Variation in palmaromedial articulations of carpometacarpal joints in Thoroughbred and Standardbred racehorses.

Background: Carpal conformation is an important factor in relation to joint soundness. The equine carpometacarpal joint (CMCJ) was reported to have variations in its three palmaromedial articulations. Lacking one or more of these articulations has not been radiographically evaluated in Thoroughbred (TB) and Standardbred (SB) racehorses. Aim: The study aimed to identify the prevalence of the variation in the palmaromedial articulation of the carpometacarpal joint (PM-CMCJ) in TB and SB horses. Additionally, to detect the probability of having each of the three articulations within and between the breeds. Finally, to establish an anatomical description for the different patterns of the articulations in these horses. Methods: 313 dorsopalmar radiographs from 174 horses (117 TB and 57 SB) were used. Three articulations at PM-CMCJ were evaluated based on their presence or absence: the articulations between the second and third carpal bones (C2-C3), the second carpal-second metacarpal (C2-Mc2), and the second and third metacarpal (Mc2-Mc3) bones. The probability of each articulation was determined in the breeds. Depending on the presence/absence of one or more of these articulations in each horse, each group of horses that had the same patterns of articulation was gathered into one category. Results: Prevalence of variation in articulations of PM-CMCJ was identified in about 28% of the horses. SB showed a higher variation than TB throughout the comparisons. C2-C3 articulation was significantly the most common articulation, especially in TB (98%). The most common pattern of articulations (73%) was found in category I, which had three articulations whereas three horses grouped in category VI had no palmaromedial articulations. Conclusion: The variations in the articulations of PM-CMCJ in TB and SB racehorse might show a breed association. C2-C3 articulation was considerably the most frequent feature and category I was the common pattern of articulations in PM-CMCJ. The potential clinical effects of the varied patterns of the articulations require investigation.

The equine patellar ligaments and the infrapatellar fat pad - a microanatomical study.

BACKGROUND: Interpretation of patellar ligament (PL) ultrasonography may be difficult, as hypoechoic or heterogenous echogenicity are common findings. Verifying suspected disease of equine PLs by histopathology is also problematic as descriptions of normal PL vascularity and histology are scarce. The current study describes the PL and infrapatellar fat pad (IFP) vascular pattern from computed tomography scans of barium perfused normal equine specimens (n = 8; age 10 days to 18 years), as well as routine histology to serve as a reference for future investigations into PL pathology and IFP disease. RESULTS: The PLs received a bipolar blood supply. Vascular architecture consisted of numerous distinct longitudinal vessels with several horizontal connections, which branched into extensive latticeworks of smaller vessels throughout the ligaments. Several vascular connections between the PLs and the IFP were identified. One distinct longitudinal vessel was seen entering each of the IFP lobes at the distocranial aspect, branching extensively into lobar vascular networks which anastomosed by several horizontal branches at the mid portion of the IFP where the two lobes merge. Histologically, there were large variations in PL interfascicular endotenon thickness, vascularity and fatty infiltration; these parameters increased with age for the intermediate and medial PL. Areas of metaplastic tenocytes / chondroid metaplasia were identified in all investigated adult medial PLs; in 2/7 in the intermediate PL and in 4/7 in the lateral PL. The adult IFP consisted of white unilocular adipose tissue, organized in lobules separated by thin connective tissue septa increasing in thickness towards the periphery and the distocentral aspect. CONCLUSIONS: The equine PLs and IFP are highly vascularized structures with ample vascular connections suggestive of crosstalk. This, together with the large variation in PL endotenon thickness, vascularity and fatty infiltration, should be taken into consideration when assessing potential PL histopathology as these changes increase with age and are found in horses without clinical signs of stifle disease. Metaplastic tenocytes / chondroid metaplasia should be considered a normal finding throughout the medial PL and is not age dependent. The role of the equine IFP in stifle disease has yet to be elucidated.

No size-dependent net particle retention in the hindgut of horses.

