Changes of Circulating Total and Free Iodothyronine in Horses After Competitive Show Jumping With Different Fence Height

The effect of exercise on circulating T₃, T_4, free (f) T₃, and fT₄ concentrations were studied before and after competitive show jumping in 24 trained jumper horses with an age range of 11–13 years and having the same level of show experience. All horses, randomly divided into three groups paired by gender, participated in three competition levels with the same circuit design over 10 fences, with five upright and five cross-pole fences .The three fence height groups were group I (n = 8), 1.10 m; group II (n = 8), 1.20 m; and group III (n = 8), 1.30 m. Repeated measures analysis of variance showed a statistically significant effect of competitive exercise on fT₃ changes in all groups, whereas the effect of competitive exercise on T₃ changes was exclusively seen in group III. Two-way repeated measures analysis of variance showed that the effect of fence height (P = .0002) and performance results were significant (P = .0486) only for T₃ changes. Performance also affected fT₃ changes (P = .0152). No significant correlation was found between total and free iodothyronines. These results suggest a dependence of T₃ and fT₃ changes on exercise-related variables and performance results and that the thyroid response is different with respect to the different exercise-related variables, such as the varying level of difficulty and performance results.     

Changes in Eye Temperature and Stress Assessment in Horses During Show Jumping Competitions

High stress levels in horses during sporting events can influence the animal’s performance in competitions as well as their welfare. This study investigated the use of infrared thermography (IRT) measurement as a rapid, noninvasive, and accurate method for stress assessment in horses during sport competitions and compared IRT with a commonly used physiological method used for stress assessment and salivary cortisol. IRT and salivary cortisol responses were measured 3 hours before the competition, immediately following the competition, and 3 hours after the competition, each day during the 3 days of a show jumping event. Salivary cortisol values ranged from −0.11 ± 4.51 ng/mL in 5-year-old animals to 1.10 ± 2.20 ng/mL in 4-year-old animals, whereas eye temperature values ranged from 35.84 ± 1.16°C in 6-year-old animals to 36.08 ± 1.11°C in 5-year-old animals. The results obtained suggested that IRT measurements constitute an effective method for detecting stress in horses subjected to the acute events of show jumping.     

The Feeding Practices and Estimated Workload in a Cohort of New Zealand Competition Horses

Data on the feeding, management, and training schedules during the week before the competition were collected via a face-to-face survey of riders competing in dressage, show jumping, or eventing at 1* and 3* level competitions. Data were collected using a pro forma recording sheet, and measurements of horse height, weight, and body condition score (BCS) were also obtained. A total of 158 of 582 riders (and horses) were surveyed, providing a response rate of 27%. The mean height, weight, and median BCS of the horses were 162 ± 1 cm, 533 ± 5 kg, and 6 (interquartile range [IQR], 5–7), respectively. The majority of horses were at pasture, most (68%, 107 of 158) 24 hr/d and fed supplementary feed either once (42%, 67 of 158) or twice daily (54%, 86 of 158). The supplementary feed was predominately a commercial premix feed (90%, 142 of 157) with additional alfalfa chaff or ensiled chopped alfalfa. The horses were offered approximately 60 MJ digestible energy (DE)/d (33–86 MJ DE/d) from supplementary feed. The horses worked for a median of 6 d/wk (IQR, 5–6 d/wk) with one rest day. The median total time trained during the week was 200 minutes (135–265 minutes), which consisted of eight separate training activities. There was no difference in time spent on different activities between the disciplines. Individual training activities were 30–40 minutes, and the median number of competitions per month was 2 (IQR, 2–3). Training workload and pattern of work were similar to reports from other countries, with the exception that many riders regularly added a “hack out” after training.     

