Behavior Observation During Conformation Evaluation at a Field Test for Danish Warmblood Horses and Associations with Rideability and Performance Traits

Reactivity in horses, defined as a state of high arousal, has an impact on the daily handling and welfare of horses and can have an impact on the risk of causing human injuries. Behavior tests have been developed to assess reactivity, but these tests are difficult to apply in practice. The objectives of this study were to investigate how reactivity measured in a practical situation associates with rideability and performance and to explore the association between the measured reactivity and reactivity assessed by the horse's owner. A total of 234 Danish Warmblood females, 3 years of age, were videotaped and scored for reactivity during the evaluation of their conformation, and a questionnaire was completed by the owners. Associations between reactivity and performance traits were investigated by computing partial correlations (Pearson, r_p). A low negative correlation was found between rideability and reactivity (r_p = −0.16, P = .02) and between reactivity and free jumping (r_p = −0.14, P = .03). These results suggest that highly reactive horses received lower grades in rideability and free jumping. However, no association with performance traits in dressage was found. Likewise, low but significant association was found between reactivity and ratings from owners (r_p = 0.15, P = .02), indicating that horses considered to be nervous by their owners also were scored as reactive. In conclusion, it appears possible to measure reactivity in a practical situation. This study also concluded low negative associations between reactivity and the two performance traits rideability and free jumping.     

Some Remarks on Repeatability and Heritability of the Bascule Technique in Jumping Horses

The genetic characteristics of jumping enable a correct selection program. Linear parameters of the jump were measured by video image analysis with and without the rider. Repeatability and heritability were calculated based on the statistical model using DMUAI, including effects of the year, month of training, obstacle height, horse conformation, and rider (if necessary). The highest repeatabilities were noted for the position of head and reached 0.45–0.56 for head position in comparison to withers and 0.48–0.55 in comparison to croup. Results varied between parameters with and without riders. Repeatability under rider was slightly higher, the opposite trend was observed in heritability. It seems that the relation of head to the rest of the body has higher heritability than the height of the head above the obstacle itself.     

The Effect of Training on the Jumping Parameters of Inexperienced Warmblood Horses in Free Jumping

Seven Warmblood horses without sport experience were trained and filmed four times during free jumping, with a 1-month interval between each investigation. Jumping parameters were measured on selected frames by means of video image analysis. Linear and angular parameters describing takeoff, landing, and lifting of limbs above the obstacle were studied. Statistical analysis revealed that the following parameters were affected by training: hind limbs distances at takeoff and landing, lifting of the limbs above the obstacle, and the angle of bascule.     

Proposal and Validation of a Scale of Composite Measure Reactivity Score to Characterize the Reactivity in Horses During Handling

This study aimed to identify the parameters related to the expression of the reactivity in horses during handling and based on that proposed and validated a scale of composite measure reactivity score to characterize horse's reactivity. To this end, the first stage (S1) proposed the scale and the second (S2) validated it. In S1, 364 Lusitano horses were evaluated, 188 were adult breeding mares (4–12 years old), and 176 were foals (males/females, aged from 2 months to 2 years). During hooves trimming, vermifuge application, palpation scores were assigned to behaviors of movement, ears and eyes position, breathing, vocalization, and urination. A response parameter called reactivity was attributed to each animal, ranging from score 1 (nonreactive/calm) to score 4 (very reactive/aggressive). The verification of the possible parameters (age, behavior), which explains the response parameter (reactivity), was taken using ordinal proportional odds model. Movement, breathing, ears and eyes position, vocalization, and age appear to explain the reactivity of horses during handling (P < .01). Therefore, based on these parameters, it was possible to propose two scales of composite measure reactivity score: one to characterize the mares and another the foals. On S2, the proposed scale was validated by the simultaneous application of Forced Human Approach Test, another commonly used test to evaluate the reactivity in horses, with a correlation of 0.97 (P < .05). The assessment of the reactivity of horses during handling by a composite measure reactivity score scale is valid, and easy to apply, without disrupting daily routine and override the impact of individual differences.     

