bluuebunny/crossref_metadata_2025 huggingface dataset:
The effects of maternal age and parity on placental and fetal development in the mare
Authors: WILSHER S. , ALLEN W. R.
Published: April 2007

Reasons for performing study: The normality of equine placentation is essential for fetal health and development. Substantial information exists on the gross morphological status of the placenta but few studies have addressed the problem of degenerative lesions that interfere with placental morphology and placental efficiency.

Hypothesis: Degenerative changes in the endometrium with increasing age and parity are reflected in the morphology and density of the placental microcotyledons.

Objective: To assess placental efficiency on the basis of foal birthweight as a function of total microscopic area of fetomaternal contact.

Methods: Stereology was used to examine the placentae of 84 Thoroughbred mares grouped on the basis of age and parity. Placental efficiency, assessed by expressing foal birthweight as a function of total microscopic area of fetomaternal contact, was also determined.

Results: Mare age and parity influenced the development of the microcotyledons and microcotyledon surface density (Sv) was lowest in aged multiparous mares, presumably due to degenerative changes in their endometrium. However, primiparous mares also showed significantly lower Sv values than young multiparous mares, despite the virginal endometrium of the former group. This apparent ‘priming’ effect of a first pregnancy on microcotyledonary Sv was illustrated further by 11 maiden mares followed in 2 successive pregnancies. They all showed significant increases in Sv values in their second parity, with equivalent improvements in foal birthweight.

Conclusions: Foal birthweight is a reflection of the balance between fetomaternal contact and placental efficiency. In creases in fetomaternal contact are correlated to reductions in placental efficiency, which may reflect the ability of the placenta to modify its exchange capabilities.

Potential relevance: Further work is needed to elucidate how such changes in microcotyledon morphology and efficiency are brought about.
The efficacy of dantrolene sodium in controlling exertional rhabdomyolysis in the Thoroughbred racehorse
Authors: Edwards J. G. T. , Newton J. R. , Ramzan P. H. L. , Pilsworth R. C. , Shepherd M. C.
Published: April 2007

Reasons for performing study: Dantrolene sodium (Dantrium) has been used extensively for the treatment of myopathies in man and anecdotal evidence suggests it is of clinical benefit in the control of exercise‐induced rhabdomyolysis (ER) in racehorses, although data to support this are currently lacking.

Objectives: To investigate the efficacy of oral dantrolene sodium in controlling ER in a randomised, double‐blind, placebo‐controlled crossover trial involving 77 Thoroughbred racehorses in Newmarket, UK.

Methods: Horses were treated on 2 occasions 1 week apart, with treatment days coinciding with a return to exercise following 2 days box rest on each occasion. For the first treatment, each horse was randomly selected to receive either 800 mg dantrolene sodium or a colour‐ matched placebo administered orally 1 h before exercise. This was followed by crossover to the other treatment on the second occasion, with each horse thereby acting as its own control.

Degree of ER was assessed using rising serum creatine kinase (CK) levels, by subtracting pre‐exercise blood CK levels from those measured in 6 h post exercise blood samples. For each horse, the difference in change between pre‐ and post exercise CK values between placebo and dantrolene treatments was calculated, with positive values indicating a greater rise with placebo than with dantrolene sodium treatment.

Results: The overall mean difference for all horses was +104.8 iu/l and the null hypothesis, that there was no true difference in non‐normally distributed post exercise rises in CK values between placebo and dantrolene treatments, was rejected (P = 0.0013) using the nonparametric Wilcoxon signed rank test. Additionally, no horses given dantrolene sodium showed clinical signs of ER, whereas 3 horses given the placebo developed ER following exercise. The incidence of ER in the study was 4% (3/77).

Conclusions: The results confirmed that oral administration of dantrolene sodium, 1 h before exercise, had a statistically significant effect on reducing the difference between pre ‐ and post exercise plasma CK levels compared with a placebo in the same animals, and preventing clinical ER in susceptible individuals.