Sieve analyses of hindgut contents of horses as well as observations in horses where plastic markers had been applied to a caecal cannula suggested that there may be a discrimination by particle size in the passage or retention of digesta. Here, we performed a similar experiment with five caecum-cannulated horses (562 ± 31 kg) fed a constant amount (6.81 kg dry matter/day) of grass hay. Passage markers representing the liquid (Co-EDTA) as well as the particulate digesta phase (Yb-undefined; Cr mordanted fibre 1-2 mm; Ce-mordanted fibre 8 mm) were given as a pulse-dose into the cannula to measure their mean retention times (MRT). The MRTs were compared by repeated-measurements analysis of variance. The MRT in the hindgut was 22.2 ± 2.4 h for Co, 25.0 ± 3.4 h for Yb, 26.2 ± 1.6 h for Cr and 26.3 ± 1.5 h for Ce. Whereas differences between the particle marker MRTs were not significant (padj. > 0.05), significant differences were observed between the solute marker Co and each of the particle markers Cr and Ce (padj. < 0.009). The results confirm the well-known significant, albeit small, difference in MRT in horses between the fluid and the particle digesta phase, and corroborate another recent study that used a combination of whole, marked hay and individual marker analysis in different particle size fractions of the faeces, which also did not detect a selective retention of any particle size class.

Morphological importance of coronary ostia in equine.

The position of the coronary ostia was investigated in 70 segments of the aorta from young adult crossbred horses. After fixation with a 4% buffered aqueous formaldehyde solution and cautious dissection of the aortic bulb, the morphometric relationships between the coronary ostium and the aortic valvar elements were digitally analysed with the support of Image-Pro Plus® software. In horses, the left coronary ostium was near to the right valvular commissure in all cases (100%) analysed in this study. The left coronary ostium was at the level of the intercommissural line in 57.1% and below it in 42.9%. The right coronary ostium was near to the left valvular commissure in 58.6% (2.14 ± 0.32 cm) and close to the right valvular commissure in 41.4% (2.27 ± 0.40 cm). Concerning the intercommissural line, the right coronary ostia was at its level in 24.3% and below it in 75.7%. Accessory coronary ostia were observed in 8.6% of the specimens. In view of the results, it was possible to assume that the positions of the coronary ostia in equines tend towards a standard morphological disposition. Thus, perfusion of the left coronary artery occurs partly more frequently in ventricular systole and complete perfusion occurs less frequently in ventricular diastole. For the right coronary artery, perfusion is mostly complete in diastole and partially in ventricular systole.

The Dmanisi Equus: Systematics, biogeography, and paleoecology.

The Equus datum has been established as a geochronologic 'instantaneous' migratory event of a North American Equus species into Eurasia at the beginning of the Pleistocene (2.58 Ma). A remarkable radiation of Equus followed across Eurasia and Africa. Dmanisi includes excellent remains of Equus, well calibrated between 1.85 and 1.76 Ma. Our morphologic and morphometric analyses of the augmented Dmanisi Equus sample support the co-occurrence of Equus stenonis and Equus altidens in the sequence. Dmanisi E. stenonis is found to be morphologically similar to the European E. stenonis populations and represents the best well-dated easternmost occurrence of this species in Eurasia. The Dmanisi E. altidens represents the oldest well-calibrated occurrence of this species in Western Eurasia. Our analyses demonstrate that E. altidens extended its range westward from west Asia to Greece, Germany, Italy, Spain, and possibly France. Our results do not support distinguishing multiple subspecies of E. altidens, including E. altidens altidens, E. altidens granatensis and E. stenonis mygdoniensis. The Dmanisi cranial and postcranial samples exhibit morphologies close both to extant hemiones and zebras. Equus altidens is believed to have been well adapted to newly emergent arid environments in western Eurasia during the late Early and early Middle Pleistocene. The first occurrence of E. altidens at Dmanisi marks an important turnover in the horse communities of the late Early Pleistocene, with a dispersion of this species from West Asia to West Europe ca. 1.8 Ma.

Equine attachment site preferences and seasonality of common North American ticks: Amblyomma americanum, Dermacentor albipictus, and Ixodes scapularis.

