Rörelseasymmetrier i trav hos islandshästar i träning

Ortopediska skador som visar sig som hältor hos hästar orsakar årligen stora konsekvenser för djurvälfärden och är en vanlig orsak till avlivningar. En hälta klassificeras som ett avvikande rörelsemönster kopplat till smärta. För att bedöma hältor studeras hästarnas rörelsemönster med fokus på huvudet och bäckenet. En människa kan endast upptäcka asymmetrier när de avviker minst 25 % från rörelsemönstret, vilket medför en svaghet i den visuella bedömningen, därmed kan hältutredningar kompletteras med objektiva mätmetoder för att mer tillförlitligt bedöma asymmetrier. Idag finns satta gränsvärden vid objektiva bedömningar för när ett rörelsemönster klassas som symmetriskt eller asymmetriskt, men flera tidigare studier har visat att en stor andel av hästarna (70-90 %) som anses friska hamnar över dessa gränsvärden och skulle vid en hältutredning kunna klassas som halta. Islandshästar är idag en populär hästras med sin förmåga till de unika gångarterna tölt och pass, men detta medför även ett annorlunda rörelsemönster. Islandshästarna har ett snabbt rörelsemönster och flera faktorer, till exempel skoning, ryttare och gener, påverkar stabiliteten och kvalitén hos hästens olika gångarter. Denna studies syfte är att med ett objektivt analyssystem mäta islandshästar, som rids kontinuerligt, i trav, för att undersöka prevalensen av asymmetrier. Sjuttiosju islandshästar i åldrarna 5-27 år deltog, både motionshästar och tävlingshästar. Analyssystemet som användes var EquiMoves, baserat på tröghetssensorer (IMUs). Hästarna mättes både för hand och under ridning. Djurägarna fick fylla i ett formulär om hästens skadehistorik, träningsvanor m.m. Gränsvärden för asymmetrier sattes till ± 12 mm för huvudet samt ± 6 mm för bäckenet. Resultaten visade på en asymmetriprevalens på 97 % vid sammanslagning av mätningen för hand och uppsuttet. 87 % var asymmetriska för hand och 82 % var asymmetriska uppsuttet. Medelvärdet för huvudets asymmetrier skiftade mellan 12-45 mm och för bäckenet 6-33 mm vilket tydde på både lindriga samt kraftiga asymmetrier. Majoriteten av asymmetrierna hade en måttligt bedömd tillförlitlighet erhållet av standardavvikelsen. Merparten av hästarna hade en asymmetri kopplat till bakbenen och det fanns även en antydan till en korrelation av ökad grad av asymmetri om hästen var femgångare samt lägre grav av asymmetri om hästen hade en historik av hälta. Prevalensen av asymmetri kan vara kopplat till hästarnas genetiska uppsättning, en lateralitet alternativt oidentifierade hälta på grund av svårigheter att bedöma rörelsemönstret subjektivt. Det går inte att säga att dessa hästar hade någon hälta trots att de var asymmetriska då ingen smärtbedömning i samband med analysen genomfördes. Det är dock troligt att några av hästarna hade oupptäckta hältor då graden av asymmetri var så stor. Det behövs mer forskning om när rörelseasymmetrier är orsakade av smärta, t.ex. i samband med diagnostiska anestesier för att lämpliga gränsvärden ska kunna tas fram. Då kan objektiva rörelseanalyser användas för att göra en korrekt bedömning av islandshästens skiftande rörelsemönster.Lameness in horses is a common problem and frequently the cause for euthanization. Lameness is defined by the alternation of movement due to pain. To evaluate lameness the movement asymmetries of the head and sacrum are assessed. Due to weaknesses of the eye’s perception, humans can only detect movement asymmetries when they differ over 25%. Therefore, the subjective assessment can nowadays often be supplemented with objective measurements. Multiple studies on movement symmetries using objective analysis have shown a high prevalence (70-90%) of asymmetries in horses in active training. Icelandic horses are a popular breed because of their unique gaits toelt and pace. Shoeing, genes, and rider have been shown to influence the horse’s gaits and its quality. This study aims to measure Icelandic horses in training, in trot, to assess the prevalence of upper body movement asymmetry. Seventy-seven horses were included, ages ranging between 5-27 years, both leisure horses as well as competition horses. Movement analysis was performed while the horses trotted in hand and while ridden. The objective movement analysis system used was IMU based, called EquiMoves. The owners answered a form with questions about the training habits of the horse, history of lameness and if the horse were five- or four-gaited. Limits for asymmetries were set to ± 12 mm for the head and ± 6 mm for the sacrum. The results showed a total asymmetry prevalence of 97%, 87% for measurements in hand and 82% for measurements when ridden. The asymmetry values ranged from 12-45 mm for the head and 6-33 mm for the sacrum, thus indicating both mild to severe asymmetries. The greater part of the values had a moderate variability, calculated from the SD value. The majority of horses had an asymmetry correlation to the sacrum and the hindlegs. There was also an indication of correlation between increased asymmetry prevalence and horses with five gaits compared to horses with four gaits, as well as lower asymmetry prevalence and history of lameness. The high prevalence of asymmetry could be related to the genetic background in these gaited horses, undetected lameness due to the difficulty to assess movements subjectively, or laterality in the population. Based on this study none of the horses can be classified as lame since the study did not evaluate pain in correlation to asymmetry. It is not unlikely however that some of the horses could be lame. Further studies are needed where the movement asymmetries are assessed in combination with diagnostic anesthesia to investigate the sensibility and specificity of the lameness thresholds established for objective motion analysis. Such studies would benefit the analysis and evaluation of Icelandic horses regarding their unique movements