Potential relevance: This study suggested that dantrolene sodium is of use in controlling ER in the Thoroughbred racehorse. Further investigation into pre‐ and post exercise myoplasmic calcium levels and the repeat of the study late in the season when horses receive a much higher energy ration and more strenuous exercise would appear to be warranted.
Gender differences in bone turnover in 2‐year‐old Thoroughbreds
Authors: Jackson B. F. , Lonnell C. , Verheyen K. , Wood J. L. N. , Pfeiffer D. U. , Price J. S.
Published: April 2007

Reasons for performing study: Injuries to the skeleton are a major cause of morbidity and mortality in racehorses and age, gender and season have all been shown to influence risk of injury.

Objectives: To use biochemical markers of bone cell activity to establish to whether cellularprocesses in bone underlie these described effects.

Methods: Blood samples were collected monthly from 2‐year‐old horses in race training between November 1998 and September 1999. Mean age at the start of the study was 20 months (range 18–23 months), with no significant difference in average age between colts (n = 84) and fillies (n = 63). Three markers were measured; osteocalcin (OC, bone formation), the carboxyte rminal cross‐linked telopeptide oftype Icollagen (ICTP, bone resorption) and the carboxyterminal propeptide oftype Icollagen (PICP), which is less ‘bone‐specific’ than the other 2 markers.

Results: Colts had, on average, 3.62 ng/ml higher O C concentrations (P = 0.044) and 0.68 mg/l higher ICTP concentrations (P = 0.01) than fillies. The effect of gender was not statistically significant for PICP. However, in May, PI CP concentrations were on average 157 mg/l higher in fillies than colts. There was no effect of age or season on marker concentrations.

Conclusions: This study has shown that there are gender differences in bone turnover markers in 2‐year‐old Thoroughbreds; however, age, within the limited range studied, did not have a significant effect on bone cell activity. Lower bone marker concentrations may reflect smaller bone size and/or earlier skeletal maturation in fillies. An increase in concentrations of PICP in fillies in spring and early summer may relect an influence of sex hormones on collagen turnover.

Potential relevance: Gender differences in bone cell activity in 2‐year‐old colts and fillies may influence bone's adaptive responses to training and risk of injury.
Results of plate fixation oftype 1bolecranon fractures in 24 horses
Authors: Swor T.M. , Watkins J. P. , Bahr A. , Honnas C. M.
Published: April 2007

Reasons for performing study: Previous olecranon fracture reports contain a small proportion oftype 1bfractures, with only a few repaired by tension band plate fixation.

Objectives: To evaluate subject details, history, clinical findings and outcome oftype 1bolecranon fractures in a large group of horses treated by tension band plate fixation.

Methods: Medical records of 77 horses diagnosed with an olecranon fracture were reviewed. Twenty‐fourhorses (31%) were classified as havingtype 1bolecranon fractures. Clinical details and follow‐up results (4–128 months postoperatively) were recorded.

Results: Treatment included open reduction and internal fixation using a narrow dynamic compression plate (n = 20), conservative therapy (n = 2) and euthanasia (n = 2). Long‐term follow‐up was available for 16 plated horses. Four were sound and in training and 9 were sound and performing athletically. Articular surface involvement, comminution, open status orremoval of anconeal process fragments did not appear to affect prognosis or soundness.

Conclusions: Internal plate fixation provides an excellent prognosis for an animal capable of athletic performance.

Potential relevance: Describing tension band plate fixation and results offers a method of fracture repair that will improve the treatment and prognosis fortype 1bolecranon fractures.
Effect of controlled exercise on middle gluteal muscle fibre composition in Thoroughbred foals
Authors: Eto D. , Yamano S. , Kasashima Y. , Sugiura T. , Nasu T. , Tokuriki M. , Miyata H.
Published: April 2007

Reasons for performing study: Most racehorses are trained regularly from about age 18 months; there fore, little information is available on the effect of training in Thoroughbred foals.

Hypothesis: Well‐controlled exercise could improve muscle potential ability for endurance running.

Methods: Thoroughbred foals at age 2 months were separated into control and training (treadmill exercise) groups and samples obtained from the middle gluteal muscle at 2 and 12 months post partum. Muscle fibre compositions were determined by histochemical and electrophoretical techniques and succinic dehydrogenase (SDH) activity was analysed in each fibre type.

