Responses Of Horses Research Articles

Serological responses of horses in response to vaccination in a farm associated with a natural outbreak of strangles

Serological responses of horses in response to vaccination in a farm associated with a natural outbreak of strangles

Metabolic effects of training endurance horses in a field setting

Abstract Changes in serum biochemistry and skeletal muscle of horses in response to individual endurance rides of varying distance have been reported, as have the effects of submaximal treadmill training. This study evaluated the effects of a controlled field endurance training programme on energy metabolism. Five Arabian horses 6.8 ± 2.0 years (mean ± standard deviation) were trained for 16 weeks over progressively longer distances. The biceps femoris, triceps long head, and semitendinosus muscles were biopsied before and after 4-weekly runs of 10, 20 and 30 miles, respectively, and before and after 10, 20, 30 and 50 miles of a fourth run at the end of the training programme to measure 3-hydroxyacyl-CoA-dehydrogenase (HAD) and succinate dehydrogenase (SDH) activities and triglyceride (TG) and glycogen concentrations in those biopsies. Blood samples were obtained simultaneously to measure serum TG, free fatty acid (FFA), glycerol, glucagon, insulin, and cortisol concentrations. Data were analysed using RM-ANOVA for effects of training and distance. was considered significant. Training increased resting glycogen and TG concentrations in the biceps (, ), triceps (, ) and semitendinosus (, ), respectively. Both HAD and SDH activities increased in the biceps femoris (; ) and triceps (; ), respectively, but not in the semitendinosus. There was no training effect detected on serum hormone responses to exercise distance although serum glycerol (), glucagon () and cortisol () concentrations increased with increasing run distance, while insulin concentration decreased (). Glucagon and cortisol concentrations were correlated (r = 0.67; ). Serum TG decreased with exercise but at a slower rate following training, and serum FFA were higher during exercise following training when compared to the partially trained state. Overall, endurance training enhanced peripheral mobilisation of fat and its utilisation by working muscle, and resting muscle glycogen stores increased.

Development of a fixed list of descriptors for the qualitative behavioral assessment of thoroughbred horses in the racing environment.

Horse racing is a major sport practiced worldwide. The environment to which horses are exposed during race meetings can influence their behavior. However, to the best of our knowledge, a method for assessing a horse's response to its surroundings during the pre- and post-race periods has not yet been reported. This study aimed to create a standard list of descriptors for use in a qualitative behavioral assessment (QBA) focused on assessing the emotional expressivity of horses before and after racing events. Seventy pre- or post-race 30-second videos of horses were randomly selected from our database of 700 videos. A panel of 8 experienced equine sports medicine specialist veterinarians watched a 60 min presentation on QBA. The panel then watched all videos randomly, simultaneously, individually, continuously, and without any verbal interaction, describing the descriptors related to the emotional expressivity of the horse after each video using a method known as free-choice profiling (FCP). The initial selection of descriptors was based on those indicated by more than one evaluator in the same video, or descriptors with more than 20 occurrences. The second selection was performed based on the content validity index (CVR) to select the descriptors retained in the previous step. Another panel of six veterinarians scored each of the descriptors retained for content validity on a visual scale. Interobserver reliability was estimated using the intraclass correlation coefficient (ICC) and its respective 95% confidence intervals (CI). A natural language processing (NLP) algorithm was used to analyze the behavior (positive or negative polarity) of the descriptors based on the lexicoPT package of R software. NLP analysis considered the descriptors "agitated," "troubled," "restless" and "irritated" to have a negative polarity, while "focused," "relaxed" and "peaceful" had a positive polarity. In the principal component analysis (PCA), descriptors in a negative state were associated with each other and inversely associated with descriptors in a positive state. We conclude with a fixed list of descriptors to be used in a QBA to assess emotional and welfare expressivity in racehorses' pre- and post-race environments.

Transcription of interleukin 31 and its receptor by leukocytes after Culicoides sp stimulation is dose dependent but is not exaggerated in allergic horses or correlated with pruritus.