En beskrivning av islandshästens gångarter

Hältor är vanligt förekommande hos hästar. För att identifiera och lokalisera var hältan sitter studeras symmetrin i hästens rörelsemönster. Islandshästens rörelsemönster skiljer sig från de flesta andra hästraser med sin utökade förmåga att röra sig i pass och tölt. Därför har denna litteraturstudie valt att studera: hur rörelsemönstret hos islandshästar ser ut, variationer inom pass och tölt och vad som påverkar rörelsemönstret. Islandshästen skiljer sig genetiskt från hästar med endast tre gångarter genom en mutation som orsakar ett aminosyrabyte. Normala genotypen, vildtypen, CC har varianterna CA och AA hos de flesta islandshästar. CA kopplas generellt till 4-gångare som utöver skritt, trav och galopp även kan tölta. AA kopplas generellt till 5-gångare som dessutom kan röra sig i pass. AAgenotypen har en förstärkande effekt på koordination av laterala gångarter och negativ effekt på diagonala rörelsemönster. Förmågan att röra sig i pass påverkar rytmen och stabiliteten i skritt, trav och galopp. Pass är en symmetrisk gångart. Steget är lateralt kopplat och stegsekvensen är VB och VF följt av ett svävmoment, sedan HB och HF, följt av ytterligare ett svävmoment. ”Grisepass” är en variant av pass som ofta sker i lägre tempon och saknar svävmoment. En frikoppling av de laterala benparen i pass ger 4-taktspass; en visuell tidsskillnad mellan isättning av samma sidas framben och bakben ses. Fyrtaktspass är positivt korrelerat till ökande hastigheter. Stora individuella skillnader kan ses mellan hästars rörelsemönster i pass. Viktboots kan positivt påverka enhetligheten och synkroniseringen av det laterala benparet framförallt hos hästar med mindre erfarenhet. Tölt är en symmetrisk gångart med både laterala och diagonala supportfaser. Stegsekvensen är VB, VF, HB, HF. Svävfaser under tölt är debatterat: tidiga definitioner beskriver tölten utan svävmoment medan nyare studier visar på mindre svävmoment hos de flesta hästar. Passtaktig tölt har en förlängd lateral supportfas medan travtaktig tölt har en förlängd diagonal supportfas. Mindre individuella skillnader ses och få hästar är naturtöltare. Avslutningsvis, islandshästen skiljer sig i sitt rörelsemönster mot vanliga 3-gångartshästar. Genuppsättning, hastighet, skoning och verkning, träningsstatus, ryttarens vikt m.m. påverkar hästens steg och resulterar i individuella variationer samt individuella svar på förändring. Kunskap om islandshästens rörelsemönster och insikten i de individuella variationerna ger bättre förutsättningar att kunna notera avvikande mönster och därmed bedöma hältor. Rörelsemönster är väldigt individuellt. Det är svårt att applicera alla studier på alla hästar. För att kunna säga exakt hur rörelsemönstret för olika typer av islandshästar ser ut och hur olika typer av islandshästar påverkas av förändring behövs flera studier som är riktade mot olika grupper av hästar: 5-gångare, 4-gångare, travtaktiga hästar, passtaktiga hästar, naturtöltare m.m. Först då kan alla variationer av rörelsemönster hos