Gait abnormalities and ridden horse behaviour in a convenience sample of the United Kingdom ridden sports horse and leisure horse population

The objectives of this study were to compare horses’ gaits in hand and when ridden; to assess static and dynamic saddle fit for each horse and rider; to apply the Ridden Horse Pain Ethogram (RHpE) and relate the findings to gait abnormalities consistent with musculoskeletal pain, rider position and balance and saddle fit; and to document noseband use and its relationship with mouth opening during ridden exercise. Data were acquired prospectively from a convenience sample of horses believed by their owners to be working comfortably. All assessments were subjective. Gait in hand and when ridden were evaluated independently, by two assessors, and compared using McNemar’s test. Static tack fit and noseband type were recorded. Movement of the saddle during ridden exercise, rider position, balance and size relative to the saddle was documented. RHpE scores were based on assessment of video recordings. Multivariable Poisson regression analysis was used to determine factors which influenced the RHpE scores. Of 148 horses, 28.4% were lame in hand, whereas 62.2% were lame ridden (P<0.001). Sixty per cent of horses showed gait abnormalities in canter. The median RHpE score was 8/24 (interquartile range 5, 9; range 0, 15). There was a positive association between lameness and the RHpE score (P<0.001). Riding School horses had higher RHpE scores compared with General Purpose horses (P = 0.001). Saddles with tight tree points (P = 0.001) and riders seated at the back of the saddle rather than the middle (P = 0.001) were associated with higher RHpE scores. Horses wearing crank cavesson compared with cavesson nosebands had higher RHpE scores (P = 0.006). There was no difference in mouth opening, as defined by the RHpE, in horses with a noseband with the potential to restrict mouth opening, compared with a correctly fitted cavesson noseband, or no noseband. It was concluded that lameness or gait abnormalities in canter may be missed unless horses are assessed ridden.     

Preliminary investigations of horses' (Equus caballus) responses to different bridles during foundation training

Throughout equitation history, bitted bridles have been the primary method of controlling the ridden horse. In response to health and behavioral concerns arising from the use of bitted bridles, bitless bridles offer new methods of steering and control. However, the effectiveness of bitless bridles on horses had not been previously examined scientifically. Therefore, the current study measured behavioral and cardiac responses of horses undergoing foundation training (bridling, long reining, and riding) wearing either a bitted or a bitless bridle.The horses wearing the bitted bridle exhibited more chewing, opening of the mouth, pawing the ground, and tail swishing than those in the bitless bridle. The horses wearing the bitless bridle exhibited more head lowering during long reining compared to those in the bitted bridle. The frequency of chewing, opening the mouth, and head raising decreased as training progressed. The number of steps taken after the application of the halt stimulus was greatest for the horses in the bitted bridle during long reining compared with those in the bitless bridle. During long reining, the heart rate and heart rate variability of the horses were higher for those in a bitted bridle compared with those in a bitless bridle.The results of this study suggest that horses wearing bitless bridles performed at least as well as, if not better than, those in bitted bridles. If the use of bitted bridles does cause discomfort to horses, as suggested by some, then the use of bitless bridles could be beneficial and certainly warrants further investigation.     

A preliminary report on estimating the pressures exerted by a crank noseband in the horse

The pressures applied to horses via restrictive nosebands are of growing concern to equitation scientists and horse sport administrators. They prevent the expression of normal behavior, may compromise blood flow, and even damage bone. This report describes an approach to estimate in vivo pressures applied to the dorsal and ventral aspects of a horse's nose via a so-called crank noseband. A load cell calibrated over a load range of 0-100 N was integrated into a commercially available crank noseband. These force values were combined with anatomical curvature data to estimate the pressure applied by the noseband to the underlying tissue at any point along the internal surface of the noseband using Laplace's law. Partial profiles of both dorsal and ventral aspects of the horse's nose, at a position corresponding to that of the noseband, were taken by contouring a flexible curve ruler to the nose. The ruler was stiff enough to retain the profile when removed from the nose, thereby allowing faithful transfer of the profile to paper for digitization. Once digitized, straightforward mathematical algorithms were used to provide an analytical expression describing each profile, to calculate profile curvature point by point, and, using measured noseband force values, to transform the curvature into a corresponding sub-noseband pressure profile. This process was used to study pressures applied when the horse chewed hay, chewed concentrate mix, and when it was cued to step backward. The calculated pressures ranged from 200 to 400 mm Hg; pressures that, in humans, are associated with nerve damage and other complications. As such, these preliminary data strongly suggest the need for more research in this domain. The current approach should inform some of the welfare concerns in ridden horses but should also be of use in studies of oral behaviors around foraging as well as crib biting and wind sucking.     