Results: All fibre types were hypertrophied with growth andtype IandIIAfibres were significantly larger in the training than the control group at age 12 months. A significant increase of SDH activity was found intype IIXmuscle fibres in the training group.

Conclusions: Training in young Thoroughbred horses can facilitate muscle fibre hy pert rophy and increase the oxidative capacity oftype IIXfibres, which could potentially enhance stamina at high speeds.

Potential relevance: To apply this result to practical training, further studies are needed to determine more effective and safe intensities of controlled exercise.
Retrospective study of 24 cases of septic calcaneal bursitis in the horse
Authors: Post E. M. , Singer E. R. , Clegg P. D. , Smith R. K. , Cripps P. J.
Published: April 2007

Reasons for performing study: Wounds to the plantar aspect of the tarsus present a diagnostic and treatment challenge. This study was undertaken to describe specific features of traumatic wounds involving the calcaneal bursa, with a view to determining which clinical examination findings and diagnostic tests results could provide reliable indicators of prognosis.

Objectives: To report clinical presentation, diagnostic findings, treatment and outcome of 24 cases of septic calcaneal bursitis; and to determine the importance of the involvement of specific anatomical structures in relation to the prognosis for survival and return to athletic function.

Methods: Records of 24 horses that had suffered traumatic wounds involving the calcaneal bursae were reviewed and divided into 3 groups, based on the bursa involved and presence or absence of involvement of the tuber calcanei. Clinical, diagnostic imaging and surgical findings were recorded for each case. Differences between groups and outcome were examined for significance with Chi‐squared, Fisher's Exact or Kruskal‐Wallis tests, as appropriate.

Results: Wounds involving only the subcutaneous bursa had an excellent prognosis for survival. Seventy‐five percent of horses with wounds involving the intertendinous calcaneal bursa survived. Involvement of the tuber calcanei presented a fair to guarded prognosis, with only 44% of horses with involvement of this structure surviving.

Conclusions: In contrast to other studies of septic synovial structures, the time between initial injury and referral did not affect the outcome. Correct identification of invasion of the calcaneal bursa(e) and/or tuber calcanei in wounds to the plantar aspect of the tarsus allows for more accurate pronostication. Damage to the tuber calcanei presents a poorer prognosis than for cases that involve only the soft tissue structures in the region.

Potential relevance: This study demonstrates the importance of correct anatomical identification of structures involved in wounds in the region of the calcaneal bursa. The use of radiography, ultrasonography and synoviocentesis are essential in these cases to provide the most appropriate treatment for the horse and accurate prognosis for the owner.
Effect of GastroGard and three compounded oral omeprazole preparations on 24 h intragastric pH in gastrically cannulated mature horses
Authors: Merritt A. M. , Sanchez L. C. , Burrow J. A. , Church M. , Ludzia S.
Published: April 2007

Reasons for performing study: Ulceration of the squamous gastric mucosa is commonly associated with intensive training programmes in horses, but only one compound (‘Gastrogard’) has been subjected to controlled scrutiny as to therapeutic efficacy.

Objectives: To compare the gastric acid inhibitory efficacy of one manufactured (‘GastroGard’) and 3 generic pharmacy‐compounded preparations of the proton pump inhibitor omeprazole (OME) in the mature horse.

Hypothesis: All OME preparations tested would induce a clinically acceptable effect.

Methods: Six healthy mature gastrically cannulated horses of various breeds, 3 mares and 3 geldings, were used. Each product was administeredper osonce daily (0730 h) at an equivalent dose of 4 mg OME/kg bwt, in a randomised complete repeated measures design for sequence of individual preparation treatment per horse. There was a minimum of 14 days between treatment regimens. A portable unit that recorded pH continuously was attached to a recording electrode fixed within the gastric lumen via the gastric cannula. Three 24 h recordings were made one day before and during Days 2 and 7 after commencement of a 7 day treatment with each of the 4 individual preparations. The horses were fed as usual throughout the study.

