Numerical evaluation of internal femur osteosynthesis based on a biomechanical model of the loading in the proximal equine hindlimb.

Femoral fractures are often considered lethal for adult horses because femur osteosynthesis is still a surgical challenge. For equine femur osteosynthesis, primary stability is essential, but the detailed physiological forces occurring in the hindlimb are largely unknown. The objective of this study was to create a numerical testing environment to evaluate equine femur osteosynthesis based on physiological conditions. The study was designed as a finite element analysis (FEA) of the femur using a musculoskeletal model of the loading situation in stance. Relevant forces were determined in the musculoskeletal model via optimization. The treatment of four different fracture types with an intramedullary nail was investigated in FEA with loading conditions derived from the model. The analyzed diaphyseal fracture types were a transverse (TR) fracture, two oblique fractures in different orientations (OB-ML: medial-lateral and OB-AP: anterior-posterior) and a "gap" fracture (GAP) without contact between the fragments. For the native femur, the most relevant areas of increased stress were located distally to the femoral head and proximally to the caudal side of the condyles. For all fracture types, the highest stresses in the implant material were present in the fracture-adjacent screws. Maximum compressive (-348 MPa) and tensile stress (197 MPa) were found for the GAP fracture, but material strength was not exceeded. The mathematical model was able to predict a load distribution in the femur of the standing horse and was used to assess the performance of internal fixation devices via FEA. The analyzed intramedullary nail and screws showed sufficient stability for all fracture types.

[Individual hormonal profiles of blood progesterone and estradiol-17ß during the course of a reproductive cycle in mares]. / Individueller Konzentrationsverlauf von Progesteron und Östradiol-17ß im Blut bei Stuten während des Zyklus.

OBJECT AND AIM: This study presents the individual course of estradiol-17ß and progesterone concentrations in blood during the reproductive cycle in mares in order to point out physiological differences between individual animals and to aid in the interpretation of hormone values. MATERIAL AND METHODS: Concentrations of estradiol-17ß and progesterone were determined in seven mares over the course of their cycle. One mare was excluded from the study due to a physiologically deviating cycle. In addition, the mares' ovaries were examined via ultrasound on a daily basis in order to match the hormone values to morphological changes of the ovaries. RESULTS: In some cases, the mares showed considerable individual differences in their hormone concentrations, which also differed from the published comparative values in the literature. For example, two mares showed progesterone levels above basal levels at the time of ovulation. The postovulatory progesterone concentrations of the mares are characterized by marked fluctuations, which makes it difficult to provide reference values in the different sections of the corpus luteum phase. The length of the plateau phases averaged 12.3±1.5 days. The mare with double ovulation showed the highest progesterone concentrations. CONCLUSION: The measurement of plasma progesterone levels in mares should be interpreted only in the context of other test results. The very wide variation in estradiol-17ß concentrations makes it questionable whether the determination of this hormone value is of diagnostic value. CLINICAL RELEVANCE: When interpreting steroid hormone values in the ingravid cycle of a mare, the individual concentration courses must be taken into consideration, as they may deviate significantly from the published reference values.

Dirt Track Surface Preparation and Associated Differences in Speed, Stride Length, and Stride Frequency in Galloping Horses.

In racehorses, the risk of musculoskeletal injury is linked to a decrease in speed and stride length (SL) over consecutive races prior to injury. Surface characteristics influence stride parameters. We hypothesized that large changes in stride parameters are found during galloping in response to dirt racetrack preparation. Harrowing of the back stretch of a half-mile dirt racetrack was altered in three individual lanes with decreasing depth from the inside to the outside. Track underlay compaction and water content were changed between days. Twelve horses (six on day 2) were sequentially galloped at a target speed of 16 ms-1 across the three lanes. Speed, stride frequency (SF), and SL were quantified with a GPS/GNSS logger. Mixed linear models with speed as covariate analyzed SF and SL, with track hardness and moisture content as fixed factors (p < 0.05). At the average speed of 16.48 ms-1, hardness (both p < 0.001) and moisture content (both p < 0.001) had significant effects on SF and SL. The largest difference in SL of 0.186 m between hardness and moisture conditions exceeded the 0.10 m longitudinal decrease over consecutive race starts previously identified as injury predictor. This suggests that detailed measurements of track conditions might be useful for refining injury prediction models.

Effect of breeding season and age on follicular dynamics and hemodynamics in embryo donor mares subjected to luteolysis after embryo flushing.