Cortisol release and heart rate variability in sport horses participating in equestrian competitions

Equestrian competitions require both physical activity and mental adaptation in horses. Cortisol, heart rate, and heart rate variability (HRV) are accepted stress parameters and, in this study, have been determined in horses (n = 13) participating in equestrian competitions for up to 3 consecutive days. Participation in competitions caused an increase in salivary cortisol concentrations (e.g., on day 1 from 1.0 ± 0.2 before to 2.2 ± 0.4 ng/mL after the competition, days 1 and 2: P < 0.001, day 3: P < 0.05) and an increase in heart rate (days 1 and 2: P < 0.001, day 3: P = 0.01). A consistent decrease in HRV occurred only in response to the final competition on day 3 (P < 0.01). When horses competing in dressage and show jumping were compared, cortisol release and HRV did not differ between groups, but after the competition, heart rate was lower in dressage than in show jumping horses (P < 0.05). Heart rate increased not only during the actual competition but already when horses were prepared in their stables (e.g., day 1: ?60 minutes, 38.6 ± 2; ?5 minutes, 77 ± 7; competition, 81 ± 10 beats per minute; P < 0.01). In conclusion, participation in equestrian competitions caused an increase in cortisol release and heart rate and a decrease in HRV variables. However, competitions were not a major stressor compared with other anthropogenic challenges such as transport, to which horses are exposed regularly.     

Effect of Experience on Adrenocortical and Thyroid Responses of Arabian Horses to Gymkhana Games

Gymkhana is an equestrian event consisting of speed pattern racing and timed games for riders on horses. The aim of the study was to evaluate the effects of gymkhana competition on total cortisol and total and free iodothyronine changes in 23 Arabian purebred horses, by taking into account the effects of previous sport experience on gymkhana riding events. Compared with pre-competition values, an increase of total cortisol concentration has been observed in experienced horses at 30 minutes (P < .001) after exercise and in inexperienced horses both at 5 minutes (P < .05) and at 30 minutes (P < .01) after exercise. Compared with pre-competition values, an increase of total triiodothyronine (T₃) concentration has been observed in experienced horses at 5 minutes (P < .05) after exercise. Data obtained showed that gymkhana riding events induced differential adrenocortical and thyroid responsiveness according to previous experience of sport horses. Hence, cortisol and iodothyronine patterns may provide additional information for the monitoring of gymkhana riding performance.     

To jump or not to jump? Strategies employed by leisure and sport horses

Show jumping is one of the most popular equestrian disciplines although strategic jumping per se is seldom used by free-living horses when negotiating obstacles that they might otherwise avoid. To establish if horses are naturally motivated to jump, we examined horses in a free-choice situation when negotiating various obstacles under test conditions. Eighteen leisure horses (LHs) and 16 sport horses (SHs) participated in a number of 2-choice tests. First, horses were presented with 2 optional routes during a “free-choice test” to reach a food stimulus. The choices were a shorter route (over an obstacle) or a longer route (around the obstacle). During 8 consecutive trials, the horses encountered an increase in obstacle height on every second trial as follows: 0, 20, 35, and 50 cm. In the “ridden test” after an initial conditioning period, the horses were tested with a Y-maze formation during 3 consecutive trials, where one element of the maze contained an obstacle arm (OA). The horses walked or trotted over the obstacle most frequently (59.9%) and jumped the obstacle in only 10.7% of the cases. For both the LH and SH groups, the horses' motivation to traverse the obstacle decreased as the obstacle height increased and only 44.1% of horses actually negotiated the 50-cm obstacle as compared with the 20-cm obstacle (85.3%). The LH group preferred to go around the obstacle significantly more often than the SH group (24 trials, 16.7% vs. 9 trials, 7.0%, for SH and LH, respectively; χ² = 6.81, N = 33, P = 0.0090). The LH group used a jumping strategy to clear the obstacle far less frequently (6 trials, 4.2%) than the SH group (23 trials, 18.0%; χ² = 9.96, N = 29, P = 0.0023). In the Y-maze trials, the LH group exhibited preference (40 per 54 trials, 74.1%; χ² = 12.5, P < 0.0001), and the SH group failed to exhibit any preference (20 per 48 trials; χ² = 1.33, P = 0.3123). There was no evidence of any correlation between the motivation to clear the obstacle and total number of OA choices in either the LH group (r_s = 0.13, P = 0.9594) or the SH group (r_s = ?0.25, P = 0.3492). The findings from the present study indicate that SHs are motivated and willing to jump obstacles more often than are LHs under similar conditions. However, the apparent reluctance of the horses overall to continue jumping as the obstacle height increases suggests that, in general, many horses could easily encounter excessive demands (overfacing) in sport. This issue should be carefully monitored in terms of equine training, competition, and welfare.     