islandshästen beskrivas och jämföras mer effektivt och vetenskapligt.Lameness in horses is a common problem. To detect and localize the lameness the symmetry and movement of the horse is analyzed. The movement of Icelandic horses differ from almost all other horse breeds with their additional gaits pace and toelt. This review is based on the theory that the additional gaits may influence the motion pattern in Icelandic horses. What does the motion pattern of Icelandic horses look like, the variations of pace and toelt as well as factors that influence the motion pattern. The Icelandic horse differ genetically from most other horse breeds due to a mutation which causes a shift in the normal genotype, the wildtype, CC. CC has the variants CA or AA among most Icelandic horses. CA horses are generally classified as four-gaiters with the additional toelt meanwhile AA horses generally also have the ability to move in pace. The AA genotype enhances the coordination of the ipsilateral gaits and negatively effects the diagonal motion patterns. The ability to pace effects the walk, trot and canter. Pace is a symmetrical gait with lateral couplet strides. The step sequence is LH and LF together followed by a suspension phase and then RH and RF together followed by another suspension phase. So called piggy-pace is a variation of pace most common at low velocity and lack suspension. A disconnection between the ipsilateral legs with a visual time difference between footfall of the front and hind leg is described as a 4-beat pace. Different horses have substantial individual variations of motion patterns in pace. The added weights of the forelimbs effect the gait-uniformity, especially in horses with less experience. Toelt is a symmetrical gait with both diagonal and lateral support phases. The stepping sequence is LH, LF, RH, RF. It is debated whether or not the toelt has a suspension phase: early definitions classify it as having no suspension while more recent studies show suspension phases among most Icelandic horses. Pacey toelt has an extended phase of lateral support whereas trotty toelt has an extended phase of diagonal support. Small individual differences are seen between horses and few horses are naturally good at toelt. The genes, velocity, shoeing and the weight of the rider affect the stride. To conclude, the motion pattern of the Icelandic horse differs from the normal tree-gaited horse. The motion pattern is affected by the genotype, age, experience, external factors etc., resulting in large individual variations and individual responses to alterations. A knowledge of the difference in the motion pattern is needed in the evaluation of the movement and the assessment of lameness. Further studies, directed towards four gaiters, five gaiters, pacey horses, trotty horses etc. are needed to evaluate, describe and compare all variations in the motion patterns among Icelandic horses in an effective and scientific matter

Prevalence of vertical movement asymmetries at trot in Standardbred and Swedish Warmblood foals