Background: Mares are the only companion animals simulating women in the large diameter of their follicles. Horses start reproduction at the age of three years, and some of them live for >30 years, so aging influences their reproductive capacity. Mares are sensitive to summer heat stress as they can sweat like humans. Aim: The current work aimed to study the effects of age (young versus senile), season (cold versus hot), and the hormonal treatments during embryo collection on the dominant and subordinate follicular dynamics and hemodynamics and circulating ovarian hormones in embryo donor mares ovulated twice spontaneously before inducing ovulation for flushing embryos. Methods: Spontaneous oestrous cycles were studied for young mares (<10 years; N = 6) or senile (>20 years; N = 5) during months of the cold season (November to April) and hot season (May to August). In young embryo donor mares, oestrous cycles after inducing ovulation and luteolysis were studied using Doppler ultrasound. Estradiol (E2), progesterone (P4), nitric oxide (NO), total cholesterol, and lactate dehydrogenase (LDH) were measured in blood serum. Results: A decrease in the dominant follicle antrum diameter (p > 0.05) and LDH (p = 0.016) was observed after inducing luteolysis in young embryo donor mares. Both human chorionic gonadotropin (hCG) and PGF2α treatments increased dominant follicle area (p = 0.0001), antrum area (p = 0.001), perimeter (p = 0.001), granulosa area (p = 0.0001), cholesterol (p = 0.0001), NO (p = 0.0001), and E2 (p = 0.0001). The dominant follicle area, antrum area, perimeter, color area, granulosa area, LDH, cholesterol, NO, and E2 increased (p = 0.0001) during the oestrous cycles of the hot season, but the circulatory % (p = 0.0001) declined. Senile mares had lower dominant follicle area (p = 0.002), antrum area (p = 0.0001), granulosa area (p > 0.05), LDH (p = 0.001), cholesterol (p = 0.0001), NO (p = 0.0001), and E2 (p = 0.0001) but higher circulatory % (p = 0.0001) and color area % (p = 0.023). The dominant follicle possesses the largest diameter, area, perimeter, granulosa area, and color area but the lowest circulatory % during spontaneous oestrous cycles, after inducing ovulation, or luteolysis with significant effects of the day of the spontaneous oestrous cycles on their dynamics and hemodynamics. Conclusion: During hot months, mares treated with hCG ovulated 24 hours later and prostaglandin-induced luteolysis was followed by new ovulation five days later. Follicles ovulated during the hot months were larger than those ovulated during the cold months and both had nearly the same color area %. Senile mares ovulated follicles with a lower area and antrum area but a higher color area %, so senile mares can be used as embryo or oocyte donors during the hot season.

Analysis of current methods and Welfare concerns in the transport of 118 horses by commercial air cargo companies.

BACKGROUND: Studies on equine air transport practices and consequences are scarce. This prospective study aimed to describe horse and air journey details and practices, document how horse behavior and health changed during the air transport phases, quantify the occurrence of welfare issues, and identify possible associations between horse and journey details, air transport practices, and welfare issues. RESULTS: Data were collected from before departure to five days after arrival on 118/597 horses traveling on 32 commercial air journeys on different routes, varying in duration and conditions. Most horses were middle-aged warmblood females, 26% of which were pregnant, and being moved by air for sales. Before flying, most were quarantined (median: 18; IQR: 9-53 days), and their fitness for travel was certified by veterinarians. At the departure airports, external temperatures varied from - 6 °C to 33 °C, and horses were loaded by experienced flight grooms (median: 35; IQR: 15-40 years) into jet stalls (three-horse: 87%, two-horse: 13%). During the flights, horses were regularly watered (water intake median: 14 L) and fed ad libitum (feed consumption median: 8 kg). At the arrival airport, horses were unloaded from the jet stalls, and external temperatures ranged from - 5 °C to 32 °C. Then, all horses were transported to arrival quarantine by road. Air transport phases affected horses' health status and behavior; increased heart and respiratory rates and behaviors, such as pawing, head tossing, and vocalization, were mainly identified at departure and arrival. Horse interaction, nasal discharge, increased capillary refill time (CRT), and abnormal demeanor were observed more often one hour before landing while resting and normal capillary refill time were more often displayed five days after arrival (all P < 0.01). One hour before landing, horses with bad temperament and horses of unknown temperament were more likely to develop nasal discharge when transported in winter and autumn (P < 0.001). The likelihood of an increased CRT was associated with shorter flights in horses of unknown travel experience (P < 0.001). Ten horses were injured, and 11 developed pleuropneumonias (i.e., shipping fever). CONCLUSIONS: Air transport is a complex procedure with several different phases affecting horse health and behavior. Therefore, experienced staff should carefully manage each horse before, during, and after air journeys to minimize welfare hazards.