Activity Behavior of Horses Housed in Different Open Barn Systems

Housing conditions do not frequently meet the natural needs of horses. German and Swiss studies have shown that merely 16% of horses are kept in group housing systems, but even these vary greatly with different effects on horses’ behavior. The objective of the survey was to determine whether horses show increased activity in barns with various options for movements and functional elements. Free movement stables allow horses to live within a herd, to decide whether to be outside or inside the herd, and to enable them fresh air supply. Data from 25 horses kept in three different open barns (O1–O3) were compared with that from two active barns with functional elements (active barn 1 and active barn 2), for example, automatic feeder, with five horses each. Activity-Lying-Temperature-pedometers fastened to a rear leg of each horse were used to measure activity. Animal data were recorded throughout a test period of 10 days per barn. The results showed a median of 46 to 68 mean daily activity impulses per 10 minutes for horses in stables O1 to O3. In stables active barn 1 to active barn 2, this measure was exceeded considerably with medians of 77 and 151. The activity impulses in the stable systems were significantly different at an error level of α = 0.05. These results support previous studies and show that activity of horses depends on their opportunities for moving. The sectioning of a stable, placement of functional elements, and feeding frequency have considerable effects on the activity level of the horse. It is useful to integrate different functional areas in a group housing system.     

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.”     

A Preliminary Study Examining the Digital Cushion in Horses

The digital cushion is important for the dissipation of impact as the foot contacts the ground. If there is inefficient energy dissipation, potential exists for changes to occur in the foot. Although ultrasonic imaging of the digital cushion has been reported, it is unknown if these measurements account for compositional changes that have been reported across age, breed, and between fore and hind feet. Therefore, the objective of this preliminary study was to establish baseline values in mature, stock type horses with adequate body condition score (BCS). To meet this objective, 24 mature, stock-type horses of similar age, height, and weight were used to establish baseline values for the digital cushion thickness in the live horse. All horses were sound at the time of data collection and had no known history of long-term lameness conditions. Digital cushion thickness of the left fore and left hind foot was determined using ultrasound through the transcuneal approach. Data were analyzed using the PROC MEANS and PROC GLM procedure of SAS with a least square means statement. Significance was set at P ≤ .05. Mean values (±standard error [SE]) for age, weight, height, and BCS were 10.7 ± 0.86 years, 476.2 ± 7.75 kg, 153.56 ± 0.90 cm, and 5.6 ± 0.12, respectively. Mean values (±SE) for the digital cushion of the left fore and left hind were 0.96 ± 0.03 and 1.02 ± 0.04 cm, respectively. When comparing the left fore and left hind, there was no significant difference observed. Overall, baseline values of digital cushion thickness for fore and hind feet were established, allowing for future studies to assess the different variables known to affect digital cushion composition.     

Equine Behavior Problems—Around Farriery: Foot Pain in 11 Horses

Although foot pain may clearly be the cause when a horse with foot pathology does not tolerate farriery, it may be overlooked or underappreciated as the cause of this behavioral problem when the pathology is mild and/or chronic. In this study, the records of 11 adult horses whose behavior for farriery initially warranted sedation for trimming and shoeing were reviewed. All 11 horses had a history of chronic lameness that was mild to moderate, but foot pain was the presenting complaint in only seven horses - all with chronic laminitis. The other four horses had abnormal foot conformation (long-toe, low-heel, or “club foot), but the lameness had not been attributed to the foot. All 11 horses showed improvement in gait with corrective trimming and shoeing. In each case, sedation for farriery could be discontinued after one to six visits, concurrent with the improvements in gait and foot pathology. On the basis of the survey results from 17 professional farriers, an ethogram of farriery-related undesirable horse behavior was developed.     

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.     

Peritoneal Lavage and Drainage with Fenestrated Balloon Catheters in Standing Horses: A Comparative Study

This experimental study compares the efficiency of two fenestrated balloon catheters in allowing drainage of fluid during abdominal lavage in 12 healthy horses. Catheter A (with multiple side holes) or catheter B (with a single side hole) was placed in the ventral abdominal wall. Lactated Ringer's solution was instilled through a catheter in each paralumbar fossa of the standing horse. Drainage was performed through two catheters A in group 1, one catheter A in group 2, and one catheter B in group 3. Drainage was not significantly faster when using two, as compared with one, catheters A (P = 1). Amount of fluids recovered was greater using catheter A compared with catheter B (P = .004). Abdominal fluid analysis on day 30 was significantly higher (P = .008) for total protein in individuals with catheter B compared with catheter A. Use of one multiple fenestrated balloon catheter may be justified in clinical cases that need abdominal lavage and drainage.     