Results: Only the GastroGard and one other preparation induced a significant increase over baseline in mean percentage of time that the pH was >4.0 and mean median intragastric pH, during the first 14 and 12 h post treatment respectively, forboth Days 2 and 7 post treatment. Both these products had a vehicle pH >8.0, in contrast to the 2 less effective products, where the vehicle pH was <6.0.

Conclusions: OME at 4 mg/kgper oss.i.d. can effectively maintain intragastric pH at an accepted anti‐ulcerogenic level for at least 12 h post administration in mature horses. In contrast to GastroGard, it should not be expected that all compounded preparations of OME are equally effective in achieving this performance. It appears that vehicle pH might play an important part in determining preparation efficacy.

Potential relevance: Optimal timing for daily dosing of athletic horses with an effective OME preparation, in order to suppress gastric squamous ulceration, might be 4–8 h prior to a training session.
Quantification and age‐related distribution of articular cartilage degeneration in the equine fetlock joint
Authors: Brommer H. , Van Weeren P. R. , Brama P. A. J. , Barneveld A.
Published: April 2007

Reasons for performing study: The equine fetlock joint has the largest number of traumatic and degenerative lesions of all joints of the appendicular skeleton.

Objective: To gain insight into the distribution of cartilage degeneration across the articularsurface in relation to age in order better to understand the dynamic nature and progression of osteoarthritis (OA).

Hypothesis: That there would be a specific age‐related distribution pattern of cartilage degeneration in the equine metacarpophalangeal joint.

Methods: The proximal articular cartilage surfaces of the first phalanges (P1) of 73 slaughter horses (age range 0.4–23 years) with different stages of osteoarthritis were scored semiquantitatively on a 0 to 5 scale and also assessed quantitatively using the cartilage degeneration index (CDIP1), which ranges from 0 to 100%. Further more, CDI values were determined for special areas of interest; medial dorsal surface (CDImds), late ral dor sal surface (CDIlds), medial central fovea (CDImcf) and lateral central fovea (CDIlcf). Correlations were calculated for CDIP1 values and CDI values at the specific areas of interest with macroscopic scores and with age.

Results: There was a high correlation between the semiquantitative macroscopic score and the quantitative CDIP1 values (r = 0.92; P<0.001). A macroscopic score of 0 (i.e. no obvious cartilage degeneration) corresponded with a CDIP1 mean ± s.e. value of 2.5 ± 2.8% and a macroscopic score of 5 (i.e. severe cartilage degeneration in localised areas) with a mean ± s.e. value of 38.1 ± 7.9%. There was a moderate but highly significant correlation between the CDIP1 value and the age of the horses (r = 0.41; P<0.001). Highest CDI values were calculated for the medial dorsal surface (from 10.6 ± 2.8% at macroscopic Grade 0 to 63.1 ± 8.4% at Grade 5). At the lateral dorsal surface, these values were 5.9 ± 1.4% and 47.2 ± 10.4%, respectively. The CDImcf and CDIlcf were significantly lower (P<0.05) than the CDImds and CDIlds at all grades. The CDImcf ranged from 1.0 ± 2.9% at Grade 0 to 43.7 ± 9.1% at Grade 5; laterally, these values were 1.5 ± 2.6% and 15.2 ± 6.2%, respectively.

Conclusions: CDI grading increased from lateral to medial and from central to dorsal. This specific distribution pattern confirms the heterogeneous nature of the OA process and strongly supports an important role for biomechanical loading, superimposed on age‐related changes, in the spread of the disorder over the joint.

Potential relevance: Knowledge of the development of OA across the articularsurface is essential forunderstanding the dynamic nature and progression of the disease and can form a basis for improvements in diagnostic and therapeutic approaches to degenerative joint disease.
Accuracy of ultrasound‐guided intra‐articular injection of cervical facet joints in horses: a cadaveric study
Authors: Nielsen J. V. , Berg L. C. , Thoefner M. B. , Thomsen P. D.
Published: April 2007

Reasons for performing study: Intra‐articular facet joint injection is an established diagnostic procedure in human medicine but there are no reports on its reliability in equine practice.