The interaction between seminal plasma, sperm, and endometrium in inter- and intra-species breeding in equids.

In brief: In some instances, extra-species breeding in equids is more successful than intraspecies breeding; however, little is known about the immunomodulatory effect of donkey semen and seminal plasma on the mare's endometrium. This study compared the mare uterine inflammatory response during extra- and intraspecies breeding. Abstract: Anecdotal experience suggests horse mares have less post-breeding inflammation and better fertility when bred with donkeys. This study aimed to compare the post-breeding inflammatory response of mares exposed to donkey and horse semen and seminal plasma and evaluate the proteome and metabolome of donkey and horse sperm and seminal plasma. Uterine edema, intrauterine fluid accumulation, polymorphonuclear neutrophils on cytology, and concentrations of progesterone, and pro- and anti-inflammatory cytokines (IL1A, IL1B, IL4, IL6, CXCL8, IL10) were assessed pre- and post infusion of semen and seminal plasma (donkey and horse). The metabolome and proteome were analyzed by LC-MS/MS. Mare cycles bred with horse semen had a greater progesterone concentration than those bred with donkey semen at 8 days post ovulation (P = 0.046). At 6 h post infusion, the inflammatory response due to the donkey semen tended to be lower (P = 0.074). Donkey seminal plasma had anti-inflammatory properties compared to horse semen and seminal plasma, as determined by fewer neutrophils on uterine cytology (P < 0.05). Horse semen resulted in greater concentrations of IL6 and lesser concentrations of IL1B (P < 0.05). PGE1, PGE3, and lactoferrin concentrations were significantly more abundant in donkey sperm and seminal plasma. Prostaglandins play an important role in immunomodulation and might contribute to the response triggered in interspecies breeding. In conclusion, breeding horse mares with donkey semen induces similar post-breeding endometritis as observed with horse semen. Donkey seminal plasma results in a lower post-infusion inflammatory response compared to other combinations in the immediate post-breeding.

Physiological and metabolic responses in Kök-Börü horses: Correlations with game outcomes.

BACKGROUND: The aim of this study was to examine variations in stress, metabolic, and physiological parameters of horses used in the traditional equestrian team sport of Kök-Börü in relation to winning and losing outcomes. MATERIAL AND METHODS: To accomplish this, blood samples were taken from horses on four different teams who participated in two separate games, both before and after game. These samples were used to measure levels of cortisol, ACTH, beta-endorphin, adrenaline, noradrenaline, triiodothyronine (T3), and thyroxine (T4) via species-specific commercial ELISA kits. The autoanalyzer tested biochemical and hematological parameters. The gathered data were then analyzed statistically based on the teams' winning or losing status. RESULTS: The results suggested that winning teams had lower MID, red blood cell, HGB, RDW-SD, HCT, platelet distribution width, and creatine kinase values post-game in comparison to their pre-game state. Conversely, mean corpuscular hemoglobin concentration (MCHC), mean corpuscular hemoglobin (MCH), and CREA values increased in the winning teams' post-game. Additionally, horses in the winning teams showed a decrease in cortisol, beta-endorphin, and ACTH levels post-game but increased levels of adrenaline and T3. Considering the pre-game values, it was found that GRA and Cl levels were lower in the winning teams. Before the game, adrenaline and T3 levels were higher in the winning teams. No significant difference was observed in post-game hematological parameters between the teams. However, post-game K, adrenaline, and noradrenaline levels were higher among the winning teams' horses, while cortisol and beta-endorphin levels were heightened in horses from the losing side. CONCLUSION: In conclusion, significant differences were not observed in the distribution of hematological and biochemical parameters of horses following the Kök-Börü games, regardless of the outcome. However, decreased post-game cortisol, ACTH, and beta-endorphin levels in winning teams may suggest better stress management abilities among these horses.

Adaptive forgetting of place/object memory for dung in the domestic horse (Equus ferus caballus): Memory for a day.

The domestic horse (Equus ferus caballus) makes dung deposits to form "stud-piles" and compulsively examines dung droppings, suggesting that dung contains species-relevant information. The present study investigates horses' use of location (place), odor (object) and memory for dung sniff encounters. Horses were video recorded in 2 indoor and 4 outdoor riding arenas as they were taken at different time intervals to experimenter-determined objects or dung deposits that they could sniff. Frame-by-frame video analysis measured approaches, sniff duration, nostril use, ear position and blinking associated with dung investigation. Horses approached and sniffed dung-deposits for longer duration than non-dung objects in all test locations. They made head movements across the extent of dung-deposits when sniffing, showed no nostril or ear preference directed to the target, and blinked as they disengage from sniffing. Reduced approach probability and sniff duration showed that they displayed good place/object memory for dung previously visited at similar and different locations on the same day but poor memory for dung visited on a previous day. Adaptive forgetting of object/place memory for dung after a previous day's dung visit may optimizes risk assessment, including the possibility of premature interruption of foraging by conspecifics.