Assessing ridden horse behavior: Professional judgment and physiological measures

The assessment of ridden horse behavior by 12 equestrian professionals (riding instructors n = 4, riders n = 4, veterinarians n = 4) was compared with observed behavior and physiological measures (salivary cortisol and eye temperature). Horses (n = 10) were ridden at walk, trot, and canter in a predefined test of approximately 2-3 minutes. Video footage of the ridden test (RT) was analyzed using Observer XT 10 and duration of behavioral states/events recorded. Saliva was collected in the stable, after the warm-up (WU) and at 0, 5, 15, 30, and 60 minutes after the RT. The saliva was analyzed for cortisol (enzyme-linked immunosorbent assay) and the difference between minimum and maximum concentration (ng/mL) and associated sample times recorded. Eye temperature was measured using an infrared thermal camera (MobIR M8), static images (stable, after WU, after RT), and video footage (WU and RT) with maximum eye temperatures derived from set intervals. Mean maximum eye temperatures during ridden work were calculated. Video footage of the RT was observed by the 12 equestrian professionals who each scored the horses on 7 performance parameters derived from the Fédération Equestre Internationale rules for dressage events and the training scale of the German National Equestrian Federation (relaxation, energy, compliance, suppleness, confidence, motivation, and happiness). These scores were compared with behavioral and physiological measures and correlations investigated (Spearman's rank order correlation). Higher percentage durations of high head carriage (ranging from 0 to 50.75% of RT) and the nose carried at an angle in front of the vertical (0%-74.29% of RT) correlated with overall less favorable assessment by the equestrian professionals (P < 0.05) and only the instructors associated neutral head carriage (32.76%-91.92% of RT) and vertical nasal angle (0.97%-68.90% of RT) as a positive sign (P = 0.03 and P = 0.04, respectively). Increases in salivary cortisol positively correlated with the duration of low head carriage (P < 0.05), suggesting that this way of going increased the demands placed on the horse. Increased eye temperature positively correlated with duration of nose carried behind the vertical when ridden (P = 0.02) and negatively correlated with duration of nose carried in front of the vertical (P = 0.01). Some discrepancy between physiological evidence and professional assessment of ridden horse behavior was evident as were differences between groups of professionals. Further evaluation of the association between behavioral signs and physiological measures is now required to ensure that the assessment of ridden horse performance is based on valid and consistent measures.     

Use of Infrared Thermography to Detect Intrasynovial Injections in Horses

Athletic horses often experience painful conditions of the musculoskeletal system, but their ability to compete can be prolonged using certain anesthetic agents. The present study investigated the ability of thermography to detect fetlock and middle carpal intrasynovial injections of bupivacaine hydrochloride in five mares. Saline injections were performed in the contralateral limbs. Thermographic evaluation was conducted at the dorsal and palmar aspects before (basal) and 15, 30, 60, 90, 120, and 1440 minutes after injection. The intrasynovial treatments resulted in increased limb temperature, with fetlock temperatures higher on the dorsal aspect at 15, 30, and 60 minutes and on the palmar aspect from 15 to 1440 minutes (P < .05) after the bupivacaine and saline injections. Increased carpal temperature was detected on the dorsal aspect at 60 and 90 minutes (P < .05). The present study demonstrates that thermography can be used to detect intrasynovial injections in horses.     