Many horses, just before and during their athletic career, show vertical movement asymmetries, to the same degree as clinically lame horses. It is unknown whether these asymmetries are caused by pain or have alternative explanations, such as inherent biological variation. In the latter case, movement asymmetries would be expected to be present at a very young age. This study aimed to investigate the prevalence of movement asymmetries in foals. Motion analysis, using an inertial measurement unit-based system (Equinosis), was performed on 54 foals (31 Swedish Warmbloods, 23 Standardbreds) during straight-line trot. The foals were between 4–13 weeks old and considered sound by their owners. Differences between the vertical minimum and maximum values recorded for the head (HDmin, HDmax) and pelvis (PDmin, PDmax) between left and right stance were calculated for each stride and an average was computed for each trial. Thresholds for asymmetry were defined as absolute trial mean >6 mm for HDmin and HDmax, and >3 mm for PDmin and PDmax. These thresholds were exceeded for one or several parameters by 83% of Standardbred foals and 45% of Swedish Warmblood foals, demonstrating surprisingly high prevalence of asymmetries in young foals, although the risk of repetitive strain injuries and cumulative risk of trauma injuries was expected to be low in this age group. Standardbred foals showed similar prevalence of asymmetries to that reported previously for yearling Standardbred trotters, so relatively higher prevalence of movement asymmetries may be expected among trotters as a breed. In general, vertical head and pelvic movement asymmetries can be anticipated among foals considered sound by their owners. A better understanding of the aetiology of asymmetries is needed for correct interpretation of objective symmetry measurements in different populations of horses

Timing of Vertical Head, Withers and Pelvis Movements Relative to the Footfalls in Different Equine Gaits and Breeds

Simple Summary Movement symmetry of the head and pelvis are used to measure lameness in horses in trot. Although head, pelvis and limb movements have been described, less is known about the temporal relationships between them. This information is needed to understand how the movements change with lameness. This is particularly relevant in gaited horses, such as the Icelandic horse that perform gaits such as tolt and pace, which are challenging to evaluate. This study used inertial measurement units to investigate head, withers and pelvis motion relative to limb movements in Icelandic, Warmblood and Iberian horses. Limb movements, together with vertical movements and lowest/highest positions of the head, withers and pelvis were calculated, and the relative timing of the events was compared across breeds. Additionally, data for tolt and pace were collected and evaluated in ridden Icelandic horses. For all gaits except walk and pace, the lowest/highest positions of the head/withers/pelvis were closely temporally related to midstance and hoof-off, respectively. Pelvic and withers total range of motion differed between all breeds. The Icelandic horses showed shorter stride duration and smaller movements of the upper body than the other breeds at trot, which may explain why lameness evaluation in this breed is challenging. Knowledge of vertical motion patterns of the axial body segments is a prerequisite for the development of algorithms used in automated detection of lameness. To date, the focus has been on the trot. This study investigates the temporal synchronization between vertical motion of the axial body segments with limb kinematic events in walk and trot across three popular types of sport horses (19 Warmbloods, 23 Iberians, 26 Icelandics) that are known to have different stride kinematics, and it presents novel data describing vertical motion of the axial body segments in tolting and pacing Icelandic horses. Inertial measurement unit sensors recorded limb kinematics, vertical motion of the axial body at all symmetrical gaits that the horse could perform (walk, trot, tolt, pace). Limb kinematics, vertical range of motion and lowest/highest positions of the head, withers and pelvis were calculated. For all gaits except walk and pace, lowest/highest positions of the pelvis and withers were found to be closely related temporally to midstance and start of suspension of the hind/fore quarter, respectively. There were differences in pelvic/withers range of motion between all breeds where the Icelandic horses showed the smallest motion, which may explain why lameness evaluation in this breed is challenging

Timing of Vertical Head, Withers and Pelvis Movements Relative to the Footfalls in Different Equine Gaits and Breeds