BACKGROUND: Ticks are common on horses, but recent publications characterizing equine tick infestations in North America are lacking. METHODS: To further understand attachment site preferences of common ticks of horses, and to document the seasonality of equine tick infestation in northeastern Oklahoma, horses from eight farms were evaluated twice a month over a 1-year period. Each horse was systematically inspected beginning at the head and moving caudally to the tail. Attachment sites of ticks were recorded and all ticks collected were identified to species and stage. RESULTS: Horses (26 males and 62 females) enrolled in the study ranged in age from 1 to 23 years (mean = 12, 95% CI 11-13). A total of 2731 ticks were collected; 84.1% (74/88) of the horses were infested (median = 3 ticks) at one or more examinations. Five tick species were identified, including Amblyomma americanum (78.2%; 2136/2731), Ixodes scapularis (18.2%; 497/2731), Dermacentor albipictus brown variant (2.6%; 71/2731), Dermacentor variabilis (0.7%; 20/2731), and Amblyomma maculatum (0.3%; 7/231). Most ticks were adults (83.6%; 2282/2731), but immature A. americanum (436/2136; 20.4%), D. albipictus (12/71; 16.9%), and A. maculatum (n = 1) were occasionally recovered. Amblyomma americanum were most often attached to the inguinal area, and I. scapularis and D. albipictus were most commonly found on the chest and axillary region (P < 0.0001). Ticks were found on horses in every month of the year. The largest number of ticks (638/2731; 23.4%) were collected in May (P < 0.0001). Amblyomma americanum, primarily immature, was the only tick recovered in September, I. scapularis and D. albipictus predominated October through February, and both A. americanum and I. scapularis were common in March. In the warmer months, April through August, A. americanum was the most common tick, followed by D. variabilis and A. maculatum. CONCLUSIONS: This research confirms that ticks common on horses in North America have attachment site preferences and that ticks infest horses in Oklahoma throughout the year, including during the winter. Additional research is warranted to fully understand the risk these infestations pose to equine health.

No modularity at ventral level in the horse skull.

Morphological integration and modularity are concepts that refer to the covariation level between the components of a structure. Morphological modules are independent subsets of highly correlated traits. The horse skull has been studied as a whole functional structure for decades, but the integrative approach towards quantitative examination of modules is scarce. We report here the first evaluation of cranial modularity in the horse at basal level. For this, we studied the modularity hypothesis for splanchnocranium and basicranium modules in the horse, two phenotipic regions under local influence by soft-tissue-hard-tissue interfaces. Using geometric morphometrics to capture the shape and location, we examined both modules in a sample of 23 dry skulls belonging to Pyrenean Horse Breed using 57 two-dimensional cranial landmarks. Modules were compared through partial least squares analyses and Escoufier (RV) coefficient. We tested whether the integration (measured by Escoufier RV coefficient) of splanchnocranium and basicranium strength modules and their covariation pattern (as analysed by partial least squares analysis) subordinate and express similar integration results. A clear modularity was observed. The lack of disproportions in the skulls of domestic horse breeds (compared to dog and cat breeds, for instance) might be an expression of the lack of single modules to evolve. On the other side, integration might have a positive impact on survival as long as the selection pressure is along the trajectory of integrated variation.

Horse choanae are directionally asymmetric / Las coanas de los caballos son direccionalmente asimétricas

SUMMARY: Studies related to the upper respiratory pathway asymmetries are still scarce in the veterinary literature. We present here a study of choanae asymmetries of a pure horses belonging to "Cavall Pirinenc Català" (Pyrenean Horse Breed). For this goal, the palates of 23 dry skulls with no apparent pathologies were photographed and evaluated using geometric morphometrics. On each photo, we identified and digitized a total of 26 points (subset of 2 mid-sagittal, 4 paired landmarks (discrete homologous points) and 10 semilandmarks (points on an outline determined by extrinsic criteria) per side on the choana. Both fluctuating and directional asymmetries appeared statistically significant, the latter accounting more than half of the total variation. The lateral bend observed in horse choanae may be due to the asymmetrically positioned nasal passages. So detected equine choana asymmetry must rather be considered functional, with no clinical implication and presents an important consideration when equine choanae shape.