Preliminary evidence supports a role for IL-31 in equine insect bite hypersensitivity (IBH) and pruritus. Our studies investigated IL-31 and IL-31 receptor-α (IL-31RA) transcription in leukocytes from normal and IBH horses in response to Culicoides nubeculosus. 19 normal and 15 IBH horses were recruited in the summer of 2019 (low-dose study) and 8 normal and 10 IBH horses in the winter of 2022 to 2023 (high-dose study). Normal horses had no history or signs of allergic skin disease, while IBH horses had a history and clinical signs compatible with IBH. Pruritus was scored using a visual analog score or a 1 to 6 grading system. Whole blood leukocytes were incubated with saline (0.9% NaCl) solution or C nubeculosus (0.26 µg/mL [low dose]; 5 μg/mL [high dose]). Transcription of IL-31 and IL-31RA was measured by quantitative RT-PCR. Transcription of IL-31 and IL-31RA significantly increased in leukocytes from normal and IBH horses following high-dose C nubeculosus, and no differences were found between populations. Following low-dose C nubeculosus IL-31RA, transcription was increased in both normal and IBH horses, but IL-31 transcription was reduced in normal horses. No positive correlation was found between pruritus scores and IL-31 transcription after low- or high-dose C nubeculosus stimulation. Exaggerated IL-31 transcription was not identified in IBH horses, suggesting that dysregulation in IL-31 signaling occurs downstream or in localized tissues or involves regulation by yet unidentified receptor splice variants or IL-31-induced increased sensitivity to other pruritogens. Further studies to understand IL-31 signaling in equine allergic skin disease are needed.

106 Use of biobehavioral responses during a novel object test to assess suitability of horses for equine assisted services

Many recent studies have demonstrated positive outcomes for human participants in a variety of equine assisted services (EAS). Horses by nature are highly sensitive and their responses to unfamiliar stimuli can have important consequences for horse and human safety. Individual variation in the personality characteristics of horses, including their reactivity, may not only create safety concerns but also influence therapeutic outcomes. To date, there are no available standardized guidelines for the selection of equine in EAS. Observation of horse behavior by equine professionals has historically been used to assess the potential suitability of equine participants. However, overall behavior of individual horses can be challenging to objectively measure. Novel object (NO) tests are often used to measure reactivity in many animal species. To our knowledge, no study has yet evaluated the reactivity of horses in response to a NO test to assess their suitability for groundwork-based EAS. The purpose of this study was to compare biobehavioral responses of 11 Quarter Horse mares (11.6 ± 4.9 yr) before, during, and after exposure to a NO (stationary flamingo pool float) as a potential measure of their suitability for participation in EAS. The experiment consisted of 3 consecutive 5 min periods: Pre-NO test (P1), NO test (P2), and Post-NO test (P3) in the same 27 × 26 mpaddock. HR was recorded using a Polar H10 equine HR monitor. Behavior was video recorded and scan sampling of video every 10 s was used to determine counts. Data were analyzed using PROC MIXED in SAS v 9.4. Horse HR differed by horse and decreased with time within all 3 periods (P < 0.01). During the NO test, locomotion increased with increasing proximity to the NO (P < 0.05). Standing alert and exploratory behaviors decreased during the NO test but were not influenced by the horse's location (P < 0.03). Interestingly, eating behaviors increased during and after the NO test (P < 0.05). This study illustrates that behavioral and physiological responses of horses are influenced by their individuality which may ultimately influence their interactions during EAS. The reduction in HR over time within each period suggests that horses can quickly acclimate to changes in their environment and the overall lack of differences in their behavioral responses across periods suggests low reactivity among this study population. However, future studies with additional novel objects and horses are needed to determine if the use of this methodology can serve to evaluate suitability for horses for participation in EAS.

Changes in Acute Phase Response Biomarkers in Racing Endurance Horses.

This study aimed to evaluate if exercise-induced acute phase response (APR) occurs in endurance horses in response to the race. The study included 23 horses competing in an endurance competition with a successfully passed clinical examination before the race. Blood samples were collected before the start and within 30 min after the end of the race. Haematological and biochemical tests were performed and correlated to acute phase biomarkers changes. Values of calprotectin and haptoglobin (Hp) decreased after the races compared to values before, while concentrations of ceruloplasmin and albumin recorded a significant increase. Greater changes in calprotectin values were noted in Arabian horses compared to other breeds. Values of Hp showed a significantly greater decrease after longer races. Based on study results, endurance racing induces APR in horses characterised by significant changes in selected acute phase biomarkers. More pronounced changes were noted at races with higher average speeds, suggesting the need for thorough horse monitoring during exhausting races.