Effect of Ergopeptines Associated with Tall Fescue Ingestion on Recovery of Horses Subjected to Standardized Exercise Tests

Ten horses were paired by body weight, age, and skill level, and one of each pair was assigned to one of two groups. Horses were fed alfalfa hay and a mixture of commercial sweet feed and pellets. Horses in group A were fed fescue seed that contained both ergovaline and ergotamine (E+), whereas those in the other group were fed seed that was free from ergot alkaloids (E−). After the first 35 days, horses were switched to the opposite seed treatment. Seed was fed at 8.2% of the diet, resulting in 406 ppb of ergotamine plus ergovaline in the E+ diet. During weeks 3, 5, 7, and 10, horses were subjected to two separate standardized exercise tests (SETs). The aerobic test consisted of walking, trotting, and loping and was designed to maintain horse's heart rate (HR) to less than 150 beats per minute (bpm). The anaerobic test consisted of 40 turns in less than 4 minutes in response to the movements of a mechanical cow and was designed to increase the horse's HR to more than 150 bpm. There were no treatment effects on water consumption or sweat production. There were also no treatment effects on rectal temperature at rest or during recovery from the anaerobic SET. However, rectal temperatures were higher (P < .05) 1 and 30 minutes after the aerobic SET for horses consuming E+ seed. When horses were on the E+ treatment, HRs were lower (P < .05), both at rest and during the SET. HRs were also lower (P < .05) for the E+ treatment at 1 minute after the aerobic test and 5 and 10 minutes after the anaerobic test. Respiration rates were higher (P < .05) 30 minutes after the aerobic SET and 30 and 60 minutes after the anaerobic SET for the E+ treatment. Horses may have increased respiration rates to compensate for a reduction in the efficiency of evaporative cooling, which resulted from vasoconstriction of peripheral blood vessels.     

Comparison of Skin Prick Tests with In Vitro Allergy Tests in the Characterization of Horses with Recurrent Airway Obstruction

We intended to identify relevant immunoallergic factors and to compare skin prick tests (SPTs) and in vitro allergy tests in the characterization of horses with recurrent airway obstruction (RAO), so as to ascertain that SPTs perform better. Forty Lusitano/cross-Lusitano horses (30 RAO cases and 10 healthy control horses)—a very valuable autochthonous breed—were studied. Clinical history, thoracic radiography, respiratory tract endoscopy, and bronchoalveolar lavage were used for diagnosis. Serum samples of all 40 horses and undiluted bronchoalveolar lavage fluid samples of 21 RAO horses and 6 control horses were submitted for evaluation by an allergen-specific immunoglobulin E (IgE) enzyme-linked immunosorbent assay. SPTs were performed on the 40 horses. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated for all diagnostic methods. Agreement between diagnostic methods was assessed by kappa statistic (Κ). Chi-square test with Yates correction showed SPT results from the RAO and control groups to be statistically different (P < .05). SPTs showed higher sensitivity, specificity, positive predictive value, and negative predictive value than both enzyme-linked immunosorbent assay tests. In human medicine, SPTs are considered to be the gold standard of allergy tests. Neither serum IgE nor bronchoalveolar lavage fluid IgE reliably detected allergen hypersensitivity, compared with SPT. SPTs performed significantly better overall than both in vitro tests. Low sensitivity of the in vitro assays indicates the need for continued study to elucidate a more sensitive specific IgE test.     

Nutrition and Exercise in the Management of Horses and Ponies at High Risk for Laminitis

Obesity, insulin resistance (IR) and hyperinsulinemia are risk factors for laminitis in horses and ponies. Alterations in management, especially diet and physical activity, can be helpful in the management of these risk factors. Caloric restriction, ideally combined with increased physical activity, to promote weight loss and improve insulin sensitivity is indicated for the management of obese animals. Strict control of dietary NSC through the elimination of grains and sweet feeds and by restricted access to NSC-rich pastures is recommended for insulin-resistant animals, regardless of whether they are obese or not. Medical treatment with levothyroxine or metformin may be indicated in obese or insulin-resistant animals that do not respond to conservative management.     

A Technique for Examining the External Ear Canal in Standing Sedated Horses

In this study ultrasonography, local anesthesia, and endoscopy were performed in both ears of 23 horses. The aim was to find a reliable technique for examination of the external ear canal in standing sedated horses and to create a grading of debris and the occurrence of abnormalities in clinically healthy horses. Local blockage of the great and internal auricular nerves was performed after caudal palpation at the base of the ear and ultrasonographic assessment of the styloid process of the auricle as a reference point for the needle placement. The otoscopic examination was accomplished with two flexible video endoscopes with 2- and 7-mm tip diameters. The depth of the styloid process varied ultrasonographically from 2.08 to 2.73 cm on the left side and from 2.04 to 2.76 cm on the right side. Local anesthesia was successful in all sedated horses, without any long-term complications. The grading of endoscopic appearance of the skin, epithelium, and ceruminous and cell debris in the cartilaginous and osseous part including tympanic membrane of the equine external ear canal ranged from I to III. Abnormalities like osteoma, granuloma, hemorrhagic or erythematous areas, and narrowing of the osseous part of the external ear canal due to stenosis (exostosis) were seen in 10 of 23 horses. The tympanic membrane was visualized in 20 of 23 horses. Local blockage of the great and internal auricular nerves was found to be a reliable method for equine ear anesthesia.     