Objectives: To investigate the accuracy of ultrasound‐guided intra‐articular injections of the cervical facet joints and to estimate factors influencing the accuracy.

Methods: Sixty injections with blue dye were performed on the facet joints between 2nd and 7th cervical vertebra (C2–C7) on horses subjected to euthanasia for nonorthopaedic reasons. The facet joints were subsequently dissected to verify accuracy of deposition.

Results: Seventy‐two percent of the injections were found to be int ra‐articul ar, 17% were intracapsular and a total of 98% were within 1 mm of the joint capsule. There was a marked effect of gained experience (P<0.01), but not of other factors tested.

Conclusions and potential relevance: The results of the present study do not translate directly to injections performed in live horses, but they indicate that the method can be applied as a diagnostic as well as therapeutic procedure in C2 to C7 and that is advisable to practise injections on cadaver specimens before applying the technique.
Comparison of efficacy and tolerability of isoflupredone and dexamethasone in the treatment of horses affected with recurrent airway obstruction (‘heaves’)
Authors: PICANDET V. , LÉGUILLETTE R. , LAVOIE J. ‐P.
Published: April 2007

Reasons for performing study: Corticosteroids are currently the most effective drugs for the control of ‘heaves’ in horses. However, there is limited information concerning the comparative efficacy and tolerability of the various corticosteroids when used for treatment.

Objectives: To compare the therapeutic and side effects of isoflupredone acetate to those of dexamethasone.

Methods: A parallel design to compare the effects of 2 corticosteroids by evaluating lung function, serum cortisol and electrolyte concentrations, response to ACTH stimulation and haematology sequentially during a 14 day control period (no treatment), followed by 14 day treatment with either isoflupredone acetate (0.03 mg/kg i.m. s.i.d., n = 6) or dexamethasone (0.04 mg/kg i.v. s.i.d., n = 6) and 7 days of wash‐out.

Results: Both drugs were well tolerated clinically and resulted in a significant improvement in lung function that started on Day 3 and lasted for the treatment and wash‐out periods. Blood cortisol levels were significantly decreased during the treatment period in both groups of horses, but a normal response to ACTH stimulation was preserved. Serum electrolytes concentration of horses receiving dexamethasone was not affected by the treatment, but horses treated with isoflupredone demonstrated a significant decrease in serum potassium level. Both treatments induced stress changes in haematology.

Conclusions and potential relevance: Isoflupredone is as effective as dexamethasone in the treatment of ‘heaves’‐affected horses but associated with hypokalaemia. Even if clinical signs of hypokalaemia were not observed, this is a side effect that deserves further investigation.
Tiludronate as a new therapeutic agent in the treatment of navicular disease: a double‐blind placebo‐controlled clinical trial
Authors: DENOIX J. ‐M. , THIBAUD D. , RICCIO B.
Published: April 2007

Reasons for performing study: Bisphosphonates, such as tiludronate, are used to normalise bone metabolism via inhibition of bone resorption. Areas of increased bone resorption and formation are typical lesions in a diseased navicular bone.

Objectives: To determine if bone remodelling changes occurring in navicular disease may be corrected with therapies regulating bone metabolism.

Methods: We designed a double‐blind, placebo‐controlled clinical trial to compare 2 doses of tiludronate, 0.5 mg/kg and 1 mg/kg bwt administered via daily i.v. injections over 10 days for the treatment of navicular disease. Seventy‐three horses, split into 2 subpopulations of recent and chronic cases, were enrolled to be followed‐up over 6 months. Of these, 33 recent and 17 chronic cases meeting the selection criteria were maintained in the final efficacy analyses. Clinical examinations were videorecorded and reviewed blindly by an independent expert.

Results: Horses treated with the higher dose showed optimal improvement of lameness and return to normal level of activity 2–6 months post treatment. The more recent the onset of clinical signs at the time of treatment, the greaterthe efficacy. The treatment did not modify the response to extension and flexion tests. The lower dose failed to significantly improve the condition.

Conclusions: Tiludronate efficacy is demonstrated in the treatment of navicular disease at the dose of 1 mg/kg bwt.