RESUMEN: Los estudios relacionados con las asimetrías de las vías respiratorias superiores aún son escasos en la literatura veterinaria. Presentamos un estudio de coanas asimetrías de un caballo puro perteneciente al "Cavall Pirinenc Català" (Raza del Caballo de los Pirineos). Para ello, se fotografiaron y evaluaron los paladares de 23 cráneos secos sin patologías aparentes mediante morfometría geométrica. En cada foto, identificamos y digitalizamos un total de 26 puntos (subconjunto de 2 puntos medio sagitales, 4 puntos de referencia emparejados (puntos homólogos discretos) y 10 puntos semillanos (puntos en un contorno determinado por criterios extrínsecos) por lado de la coana. Ambos fluctúan Las asimetrías direccionales aparecieron estadísticamente significativas, representando estas últimas más de la mitad de la variación total. La curvatura lateral observada en las coanas de caballo puede deberse a los conductos nasales asimétricamente posicionados. Por lo tanto, la asimetría de coanas equinas detectada debería considerarse funcional, sin implicación clínica y presenta una importante consideración cuando se forman coanas equinas.

Elastosonographic features of the metacarpophalangeal joint capsule in horses.

BACKGROUND: Capsulitis leads to the release of inflammatory mediators in the joint, causing capsular fibrosis and osteoarthritis (OA). Strain elastosonography (SE) measures the elasticity of tissue by evaluating its strain in operator-dependent deformation. The aims of the study were to assess the feasibility, repeatability, and reproducibility of SE for imaging the distal attachment of the joint capsule (DJC) of metacarpophalangeal joints in sound horses (Group S) and in horses with metacarpophalangeal OA (Group P) and to evaluate differences in the elastosonographic patterns of these horses. After a whole lameness examination, fore fetlock DJCs were assigned to Group S and Group P and were thereafter examined by two operators using SE. Qualitative (i.e., colour grading score) and semi-quantitative (i.e., elasticity index (EI) and strain ratio (SR)) methods were used to evaluate the elastograms. The inter-rater reliability (IRR), intraclass correlation coefficient (intra-CC) and interclass correlation coefficient (inter-CC) were used to compare colour grading scores and the repeatability and reproducibility of EI and SR outcomes. The same parameters were compared between groups. P < 0.05 indicated a significant finding. RESULTS: Forty-one horses were included: 11 were in Group S and 30 were in Group P (16 with bilateral OA, 8 with left OA and 6 with right OA). IRR outcomes ranged from good to excellent. For transverse and longitudinal ultrasound scans, the colour grading score of Group S was significantly higher than the metacarpophalangeal DJCs of Group P. Both Inter-CC and intra-CC were higher in Group S than in Group P, with values always > 0.8. Significative differences in EI and SR were detected between groups and between Group S and the affected limb of Group P; values were lower in Group S than in Group P. CONCLUSIONS: SE can be a useful technique for evaluating DJCs, with good repeatability and reproducibility. DJCs appear softer in sound horses.

Evolution of Old World Equus and origin of the zebra-ass clade.

Evolution of the genus Equus has been a matter of long debate with a multitude of hypotheses. Currently, there is no consensus on either the taxonomic content nor phylogeny of Equus. Some hypotheses segregate Equus species into three genera, Plesippus, Allohippus and Equus. Also, the evolutionary role of European Pleistocene Equus stenonis in the origin of the zebra-ass clade has been debated. Studies based on skull, mandible and dental morphology suggest an evolutionary relationship between North American Pliocene E. simplicidens and European and African Pleistocene Equus. In this contribution, we assess the validity of the genera Plesippus, Allohippus and Equus by cladistic analysis combined with morphological and morphometrical comparison of cranial anatomy. Our cladistic analysis, based on cranial and postcranial elements (30 taxa, 129 characters), supports the monophyly of Equus, denies the recognition of Plesippus and Allohippus and supports the derivation of Equus grevyi and members of the zebra-ass clade from European stenonine horses. We define the following evolutionary steps directly relevant to the phylogeny of extant zebras and asses: E. simplicidens-E. stenonis-E. koobiforensis-E. grevyi -zebra-ass clade. The North American Pliocene species Equus simplicidens represents the ancestral stock of Old World Pleistocene Equus and the zebra-ass clade. Our phylogenetic results uphold the most recent genomic outputs which indicate an age of 4.0-4.5 Ma for the origin and monophyly of Equus.