Knowledge of vertical motion patterns of the axial body segments is a prerequisite for the development of algorithms used in automated detection of lameness. To date, the focus has been on the trot. This study investigates the temporal synchronization between vertical motion of the axial body segments with limb kinematic events in walk and trot across three popular types of sport horses (19 Warmbloods, 23 Iberians, 26 Icelandics) that are known to have different stride kinematics, and it presents novel data describing vertical motion of the axial body segments in tölting and pacing Icelandic horses. Inertial measurement unit sensors recorded limb kinematics, vertical motion of the axial body at all symmetrical gaits that the horse could perform (walk, trot, tölt, pace). Limb kinematics, vertical range of motion and lowest/highest positions of the head, withers and pelvis were calculated. For all gaits except walk and pace, lowest/highest positions of the pelvis and withers were found to be closely related temporally to midstance and start of suspension of the hind/fore quarter, respectively. There were differences in pelvic/withers range of motion between all breeds where the Icelandic horses showed the smallest motion, which may explain why lameness evaluation in this breed is challenging

A systematic review of progranulin concentrations in biofluids in over 7,000 people—assessing the pathogenicity of GRN mutations and other influencing factors

Background: Pathogenic heterozygous mutations in the progranulin gene (GRN) are a key cause of frontotemporal dementia (FTD), leading to significantly reduced biofluid concentrations of the progranulin protein (PGRN). This has led to a number of ongoing therapeutic trials aiming to treat this form of FTD by increasing PGRN levels in mutation carriers. However, we currently lack a complete understanding of factors that affect PGRN levels and potential variation in measurement methods. Here, we aimed to address this gap in knowledge by systematically reviewing published literature on biofluid PGRN concentrations. Methods: Published data including biofluid PGRN concentration, age, sex, diagnosis and GRN mutation were collected for 7071 individuals from 75 publications. The majority of analyses (72%) had focused on plasma PGRN concentrations, with many of these (56%) measured with a single assay type (Adipogen) and so the influence of mutation type, age at onset, sex, and diagnosis were investigated in this subset of the data. Results: We established a plasma PGRN concentration cut-off between pathogenic mutation carriers and non-carriers of 74.8 ng/mL using the Adipogen assay based on 3301 individuals, with a CSF concentration cut-off of 3.43 ng/mL. Plasma PGRN concentration varied by GRN mutation type as well as by clinical diagnosis in those without a GRN mutation. Plasma PGRN concentration was significantly higher in women than men in GRN mutation carriers (p = 0.007) with a trend in non-carriers (p = 0.062), and there was a significant but weak positive correlation with age in both GRN mutation carriers and non-carriers. No significant association was seen with weight or with TMEM106B rs1990622 genotype. However, higher plasma PGRN levels were seen in those with the GRN rs5848 CC genotype in both GRN mutation carriers and non-carriers. Conclusions: These results further support the usefulness of PGRN concentration for the identification of the large majority of pathogenic mutations in the GRN gene. Furthermore, these results highlight the importance of considering additional factors, such as mutation type, sex and age when interpreting PGRN concentrations. This will be particularly important as we enter the era of trials for progranulin-associated FTD.</p

Perceived sidedness and correlation to vertical movement asymmetries in young warmblood horses

The prevalence of vertical asymmetries is high in "owner-sound" warmblood riding horses, however the origin of these asymmetries is unknown. This study investigated correlations between vertical asymmetries and motor laterality. Young warmblood riding horses (N = 65), perceived as free from lameness were evaluated on three visits, each comprising objective gait analysis (inertial measurement units system) and a rider questionnaire on perceived sidedness of the horse. A subgroup (N = 40) of horses were also subjected to a forelimb protraction preference test intended as an assessment of motor laterality. We hypothesized associations between vertical asymmetry and motor laterality as well as rider-perceived sidedness. Vertical asymmetry was quantified as trial means of the stride-by-stride difference between the vertical displacement minima and maxima of the head (HDmin, HDmax) and pelvis (PDmin, PDmax). Laterality indexes, based on counts of which limb was protracted, and binomial tests were used to draw conclusions from the preference tests. In the three visits, 60-70% of horses exhibited vertical asymmetries exceeding clinically used thresholds for & GE;1 parameter, and 22% of horses exhibited a side preference in the preference test as judged by binomial tests. Linear mixed models identified a weak but statistically significant correlation between perceived hindlimb weakness and higher PDmin values attributable to either of the hindlimbs (p = 0.023). No other statistically significant correlations to vertical asymmetry were seen for any of the questionnaire answers tested. Tests of correlation between the absolute values of laterality index and asymmetry parameters (HDmin, HDmax, PDmin, PDmax) identified a weak correlation (p = 0.049) with PDmax, but when accounting for the direction of asymmetry and motor laterality, no correlations were seen for either of the asymmetry parameters. No convincing evidence of associations between vertical asymmetries and motor laterality were seen and further studies investigating motor laterality and the origin of vertical asymmetries are needed