Effects of Steel and Aluminum Shoes on Forelimb Kinematics in Stock-Type Horses as Measured at the Trot

To meet the needs of sport horses, horseshoes of various styles and materials have been implemented to enhance performance. Steel shoes are commonly used for their affordability and longevity; however, the use of aluminum horseshoes is being adopted to satisfy the various requirements of certain equestrian activities. Owing to the importance of the allure of movement in many aspects of competitive riding, the lightweight nature of aluminum horseshoes has been recognized to accentuate foreleg action. By performing a repeated-measures crossover study on nine healthy stock-type horses, the effects of these two horseshoe types on forelimb action were analyzed at the trot using two-dimensional kinematics. Horses were trotted in hand for three repetitions over a distance of 50.1 meters on days 4, 18, 32, and 46 postshoeing for two 6-week shoeing cycles. Video footage was collected and analyzed using gait analysis software (EquineTec) for each repetition. The measured stride length, fetlock extension, elbow and knee range of motion, and minimum and maximum elbow angle remained constant between treatments. However, there was a significant treatment effect on minimum carpal angle and maximum hoof height, with aluminum shoes having a larger minimum carpal angle than those in steel shoes (P < .05) and a lower maximum hoof height (P < .05). An overall 3-degree difference in minimum carpal angle and approximate 2.5-cm difference in maximum hoof height was observed between treatments. This finding is of particular importance to performance horse disciplines for which a lesser degree of knee action is desirable.     

Temporary Turnout for Free Exercise in Groups: Effects on the Behavior of Competition Horses Housed in Single Stalls

In Germany, most competition horses are housed in single stalls and free exercise is not permitted in many cases. The reason for not allowing free exercise is mostly the risk of injury. Additionally, opinions exist that the horses’ demand for exercise is fulfilled by training and that the horses’ willingness to perform is negatively influenced by free exercise. In the present study, three turnout practices were investigated with regard to their effect on the behavior of four horses: daily training without free exercise (no turnout), 2-hour turnout (for free exercise) before training, and 2-hour turnout after training. The aim of this study was to determine any differences in the horses’ behavior between the three treatments. The horses’ behavior in the stable was observed through video recordings. The behavior during turnout was observed directly and during training was evaluated by the riders with the aid of a questionnaire. Additionally, the distance covered during turnout was measured by Global Positioning System devices. The behavior within the stall was more restless in the treatment without turnout—which became apparent in significantly more frequent changes between behaviors as compared with the treatments with turnout. The results of Global Positioning System measurement during turnout showed a significantly shorter distance covered when horses were trained before they were turned out compared with turnout before training. If the horses were turned out after training, they also showed less trotting and cantering and more dozing. The horses’ willingness to perform was not significantly different between the three treatments.     

Effects of Different Bedding Materials on the Behavior of Horses Housed in Single Stalls

The effects of three different bedding materials (straw, wood shavings, and straw pellets) on the behavior of six warmblood horses (four mares, two of them with foals) housed in single stalls were analyzed. Each material was used for 2 weeks in three consecutive runs. The behavior of the horses was videotaped and analyzed on the first and last 3 days for each bedding alternative in the last of the three runs. The time budgets for the behaviors including standing, eating, lying, occupation with bedding material, and other were generated. Compared with straw pellets and wood shavings, the application of straw bedding led to a significantly higher frequency and longer duration of occupation with bedding material and in turn, shorter fractions of standing and other behaviors. The total duration of lying was significantly longer on straw than on straw pellets. Straw pellets resulted in the least mean recumbency duration per occurrence of this behavior. Because occupation is one of the important functions that bedding material is supposed to fulfill, we concluded that in regard to horse behavior, straw bedding was the best among the three materials analyzed. Further investigations with a more homogeneous group of probands are necessary to verify the observed behavioral reactions.     

Assessing the Association Between Hoof Thermography and Hoof Doppler Ultrasonography for the Diagnosis of Lameness in Horses

The objectives of this study were to assess the correlation between hoof surface temperature and ultrasonographic measurements of digital blood vessels in horses and to evaluate the measurements' potential as predictors for clinical lameness. Twelve 3-year-old American Quarter Horses, 6 geldings and 6 mares, with average initial body weight of 459 ± 31 kg were used. On days 0, 30, 60, and 90 of the study, horses were weighed and subjected to clinical lameness examinations. Doppler ultrasonography was used to measure diameter of the medial palmar artery in the distal left forelimb and velocity of blood flow through that artery, starting at 60 minutes after morning feeding and repeated at 30-minute intervals. Temperature measurements on the hoof were collected at 15-minute intervals beginning 75 minutes after feeding, using a digital thermographic camera. A series of bivariate linear mixed models were fitted to estimate the correlation between Doppler and temperature measurements. The within-horse and between-horse correlations between hoof surface temperature and velocity of blood flow in the distal limb through the medial palmar artery was estimated at 0.40 (P > .50) and 0.99 (P < .001), respectively. These results indicate that at the horse level, the correlation between hoof temperature and velocity of blood flow in the distal limb was very high but that the within-horse correlation was not significantly different from 0. Velocity of blood flow at 60 minutes after feeding improved model fit to the lameness data, so it was included as a model predictor for lameness.     