Efeitos da nutrição parenteral ou enteral, associadas ou não à glutamina, sobre a motilidade gastrintestinal em equinos submetidos à inanição e realimentação / Effects of parenteral or enteral nutrition, associated or not with glutamine, on gastrointestinal motility in horses submmited to starvation and refeeding

Este estudo teve por objetivo avaliar os efeitos da nutrição parenteral total ou enteral, associadas ou não à glutamina, sobre a motilidade gastrintestinal em equinos submetidos à inanição e realimentação. Foram utilizados 16 equinos adultos hígidos, sem raça definida, de ambos os sexos, quatro machos e 12 fêmeas, com idade variando entre quatro e 14 anos e peso corporal médio de 248,40 + 2,28 kg, divididos em quatro grupos, quatro animais por grupo: Grupo I (ENTGL): fluidoterapia enteral com eletrólitos associada a glutamina; Grupo II (PARGL): Nutrição parenteral total (NPT) associada a glutamina; Grupo III (ENTFL): fluidoterapia enteral com eletrólitos; Grupo IV (PARFL): fluidoterapia parenteral. O delineamento experimental foi inteiramente ao acaso, em um esquema fatorial 4x12 (grupos x tempo de colheita), para cada fase, e suas médias comparadas pelo teste de Duncan ao nível de 5% de significância. Independente do grupo experimental ocorreu redução da motilidade gastrintestinal durante a fase de inanição, mais pronunciada nos grupos PARGL e PARFL. Uma vez restabelecida a alimentação a motilidade gastrintestinal retornou à normalidade.

This study aimed to evaluate the effects of enteral or total parenteral nutrition, associated or not with glutamine, on gastrointestinal motility in horses subjected to starvation and refeeding. 16 healthy, mixed-breed adult horses of both sexes, four geldings and 12 mares, with ages ranging from four to 14 years and an average body weight of 248.40 + 2.28 kg, were divided into four groups, four animals per group: Group I (ENTGL): enteral fluid therapy with electrolytes associated with glutamine; Group II (PARGL): total parenteral nutrition (TPN) associated with glutamine; Group III (ENTFL): enteral fluid therapy with electrolytes; Group IV (PARFL): parenteral fluid therapy. The experimental design was entirely randomized, in a 4x12 factorial scheme (groups x harvest time), for each phase, and their means compared by the Duncan test at the level of 5% significance. Regardless of the experimental group, there was a reduction in gastrointestinal motility during the starvation phase, which was more pronounced in the PARGL and PARFL groups. Once the food was restored, gastrointestinal motility returned to normal.

Construction of a Realistic, Whole-Body, Three-Dimensional Equine Skeletal Model using Computed Tomography Data.

Therapies based upon whole-body biomechanical assessments are successful for injury prevention and rehabilitation in human athletes. Similar approaches have rarely been used to study equine athletic injury. Degenerative osteoarthritis caused by mechanical stress can originate from chronic postural dysfunction, which, because the primary dysfunction is often distant from the site of tissue injury, is best identified through modeling whole-body biomechanics. To characterize whole-body equine kinematics, a realistic skeletal model of a horse was created from equine computed tomography (CT) data that can be used for functional anatomical and biomechanical modeling. Equine CT data were reconstructed into individual three-dimensional (3D) data sets (i.e., bones) using 3D visualization software and assembled into a complete 3D skeletal model. The model was then rigged and animated using 3D animation and modeling software. The resulting 3D skeletal model can be used to characterize equine postures associated with degenerative tissue changes as well as to identify postures that reduce mechanical stress at the sites of tissue injury. In addition, when animated into 4D, the model can be used to demonstrate unhealthy and healthy skeletal movements and can be used to develop preventative and rehabilitative individualized therapies for horses with degenerative lamenesses. Although the model will soon be available for download, it is currently in a format that requires access to the 3D animation and modeling software, which has quite a learning curve for new users. This protocol will guide users in (1) developing such a model for any organism of interest and (2) using this specific equine model for their own research questions.

Morphometric analysis of cardiac conduction fibers in horses and dogs, a comparative histological and immunohistochemical study with findings in human hearts.

