Sleep Deprivation in Horses Sleep Is a Vital Aspect of Overall Health; But, Unfortunately, Equine Sleep Disorders Are Poorly Understood

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Sleep deprivation in horses Sleep is a vital aspect of overall health; but, unfortunately, equine sleep disorders are poorly understood. There are few peer-reviewed publications on the subject and many veterinary professionals and owners are left to manage situations based upon their personal experience, rather than evidence-based medicine.

Sleep deprivation is a (SWS), the head will hang prey animal, this is not in their noticeable ailment which lower, and if the horse is survival nature. Horses need Joanna de Klerk suggests there are underlying content in its environment, it BVetMed (Hons) MScTAH MRCVS a minimum of approximately factors in the horse’s health will lie down in either sternal three to five hours sleep per Jo is a graduate of the Royal or environment that need to or lateral recumbency. 24-hour period. This time Veterinary College, London. be addressed. Equine sleep must include both SWS and She has a Masters Degree in patterns are adaptable – This is not essential REM sleep. Tropical Animal Health, and because, in the wild, horses though, because through has spent most of her career may have periods of time when the mechanism of the ‘stay Foals, on the other hand, working in mixed veterinary they must be more alert for apparatus’, a horse can require much more sleep than practice. Recently, she has predators. Therefore, a horse sleep in the SWS phase of an adult horse. Foals spend become involved in one of the can go for up to three days the cycle with relatively little 15 to 33 per cent of their time UK’s fasted growing veterinary with inadequate sleep before effort. The SWS is a shallow resting in lateral recumbency telemedicine services. sleep deprivation sets in, and sleep where the muscles are when they are newborn, in exceptional circumstances, inactive, and there is little which gradually decreases to Jo is a published author of two up to three months before to no eye movement. The two per cent after weaning books, and enjoys working as collapse caused by sleep eyelids, however, may stay (Boy and Duncan, 1979). a freelance veterinary content deprivation is apparent partially open. Therefore, foals are less able writer around her clinical work. (Houpt et al, 2001). to compensate for lack of She has a strong interest in Following SWS, the horse sleep and may display signs of equine pain management and Sleep cycles will lie down into lateral sleep deprivation sooner than rehabilitation, as well as global As is the case with humans, recumbency and slip into adult horses. veterinary medicine horses go through a series rapid eye movement (REM) and welfare. of sleep cycles during their sleep, which is sometimes Sleep deprivation sleep time. These cycles have also known as ‘paradoxical’ vs narcolepsy In her spare time, Jo enjoys several different stages, all of sleep. During REM sleep, the Both sleep deprivation and spending time with her horse which are characterised very muscles are totally relaxed narcolepsy can cause episodic and her family. differently. The time spent in and the eyelids are completely collapse in an apparently each of these stages will vary closed – although the eyes healthy horse. This is when from individual to individual, may move about under the there is a loss of postural tone based on their circumstances lids. The total sleep cycle in that may lead to recumbency. (Belling, 1990) including: the horse is short in nature This can be alarming to the type of housing – sometimes as little as 15 observer. The actual collapse age minutes – with SWS followed or partial collapse looks social dynamics by REM sleep, followed again identical with both sleep feeding routine by SWS (Belling, 1990). deprivation and narcolepsy, daily monotony so they are commonly unfamiliar surroundings Horses are known as confused. Sleep deprivation, wild temperament ‘polyphasic’ sleepers, and however, is caused primarily time have multiple short periods by insufficient sleep and outside weather. – some throughout the day, increased drowsiness; and most at night. Horses whereas narcolepsy is a Horses usually begin to fall will mainly sleep from 8pm to triggered neurological asleep in a standing position. 5am, with the majority of the disorder caused by certain The head begins to hang at SWS and REM sleep occurring activities or emotions. a medium level, the eyes are between 12am to 4am (Keiper semi-open and the bottom and Keenan, 1980). They will Signs lip is loose. When the horse also sleep during daylight Signs vary between different slips into a slow wave sleep hours if possible – being a horses, depending on the extremity of the sleep *Suggested Personal & Professional deprivation. Some – or all – of Development (PPD) “As is the case with humans, horses go the following may be observed: through a series of sleep cycles during complete collapse BEHAVIOUR AND WELLBEING collapse of the front end their sleep time” into a bowing position

are there any new horses in the same field that are challenging the hierarchy? has anyone witnessed the horse lie down or roll recently? what is the normal routine of the horse? Is it required to stand still for long periods of time? has the weather changed recently and is the rug being worn appropriate for the temperature?