Comparison of the Head and Neck Positions in Ridden Horses Advertised in an Australian Horse Sales Magazine: 2005 Versus 2018

The impact of head and neck position (HNP) on horse welfare has received much attention in the scientific literature within the last two decades. Studies have identified physiological and behavioral signs of distress in horses ridden for prolonged time in an HNP with their noseline behind the vertical (BTV), which may compromise their welfare. The objective of this study was to compare potential differences of HNPs shown in horse sales photographs advertised in an Australian horse sales magazine (Horse Deals) from the years 2005 and 2018. In addition, factors potentially impacting HNPs, such as type of tack presented in (e.g., noseband type), riding discipline, and competition experience of the horse, were investigated. The sample population (n = 570) comprised horses ridden with headgear and bit in walk, trot, or canter/gallop, advertised in an Australian horse sales magazine. Issues from April 2005 and October/November 2018 were selected. Head and neck position was categorized as BTV, on the vertical (OV), slightly in front of the vertical (IFV), or extremely in front of the vertical (EIFV; any HNP >30° IFV). Data were analyzed using the chi-squared test and post hoc testing via a multiple regression approach through SPSS and test of proportions via the Z-score calculator for two independent population proportions. Analysis of combined data from years 2005 and 2018 showed 47.0% (n = 570) of the horse sample population were advertised with HNPs BTV. Behind-the-vertical HNP was observed as the predominant HNP (57.8%; n = 268) in the warmblood/eventers/show/performance (WESP) category (P < .0005). In 2005, 53.4% (n = 303) of the sample population were ridden BTV compared with 39.7% (n = 267) in 2018 (P < .001), 12.9% (n = 303) were OV in 2005 compared with 15.0% (n = 267) in 2018 (P > .05), and 10.9% (n = 303) were IFV in 2005 compared with 27.3% (n = 267) in 2018 (P < .0004). These results suggest a positive development with fewer vendors/riders selecting images where the horse’s nose was BTV. However, this may be explained by the larger proportion of horses advertised in the WESP category in 2005 (63.0%; n = 303) versus 2018 (28.5%; n = 267), and the WESP category predominantly comprised of dressage, jumper, and eventing horses. In addition, the reduction of HNPs BTV from 53.4% (n = 303) in 2005 to 39.7% (n = 267) in 2018 could be attributed to the observation that in 2018, a larger proportion of horses were listed in categories that do not require the horses to be worked with a flexed HNP referred to as “on-the-bit” (e.g., western, endurance, Australian sStock horses). The HNP BTV remains preferential by a substantial proportion of the horse-owning public when advertising horses for sale, particularly in disciplines where the horse is worked in a flexed HNP or “on-the-bit.”     

Management,health, and abnormal behaviors of horses: A survey in small equestrian centers in Brazil

Care conditions of horses housed in small equestrian establishments and the occurrence of health and behavioral problems were assessed in 197 animals. Based on questionnaires and direct observations of the animals, it was noted that 8% of all animals were fed exclusively on pasture, whereas 92% received commercial concentrate or grain with limited or no grass. Sixty percent of the horses spent 20-24 hours/day in the stalls, 30% spent 12 hours/day, and 10% were kept outdoors. Eighty five percent exercised regularly, whereas 15% did not exercise at all. Wounds (18%), colic (6%), and strangles (3%) were the most cited diseases in the interviews. Fifty-six percent of the horses showed behavioral problems; the frequency and type of abnormal behavior varied according to horse use (P < 0.001). The management of the horses presented numerous concerns regarding feeding and housing, probably leading to increased behavioral problems. The results presented here would be a useful tool for the education of owners and caretakers.     