The principal function of the ventricular conduction system is rapid electrical activation of the ventricles. The aim of this study is to conduct a morphometric study to pinpoint the morphological parameters that define cardiac conduction cells, allowing us to distinguish them from other cells. Five male horse hearts and five male dog hearts were used in the study. The hearts were fixed in a 5% formaldehyde solution. Histological sections of 5 µm thickness were acquired and stained with hematoxylin-eosin and Masson's trichrome and cardiac conduction cells and their junctions were identified by desmin, connexin 40 and a PAS method. We found statistically significant differences in cardiac conduction fibers density and thickness, which was much higher in horses than in dogs (p = 0.000 for both values). By comparing the measured parameters of the cells in both species, we determined that cardiac conduction cells area and diameters were greater in horses than in dogs (p = 0.000 for all values). In dogs there are more junctions (30.8%) than in horses (26.1%), a statistically significant difference (p = 0.041). Our findings regarding the cardiac conduction fibers distribution in the animal species studied becomes new knowledge that contributes to the morphological study of this component of the cardiac conduction system and also makes it possible to locate exactly the site with the highest density of cardiac conduction fibers as a contribution to the cardiological study of these structures that lead to the prevention of ventricular arrhythmias and the identification of their treatment site.

Volumetric measurements of paranasal sinuses and examination of sinonasal communication in healthy Shetland ponies: anatomical and morphometric characteristics using computed tomography.

BACKGROUND: Despite clinical importance and frequent occurrence of sinus disease, little is known about the size of paranasal sinuses and their communication in ponies and small horses. To examine the shape and volume of the paranasal sinuses and evaluate the sinonasal communication, three-dimensional (3D) reconstructions of computed tomography (CT) datasets of 12 healthy adult Shetland ponies were performed and analysed. Linear measurements of head length and width were taken. Using semi-automatic segmentation, 3D-models of all sinus compartments were created. Volumetric measurement of the seven sinus compartments were conducted and statistical analysis was performed. Sinus volumes were compared between the left and right sinuses and the relation to age and head size was evaluated. RESULTS: Structure and shape of the paranasal sinus system in Shetland ponies was similar to that of large horses. All seven sinus compartments on each side of the head were identified (rostral maxillary sinus, ventral conchal sinus, caudal maxillary sinus, dorsal conchal sinus, middle conchal sinus, frontal sinus, sphenopalatine sinus). The existence of a bilateral cranial and a caudal system formed by a maxillary septum was visible in all 12 individuals. The volumetric sizes of the left and right sinuses did not differ significantly (p > 0.05). A positive correlation between the size of the paranasal sinuses and the head length was shown. A relation between sinus volumes and age could not be proved in adult ponies aged > six years. Communication between single sinus compartments was identified. Furthermore, communication with the nasal cavity over the nasomaxillary aperture (Apertura nasomaxillaris) and a common sinonasal channel (Canalis sinunasalis communis) as well as its splitting up into a rostral and a caudolateral channel could be seen. Examination of the sinonasal communication was challenging and only a descriptive evaluation was possible. CONCLUSIONS: Our findings concerning the size, shape and volumetric dimensions of Shetland pony CT images could help improve CT interpretation of abnormal clinical cases as well as aiding clinicians to develop and select appropriate instruments for medical inspection and treatments.

Avaliação ultrassonográfica dos tendões flexores dos membros anteriores em equinos de vaquejada na microrregião do Alto Médio Gurgueia, Sul do Piauí, Brasil / Ultrasound evaluation of the flexor tendons of the forelimbs in horses in vaquejada horses in theAlto Médio Gurgueia, South of Piauí, Brazil

