Using Movement Sensors to Assess Lying Time in Horses With and Without Angular Limb Deformities

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

“…The time budgets of several welfare relevant behaviors, such as foraging, resting, and lying, can already be accurately determined with commercially available sensors and can be used as welfare indicators to identify welfare problems and monitor the success of interventions [ 32 , 44 ]. Furthermore, real-time analysis of equine behavior may also facilitate early detection of health problems, such as colic, lameness or other painful conditions and accelerate therapeutic interventions [ 4 , 40 , 51 , 52 , 53 , 54 , 55 ]. Indeed, time budgets for specific behavior have been identified as more sensitive indicators of equine discomfort than repeated direct observation of specific events and postures and thus could facilitate rapid detection of painful conditions and objective, quantitative monitoring of the success of therapeutic interventions [ 40 , 54 , 55 ].…”

“…Four stages of horses’ sleep-wake rhythm are typically differentiated and defined by specific cortical electronic activity and movement patterns: wakefulness, drowsiness, slow-wave-sleep, and paradoxical or rapid eye movement (REM) sleep, with the majority of sleep occurring between midnight and 5:00 am [ 39 , 44 , 46 , 60 , 72 , 75 , 76 ]. While sleep in horses is not uniquely associated with recumbency as horses can sleep standing, recumbency (sternal or lateral) is required for rapid eye movement (REM) sleep, which is vital for many physiological and cognitive functions [ 53 , 72 ]. Indeed, in other species including humans, REM-sleep deprivation has been linked to hyperalgesia and persistent chronic pain [ 53 , 77 , 78 ].…”

“…While sleep in horses is not uniquely associated with recumbency as horses can sleep standing, recumbency (sternal or lateral) is required for rapid eye movement (REM) sleep, which is vital for many physiological and cognitive functions [ 53 , 72 ]. Indeed, in other species including humans, REM-sleep deprivation has been linked to hyperalgesia and persistent chronic pain [ 53 , 77 , 78 ].…”

“…In horses, decreased lying time budgets were associated with inappropriate environmental conditions, stress, and painful musculoskeletal issues [ 4 , 40 , 50 , 52 , 53 ]. In contrast, increased lying times were observed in animals with higher social rank [ 79 ], larger stall size [ 80 ], straw bedding compared to shavings [ 81 ], and following administration of analgesics to horses suffering from orthopedic pain [ 4 , 52 , 53 ].…”

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

“…While adult horses sleep only 2.5–5 h/day, 80% of which is in a standing position, they need a minimum of 30 min of recumbency per day to achieve 3.5–4.5 min of REM sleep and avoid REM sleep deprivation with excessive secondary drowsiness and collapse [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ]. However, as a prey species, horses only lie down when they feel comfortable to do so [ 2 , 4 , 5 , 14 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ]. Hence, measuring lying behavior is an essential component of equine welfare assessment [ 12 , 13 ].…”