Lipid Utilization Pathways Induced by Early Training in Standardbred Trotters and Thoroughbreds

Controversial results on lipid utilization as an energy source during training in horses are found in the literature. The objective of this study was to assess blood lipid profile during different training programs in horses. Seventeen Standardbred horses (400 ± 50 kg) and 17 Thoroughbred horses (380 ± 15 kg) followed different training programs. Blood lipid profile, including triglycerides (TGs), total cholesterol, high-density lipoprotein (HDL), and low-density lipoprotein (LDL), was analyzed, and very-low-density lipoprotein (VLDL) concentration was calculated. Data were analyzed using Student t test, and linear regressions were done. Cholesterol and LDL decreased during training programs in Standardbred trotters (P = .0001 and P = .0053, respectively), and VLDL was found to be close to the significance level (P = .053). Blood lipid profile, including TGs (P = .0014), cholesterol (P = .0057), HDL (P = .0128), LDL (P = .0091), and VLDL (P = .0014), varied throughout the training program in Thoroughbred horses. Negative slope of blood lipids and positive slope of TG linear regression in Standardbred trotters were significant for all parameters (P ≤ .05), whereas cholesterol and LDL regression showed poor P and r² values and HDL P value was slightly above the significance level (P = .069) in Thoroughbred horses. TGs and VLDL showed a positive linear trend in Thoroughbred horses (P = .002). Exercise and different training programs lead to significant variations of lipid profile and lipid utilization in horses. Lipid utilization as an energy source improved with training in Standardbred trotters, whereas this was not the case in Thoroughbred horses. Further studies on the effect of training programs using different conditions and horse breeds would be necessary to understand lipid utilization as an energy source in athletic horses.     

The Influence of Stable Management and Feeding Practices on the Abnormal Behaviors Among Stabled Horses in Malaysia

The present study aimed to provide preliminary data on the prevalence of oral stereotypic, locomotory stereotypic, and redirected behaviors as well as their associations with stable management and feeding practices. In this cross-sectional study, a total of 207 working horses used for leisure riding, equestrian sport, polo, endurance, and patrolling were selected from seven equine facilities. Data on the stable management and feeding practices were obtained through the stable records, interviews, and on-site monitoring visits, whereas the prevalence of abnormal behaviors in the studied population was determined using the instantaneous scan sampling method. Most horses in the present study worked for more than 8 hours per week (n = 93). In addition, more horses were fed three times per day (n = 65) with different amounts of hay, concentrate, and chaff. Among the study population, oral stereotypic behaviors had the highest prevalence (n = 281; 54%), followed by redirected behavior (n = 181; 34%), and locomotory stereotypic behaviors had the lowest prevalence (n = 63; 12%). The oral stereotypic behavior was found to be significantly influenced (P < .05) by the working hours, amount of hay, and amount of concentrate. Both locomotory stereotypic and redirected behaviors were found to be influenced (P < .05) by the number of feedings per day and the amount of hay. In summary, the present study has proven that the stable management and feeding practices could influence the prevalence of different abnormal behaviors in the majority of working horses, with oral stereotypy being the most common abnormal behavior in this country.     

Stress Response of Three-year-old Horse Mares to Changes in Husbandry System During Initial Equestrian Training

For initial training, horses are often transferred from group housing to individual boxes, which is a potential stressor. In this study, salivary cortisol concentrations, locomotion activity, and heart rate (HR) were analyzed and the HR variability (HRV) variables standard deviation of beat-to-beat interval (SDRR) and root mean square of successive RR differences (RMSSD) were calculated in 3-year-old mares (n = 8). Mares were transferred abruptly from a group stable with access to a paddock to individual boxes without a paddock and were studied from 4 days before to 5 days after changing the stable. Mares underwent routine equestrian training for young horses. On the days before mares were moved to individual boxes, cortisol concentrations showed a diurnal rhythm with values approximately 0.6 ng/ml in the morning and a decrease throughout the day. When horses were moved to individual boxes, cortisol concentrations increased to 1.8 ± 0.2 ng/ml within 30 minutes and did not return to baseline values within 6 hours (0.7 ± 0.1 ng/ml, P < .05 over time). On the following days, a diurnal rhythm was re-established but at a higher level than before the change of stable. Locomotion activity was higher when mares had access to a paddock than when kept in individual boxes. Heart rate increased for approximately 60 minutes when mares were separated from their group. In conclusion, separating young horses from their group and individual stabling are perceived as stressful.     