Objetivou-se com este estudo demonstrar a influência do tipo de treinamento sobre as medidas dos tendões flexores palmares em equinos de vaquejada que correm à direita do boi na microrregião do Alto Médio Gurgueia, Sul do Piauí, Brasil. Foram utilizados oito animais, da raça quarto de milha e seus mestiços, de diferentes idades, peso e sexo, selecionados e questionados sobre o tempo que exerciam a atividade de vaquejada e o tipo de treinamento a qual eram submetidos, que refere-se a maneira como praticavam a prova correndo de que lado do boi, em uma prova de vaquejada no município de Cristino Castro, Sul do Piauí, Brasil, onde os participantes eram provenientes de diferentes haras da Microrregião do Alto Médio Gurgueia, Sul do Piauí, Brasil. Em cada animal foi realizada ultrassonografia das zonas IB, IIB e IIIB dos tendões flexores digital superficial (TFDS) e digital profundo (TFDP), obtendo-se as medidas dos diâmetros médio lateral (DML) e dorso palmar (DDP) através do plano transverso em cada uma das diferentes zonas. Os dados foram submetidos a análise estatística (ANOVA), utilizando-se o teste t a nível de significância de (p<0,05), observando-se que não houve diferença significativa entre as medidas avaliadas. De acordo com os resultados obtidos, cavalos atletas que correm a direita do boi não apresentam diferença significativa nos diâmetros médio lateral e dorso palmar dos tendões flexores entre os antímeros direito e esquerdo do membro torácico.

The objective of this study was to demonstrate the influence of the type of training on the measurements of the palmar flexor tendons in vaquejada horses that run to the right of the ox in the microregion of the Alto Médio Gurgueia, South of Piauí, Brazil. Eight animals of the quarter-mile breed and their crossbreed, of different ages, weight and sex, were selected and asked about the time they were engaged in the activity of the vaquejada and the type of training they were submitted to as they practiced running on which side of the ox, in a vaquejada test in the municipality of Cristino Castro, South of Piauí, Brazil, where the participants came from different farms of the microregion of the Alto Médio Gurgueia, South of Piauí, Brazil. The ultrasonography of the IB, IIB and IIIB zones of the superficial digital (TFDS) and deep digital flexor tendons (TFDP) were performed in each animal, obtaining the measurements of the lateral diameters (DML) and palmar dorsum (DDP) through the transverse plane in each of the different zones. Data were submitted to statistical analysis (ANOVA), using the t test at the significance level of (p <0.05), observing that there was no significant difference between the measures evaluated. According to the results, horses for vaquejada athletes do not present significant difference in the lateral diameters and palmar dorsum of the flexor tendons between the right and left thoracic limb antimeres.

Thyrohyoideus muscle innervation in the horse.

OBJECTIVE: To describe the innervation of the thyrohyoideus (TH) muscle and to confirm our findings with stimulation of first cervical (C1) nerve branches. STUDY DESIGN: Ex vivo phase 1 and clinical phase 2. ANIMALS: Fourteen head and neck specimens and 17 client-owned horses. METHODS: In phase 1, the cranial nerve (CN) XII and the C1 nerve were dissected with their branches in 20 dissections were performed on 14 specimens (6 left and right side and 8 only left or right) Anatomy was noted. Samples of nerve bifurcations were collected for histological confirmation of anatomical findings. First cervical nerve branches were stimulated in horses undergoing cervical nerve graft to treat laryngeal hemiplegia. RESULTS: The nerve innervating the TH muscle arose directly from the C1 nerve in 17 of 20 dissections, from an anastomotic branch between CN XII and the C1 nerve in two of 20 dissections, and from the C1 nerve and the anastomotic branch in one of 20 dissections. No direct connection between the TH muscle and CN XII was found. Histological examination revealed that the anastomosis was composed of C1 nerve fibers passing over to CN XII. First cervical stimulation resulted in TH muscle contraction in 16 of 17 horses. CONCLUSIONS: The innervation of the TH muscle originated from the C1 nerve according to dissection, histological, and conduction studies, with variation in the branching pattern. CLINICAL SIGNIFICANCE: Care should be taken to preserve the C1 nerve during prosthetic laryngoplasty. The surgical technique for C1 nerve grafts should be reconsidered in light of these findings, along with new options to treat dorsal displacement of the soft palate..

Ultrastructural evidence for telocytes in equine tendon.

