Research Article Sample Entropy Analysis of Horses with and without Lameness at Trot before and after Sedation Jing Zhao , 1 Dan B. Marghitu, 1 Amey Rane, 1 and John Schumacher 2 1 Mechanical Engineering Department, Auburn University, Auburn 36849, AL, USA 2 Department of Clinical Sciences, College of Veterinary Medicine, Auburn University, Auburn 36849, AL, USA CorrespondenceshouldbeaddressedtoJingZhao;jzz0053@auburn.edu Received 26 May 2020; Revised 20 June 2020; Accepted 25 June 2020; Published 13 July 2020 GuestEditor:CarlosLlopis-Albert Copyright©2020JingZhaoetal.isisanopenaccessarticledistributedundertheCreativeCommonsAttributionLicense, whichpermitsunrestricteduse,distribution,andreproductioninanymedium,providedtheoriginalworkisproperlycited. ehorsesweretrottedinastraightline,andtheaccelerationdatawererecordedfromthemovementofthehorse’shead.Inertial sensorswereusedtocollecttheinformation.esampleentropywasusedtocharacterizethedynamicsofhorsegait.egaitof soundandlamehorseswascompared,andthesoundhorseshadsmallervaluesofthesampleentropy.eeffectsofsedative detomidineonthegaitoflamehorseswerealsoexamined.evaluesofsampleentropyforsedatedhorsesweresmallerthanthe valuesofthesampleentropyforuntreatedhorses.esampleentropycanprovideimportantinformationaboutthedynamicsof the equine gait. 1. Introduction e concept of entropy originated from information tech- nology and was introduced to quantify the amount of in- formation obtained in communication signal [1]. e approximateentropy(ApEn)hasbeendevelopedtoclassify complex systems that include both deterministic and sto- chastic processes [2]. e approximate entropy was not suitablefortheanalysisofthenoisydatathatareprevalentin biologicalstudies,andinconsistentresultswereproduced.As a modification of the ApEn, the sample entropy (SampEn) wasdesignedtoincreasetheaccuracyofApEnoverabroad rangeofconditions[3].esampleentropyhasbeenusefulin thestudyoftheposturalcontrolandthecenterofpressure displacements [4, 5]. Stergiou et al. adopted entropy to measure the change in postural control for an infant with cerebral palsy and found that entropy values decreased sig- nificantlyfrompropsittingtobeginningindependentsitting [6].Jiaetal.reportedthatsampleentropyofthefunctional connections of brain regions in healthy subjects decreased withadvancingage[7].AsmallervalueoftheSampEnalso indicates more self-similarity in dataset or less noise. e sampleentropyhashighervalueformorecomplicatedtime series. For cardiovascular time series, one fundamental hypothesis is that healthy subjects have more complicated time series than cardiovascular patients [8]. Lamenessinhorsescausesseriouseconomiclossestothe equine industry [9]. Detection of lameness is not difficult whenlamenessismoderatetosevere,butconfusionappears when lameness is subtle. ere are disagreements between equinecliniciansduringsubjectivelyevaluatinglamenessdue to diversity of skills developed for lameness recognition. Cliniciansarenotabletocapturesmallchangesinlocomotion pattern because of the relatively low image capturing fre- quency of human eye [10]. Detomidine, a commonly used sedativeinhorses,isoftenadministeredtounrulyhorsesto facilitatelamenessexamination[11,12].However,thereisa concernamongveterinariansabouttheeffectofsedationon movement patterns of horses [13, 14]. Many clinicians are reluctanttousesedativeduringlamenessexaminationasthey believe it might affect the identification of subtle lameness because of the inherent analgesic property of this drug [15,16].eeffectofsedationonthegaitoflamehorseshas beenstudiedusingvectorsumsofmaximumandminimum headheightandthesumofhipdropandhiphike[17]. Multiple methods have been initiated for studying the nonlineardynamicsofgaitandhumanmotionwhichmay include model development, dynamic formulation, and Hindawi Mathematical Problems in Engineering Volume 2020, Article ID 4827587, 7 pages https://doi.org/10.1155/2020/4827587