Position of the Proximal Manica Flexoria under different grades of fetlock joint extension - A biomechanical observational study in the equine fore- and hindlimb.

OBJECTIVE: The aim of this study was to examine the position of the proximal manica flexoria and the proximal scutum under different grades of fetlock joint extension and to describe measurements and compare findings between equine fore- and hindlimbs. STUDY DESIGN: It was an observational study. RESULTS: During fetlock joint extension, the proximal manica flexoria and the proximal scutum displace distally relative to the palmar/plantar extent of the sagittal ridge of the cannon bone. The proximal manica flexoria is further displaced distal to the proximal scutum within the fetlock canal. No significant differences were identified between fore- and hindlimbs at different levels of fetlock joint extension. The proximal scutum was observed to be longer and thicker and the tendinous part of the manica flexoria was longer in forelimbs compared with hindlimbs. CONCLUSION AND CLINICAL RELEVANCE: The described findings contribute to the understanding of the pathogenesis of manica flexoria tearing. The fact that the proximal scutum and the tendinous part of the manica flexoria are shorter in the hindlimb might explain why the manica flexoria is more likely to get caught on the proximal aspect of the scutum and develop a tear in the equine hindlimb.

Christmas article: High incidence of ponytail in polytraumatised riders.

Introduction Imaging experience made us suspect an overrepresentation of ponytails in riders admitted as polytrauma after falling from their horse. Methods In a single-centre case-control study conducted over three months, we reviewed the records of all admitted polytraumatised patients for trauma mechanism and presence of ponytail on CT. Cerebral CTs were reviewed in the three standard imaging planes using a bone or lung window. Ponytail was diagnosed if most or all of the hair on the head was gathered and secured at the back of the head with a hair tie. Data were analysed with Fisher's exact test. Results Seven female riders (mean age 22 years) were admitted after falling from their horse (study group); six of these riders wore a ponytail. No male riders were admitted. Therefore, only female polytraumatised patients having suffered any other trauma were selected as controls. The control group consisted of 13 patients (mean age 33,5 years), two of whom wore a ponytail. In three controls, all without ponytails, the trauma also had been related to a horse. Thus, horses were involved in 50% of the traumas included in this study. Ponytail was found more frequently in riders admitted after falling from their horse, p less-than 0,005. Conclusion Having an almost circumferential vision, horses may be scared by the sideways swaying of a ponytail worn by their own rider. In riders, ponytails can trigger a sensation of tightness or even headache which may impair focus. Thus, while female riders most likely wear ponytails for practicality, ponytails may increase the risk of accident by affecting rider and horse. Further studies are required to determine if the observed association between ponytails and trauma is causal. Funding none. Trial registration not applicable.

Kinematics of the equine distal sesamoid (navicular) bone of the thoracic limb.

OBJECTIVE: To quantify the translation and angular rotation of the distal sesamoid bone (DSB) using computed tomography (CT) and medical modeling software. SAMPLE: 30 thoracic limbs from equine cadavers. PROCEDURES: Partial (n = 12), full (8), and matched full and subsequently transected (10) thoracic limbs were collected. Bone volume CT images were acquired in three positions: extension (200° metacarpophalangeal angle), neutral (180°), and maximal flexion (110°). Mean translation and angular rotation of each DSB were recorded. Differences were determined with two-way ANOVA and post hoc Tukey's tests for pairwise comparisons; P value was set at < 0.05. RESULTS: Dorsal translation was significant during extension (1.4 ± 0.4 mm full limbs and 1.3 ± 0.2 mm partial limbs, P < 0.001). Distal translation was significant during extension (1.9 ± 0.4 mm full and 1.1 ± 0.4 mm partial) and flexion (5.4 ± 0.7 mm full and 6.22 ± 0.6 mm partial, P < 0.001). Rotation was significant (P < 0.001) about the mediolateral axis during extension (17.1° ± 1.4°) and flexion (2.6° ± 1.3°). Translation and rotation of the DSB were significantly different (P < 0.001) between full and partial limbs. CLINICAL RELEVANCE: This study provides the first quantification of translation and angular rotation of the DSB within the equine hoof. Partial limbs had significantly reduced movement compared to full limbs, suggesting that transection of flexor tendons alters distal thoracic limb kinematics. Further studies are required to determine if pathologic changes in the podotrochlear apparatus have an impact in clinical lameness outcomes.