The three-dimensional ultrastructure of the tendon is complex. Two main cell types are classically supported: elongated tenocytes and ovoid tenoblasts. The existence of resident stem/progenitor cells in human and equine tendons has been demonstrated, but their location and relationship to tenoblasts and tenocytes remain unclear. Hence, in this work, we carried out an ultrastructural study of the equine superficial digital flexor tendon. Although the fine structure of tendons has been previously studied using electron microscopy, the presence of telocytes, a specific type of interstitial cell, has not been described thus far. We show the presence of telocytes in the equine inter-fascicular tendon matrix near blood vessels. These telocytes have characteristic telopodes, which are composed of alternating dilated portions (podoms) and thin segments (podomers). Additionally, we demonstrate the presence of the primary cilium in telocytes and its ability to release exosomes. The location of telocytes is similar to that of tendon stem cells. The telocyte-blood vessel proximity, the presence of primary immotile cilia and the release of exosomes could have special significance for tendon homeostasis.

Ultrasonographic evaluation of the width, thickness, and length of the normal linea alba in standing and dorsal recumbent horses.

OBJECTIVE: To determine the variability in length, width, and thickness of the equine linea alba (LA) and the effect of a standing vs dorsal recumbent position on these measurements. STUDY DESIGN: Descriptive anatomical comparative study. ANIMALS: Standing horses (N = 75; in 30 horses, measurements were obtained in dorsal recumbency first and repeated after horses were standing). METHODS: Linea alba length was measured in standing position from xiphoid to umbilicus, and transverse ultrasonographic images were obtained at five reference points to measure LA width and thickness. In 30 horses, measurements were obtained in dorsal recumbency first and repeated after horses were standing. RESULTS: There was wide variation in LA width and thickness between standing horses, with gradual increase from xiphoid (range, 0.14-0.64 cm) to umbilicus (range, 0.2-2.97 cm). Linea alba length in standing position was 51.09 ± 6.219 cm. Width was independent of the size of the horse; thickness and length were correlated at some reference points to height (r = 0.346-585, P < .05) and weight (r = 0.324-0.642, P < .05). Different LA shapes could be identified. In dorsal recumbency, the LA was smaller in width at all reference points (15%-23%, P < .05) and shorter (20%, P < .001) compared with standing. CONCLUSION: In addition to the wide variability in LA measurements and shapes between horses, there was a significant decrease in LA width and length when horses changed from standing to dorsal recumbency. CLINICAL SIGNIFICANCE: The difference in LA length and width between dorsal recumbency and when standing could increase tension on sutures after laparotomy and should be taken into account when surgeons are closing the abdomen.

Morphometric analysis of the intercarpal ligaments of the equine proximal carpal bones during simulated flexion and extension of cadaver limbs.

Despite many reported cases of carpal lameness associated with intercarpal ligament injuries in horses, the morphometry, movement pattern and general intrinsic biomechanics of the carpus are largely unknown. Using osteoligamentous preparation of the carpus prepared from 14 equine cadaver forelimbs (aged 9.62 ± 4.25 years), locomotory simulations of flexion and extension movements of the carpal joint were carried out to observed carpal biomechanics and, thereafter, the limbs were further dissected to obtain morphometric measurements of the medial and lateral collateral ligaments (MLC and LCL); medial and lateral palmar intercarpal ligaments (MPICL and LPICL); intercarpal ligaments between radial (Cr) and intermediate (Ci) carpal bones (Cr-Ci ICL); and intercarpal ligaments between Ci and ulnar (Cu) carpal bones (Ci-Cu ICL). The Cr, Ci, Cu and Ca are held together by a series of intercarpal ligaments and move in unison lateropalmarly during flexion, and mediodorsally during extension with a distinguishable proximo-distal sliding movement (gliding) of Cr and Ci against each other during movement. The mean length of MCL (108.82 ± 9.64 mm) was significantly longer (p = 0.042) than LCL (104.43 ± 7.65 mm). The Cr-Ci ICL has a dorsopalmar depth of 37.58 ± 4.14 mm and a midpoint width of 12.05 ± 3.09 mm and its fibres ran diagonally from the medial side of the Ci in a proximo-palmar disto-dorsal direction (i.e. palmarodistally) to the lateral side of the Cr. The specialized movement of the Cr-Ci ICL, which appeared to be further facilitated by a longer MCL suggest a biomechanical function by which carpal damage may be minimized in the equine carpus.