Oxidative Stress Associated With Spasmodic,Flatulent, and Impaction Colic in Draft Horses

The aim of the present study was to evaluate the oxidative stress level and antioxidant trace elements status associated with spasmodic, flatulent, and impaction colic in draft horses. For this purpose, venous blood samples were obtained from 20 randomly selected clinically healthy draft horses (control group) and 60 draft horses with different types of colic (spasmodic colic, n = 20; flatulent colic, n = 20; and impaction colic, n = 20). In horses with flatulent and impaction colic, there was a significant (P < .05) decrease in the total antioxidant capacity and activity of reduced glutathione (GSH) and catalase (CAT) as well as level of selenium, copper, zinc, and iron. However, there was a significant (P < .05) increase in the activity of superoxide dismutase (SOD) and in the level of malondialdehyde (MDA), interleukin-6 (IL-6), and manganese. Meanwhile, glutathione reductase (GR) was significantly (P < .05) increased in flatulent colic and significantly (P < .05) decreased in impaction colic. The oxidative stress index (OSI) was significantly (P < .05) increased in horses with flatulent and impaction colic. In horses with flatulent colic, there was a negative correlation between CAT and SOD (r = −0.446), MDA and zinc (r = −0.450), and IL-6 and zinc (r = −0.470). However, those with impaction colic, a negative correlation was recorded between CAT and MDA (r = −0.602), copper and GSH (r = −0.474), iron and GR (r = −0.511), and OSI and GR (r = −0.662). The results of the present study indicate that oxidative stress, with alteration of antioxidant trace element levels, is a feature of flatulent and impaction colic in draft horses.     

Nasal bacterial microbiota during an outbreak of equine herpesvirus 1 at a farm in southern Ontario

The objective of this study was to investigate the nasal bacterial microbiota of healthy horses and horses infected with equine herpesvirus 1 (EHV-1). The nasal bacterial microbiota of 10 horses infected with EHV-1 and 11 control horses from a farm experiencing an outbreak was characterized using the Illumina MiSeq platform targeting the V4 region of the 16S ribosomal RNA gene. The nasal bacterial microbiota of healthy horses and EHV-1 horses was significantly different in community membership and structure. Horses shedding EHV-1 had lower bacterial richness (P = 0.002), evenness (P = 0.008), and diversity (P = 0.026) than healthy horses. Healthy horses had a higher relative abundance of Firmicutes and Bacteroidetes, but lower Proteobacteria than horses with EHV-1 (P < 0.05). This study provides the basis for generating hypotheses and investigations on the role of bacterial-viral interactions in the health and diseases of adult horses.     

Preliminary results suggest an influence of psychological and physiological stress in humans on horse heart rate and behavior

People may involuntarily emit fear or distress signals when around horses, and interpreting how horses respond to these messages is important, particularly for human safety around horses. No studies have been done to determine if horses can differentiate between humans who are physiologically stressed (e.g., after exercising) as opposed to psychologically stressed (e.g., afraid). Horses (N = 10) loose in a round pen were randomly subjected to the presence of a stationary blindfolded human in each of 4 treatments: (1) calm human comfortable around horses (CALM), (2) physically stressed human (PHYS; exercised to 70% maximum heart rate [HR]), (3) psychologically stressed human (PSYCH; afraid of horses), or (4) no human (CONTROL). Both humans and horses were equipped with an HR monitor. Physiological and behavioral observations (gait, head position relative to the withers, distance and orientation toward human) were recorded and analyzed using a mixed model with horse and human as random effects. Increasing human fearfulness was associated with a decrease in horse HR (P = 0.0156). Horses moved at a slower gait in PSYCH (P < 0.0001), and horse head position was lower during PHYS and PSYCH compared with CALM or CONTROL (P < 0.0001). Human HR was highest in PHYS (P < 0.0001) and decreased over time in all treatments. Human HR increased when the horse was facing away (P = 0.0395). Overall, horses appear less stressed in the presence of a stationary fearful or physically stressed human than a calm person. Thus, horses in the presence of fearful humans, particularly where participants may not be comfortable around horses, should not pose any additional risk provided normal safety precautions are used.     