The effect of stress and exercise on the learning performance of horses.

Domestic horses are widely used for physically demanding activities but the effect of exercise on their learning abilities has not been explored. Horses are also frequently exposed to stressors that may affect their learning. Stress and exercise result in the release of glucocorticoids, noradrenaline and other neurotransmitters that can influence learning. It is not currently possible to directly measure concentrations of neurotransmitters in the brains of behaving horses, however the inference of neurobiological processes from peripheral markers have been widely used in studies of human cognition. We assigned 41 horses to either ridden exercise, uncontrollable stress or inactivity and evaluated their acquisition of an industry-style aversive instrumental learning task. Exercised horses achieved the learning criterion in the fewest number of trials compared to the stressed and inactive horses whose performance did not differ. The exercised horses' salivary cortisol concentrations decreased during learning whereas the concentrations of the other groups increased. Spearman's correlations revealed that horses with the highest cortisol concentrations required the most trials to reach the criterion. We present novel data that exercise prior to learning may enhance the acquisition of learning in horses. Conversely, activities that expose horses to uncontrollable stressors causing strong cortisol release may impair learning. It is proposed that these effects may be due to the influence of neurotransmitters such as cortisol and noradrenaline on brain regions responsible for learning.

Adaptation and acceptability testing of the Expector® vibration vest in horses / Adaptação e teste de aceitabilidade do colete de vibração Expector® em equinos

The project is based on a test of a thoracic vibration vest prototype, adapted to equines by the Expector® vest's company, on healthy animals. Ten (10) equines were used in the project, male or female, adults, healthy, belonging to FMVZ-USP or private owners. Each animal went through two phases: A and B. Phase A consisted of the placement of the vest without turning on the vibrators, evaluating the animal's acceptability, facility, adaptation to the animal's body, and discomfort due to the vest's use. Phase B included the placement of the vest and turning on the vibrators, evaluating the animal's acceptability, reaction to the vibrators, and, if present, to which velocity/type of vibration, and the presence of adverse effects. Both phases were done three times on separate days. The behavioral parameters: "placement facility" and "adaptation to the animal's body" were observed. In phase B, the response to the vibration was classified from 0 to 5. The answer was evaluated on low and high intensities for the four vibration types. The heart rate (HR) and respiratory rate (RR) were also evaluated at the beginning and end of each repetition. The animals' HR was kept on normal, except for one animal on one day of the test. Concerning the RR, most animals presented moments of tachypnea. On the experiment's first day, 100% of grade Great to "facility of placement" and "adaptation to the animal's body" was obtained, but on days 2 and 3 this value dropped to 90% due to alterations in one animal's responses. Regarding vibration's responses, 77.3% were evaluated as no discomfort (grade 0), 17.1% little discomfort (grade 1), 3.3% medium discomfort (grade 2), 0.4% great discomfort (grade 3), 0.21% extreme discomfort (grade 4), and 1.6% non-acceptance of the vest (grade 5). Some possible changes on the prototype were also verified to be suggested to the manufacturer, such as the change of the buckle and the use of wireless control. Vest use appears promising for equine respiratory physiotherapy, considering the acceptability was good, and its efficiency on the expectoration of diseased animals must be tested.

