The effect of altering routine husbandry factors on sleep duration and memory consolidation in the horse

The Most Common Environmental Risk Factors for Equine Asthma-A Narrative Review

Equine asthma is a popular subject of research. Many factors influencing the methods used to improve the welfare of asthmatic horses remain unclear. This study reviews scientific articles published after 2000 to collect the most important information on the terminology, symptoms, and potential environmental factors influencing the development and course of equine asthma. Our work highlights the impact of environmental factors on the severity of equine asthma and why these factors should be controlled to improve treatment outcomes. The present article provides horse owners and veterinarians with valuable information on how to improve the well-being of horses that are at risk of developing asthma symptoms.

Sleep Pattern Interference in the Cognitive Performance of Lusitano Horses

Like most mammalian, polyphasic sleep, equine sleep can be divided into two phases: the REM (rapid eye movement) phase and the NREM (non-rapid eye movement) phase. For this study, a randomized crossover experiment was conducted using ten purebred Lusitano horses, all dressage athletes aged from three to seven years old. The horses were filmed before the intervention to characterize their sleep patterns. REM sleep deprivation was achieved by not letting the horses attain sternal or lateral recumbency for three consecutive days, totaling 72 h. A spatial memory task and a visual attention test were performed. A recording time of 48 h appeared to be long enough to characterize the sleep patterns of the stalled horses. The total recumbency time of the studied population was lower than that previously reported in horses. Although the recumbency times before and after the intervention were similar, there was a tendency shown by the delta (p = 0.0839) towards an increased time needed to resolve spatial memory tasks in the sleep-deprived group. Future studies may deepen the understanding of horse sleep requirements and patterns, and the effects of environmental changes on horse sleep.

Towards an objective measurement of sleep quality in non-human animals: using the horse as a model species for the creation of sleep quality indices

Sleep disturbance is observed across species, resulting in neurocognitive dysfunction, poor impulse control and poor regulation of negative emotion. Understanding animal sleep disturbance is thus important to understand how environmental factors influence animal sleep and day-to-day welfare. Self-reporting tools for sleep disturbance commonly used in human research to determine sleep quality cannot be transferred to non-verbal animal species research. Human research has, however, successfully used frequency of awakenings to create an objective measurement of sleep quality. The aim of this study was to use a novel sleep-quality scoring system for a non-human mammalian species. Five separate sleep quality indices calculations were developed, using frequency of awakenings, total sleep time and total time spent in different sleep states. These indices were applied to a pre-existing data set of equine sleep behaviour taken from a study investigating the effects of environmental change (lighting and bedding) on the duration of time in different sleep states. Significant treatment effects for index scores both differed and aligned with the original sleep quantity results, thus sleep quality may be a useful alternative measurement of sleep disturbance that could be used to investigate impactful (emotional, cognitive) effects on the animal.

A Review of Equine Sleep: Implications for Equine Welfare

Sleep is a significant biological requirement for all living mammals due to its restorative properties and its cognitive role in memory consolidation. Sleep is ubiquitous amongst all mammals but sleep profiles differ between species dependent upon a range of biological and environmental factors. Given the functional importance of sleep, it is important to understand these differences in order to ensure good physical and psychological wellbeing for domesticated animals. This review focuses specifically on the domestic horse and aims to consolidate current information on equine sleep, in relation to other species, in order to (a) identify both quantitatively and qualitatively what constitutes normal sleep in the horse, (b) identify optimal methods to measure equine sleep (logistically and in terms of accuracy), (c) determine whether changes in equine sleep quantity and quality reflect changes in the animal's welfare, and (d) recognize the primary factors that affect the quantity and quality of equine sleep. The review then discusses gaps in current knowledge and uses this information to identify and set the direction of future equine sleep research with the ultimate aim of improving equine performance and welfare. The conclusions from this review are also contextualized within the current discussions around the “social license” of horse use from a welfare perspective.