Potential relevance: Our results support the clinical relevance of bone remodelling changes in the outcome of navicular disease.
Correlation of racing performance with radiographic changes in the proximal sesamoid bones of 487 Thoroughbred yearlings
Authors: SPIKE‐PIERCE D. L. , BRAMLAGE L. R.
Published: April 2007

Reasons for performing study: Proximal sesamoiditis has been a common and confusing radiographic diagnosis in Thoroughbred yearling surveys. This study categorised the radiographic appearance of yearling proximal sesamoid bones and determined their effect on the number of races started and earning potential for racing at ages 2 and 3 years.

Hypothesis: Yearlings with moderate to severe proximal sesamoiditis have decreased performance at age 2 and 3 years.

Methods: Survey radiographs of 487 Thoroughbred yearlings were reviewed. Proximal sesamoid bones were examined and findings placed into 7 categories, 5 of which measured size, shape, and number of vascular canals, and 2 examined the radiographic shape of the sesamoid abaxial surface. Records of horses age 2 and 3 years were reviewed to obtain the number of races completed and money won in those races.

Results: Vascular canals with parallel sides <2 mm in width in any number were normal. Yearlings with 1 or 2 abnormally conformed vascular canals (nonparallel sides and >2 mm in width) had a decrease in number of race starts at age 2 years when compared to normal horses. This same change in the fore‐ or hindlimbs was associated with decreases in starts and earnings at age 2 years. If uniformly present in both fore‐ and hindlimbs there was no difference from normal horses. Yearlings with >2 irregular vascular canals had a decrease in number of race starts and earnings at age 2 and 3 years. Changes in proximal sesamoid bone contour did not affect performance.

Conclusions: Horses with enlarged vascular canals, within their sesamoids as yearlings, start fewer races and earn less prize money than horses with normal vascular canals.

Potential relevance: One or two enlarged canals affected horses as 2‐year‐olds. Three or more enlarged vascular canals affected horses at ages 2 and 3 years, which should be taken into account when examining radiographs for potential purchase of young horses.
Retrospective evaluation of equine prepurchase examinations performed 1991–2000
Authors: van HOOGMOED L. M. , SNYDER J. R. , THOMAS H. L. , HARMON F.A.
Published: April 2007

Reasons for performing study: Prepurchase examinations of horses are used increasingly as a means of evaluating future soundness. Data is lacking in the literature of the radiographic findings and results of the lameness examination of comprehensive prepurchase examinations.

Objective: To summarise the clinical and radiographic findings of prepurchase examinations and determine if radiographic findings correlated with the lameness examination and sale outcome.

Methods: Records of 510 cases were reviewed, radiographs evaluated and grades assigned the navicular bone, distal phalanx, and tarsus. Follow‐up information on the horse status was obtained by telephone interviews for 173 horses.

Results: Thoroughbred geldings represented the most common breed and sex, mean age 8 years, mean asking price $12,439.40, and 52.8% were lame. Radiography was the most common diagnostic procedure performed (61.6%), with views of the front feet requested most often (86.6%) followed by the tarsi (68.1%).Grade 1was most common for the navicular bone whileGrade 2predominated for the distal phalanx. The number of sound horses decreased as grades became more severe. For the tarsi,Grades 0and1were most common for the proximal intertarsal and distal intertarsal/metatarsal joints, respectively. Horses with significant tarsal changes were still able to compete at their expected level. With respect to the radiographic examination, the mean ± s.d. grade of the horses which were not lame at follow‐up was 1.2 ± 0.9 for the navicular bone and 1.5 ± 0.8 for the third phalanx. The mean ± s.d. grade of sound horses for the distal intertarsal joint was 0.7 ± 0.6 and 1.14 ± 0.8 for the tarsometatarsal joint. Horses for which owner follow‐up was available and which had aGrade 3score were also evaluated. Forthe navicularbone, 17/31 with aGrade 3remained in active use at follow‐up and for the distal phalanx 21/27 were in active use. For the distal intertarsal and tarsometatarsal joints, 20/21 with aGrade 3were still in active use.