O projeto consistiu no teste de um protótipo de colete de vibração torácica, adaptado aos equinos pela empresa do colete Expector®, em animais saudáveis. Foram utilizados 10 equinos, machos ou fêmeas, adultos, saudáveis, pertencentes à FMVZ-USP e a proprietários particulares. Cada animal passou por duas fases: A e B. A Fase A consistiu na colocação do colete sem ligar os vibradores, avaliando-se a aceitabilidade do animal; facilidade; adaptação ao corpo do animal e incômodo do mesmo à sua presença. Já a Fase B contava com a colocação do colete e funcionamento dos vibradores, avaliando-se a aceitabilidade do animal; reação aos vibradores e, se presente, a qual velocidade/tipo de vibração; presença de reações ou efeitos adversos. As duas fases foram realizadas em triplicata em dias separados. Foram observados os parâmetros comportamentais "facilidade de colocação" e "adaptação ao corpo do animal". Na fase B, a resposta à vibração foi classificada de 0 a 5. A resposta foi avaliada nas intensidades baixa e alta para os quatro diferentes tipos de vibração. Foram avaliadas também as frequências cardíaca (FC) e respiratória (FR) no início e final de cada repetição. A FC dos animais se manteve dentro do intervalo de normalidade, com exceção de um animal em um dia de avaliação. Em relação à FR, a maioria apresentou momentos de taquipneia. No primeiro dia de experimento obteve-se 100% de avaliação Ótima para "facilidade de colocação" e "adaptação ao corpo do animal", mas nos dias 2 e 3 esse valor caiu para 90% devido à alteração na resposta de um animal. Em relação à resposta à vibração, 77,3% das respostas foram avaliadas como nenhum incômodo (nota 0), 17,1% pouco incômodo (nota 1), 3,3% médio incômodo (nota 2), 0,4% muito incômodo (nota 3), 0,21% incômodo extremo (nota 4) e 1,6% não aceitação do colete (nota 5). Foram também verificadas algumas possíveis mudanças no protótipo a serem sugeridas ao fabricante, como mudança do tipo de fivela e uso de controle sem fio. A utilização do colete parece ser muito promissora para a fisioterapia respiratória em equinos, visto que a aceitabilidade foi muito boa, devendo-se agora realizar a avaliação de sua eficácia na expectoração de animais enfermos.(AU)

Comparison of insulin sensitivity between healthy neonatal foals and horses using minimal model analysis.

The equine neonate is considered to have impaired glucose tolerance due to delayed maturation of the pancreatic endocrine system. Few studies have investigated insulin sensitivity in newborn foals using dynamic testing methods. The objective of this study was to assess insulin sensitivity by comparing the insulin-modified frequently sampled intravenous glucose tolerance test (I-FSIGTT) between neonatal foals and adult horses. This study was performed on healthy neonatal foals (n = 12), 24 to 60 hours of age, and horses (n = 8), 3 to 14 years of age using dextrose (300 mg/kg IV) and insulin (0.02 IU/kg IV). Insulin sensitivity (SI), acute insulin response to glucose (AIRg), glucose effectiveness (Sg), and disposition index (DI) were calculated using minimal model analysis. Proxy measurements were calculated using fasting insulin and glucose concentrations. Nonparametric statistical methods were used for analysis and reported as median and interquartile range (IQR). SI was significantly higher in foals (18.3 L·min-1· µIU-1 [13.4-28.4]) compared to horses (0.9 L·min-1· µIU-1 [0.5-1.1]); (p < 0.0001). DI was higher in foals (12 × 103 [8 × 103-14 × 103]) compared to horses (4 × 102 [2 × 102-7 × 102]); (p < 0.0001). AIRg and Sg were not different between foals and horses. The modified insulin to glucose ratio (MIRG) was lower in foals (1.72 µIUinsulin2/10·L·mgglucose [1.43-2.68]) compared to horses (3.91 µIU insulin2/10·L·mgglucose [2.57-7.89]); (p = 0.009). The homeostasis model assessment of beta cell function (HOMA-BC%) was higher in horses (78.4% [43-116]) compared to foals (23.2% [17.8-42.2]); (p = 0.0096). Our results suggest that healthy neonatal foals are insulin sensitive in the first days of life, which contradicts current literature regarding the equine neonate. Newborn foals may be more insulin sensitive immediately after birth as an evolutionary adaptation to conserve energy during the transition to extrauterine life.

Thermal and behavioral response of horses submitted to functional exercises and acupuncture / Resposta térmica e comportamental de equinos submetidos a exercícios funcionais e acupuntura

The present research evaluated muscle activation degrees and relaxation of patrolling horses submitted to dynamic mobilization exercises, associated or not with acupuncture. Twelve mixed breed gelding, aged 10 ± 2.0 years, were distributed in three treatments. Treatment with a single session of dynamic mobilization exercises (longitudinal cervical flexion of head between hooves, between carpus and to up to chest); treatment with a single acupuncture session during 20 minutes, and treatment with a single session of dynamic mobilization exercises with acupuncture. Thermographic images were analyzed before and after applying treatments to the cervical, thoracic, dorsal, abdominal and pelvic regions. Animal behavior was assessed through five minutes filming, before and ten minutes after the end of each treatment application, in an uninterrupted way. Increase in animals body temperature at the end of the single session of functional exercises (P < 0.0001) at all animal regions were reported, being cervical and thoracic areas with highest final temperature values. There was no temperature variation for other treatments (P > 0.05). All treatments stimulated higher expression frequency (P < 0.05) of relaxation behaviors. A single dynamic mobilization exercises session is enough to promote intense muscular response in entire horse body; and with acupuncture, individually or associated, promoted muscle and mental relaxation, interfering positively in animal welfare.