Psyllium Lowers Blood Glucose and Insulin Concentrations in Horses

A total of 16 mature healthy horses (body weight: 515.3 ± 37 kg [mean ± SD]) were used in two experiments to determine (1) how psyllium affects postprandial blood glucose and insulin concentrations, and (2) how psyllium affects blood glucose and insulin concentrations after an intravenous glucose infusion. Psyllium was fed along with a grain and hay ration (given twice daily) for 60 days. Treatments were as follows: (1) 90 g psyllium/d, (2) 180 g psyllium/d, (3) 270 g psyllium/d, (4) an isocaloric, no supplemental psyllium control. Pre- and postprandial blood samples were collected on day 60 for experiment 1, and blood samples collected before and after intravenous glucose infusion were analyzed for experiment 2. In experiment 1, horses fed with psyllium for 60 days had lower (P < .01) mean postprandial blood glucose concentrations and there was a treatment × time effect for glucose (P < .001) and insulin (P = .03). Plasma glucose was lower at 90 minutes (P = .05) and 120 minutes (P < .001) after a meal in horses fed with psyllium as compared with an isocaloric control. Postprandial serum insulin concentrations were lower at 90 minutes (P = .002) and 300 minutes (P < .001) after a meal in horses fed with psyllium as compared with an isocaloric control. In experiment 2, peak glucose concentrations were lower (P = .01) in horses fed with psyllium for the previous 60 days compared with untreated horses and there was a treatment by time effect for glucose (P = .05). Peak blood glucose response was lower (P = .01) in horses fed with psyllium as compared with an isocaloric control after intravenous glucose infusion, whereas peak insulin concentrations and average insulin concentrations remained similar. Psyllium fed daily for 60 days alters postprandial glycemia and insulinemia in normal, nonobese, and unexercised horses.     

Effect of Age and Performance on Physical,Hematological, and Biochemical Parameters in Endurance Horses

Endurance horses are subjected to heightened stress even after several conditioning protocols. Hence, the goal of this study was to examine the effect of age and performance on the hematology, biochemistry, and physical parameters after an endurance race. Eighteen horses aged 6-15 years were grouped into 80-km race category. All the horses were physically examined, and blood samples were collected postrace. After physical examination, the poor (n = 9) and good (n = 9) performance horses were identified. Potassium concentration was significantly higher (P < .05) in the good performance horses; chloride concentration was significantly higher (P < .05) in the poor performance horses. The mean blood glucose concentration of the poor performance horses in all the age-groups was significantly higher (P < .05). The mean blood lactate concentration was significantly lower (P < .05) in the poor performance horses. There was significant effect of performance on heart rate (P < .031), capillary refill time (P < .013), and gut motility (P < .05). Univariate Fisher exact test results were significantly higher for skin recoil (P < .03), mucous membrane (P < .03), and gait (P < .04) in the performance categories. In conclusion, the influence of age was seen in the poor performance category in relation to lactate, but age did not influence other physical, hematological, and biochemical parameters of the endurance horses. Thus, further studies are required to determine whether physical, hematological, and biochemical parameters during training could be used to estimate performance in endurance horses based on age.     

Relationship Between Magnitude and Direction of Asymmetries in Facial and Limb Traits in Horses and Ponies

Directionality of limb and facial asymmetries in nonelite equine populations has been previously reported with results indicating strong similarities to those reported in racehorses. This investigation aimed to consider the relationship between the magnitude of the asymmetries presented within the general equine population, and their previously reported directionality. Direct measurements of 15 bilateral traits (four facial and 11 limb) were captured from a mixed population of 100 horses and ponies. The pooled (whole) population was considered further as horse (withers height >148 cm) and pony (withers height ≤148 cm) groupings. Each of the three groups was further subdivided for each trait, into individuals presenting with larger left or larger right sides. Asymmetries were compared as mean asymmetries and as percentages of the trait size at each grouping level. Asymmetry magnitudes were largely reflective of the directional asymmetries previously recorded. Both the horse and pony groups presented with significantly longer right side third metacarpal (P ≤ .001) and third metatarsal (P ≤ .05 and P ≤ .001) bones, whereas in the horse group, the left fore proximal phalanx was both longer and wider than the right (P ≤ .001 and P ≤ .05). This pattern is reflective of the biomechanical preference for left lead anticlockwise canter, previously only observed in racehorses. The proximal phalanx of the forelimb potentially compensates for the higher loading forces associated with the lead forelimb. When scaled as percentages of trait size, the asymmetry magnitudes largely reflected those reported in humans, suggesting similar measurement criteria could be applied when considering stock selection and controlling for injury predisposition in horses.