Trigeminal‐mediated headshaking: A diagnostic challenge

Trigeminal‐mediated headshaking: A diagnostic challenge

Profiling the Aerobic Window of Horses in Response to Training by Means of a Modified Lactate Minimum Speed Test: Flatten the Curve.

There is a great need for objective external training load prescription and performance capacity evaluation in equestrian disciplines. Therefore, reliable standardised exercise tests (SETs) are needed. Classic SETs require maximum intensities with associated risks to deduce training loads from pre-described cut-off values. The lactate minimum speed (LMS) test could be a valuable alternative. Our aim was to compare new performance parameters of a modified LMS-test with those of an incremental SET, to assess the effect of training on LMS-test parameters and curve-shape, and to identify the optimal mathematical approach for LMS-curve parameters. Six untrained standardbred mares (3–4 years) performed a SET and LMS-test at the start and end of the 8-week harness training. The SET-protocol contains 5 increments (4 km/h; 3 min/step). The LMS-test started with a 3-min trot at 36–40 km/h [until blood lactate (BL) > 5 mmol/L] followed by 8 incremental steps (2 km/h; 3 min/step). The maximum lactate steady state estimation (MLSS) entailed >10 km run at the LMS and 110% LMS. The GPS, heartrate (Polar®), and blood lactate (BL) were monitored and plotted. Curve-parameters (R core team, 3.6.0) were (SET) VLa1.5/2/4 and (LMS-test) area under the curve (AUC>/<LMS), LMS and Aerobic Window (AW) via angular vs. threshold method. Statistics for comparison: a paired t-test was applied, except for LMS: paired Wilcoxon test; (p < 0.05). The Pearson correlation (r > 0.80), Bland-Altman method, and ordinary least products (OLP) regression analyses were determined for test-correlation and concordance. Training induced a significant increase in VLa1.5/2/4. The width of the AW increased significantly while the AUC</>LMS and LMS decreased post-training (flattening U-curve). The LMS BL steady-state is reached earlier and maintained longer after training. BLmax was significantly lower for LMS vs. SET. The 40° angular method is the optimal approach. The correlation between LMS and VMLSS was significantly better compared to the SET. The VLa4 is unreliable for equine aerobic capacity assessment. The LMS-test allows more reliable individual performance capacity assessment at lower speed and BL compared to SETs. The LMS-test protocol can be further adapted, especially post-training; however, inducing modest hyperlactatemia prior to the incremental LMS-stages and omitting inclusion of a per-test recovery contributes to its robustness. This LMS-test is a promising tool for the development of tailored training programmes based on the AW, respecting animal welfare.

Horses’ perception of a threat posed by sounds of different origin

The aim of the study was to assess the behavioural reaction and emotional arousal of warmblood horses in response to sounds of different origin, and to classify those sounds into neutral ones, those causing a behavioural change and those causing a behavioural and physiological stress response. We tested the hypothesis that the perception of a sound as neutral or potentially threatening does not simply depend on the sound origin per se, but rather on the context in which the sound occurrs (predictability), additionally enhanced by the novelty effect. Recordings of 40 sounds, known (KS) and unknown (US), from four groups: anthropogenic (AS), neutral animal (NAS), predator (PS), and inanimate environment sounds (IES), were played to 20 warmblood horses remaining in their familiar paddock. The duration, frequency or occurrence of certain behaviours (e.g. walking, feeding, standing alert, stopping current activity), the heart rate (HR) and heart rate variability (HRV) were measured. The horses’ reactions were rather weak and short-term. Most of the sounds resulted in distraction (increase in alertness). The horses ate less, walked and stood alert longer, and had a higher HR after certain sounds were played. The strongest stress response (physiological and behavioural) to NAS, mostly US, was observed. PS caused behavioural disturbance, but no cardiac activity changes. The weakest responses were observed for AS and IES. Modern, stable-kept horses remain vigilant to auditory stimuli in their environment and differentiate their responses to different sounds. The perception of a threat posed by sounds depends on their unpredictability and novelty.

Thermographic Analysis of the Metacarpal and Metatarsal Areas in Jumping Sport Horses and Leisure Horses in Response to Warm-Up Duration.