Objetivou-se avaliar o grau de ativação e relaxamento muscular de equinos de patrulhamento submetidos à exercícios de mobilização dinâmica associados ou não à acupuntura. Doze cavalos castrados, sem raça definida, com idade de 10 ± 2,0 anos, foram distribuídos em três tratamentos: tratamento com uma sessão única de exercícios de mobilização dinâmica (flexão cervical longitudinal da cabeça entre os cascos, entre os carpos e até o peito); tratamento com sessão única de acupuntura (20 minutos); e tratamento com sessão única composta por exercícios de mobilização dinâmica associados a acupuntura. Foram analisadas imagens termográficas antes e após a aplicação dos tratamentos das regiões cervical, torácica, dorsal, abdominal e pélvica. A avaliação comportamental foi obtida por meio de filmagens 5 minutos antes e 10 minutos após o término da aplicação dos tratamentos, de maneira ininterrupta. Houve aumento (P < 0,0001) na temperatura corporal dos animais ao final da sessão única de exercícios funcionais para todas as regiões estudadas, sendo a cervical e torácica aquelas com maior valor de temperatura final. Não houve variação da temperatura nos demais tratamentos (P > 0,05). Todos os tratamentos geraram maior frequência (P < 0,05) na expressão de comportamentos relacionados ao relaxamento. A realização de uma sessão única de exercícios de mobilização dinâmica é suficiente para promover uma intensa resposta muscular em todo o corpo do equino, e tanto os exercícios funcionais quanto a acupuntura, de maneira individual ou associada, foram capazes de promover relaxamento muscular e mental, interferindo de maneira positiva no bem-estar dos animais.

Moderate-intensity training in hypoxia improves exercise performance and glycolytic capacity of skeletal muscle in horses.

We investigated whether moderate-intensity training of horses in moderate hypoxia for 4 weeks elicits greater adaptations in exercise performance, aerobic capacity, and glycolytic/oxidative metabolism in skeletal muscle compared to normoxic training. In a randomized crossover study design, seven untrained Thoroughbred horses (5.9 ± 1.1 years, 508 ± 9 kg) completed 4 weeks (3 sessions/week) of two training protocols consisting of 3-min cantering at 70% of maximal oxygen consumption ( V˙O2max ) in hypoxia (HYP; FI O2  = 14.7%) and normoxia (NOR; FI O2  = 21.0%) with a 4-month washout period. Normoxic incremental exercise tests (IET) were conducted before and after training. Biopsy samples were obtained from the middle gluteal muscle before IET and monocarboxylate transporter (MCT) protein expression and glycolytic/mitochondrial enzyme activities were analyzed. Data were analyzed using mixed models (p < 0.05). Running speed was 7.9 ± 0.2 m/s in both groups and arterial oxygen saturation during training in NOR and HYP were 92.9 ± 0.9% and 75.7 ± 3.9%, respectively. Run time in HYP (+9.7%) and V˙O2max in both groups (NOR, +6.4%; HYP, +4.3%) at IET increased after 4 weeks of training. However, cardiac output, arterial-mixed venous O2 difference, and hemoglobin concentration at exhaustion were unchanged in both conditions. While MCT1 protein and citrate synthase activity did not increase in both conditions after training, MCT4 protein (+13%), and phosphofructokinase activity (+42%) increased only in HYP. In conclusion, 4 weeks of moderate-intensity hypoxic training improves exercise performance and glycolytic capacity of skeletal muscle in horses.

Long-Term Evaluation of Poly(lactic acid) (PLA) Implants in a Horse: An Experimental Pilot Study.

In horses, there is an increasing interest in developing long-lasting drug formulations, with biopolymers as viable carrier alternatives in addition to their use as scaffolds, suture threads, screws, pins, and plates for orthopedic surgeries. This communication focuses on the prolonged biocompatibility and biodegradation of PLA, prepared by hot pressing at 180 °C. Six samples were implanted subcutaneously on the lateral surface of the neck of one horse. The polymers remained implanted for 24 to 57 weeks. Physical examination, plasma fibrinogen, and the mechanical nociceptive threshold (MNT) were performed. After 24, 28, 34, 38, and 57 weeks, the materials were removed for histochemical analysis using hematoxylin-eosin and scanning electron microscopy (SEM). There were no essential clinical changes. MNT decreased after the implantation procedure, returning to normal after 48 h. A foreign body response was observed by histopathologic evaluation up to 38 weeks. At 57 weeks, no polymer or fibrotic capsules were identified. SEM showed surface roughness suggesting a biodegradation process, with an increase in the median pore diameter. As in the histopathological evaluation, it was not possible to detect the polymer 57 weeks after implantation. PLA showed biocompatible degradation and these findings may contribute to future research in the biomedical area.