Conclusions: Prepurchase examinations can have a significant effect on the outcome of the sale. For the navicular bone and distal phalanx, higher grades were associated with lameness. In contrast, higher grades in the tarsus were less likely to be associated with lameness. Warmbloods tended to have more extensive changes in the navicular bone and distal phalanx relative to Thoroughbreds but were not as lame.

Potential relevance: Radiographic changes detected in the navicular bone, distal phalanx and tarsus should be interpreted with consideration to the clinical examination.
Responses of horses in behavioural tests correlate with temperament assessed by riders
Authors: VISSER E. K. , REENEN C. G. Van , RUNDGREN M. , ZETTERQVIST M. , MORGAN K. , BLOKHUIS H. J.
Published: April 2007

Reasons for performing study: Behavioural tests as well as observers' ratings have been used to study horses' temperament. However, the relationship between the ratings and the responses in behavioural tests has not yet been studied in detail.

Objectives: The aim of the present study was to examine this relationship between ratings and responses.

Methods: Eighteen mature Swedish Warmblood horses were subjected to 2 behavioural tests, one relating to novelty (novel object test) and one to handling (handling test). Subsequently, 16 of these horses were ridden by 16 equally experienced students, having no former experience with the horses. Immediately after each ride, the students scored the horse for10 temperamental traits using a line rating method.

Results: It was shown that for each temperamental trait all 16 riders agreed on the ranking of the horses (0.212<W<0.505, P<0.001).

Conclusions: Correlations between behavioural and heart rate variables in the behavioural tests revealed that horses with a high level of locomotion or much restlessness behaviour exhibited high mean heart rate and low heart rate variability. In particular, heart rate variables in the behavioural tests were found to correlate with riders' rating scores. Furthermore, the underlying components of the handling test, retrieved with a principal component analysis (PCA) correlated with riders' rating scores while the underlying components of the novel object test did not.

Potential clinical relevance: It is concluded that it is possible for a large panel of assessors to agree upon a horse's temperament and that objective measures from behavioural tests correlate significantly with temperamental traits assessed by a panel of assessors.
Effects of imprint training procedure at birth on the reactions of foals at age six months
Authors: WILLIAMS J. L. , FRIEND T. H. , COLLINS M. N. , TOSCANO M. J. , SISTO‐BURT A. , NEVILL C. H.
Published: April 2007

Reasons for performing study: While imprint training procedures have been promoted in popular magazines, they have received limited scientific investigation.

Objectives: To determine the effects of a neonatal imprint training procedure on 6‐month‐old foals and to determine if any one session had a greater effect than others.

Methods: Foals (n = 131) were divided into the following treatments: no imprint training, imprint training at birth, 12, 24 and 48 h after birth orimprint training only at birth, 12, 24, 48, or 72 h after birth. Foals then received minimal human handling until they were tested at 6 months.

Results: During training, time to complete exposure to the stimulus was significant for only 2 of 6 stimuli. Percentage change in baseline heart rate was significant for only 2 of 10 stimuli. These 4 effects were randomly spread across treatments.

Conclusions: Neither the number of imprint training sessions (0, 1, or 4) nor the timing of imprint training sessions (none, birth, 12, 24, 48, or 72 h after birth) influenced the foal's behaviour at 6 months of age.

Potential clinical relevance: In this study, imprint training did not result in better behaved, less reactive foals.
Brain abscesses as a metastatic manifestation of strangles: symptomatology and the use of magnetic resonance imaging as a diagnostic aid
Authors: SPOORMAKERS T. J. P. , ENSINK J. M. , GOEHRING L. S. , KOEMAN J. P. , BRAAKE F. TER , VLUGT‐MEIJER R. H. van der , BELT A. J. M. van der
Published: April 2007

Reasons for performing study: The occurrence of unexpectedly high numbers of horses with neurological signs during two outbreaks of strangles required prompt in‐depth researching of these cases, including the exploration of magnetic resonance imaging (MRI)as a possible diagnostic technique.

Objectives: To describe the case series and assess the usefulness of MRI as an imaging modality for cases suspected of space‐occupying lesions in the cerebral cavity.