HOSPITALISATION AND DISEASE SEVERITY ALTER THE RESTING PATTERN OF HORSES

In humans, hospitalisation, disease type, and environmental factors evidently affect the quality of sleep, further influencing patient recovery. The objective of the present study was to report the resting and lying behaviour of hospitalised horses, and whether lying behaviours differ depending on the physiological severity of joint damage. We hypothesised that the resting and lying behaviour can change during the hospitalisation and physiological severity of joint damage affect the time of rest in horses. A descriptive observational study was performed to evaluate the effect of hospitalisation on the recumbency time of eight adult horses with different degrees of osteoarthritis of the metacarpophalangeal joint. The horses' rest time was monitored using cameras during the first 5 days of hospitalisation. The total time of lateral recumbency and frequency of recumbency were greater after the 4th day of hospitalisation (p<0,05), while the total time of sternal recumbency was greater after the 3rd day (p<0,05). Furthermore, we compared the recumbency time among animals with different degrees of osteoarthritis on the 5th day of hospitalisation. Increased recumbency time in mild osteoarthritis spared the animal's limb and reduced the overload on the affected limb; however, severe osteoarthritis decreased the frequency and time of recumbency probably due to greater difficulty during joint flexion in the transition from standing to recumbency. The severity of disease appeared to affect recumbency time, as horses with mild osteoarthritis spent more time in recumbency whilst those with severe osteoarthritis may have been partially sleep-deprived because they lay down less.

Recumbency as an Equine Welfare Indicator in Geriatric Horses and Horses with Chronic Orthopaedic Disease

Recumbency is a prerequisite for horses achieving rapid eye movement (REM) sleep and completing a full sleep cycle. An inability to lie down due to environmental insecurities or pain results in REM sleep deficiency, which can cause substantial impairment of welfare and health. Therefore, the present study used wearable automated sensor technology on 83 horses housed in an animal sanctuary to measure and compare the recumbency, locomotion, and standing time budgets of geriatric horses with and without chronic lameness to younger adult sound and lame horses. Recumbency times ranged from 0 to 319 min per day with an overall mean of 67.4 (±61.9) minutes; the time budget for locomotion was 19.1% (±11.2% s.d.) and for standing 75.6% (±13.1 s.d.). Interestingly, neither age nor lameness due to chronic orthopedic disease had a significant influence on recumbency times in this study. Eight horses showed symptoms of REM deficit. These horses had significantly shorter lying times (7.99 ± 11.4 min) and smaller locomotion time budgets than the other horses enrolled in this study (73.8 ± 61.8 min), indicating a general compromise of well-being. Thus, wearable sensor technology can be used to identify horses with low recumbency times at risk for REM sleep deficiency and to assess and monitor equine welfare objectively.

Activity Time Budgets-A Potential Tool to Monitor Equine Welfare?

Simple Summary

Horses’ behavior is a good indicator of their welfare status. However, its complexity requires objective, quantifiable, and unambiguous evidence-based assessment criteria. As healthy, stress-free horses exhibit a highly repetitive daily routine, horses’ time budget (amount of time in a 24 h period spent on specific activities) can assist in equine welfare assessment. A systematic review of the literature yielded 12 papers that assessed equine time budgets for eating, resting and movement for a minimum of 24 continuous hours. A total of 144 horses (1–27 years old), 59 semi-feral and 85 domesticated horses, are included in this review. The reported 24 h time budgets for eating ranged from 10% to 66.6%, for resting from 8.1% to 66%, for lying from 2.7% to 27.3%, and for movement from 0.015% to 19.1%. The large variance in time budgets between studies can largely be attributed to differences in age and environmental conditions. Management interventions (free access to food, increased space, decreased population density) in domesticated horses yielded time budgets similar to semi-feral horses. The data support the importance of environmental conditions for horses’ well-being and the ability of time budgets to assist in monitoring horses’ welfare.

Abstract

Horses’ behavior can provide valuable insight into their subjective state and is thus a good indicator of welfare. However, its complexity requires objective, quantifiable, and unambiguous evidence-based assessment criteria. As healthy, stress-free horses exhibit a highly repetitive daily routine, temporal quantification of their behavioral activities (time budget analysis) can assist in equine welfare assessment. Therefore, the present systematic review aimed to provide an up-to-date analysis of equine time budget studies. A review of the literature yielded 12 papers that fulfilled the inclusion criteria: assessment of equine time budgets for eating, resting and movement for a minimum of 24 continuous hours. A total of 144 horses (1–27 years old), 59 semi-feral and 85 domesticated horses, are included in this review. The 24 h time budgets for foraging or eating (10–6.6%), resting (8.1–66%), lying (2.7–27.3%), and locomotion (0.015–19.1%) showed large variance between studies, which can largely be attributed to differences in age and environmental conditions. Management interventions in domesticated horses (ad libitum access to food, increased space, decreased population density) resulted in time budgets similar to their (semi-)feral conspecifics, emphasizing the importance of environmental conditions and the ability of time budgets to assist in monitoring horses’ welfare.