Proximal Digital Annular Ligament Desmotomy in Horses: A Cadaveric Study

Proximal digital annular ligament (PDAL) desmitis occurs in horses for which PDAL desmotomy is the only reported treatment. The presented work aims to develop a technique for safely performing PDAL desmotomy in horses. Twenty hind limbs and 13 forelimbs, harvested from horses dead or euthanized for reasons unrelated to any structure in the pastern region, were used. All horses were free of disease at the level of their PDAL. Proximal digital annular ligament desmotomy was performed using a minimally invasive approach to the digital flexor tendon sheath between the palmar (plantar) annular ligament and the PDAL, using a medial or a lateral access. Limbs were immediately dissected after the procedure to assess the completeness of the PDAL desmotomy and any possible damage to surrounding structures. The PDAL was successfully transected in all limbs except one. Damage to the surrounding tissue included transection of the palmar digital nerve (n = 1), longitudinal tear of the superficial digital flexor tendon (n = 3), and transection of the ligament of the ergot (n = 21). A medial approach was found to be safer than a lateral approach. In conclusion, PDAL desmotomy can be performed in a safe, repeatable, and technically easy way. This is, to our knowledge, the first report of a standardized technique for performing a PDAL desmotomy in the horse.     

Biokinematics Under Competitive Racing Conditions in Young Standardbred Trotter Horses: A Preliminary Report

The aim of this study was to evaluate equine performance in competitive trotter horses under normal racing conditions. Data of stride length, stride frequency, and mean horse speed were obtained from 50 2-year-old Italian fillies that were winners during the racing and the sprint laps of competition. The enhancement of speed in the sprint lap was obtained by increasing both stride length and stride frequency. Stride frequencies for the racing and the sprint laps were (mean ± SD) 133.63 ± 3.93 and 138.97 ± 6.62 strides per minute, respectively, and stride lengths for the racing and the sprint laps were 7.17 ± 0.17 and 7.30 ± 0.11 m, respectively; mean speed was 48.18 ± 1.09. The usefulness of the kinematic assessments as well as its potential reference for future indicators of performance is discussed in this study.     

Glycated Hemoglobin is an Indicator of Blood Glucose Status in Horses: Preliminary Study

Glycated hemoglobin (HbG) concentration is a retrospective measure of mean blood glucose level and is not affected by recent stresses, food ingestion, or exercise. Although HbG has been determined in various wild and domestic animals such as kestrels, mankhor, mouflon, aoudad, deer, goat, sheep, dog, camel, ostrich, and horse, there is no information about diagnostic values of HbG as an indicator of blood glucose status in horses. The purposes of this study were to determine normal value of HbG in Iranian crossbred horses and to investigate its relation to fasting plasma glucose. Blood samples were collected from jugular veins of 193 clinically healthy adult crossbred horses (102 males and 91 females). After separation and washing of red blood cells, hemolysate was prepared and subjected to weak cation exchange chromatography for determination of HbG. Glucose was measured in fasting plasma samples. HbG percent (HbG%) in the studied horses was 3.21 ± 0.56 in males and 3.34 ± 0.72 in females. Fasting plasma glucoses were 81.3 ± 7.6 and 84.2 ± 14.5 mg/dL in males and females, respectively. HbG% and plasma glucose were highly correlated (r = 0.81, P < .01). We concluded that HbG% can be considered as a good indicator of blood glucose status in the horse. Two horses with abnormally higher HbG% were found in this study showing persistent high fasting plasma glucose. We concluded that HbG determination could be a more reliable indicator of basal blood glucose concentrations in horses.     

Competition Horses Housed in Single Stalls (I): Behavior and Activity Patterns during Free Exercise According to Its Configuration

Although welfare of animals has become more important, housing horses in systems that limit natural behavior patterns is still widespread. Single stalls are the predominant housing system in Germany, especially for competition horses. Free exercise on fields or paddocks helps to improve welfare for the animals, but allowing it is not taken for granted by many horse keepers. In the present study, three common management practices were investigated with regard to their effect on the behavior of six competition horses housed in single stalls: 2-hour turnout after training in groups of two horses (group turnout [GT]), solitary turnout (ST) after training for 2 hours, and no turnout (NT) in addition to training. The aim of the study was to determine the differences in the horses’ behavior during turnout, training, and in the stable caused by the treatments. This article focuses on the behavior and activity patterns during turnout. The horses’ behavior was observed directly by the scan sampling method (5-minute interval), and the distance covered during turnout was measured by global positioning system devices. During turnout, the horses spent most of the time eating. After 1 hour of being turned out, eating decreased, and occupation, locomotion, and social interaction increased. When turnout was allowed in groups (GT), the horses spent more time in social interactions and less time walking and trotting than in ST. Therefore, they also covered a greater distance in ST than in GT. The distance covered in ST also showed a greater deviation both within and between days compared with GT.     