Simple SummaryA warm-up prepares the body for effort by improving blood supply to muscles and increasing the flexibility of joints, ligaments, and tendons. Warm-up is considered as a necessary preliminary step of each training session. This study assessed the impact of different regimes of warm-up on the surface temperature of the distal parts of limbs in horses used for jumping and leisure riding. Six showjumping horses and six leisure horses were included in the study. The studied horses were warmed up by walking and trotting for various time periods. The rectal temperature and body surface temperature of the distal parts of the four limbs were measured before warm-up, just after it, and during recovery. The warm-up-induced increase in analysed temperatures was higher in jumping sport horses than in leisure horses.This study aimed to assess the impact of various types of warm-up on the metacarpal and metatarsal surface temperature in jumping sport horses in comparison to leisure horses, which work usually less intensively. Six clinically healthy sport geldings, contestants in showjumping competitions, and six geldings used for leisure riding were included in the study. The experiment was conducted for four consecutive days, during which the horses were warmed up by walking and trotting for various durations. Images were taken with a FLUKE Ti9 thermal imager to determine the resting, post-effort, and recovery temperature of the dorsal and plantar surface of the metacarpus and metatarsus of the four limbs. The obtained data were analysed with SmartView 4.1. software. The increase of measured rectal and surface temperatures was proportional to the warm-up duration. The surface temperature increase in the distal limb parts in jumping sport horses was greater than in horses used for leisure. The plantar surface was also warmer than the dorsal surface of the metacarpal/metatarsal areas, with a forelimb being warmer than a hind limb. Elevated temperatures after warm-up persist for 30 min in the recovery period, especially in jumping sport horses compared to leisure horses. Thus, the warming up effect is achieved earlier and lasts longer in heavily trained horses than in non-performance horses.

Effect of temperament on recovery in isoflurane-anaesthetised horses

Background:Recovery is a crucial phase of equine anaesthesia and factors influencing recovery quality are an active area of research.Aim:To investigate the effect of temperament on recovery score after isoflurane-anaesthesia in 30 adult horses undergoing elective surgery.Methods:Two veterinarians used a numerical rating scale to score each horse's response to five tests as a gauge of temperament. Owners used a numerical rating scale to score their horse's temperament according to seven behaviour-related questions. Horses underwent elective surgery under general anaesthesia using a standardised protocol. Recovery was recorded and scored by a blinded assessor using the simple descriptive scale for scoring recovery (R1) and the Edinburgh system (R2).Findings:There was no correlation between veterinarian or owner-assessed temperament and recovery score. Veterinary-assessed temperament score was negatively correlated with pre-induction romifidine and total romifidine dose. Both recovery scores were negatively correlated with anaesthetic duration and R1 was positively correlated with time to first movement in recovery.Conclusions:Temperament did not influence recovery score in our population of horses.

Peripheral blood basophils are the main source for early interleukin-4 secretion upon in vitro stimulation with Culicoides allergen in allergic horses

Interleukin-4 (IL-4) is a key cytokine secreted by type 2 T helper (Th2) cells that orchestrates immune responses during allergic reactions. Human and mouse studies additionally suggest that basophils have a unique role in the regulation of allergic diseases by providing initial IL-4 to drive T cell development towards the Th2 phenotype. Equine Culicoides hypersensitivity (CH) is a seasonal immunoglobulin E (IgE)-mediated allergic dermatitis in horses in response to salivary allergens from Culicoides (Cul) midges. Here, we analyzed IL-4 production in peripheral blood mononuclear cells (PBMC) of CH affected (n = 8) and healthy horses (n = 8) living together in an environment with natural Cul exposure. During Cul exposure when allergic horses had clinical allergy, IL-4 secretion from PBMC after stimulation with Cul extract was similar between healthy and CH affected horses. In contrast, allergic horses had higher IL-4 secretion from PBMC than healthy horses during months without allergen exposure. In addition, allergic horses had increased percentages of IL-4+ cells after Cul stimulation compared to healthy horses, while both groups had similar percentages of IL-4+ cells following IgE crosslinking. The IL-4+ cells were subsequently characterized using different cell surface markers as basophils, while very few allergen-specific CD4+ cells were detected in PBMC after Cul extract stimulation. Similarly, IgE crosslinking by anti-IgE triggered basophils to produce IL-4 in all horses. PMA/ionomycin consistently induced high percentages of IL-4+ Th2 cells in both groups confirming that T cells of all horses studied were capable of IL-4 production. In conclusion, peripheral blood basophils produced high amounts of IL-4 in allergic horses after stimulation with Cul allergens, and allergic horses also maintained higher basophil percentages throughout the year than healthy horses. These new findings suggest that peripheral blood basophils may play a yet underestimated role in innate IL-4 production upon allergen activation in horses with CH. Basophil-derived IL-4 might be a crucial early signal for immune induction, modulating of immune responses towards Th2 immunity and IgE production.

