement is usually positive, such as that associated with playing or feeding time. It is rare that a horse will suffer from a narcoleptic episode while working under saddle, but anecdotal evidence suggests it can happen. It is thought to have a genetic component and there is a strong familial association of the disorder in Miniature horses.
Clinical signs of sleep deprivation may include "rub" sores on the knees and fetlocks from falling, and periodic episodes of falling asleep during grooming, with subsequent collapse. Some individuals present with trauma to the nose, teeth and lips from hitting their faces during collapse episodes. Pain while the horse is working and other clinical signs such as a poor appetite or difficulty eating may provide clues to your veterinarian.
A comprehensive physical exam and requisite blood work, in addition to a thorough medical and behavioral history, is the best place to start.
COMING TO A DIAGNOSIS
Given that narcolepsy in horses is not widely understood and is relatively rare, it can be difficult to determine whether your horse is struggling with this condition, or has simple sleep deprivation. If you feel he may be suffering from either sleep deprivation or narcolepsy, it is very helpful to videotape him in his normal environment for 24 to 48 hours. This will allow you to figure out when and how often your horse's episodes occur. Determine whether these episodes are preceded by external stimuli such as playing or feeding. Evaluate the paddock to identify sources of excessive noise or disruption. If you have multiple horses, determine whether the affected horse is dominant or submissive. All this information will help your veterinarian formulate an accurate diagnosis. Your veterinarian will also want to perform a full physical exam and possibly use blood work to help rule out medical conditions.
A horse that is unsteady on his feet or falling to the ground can be scary to see. These are large animals and have the potential to injure themselves or the people around them in such situations. If your horse is displaying any symptoms that lead you to believe he might be suffering from sleep deprivation or narcolepsy, begin working with your veterinarian right away to try to determine the cause and develop a solution.
Dr. Dana Shackelton is a mixed animal veterinarian practicing at Middletown Animal Hospital. Her interest in animals, particularly horses, started at a young age. At 15 she started volunteering for the Horse Patrol in Yosemite National Park. Through this job her interest in pack mules, backcountry camping and emergency medicine gained a foothold. Her passion for veterinary medicine was solidified during time spent working as a veterinary technician on the Big Island of Hawaii. She attended veterinary school at UC Davis, specializing in a combination of horsesand small animals. After vet school she completed a one-year internship at Pioneer Equine Hospital, honing her skills as an equine veterinarian. Middletownvet.net