Competition Horses Housed in Single Stalls (II): Effects of Free Exercise on the Behavior in the Stable, the Behavior during Training, and the Degree of Stress

Although housing horses in single stalls limits their natural behavior to a great extent, this housing system is widespread in Germany, especially for competition horses. To improve the welfare of this system, free exercise on pastures or paddocks is deemed suitable, but it is also feared because of injuries and decreased willingness or motivation to perform. In the present study, three treatments were investigated with regard to their effect on the behavior of six competition horses in the stable, behavior during training, and on their degree of stress: daily training without free exercise (no turnout [NT]), solitary turnout for 2 hours after training, and 2-hour turnout in groups of two after training (group turnout). The horses’ behavior in the stable was continuously analyzed through video recordings (2 pm to 6 am) on 3 days at the end of each treatment. The degree of stress was evaluated daily by heart rate variability at rest. The behavior during training was evaluated by a questionnaire answered by the riders, and the distance covered during training was measured by global positioning system. When NT was allowed, the horses showed less lying in the stable compared with the treatments with turnout. Heart rate variability measurements resulted in great individual differences, but generally, there was a higher degree of stress shown with the treatment NT according to the following parameters: standard deviation of inter-beat-intervals (SDNN), square root of the mean of the sum of the squares of differences between successive inter-beat-intervals (RMSSD), and ratio between low frequency and high frequency (LF/HF). The willingness to perform was evaluated as being slightly better in the treatments with turnout than in the treatment without turnout.     

A Controlled Safety Study of Elevated Dosages of Trimethoprim Plus Sulfadiazine in Mature Horses

A novel, proprietary, oral suspension of trimethoprim plus sulfadiazine (TMP/SDZ) had no serious adverse effects on clinical, laboratory, or pathologic parameters of mature horses when administered at up to five times the intended combined dosage of 24 mg/kg twice daily for 30 consecutive days. Loose feces was the most common observation that was likely related to TMP/SDZ treatment, and the incidence of loose feces was greater in groups treated with higher dosages of TMP/SDZ. However, all episodes were self-limiting, and no horses were treated for loose feces.     

Long Toes in the Hind Feet and Pain in the Gluteal Region: An Observational Study of 77 Horses

This study deals with the relationship between long toes in the hind feet and pain in the gluteal region in horses, and the remedial value of trimming/shoeing that moves the breakover point back at the toe. Seventy seven client-owned horses were studied, 67 shod riding horses retrospectively and 10 barefoot broodmares prospectively. The 10 mares were evaluated twice, and 24 of the 67 riding horses were re-evaluated at the next shoeing, for a total of 111 observations. Each horse underwent gluteal palpation and lateral radiographs of both hind feet. Toe length was quantified as breakover distance (BD), the horizontal distance between the tip of the third phalanx and the dorsalmost point at which the wall/shoe was in contact with the ground. The BD was then shortened with trimming +/− shoeing to a length of ≤15mm (shod horses) or ≤20 mm (barefoot horses). The 24 riding horses were re-evaluated 4-6 weeks later and the 10 broodmares 1 week after trimming.     

Exercising Blood Gas Analysis, Dynamic Upper Respiratory Tract Obstruction, and Postexercising Bronchoalveolar Lavage Cytology—A Comparative Study in Poor Performing Horses

Respiratory abnormalities are common causes of decreased performance in horses presumably because of impaired pulmonary gas exchange. The objectives of the present study were to describe respiratory abnormalities in poorly performing horses and to investigate the relationships between dynamic upper respiratory tract (URT) videoendoscopy, postexercising bronchoalveolar lavage (BAL) cytology, and exercising arterial blood gas analysis. Medical records of 93 horses with exercise intolerance, which presented for treadmill evaluation, were reviewed. Relationships between horse demographics, treadmill endoscopic findings, exercising blood gas values, and BAL cytology results were examined. A total of 25 (27%) horses had a URT obstruction and 91 (98%) horses had abnormal BAL cytology; 73 (78%) had evidence of inflammatory airway disease (IAD) and 83 (89%) had exercise-induced pulmonary hemorrhage (EIPH). In all, 39 (42%) horses had abnormal blood gas values. Dynamic URT obstruction was significantly associated with exercising hypoxemia (P = .036). There were no significant relationships between gas exchange and IAD or between EIPH. Out of 24 (26%) horses with combined URT obstruction and abnormal BAL, horses with URT obstruction and EIPH were more likely to be hypoxic during exercise (P = .037). It was concluded that horses with dynamic URT abnormalities are likely to have exercising hypoxemia. Although IAD and EIPH were commonly indentified in poor performers, they were not significantly associated with abnormal exercising blood gas analysis.     