Identification of Host Factors Associated with the Development of Equine Herpesvirus Myeloencephalopathy by Transcriptomic Analysis of Peripheral Blood Mononuclear Cells from Horses.

Equine herpesvirus-1 is the cause of respiratory disease, abortion, and equine herpesvirus myeloencephalopathy (EHM) in horses worldwide. EHM affects as many as 14% of infected horses and a cell-associated viremia is thought to be central for EHM pathogenesis. While EHM is infrequent in younger horses, up to 70% of aged horses develop EHM. The aging immune system likely contributes to EHM pathogenesis; however, little is known about the host factors associated with clinical EHM. Here, we used the “old mare model” to induce EHM following EHV-1 infection. Peripheral blood mononuclear cells (PBMCs) of horses prior to infection and during viremia were collected and RNA sequencing with differential gene expression was used to compare the transcriptome of horses that did (EHM group) and did not (non-EHM group) develop clinical EHM. Interestingly, horses exhibiting EHM did not show respiratory disease, while non-EHM horses showed significant respiratory disease starting on day 2 post infection. Multiple immune pathways differed in EHM horses in response to EHV-1. These included an upregulation of IL-6 gene expression, a dysregulation of T-cell activation through AP-1 and responses skewed towards a T-helper 2 phenotype. Further, a dysregulation of coagulation and an upregulation of elements in the progesterone response were observed in EHM horses.

Heart rate variability in Konik and purebred Arabian horses in response to different predator vocalisations

The current predation threat of domestic horses is generally low, and horses do not know predators' frightening cues. We studied whether horses still recognise predation threats. The aim of the study was to analyse the emotional response of purebred Arabian horses (Arabian) and Polish Konik horses (Konik) to an Arabian panther (Panthera pardus nimr) (panther) growl and a grey wolf (Canis lupus) (wolf) howl. Panther vocalisation was known to Arabian ancestors, whereas ancestors of Konik knew wolf vocalisation. The response to the howls of golden jackals (Canis aureus) (jackal), which did not prey on equids, was also studied comparatively. Two groups of 10 adult horses of each breed were subject to predator sounds of one predator daily for 5 min during a turn out on pasture. The test was performed for 18 days in total. The sound of each predator was interchangeably featured from one loudspeaker for 3 days followed by four loudspeakers simultaneously to imitate a group of predators for 3 days. The horses' emotional agitation in response to the sounds was measured based on the parameters of heart rate variability (HRV) using telemetric devices. The results showed that the predators' sounds were identified by horses as stressful or neutral. Horses generally retained their anti-predator responses even in the current habitat, which typically lacks predation cues. The results are not always coherent and may demonstrate that the response is somewhat attenuated. The wolf howl elicited a stronger response in Koniks. The panther growl more strongly influenced Arabians, whereas the jackal howl minimally elicited an agitation in the horses. The differentiated response of the two horse breeds to the three predator species suggests that the response is an innate adaptation to the predation risk in the habitat of the breed ancestors. This response occurs regardless of the emotional arousal specific to a breed, and the frightening cue is not the sound per se but the possible attack of predators. Horses display a type of understanding of the sound meaning. Their HRV response seems to be adequate for the threat signalised by the sound.

Social Behaviour of Horses in Response to Vocalisations of Predators.