Prevalence of vertical movement asymmetries at trot in Standardbred and Swedish Warmblood foals

Many horses, just before and during their athletic career, show vertical movement asymmetries, to the same degree as clinically lame horses. It is unknown whether these asymmetries are caused by pain or have alternative explanations, such as inherent biological variation. In the latter case, movement asymmetries would be expected to be present at a very young age. This study aimed to investigate the prevalence of movement asymmetries in foals. Motion analysis, using an inertial measurement unit-based system (Equinosis), was performed on 54 foals (31 Swedish Warmbloods, 23 Standardbreds) during straight-line trot. The foals were between 4–13 weeks old and considered sound by their owners. Differences between the vertical minimum and maximum values recorded for the head (HDmin, HDmax) and pelvis (PDmin, PDmax) between left and right stance were calculated for each stride and an average was computed for each trial. Thresholds for asymmetry were defined as absolute trial mean >6 mm for HDmin and HDmax, and >3 mm for PDmin and PDmax. These thresholds were exceeded for one or several parameters by 83% of Standardbred foals and 45% of Swedish Warmblood foals, demonstrating surprisingly high prevalence of asymmetries in young foals, although the risk of repetitive strain injuries and cumulative risk of trauma injuries was expected to be low in this age group. Standardbred foals showed similar prevalence of asymmetries to that reported previously for yearling Standardbred trotters, so relatively higher prevalence of movement asymmetries may be expected among trotters as a breed. In general, vertical head and pelvic movement asymmetries can be anticipated among foals considered sound by their owners. A better understanding of the aetiology of asymmetries is needed for correct interpretation of objective symmetry measurements in different populations of horses

Prevalence of vertical movement asymmetries at trot in Standardbred and Swedish Warmblood foals.

Many horses, just before and during their athletic career, show vertical movement asymmetries, to the same degree as clinically lame horses. It is unknown whether these asymmetries are caused by pain or have alternative explanations, such as inherent biological variation. In the latter case, movement asymmetries would be expected to be present at a very young age. This study aimed to investigate the prevalence of movement asymmetries in foals. Motion analysis, using an inertial measurement unit-based system (Equinosis), was performed on 54 foals (31 Swedish Warmbloods, 23 Standardbreds) during straight-line trot. The foals were between 4-13 weeks old and considered sound by their owners. Differences between the vertical minimum and maximum values recorded for the head (HDmin, HDmax) and pelvis (PDmin, PDmax) between left and right stance were calculated for each stride and an average was computed for each trial. Thresholds for asymmetry were defined as absolute trial mean >6 mm for HDmin and HDmax, and >3 mm for PDmin and PDmax. These thresholds were exceeded for one or several parameters by 83% of Standardbred foals and 45% of Swedish Warmblood foals, demonstrating surprisingly high prevalence of asymmetries in young foals, although the risk of repetitive strain injuries and cumulative risk of trauma injuries was expected to be low in this age group. Standardbred foals showed similar prevalence of asymmetries to that reported previously for yearling Standardbred trotters, so relatively higher prevalence of movement asymmetries may be expected among trotters as a breed. In general, vertical head and pelvic movement asymmetries can be anticipated among foals considered sound by their owners. A better understanding of the aetiology of asymmetries is needed for correct interpretation of objective symmetry measurements in different populations of horses