Severe Intermittent Hind Limb Lameness Caused by a Synovial Swelling on the Dorsolateral Aspect of the Tarsus in a Dutch Warmblood Mare

Soft tissue swelling and synovial distension associated with the tarsus is very common in horses and may be associated with pain and lameness. In this case, a fluid swelling of synovial origin that initially appeared to be completely separate from any other synovial structure was present in a mare with severe intermittent hind limb lameness. Nuclear scintigraphy, diagnostic analgesia, contrast radiography, and ultrasonography were used to confirm the synovial swelling as the source of lameness. Surgical en-bloc resection of the synovial swelling has been curative. It is hypothesized that an acute trauma caused herniation of the tarsocrural joint synovial membrane. The fistula then sealed but became patent during specific phases of movement, resulting in a sudden influx of synovial fluid and a buildup of pressure. Ultrasonographic examination, contrast radiography, and distension of the tarsocrural joint at surgery all failed to identify this fistula. The associated severe pain and lameness could have been the result of physical distension of the fluid swelling or pressure applied to the surrounding nerves.     

Effects of Density and Water Availability on the Behavior, Physiology, and Weight Loss of Slaughter Horses during Transport

The aim of this study was to determine the effects of density and provision of water on aggressive behavior, stress, and weight loss in slaughter horses during transport. A 16.2-m, single deck semi-trailer was divided into three compartments to create high, medium, and low density (397 ± 6.5 kg/m², 348 ± 5.2 kg/m², and 221 ± 7.6 kg/m² per compartment) groups of unrestrained horses. Six shipments containing 23 to 30 horses per shipment were transported in June and July of 2004 for 18 to 20 hours. While the truck was stopped for 1 hour after 8 hours of transport and then again just before unloading, horses in each of two compartments received water for 1 hour from six water bowls (three bowls mounted on each side of a compartment). The third, non-watered compartment served as a control. Aggressive behavior of the horses was recorded using 12 video cameras installed in the trailer. All occurrences of aggressive behavior were counted from 15-minute segments of video during 2-hour intervals for each horse that was visible in each density group. Neither density nor water significantly affected (P > 0.21) aggressive behavior, cortisol, plasma chemistry profile, dehydration, or weight loss. Aggression did not differ (P = 0.49) between the first and second halves of the shipments, indicating that fatigue had not advanced to the stage where aggression was suppressed. Individual horses, rather than density were the major cause of aggressive behavior. However, two horses went down in the high density treatment, indicating that factors in high density could lead to increased morbidity or death.     

Preliminary Study on Age- and Sex-Dependent Alterations in the Composition of Skeletal Muscle Fibers of Brasileiro de Hipismo Horses

The aim of this work was to characterize the distribution of myofibers in the gluteus medius muscle of inactive horses of the Brasileiro de Hipismo (BH) breed at different ages by means of histochemical analyses, according to sex and depth of the biopsy. A total of 78 inactive horses (9 castrated males, 35 stallions, and 34 females) of the BH breed, aged 1 to 4 years, were used. A percutaneous muscle biopsy was obtained with a 6.0-mm Bergström-type needle, which allowed the removal of muscle fragments at depths of 20 and 60 mm. Myofiber types were determined based on myofibrillar adenosine triphosphatase (mATPase) and nicotinamide dinucleotide tetrazolium reductase (NADH-TR) techniques. Morphometry of the fibers was determined based on cross-sectional area (CSA), mean frequency (F), and relative cross-sectional area (RCSA). The current study demonstrated that BH horses 3 and 4 years of age show a greater percentage of, and area occupied by, type IIA fibers and lower percentage of type IIX fibers in the gluteus medius muscle compared with horses 1 and 2 years of age. No difference was found between sexes in the frequency of and area occupied by the different fiber types at any of the depths and ages studied. In this study, females showed a greater CSA for all fibers in comparison with males, at 1 year of age. The results of the current study indicate that the gluteus medius muscle of inactive BH horses shows modifications in its structural and biochemical composition during the growth of the animals, leading to a better oxidative capacity.