Simple SummaryAnimal social strategies are of importance when avoiding predation. Since horses are the least hunted among all farm animal species, we suppose that the alert reaction to a predator’s vocalisation, followed by anti-predator social behaviour, still exists in domestic horses. Recorded vocalisations of three different predators (grey wolf, Arabian leopard and golden jackal) were played to 20 horses of two horse breeds—namely, Konik polski and Arabian. Social responses and tactics in antipredator behaviour differed between the breeds and between predators. Koniks exposed to vocalisations of a howling wolf resulted in tight groupings, while Arabians exposed to the growling of a leopard responded with linear group formation. The behaviour of studied horses, expressed by alertness and defensive formations, indicates existence of the social anti-predator behavior, which in turn may explain the low rates of horses falling prey to predators as compared with other farm animal species.We tested the hypothesis that social defensive responses to the vocalisation of a predator still exist in horses. The recordings of a grey wolf, an Arabian leopard and a golden jackal were played to 20 Konik polski and Arabian mares. Durations of grazing, standing still, standing alert and the number of steps in walk and trot/canter were measured. In one-minute scans, the distances of the focal horse from the reference horse (DIST-RH) and from the nearest loudspeaker (DIST-LS) were approximated. The vocalisation of a leopard aroused the Arabians more than the Koniks (less grazing, stand-still and walk, more stand-alert and trotting/cantering). Koniks showed more relaxed behaviours to the leopard vocalisation (more grazing, stand-still and walk), but high alertness to the wolf playback (stand-alert, trotting/cantering). Spatial formation of the herd of Koniks showed tight grouping (lower DIST-RH) and maintaining distance from the potential threat (DIST-LS) in response to the wolf howling, while the Arabians approached the loudspeakers in linear herd formation when the leopard growls were played. Adult horses responded to potential predation by changing spatial group formations. This ability to apply a social strategy may be one of the explanations for the least number of horses among all hunted farm animal species.

The intensity of physiological and behavioral responses of horses to predator vocalizations

BackgroundPredatory attacks on horses can become a problem in some parts of the world, particularly when considering the recovering gray wolf populations. The issue studied was whether horses transformed by humans and placed in stable-pasture environments had retained their natural abilities to respond to predation risk. The objective of the study was to determine the changes in cardiac activity, cortisol concentrations, and behavior of horses in response to the vocalizations of two predators: the gray wolf (Canis lupus), which the horses of the breed studied had coevolved with but not been exposed to recently, and Arabian leopard (Panthera pardus nimr), from which the horses had been mostly isolated. In addition, we hypothesized that a higher proportion of Thoroughbred (TB) horse ancestry in the pedigree would result in higher emotional excitability in response to predator vocalizations. Nineteen horses were divided into groups of 75%, 50% and 25% TB ancestry. The auditory test conducted in a paddock comprised a 10-min prestimulus period, a 5-min stimulus period when one of the predators was heard, and a 10-min poststimulus period without any experimental stimuli.ResultsThe increase in heart rate and saliva cortisol concentration in response to predator vocalizations indicated some level of stress in the horses. The lowered beat-to-beat intervals revealed a decrease in parasympathetic nervous system activity. The behavioral responses were less distinct than the physiological changes. The responses were more pronounced with leopard vocalizations than wolf vocalizations.ConclusionsThe horses responded with weak signs of anxiety when exposed to predator vocalizations. A tendency towards a stronger internal reaction to predators in horses with a higher proportion of TB genes suggested that the response intensity was partly innate. The more pronounced response to leopard than wolf may indicate that horses are more frightened of a threatening sound from an unknown predator than one known by their ancestors. The differing response can be also due to differences in the characteristic of the predators’ vocalizations. Our findings suggested that the present-day horses’ abilities to coexist with predators are weak. Hence, humans should protect horses against predation, especially when introducing them into seminatural locations.

Histologic changes and gene expression patterns in biopsy specimens from bacteria-inoculated and noninoculated excisional body and limb wounds in horses healing by second intention.

To evaluate histologic changes and gene expression patterns in body and limb wounds in horses in response to bacterial inoculation. Wound biopsy specimens from 6 horses collected on days 7, 14, 21, and 27 after excisional wounds (20 wounds/horse) were created over the metacarpal and metatarsal region and lateral thoracic region (body) and then inoculated or not inoculated on day 4 with Staphylococcus aureus and Pseudomonas aeruginosa. Specimens were histologically scored for the amount of inflammation, edema, angiogenesis, fibrosis organization, and epithelialization. Quantitative PCR assays were performed to quantify gene expression of 10 inflammatory, proteolytic, fibrotic, and hypoxia-related markers involved in wound healing. Except for gene expression of interleukin-6 on day 27 and tumor necrosis factor-α on day 14, bacterial inoculation had no significant effect on histologic scores and gene expression. Gene expression of interleukin-1β and -6, serum amyloid A, and matrix metalloproteinase-9 was higher in limb wounds versus body wounds by day 27. Gene expression of cellular communication network factor 1 was higher in limb wounds versus body wounds throughout the observation period. The lack of clear markers of wound infection in this study reflected well-known difficulties in detecting wound infections in horses. Changes consistent with protracted inflammation were evident in limb wounds, and gene expression patterns of limb wounds shared similarities with those of chronic wounds in humans. Cellular communication network factor warrants further investigation and may be useful in elucidating the mechanisms underlying poor limb wound healing in horses.