Circulating Transcriptional Profile Modulation in Response to Metabolic Unbalance Due to Long-Term Exercise in Equine Athletes: A Pilot Study.

Physical exercise has been associated with the modulation of micro RNAs (miRNAs), actively released in body fluids and recognized as accurate biomarkers. The aim of this study was to measure serum miRNA profiles in 18 horses taking part in endurance competitions, which represents a good model to test metabolic responses to moderate intensity prolonged efforts. Serum levels of miRNAs of eight horses that were eliminated due to metabolic unbalance (Non Performer-NP) were compared to those of 10 horses that finished an endurance competition in excellent metabolic condition (Performer-P). Circulating miRNA (ci-miRNA) profiles in serum were analyzed through sequencing, and differential gene expression analysis was assessed comparing NP versus P groups. Target and pathway analysis revealed the up regulation of a set of miRNAs (of mir-211 mir-451, mir-106b, mir-15b, mir-101-1, mir-18a, mir-20a) involved in the modulation of myogenesis, cardiac and skeletal muscle remodeling, angiogenesis, ventricular contractility, and in the regulation of gene expression. Our preliminary data open new scenarios in the definition of metabolic adaptations to the establishment of efficient training programs and the validation of athletes' elimination from competitions.

Epigenetic models developed for plains zebras predict age in domestic horses and endangered equids.

Effective conservation and management of threatened wildlife populations require an accurate assessment of age structure to estimate demographic trends and population viability. Epigenetic aging models are promising developments because they estimate individual age with high accuracy, accurately predict age in related species, and do not require invasive sampling or intensive long-term studies. Using blood and biopsy samples from known age plains zebras (Equus quagga), we model epigenetic aging using two approaches: the epigenetic clock (EC) and the epigenetic pacemaker (EPM). The plains zebra EC has the potential for broad application within the genus Equus given that five of the seven extant wild species of the genus are threatened. We test the EC's ability to predict age in sister taxa, including two endangered species and the more distantly related domestic horse, demonstrating high accuracy in all cases. By comparing chronological and estimated age in plains zebras, we investigate age acceleration as a proxy of health status. An interaction between chronological age and inbreeding is associated with age acceleration estimated by the EPM, suggesting a cumulative effect of inbreeding on biological aging throughout life.

Heart rate variability before and after 14 weeks of training in Thoroughbred horses and Standardbred trotters with different training experience.

Changes in heart rate and heart rate variabilty (HRV) were investigated in untrained (UT; starting their first racing season) and detrained (DT; with 1-3 years of race experience) racehorses before and after 14-week conventional training. HRV was measured at rest over 1 h between 9:00 and 10:00 AM on the usual rest day of the horses. The smallest worthwhile change (SWC) rate was calculated for all HRV parameters. UT horses had significantly higher heart rate compared to DT (P<0.001). There were no gender- or training-related differences in heart rate. The root-mean-square of successive differences (rMSSD) in the consecutive inter-beat-intervals obtained after the 14-week training period was lower compared to pre-training rMSSD (P<0.001). The rMSSD was not influenced by breed, age or gender. In DT horses, there was a significant decrease in the high frequency (HF) component of HRV (P≤0.05) as the result of the 14-week training. These results may reflect saturation of high-frequency oscillations of inter-beat intervals rather than the reduction in parasympathetic influence on the heart. The HF did not differ significantly between the two measurements in UT horses; however, 16.6% of the animals showed a decrease in HF below SWC (P≤0.05). This supports the likelihood of parasympathetic saturation. Although no significant decrease in heart rate was found for the post-training, 30.0% of DT and 58.3% of UT horses still showed a decrease in heart rate below the SWC. Also by individual examination, it was also visible that despite significant post-training decrease in rMSSD, 1 (4.6%) DT and 2 (6.7%) UT horses reached SWC increase in rMMSD. In the case of these horses, the possibility of maladaptation should be considered. The present results indicate that similar to as found in human athletes, cardiac ANS status of racehorses also changes during the physiological adaptation to training. To explore more precise links between HRV and training effectiveness in horses, a more frequent recording would be necessary. Detailed analysis of HRV parameters based on SWC will be able to highlight the importance of fitness evaluation at individual level.