Seminal Characteristics in Spanish Purebred Stallions: A Retrospective Study

In this work, we studied retrospectively the influence of several factors on semen quality of the Spanish Purebred (SPB) stallion. Among these factors, we considered stallion age, season, and interval between two consecutive collections. The semen was collected from 11 SPB stallions (634 ejaculates). Semen quality was evaluated based on volume, concentration, and motility of the ejaculates. Results showed that the semen collected in autumn and winter was more concentrated in comparison with that collected in spring and summer, when the volume of ejaculate was the highest. Those ejaculates collected from younger stallions were characterized by having the smallest volume and the highest sperm concentration. When incorporating an SPB stallion into a program of artificial insemination, it is important to take into account all of these factors to achieve the maximum reproductive potential of the animal.     

Equine Coronavirus-Associated Colitis in Horses: A Retrospective Study

Equine coronavirus (ECoV) is a known cause of fever, anorexia, and lethargy in adult horses. Although there are multiple reports of ECoV outbreaks, less is known about the clinical presentation of individual horses during a nonoutbreak situation. The purpose of this study was to describe the clinical presentation of horses diagnosed with ECoV infection that were not associated with an outbreak. Medical records of all horses admitted to Washington State University, Veterinary Teaching Hospital, during an 8-year period were reviewed (2010–2018). The five horses included in this study were older than 1 year of age, were diagnosed with colitis, tested positive for ECoV using real-time polymerase chain reaction, and were negative to other enteric pathogens. Interestingly, 4 of 5 horses had moderate to severe diarrhea, 3 had abnormal large colon ultrasonography, 2 had transient ventricular tachycardia and 2 had clinicopathologic evidence of liver dysfunction. ECoV should be included as a differential diagnosis for individual horses presenting with anorexia, fever, lethargy, and colitis. Early identification of ECoV cases is key to implement appropriate biosecurity measures to prevent the potential spread of this disease.     

A Field Study on the Effect of Some Anthelmintics on Cyathostomins of Horses in Sweden

The objective of the study was to investigate different aspects on the efficacy of three anthelmintics on cyathostomin nematodes of Swedish horses. A faecal egg count reduction (FECR) test was performed on 26 farms. Horses were treated orally with recommended doses of ivermectin, pyrantel pamoate or fenbendazole. Faecal samples were collected on the day of deworming and 7, 14 and 21 days later. No resistance was shown against ivermectin; the FECR was constantly >99%. The effect of pyrantel was assessed as equivocal in 6 farms 14 days after treatment; the mean FECR was 99%. As many as 72% of the fenbendazole-treated groups met the criteria for resistance; the mean FECR was 86%, ranging from 56% to 100%. A re-investigation of two farms where pyrantel resistance had been suspected clearly revealed unsatisfactory efficacy of pyrantel on one of these farms; the FECR varied from 72% to 89%. Twenty-six of the horses previously dosed with pyrantel or fenbendazole, and which still excreted ≥150 eggs per gram of faeces 14 days after treatment, were dewormed with ivermectin and fenbendazole or pyrantel in order to eliminate the remaining cyathostomins. A total of 13 cyathostomin species were identified from horses that initially received fenbendazole and seven species were identified from pyrantel-treated individuals. The egg reappearance period (ERP) following treatment with ivermectin and pyrantel was investigated on two farms. The shortest ERP after ivermectin treatment was 8 weeks and after pyrantel was 5 weeks. We conclude that no substantial reversion to benzimidazole susceptibility had taken place, although these drugs have scarcely been used (<5%) in horses for the last 10 years. Pyrantel-resistant populations of cyathostomins are present on Swedish horse farms, but the overall efficacy of pyrantel is still acceptable.