Distribution of Superficial Body Temperature in Horses Ridden by Two Riders with Varied Body Weights

Simple SummaryLeisure horse riding is becoming an increasingly popular activity, but often the regard for the welfare of recreational horses is insufficient. Most often, this situation is associated with workload or insufficient knowledge of the owners. Another problem may be overloading the animals with excessive weight of the rider, because the problem of obesity affects more and more societies. Carrying heavy loads significantly reduces horse comfort and affects movement mechanics. Prolonged use of the horse in this way may translate into health and lameness issues in the back and limbs. There are currently no strict weight limits for riders. However, we believe that horse users should pay more attention to this problem. As shown in this study, a horse’s load above 20% of his body weight, even with little effort, affects changes in surface temperature and the activity of the autonomic nervous system.It was assumed that a horse with its rider body weight found in the upper limit may negatively impact the horse’s welfare. The objective of this paper was to analyze the differences in body temperature and selected heart rate parameters in horses in response to physical exercise accompanied by various rider’s body weight loads. The study was carried out on 12 leisure, 10–15-year-old warmblood geldings. The horses were ridden by two equally qualified riders whose body weights were about 20% and 10% of the average body weight (BW) of the animals (about 470 kg). Each rider rode each of the 12 horses for 13 min walking and 20 min of trotting. Images of the horse at rest, after physical exercise directly after unsaddling, and during the recovery phase (10 min after unsaddling) were taken with an infrared thermography camera. For analysis, the temperatures of selected body parts were measured on the surface of the head, neck, front, middle, and back (croup) parts of the trunk, forelimb, and hind limb. Immediately after the infrared thermography images were taken, the rectal temperature of the horse was measured. The heart rate parameters were measured at rest for 10 min directly before, during, and 10 min following the end of a training session. A multivariate analysis of variance (ANOVA) for repeated measurements was performed. Statistical significance was accepted for p < 0.05. A rider BW load on a horse of approximately 20% of the horse’s BW led to a substantial increase in the superficial temperatures of the neck, front, middle, and back parts of the trunk in relation to these body parts’ average temperatures when the load was about 10% BW. The head and limb average temperatures were not significantly affected by the load of the exercised horse. A horse’s load above 20% of his body weight, even with little effort, affects changes in surface temperature and the activity of the autonomic nervous system.

The Influence of Training and Simulated Race on Horse Plasma Serotonin Levels

Exercise represents a physical stress that challenges homeostasis affecting central and peripheral serotoninergic systems. The influence of the exercise on circulating serotonin (5-hydroxytryptamine [5-HT]) levels depends on training state as well as the exercise protocol. The purpose of the present research was to determine changes of plasma 5-HT in sport horses in response to training (T) and simulated race (SR) and in addition to assess the possible presence of significant differences on circulating 5-HT between two different sessions of exercise. In particular, the research was carried out on 18 trained horses performing daily training and race activity. Plasma 5-HT levels were analyzed in platelet poor plasma fraction by ELISA assay at T0 (before exercise), T1 (30 minutes after exercise) and T2 (2 hours after exercise). The hypothesis was that both exercise sessions could affect plasma 5-HT levels. Results showed a significant increase of plasma 5-HT levels at T1, compared with T0, both after simulated race and training activity. These effects are probably related to an increased 5-HT release from platelets and/or an increased peripheral 5-HT synthesis induced from exercise. At T2, plasma 5-HT concentrations showed a significant decrease to physiological levels in both sessions. Moreover, plasma 5-HT levels at T1 (SR) were significantly higher than those at T1 (T). Targeting peripheral 5-HT could be useful to assess the physiological adaptability of horses to the exercise, together with other selection techniques of sport horses.

Hematological changes and resistance of erythrocytes of horses in response to 32 km races

Hematological changes and resistance of erythrocytes of horses in response to 32 km races