Treatment If the sleep deprivation is caused by an underlying medical issue – such as one of the ones previously mentioned – that issue should be dealt with in the first instance. In the case of musculoskeletal disease, treatment modalities Figure 1. Indications vary between different horses, depending on the extremity of the sleep may include non-steroidal deprivation. Collapse of the front end into a bowing position is one such sign. anti-inflammatories, corticosteroid joint injections (Figure 1), praying position prolonged period of time, they often easily diagnosed through and nutraceuticals. Gastric or onto the knees must stand quietly. Examples a process of elimination. ulcers may require treatment lack of evidence of lying are police horses, show horses with omeprazole; and down in the stable standing to be plaited and The horse should initially other internal causes of increased drowsiness during riding school ponies saddled have a thorough clinical inflammation must be the day and waiting for their lessons. examination to rule out any addressed directly poor performance cardiac or neurological forms and specifically. fetlock or carpal abrasions Environmental insecurity of collapse. Once these are from falling. Sleep deprivation caused by eliminated, sources of pain Discomfort resulting from late environmental insecurity will should be investigated. This pregnancy usually resolves Types of sleep deprivation require some investigative may include a lameness instantaneously with giving There are four recognised work in order to determine work-up, radiographs, birth. Until then, providing the types of sleep deprivation. the root cause. Issues may blood work for acute phase mare with a comfortable deep include stable relocation, proteins (APP) such as straw bed will encourage her Pain-associated stable size changes, loss of serum amyloid A (SAA) and to lay down and rest. Pain-associated sleep field-mates, rugging issues fibrinogen (Jacobsen, 2007) deprivation is probably the and inclement weather. and gastroscopy. Sleep deprivation resulting most common type of sleep These lead to the horse from environmental or deprivation in horses. It being too psychologically If, after a thorough clinical dominance factors, and is seen in horses that have uncomfortable to lie down. investigation, the horse is monotony-induced sleep been diagnosed with painful shown to be in prime health, deprivation, can all only be conditions, such as advanced Dominance displacement the owner should then treated by pinpointing and joint disease, gastric ulcers, If a horse is constantly consider some of the following addressing the root cause. late pregnancy, polysaccharide excessively dominant in a questions to address any Considerable hours of storage myopathy, and other herd, it is most likely to be changes in the horse’s lifestyle: observation may be needed musculoskeletal disorders. As suffering from dominance to understand what must be a consequence of the pain, displacement sleep has the horse been tackled. For example, observe the horse is unable to lie deprivation. All its energy transported recently – such where the horse appears most down comfortably in lateral goes into dominance and as to a new yard or to a relaxed – is it the stable or the recumbency in order to gain they do not relax. This is most show? field? A field-kept horse may sufficient REM sleep. common in geldings. It leads have the horse’s normal not be suited to this routine to anxiety and insecurities, living conditions changed and may require a period of Monotony-induced and is often resolved with recently – such as a new stabling each day/night to Monotony-induced sleep the introduction of a stable or field? relax properly; or a stabled deprivation is most often seen dominant mare. in horses that are tied up with ‘cross-ties’ for long periods Diagnosis “There are four recognised types of of time. It is also occasionally The underlying problems in seen in horses where, for a cases of sleep deprivation are sleep deprivation”

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horse may actually suffer from References claustrophobia and be more relaxed living out? PPD Questions Belling TH (1990). Sleep patterns in the horse. Equine Practice 12: 2-26. A horse suffering from 1. How much sleep do horses require in a 24-hour period? arthritis may need to live out A. one to two hours Boy V and Duncan P (1979). in order to stay on the move B. three to five hours Time-budgets of Camargue horses and may seize up in the stable. C. five to seven hours I. Developmental changes in the Also, if the horse is unable to D. seven to nine hours time-budgets of foals. Behaviour, relax in the field because it has E. 10-12 hours. taken on the responsibility of 71(3): 187-201. dominance, it may be better suited to living in a bigger 2. What is not a type of sleep deprivation? Houpt K et al (2001). The effect of herd where it feels protected A. pain-associated exercise deprivation on the behav- enough to sleep. B. boredom-associated iour and physiology of straight stall C. monotony-associated confined pregnant mares. Animal Ensure there is adequate D. dominance displacement Welfare-Potters Bar 10(3): 257-268. shelter in the field, both from E. environmental insecurity. Jacobsen S (2007). Review of wind and rain, and from equine acute-phase proteins. In Annual Convention of the American the sun, and that ground 3. Sleep deprivation and narcolepsy are caused by a similar Association of Equine Practitioners conditions are suited to lying pathogenesis. True or false? 53: 230-235. down. If the field is poorly A. true drained, this may need to be B. false. addressed, and maybe hard Keiper RR and Keenan MA (1980). standing and a field shelter Nocturnal activity patterns of feral installed. Also check for any 4. The following is an acute phase protein and, therefore, a ponies. Journal of Mammalogy, other potential stress factors, biochemical indicator of inflammation… 61(1): 116 -118. such as neighbouring horses A. ALT or livestock. B. HGB C. MCHC Conclusion D. SAA Once the cause has been E. CKK. removed, the prognosis for these horses is very good. 5. Horses can be in slow wave sleep in standing, sternal recumbency and lateral recumbency; however, REM sleep can only happen in lateral recumbency. True or false? A. true

B. false.

A D 4. B 3. B 2. B 1. 5. Answers

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