Methods: Four cases suspected of suffering from cerebral damage due to Streptococcus equi subsp. equi infection were examined clinically, pathologically, bacteriologically, by clinical chemistry (3 cases) and MRI (2 cases). In one case, MRI findings were compared to images acquired using computer tomography (CT).

Results: In all cases, cerebral abscesses positive for Streptococcus equi subsp. equi were found, which explained the clinical signs. Although the lesions could be visualised with CT, MRI images were superiorin representing the exact anatomic reality of the soft tissue lesions.

Conclusions: The diagnosis of bastard strangles characterised by metastatic brain abscesses was confirmed. MRI appeared to be an excellent tool for the imaging of cerebral lesions in the horse.

Potential clinical relevance: The high incidence of neurological complications could not be explained but possibly indicated a change in virulence of certain strains of Streptococcus equi subsp. equi. MRI images were very detailed, permitting visualisation of much smaller lesions than demonstrated in this study and this could allow prompt clinical intervention in less advanced cases with a better prognosis. Further, MRI could assist in the surgical treatment of brain abscesses, as has been described earlier for CT.
A retrospective case‐control study of horse falls in the sport of horse trials and three‐day eventing
Authors: SINGER E. R. , SAXBY F. , FRENCH N. P.
Published: April 2007

Reasons for performing study: Serious injuries to horses and riders in horse trials (HT) and three‐day events (3DE) are usually associated with falls of horses, which invariably involve falls of the riders. Many potential causes for these falls have been discussed.

Objectives: The aim of this case‐control study was to investigate the risk factors for horse falls on the cross‐country phase of horse trials and three‐day events.

Methods: Using retrospective data, significant risk factors identified with unvariable analysis (P value <0.2) were entered into a multivariable logistic regression model. Significant risk factors (P value <0.05) were included in the final model.

Results: It was revealed that a number of course, obstacle and rider variables were significantly and independently associated with the risk of railing. Falling was associated with obstacles sited downhill (Odds ratio [OR] 8.41) and with obstacles with ditches in front (OR = 5.77).

Conclusions: The relationship between course variables and the risk of falling was characterised and showed a significantly increased risk with increasing numbers of jumps on the course and for jumping efforts later in the course. In contrast, after allowing for the total number of obstacles on the course, an increase in the total number of jumping efforts appeared to have a protective effect. A later cross‐country start time was associated with a decreased risk of a horse fall. Amateur event riders were approximately 20 times more likely to fall than professional riders.

Potential clinical relevance: This study has identified a number of risk factors associated with horse falls and highlights areas that can be altered to improve safety in cross‐country competitions.
Effect of foot balance on the intra‐articular pressure in the distal interphalangeal jointin vitro
Authors: VIITANEN M. J. , WILSON A. M. , McGUIGAN H. P. , ROGERS K. D. , MAY S. A.
Published: April 2007

Reasons for performing study: Increased joint pressure has been implicated in the progression of osteoarthritis.

Hypothesis: That intra‐articular pressure in the distal interphalangeal joint (DIP) is significantly higher in legs loaded with heel up (HU), low heel (TU), lateral side up (LU) and medial side up (MU) imbalance compared to the balanced position.

Methods: Twelve elbow down limbs were compressed in a hydraulic loading jig and DIP pressure measured.

Results: Elevating the heels by 5° significantly increased DIP pressure. After 5 ml of contrast was injected into the joint, heel elevation caused a greaterincrease in DIP pressure and heel lowering decreased DIP pressure. Silicone rubber castings were taken of 20 DIP whilst under load. The articular contact area was localised on the dorsal aspect in the HU position, palmar aspect in the TU position and towards the elevated side with lateromedial imbalance.

Conclusions: Altered foot orientation, which could result from trimming and shoeing, therefore influences intra‐articular pressure in the DIP and the articular contact area.

Potential clinical relevance: The results support the view that a balanced foot is the ideal and that the elevated heels may be detrimental to long term viability of the DIP joint.
Risk factors associated with behavioural disorders of crib‐biting, weaving and box‐walking in Swiss horses
Authors: BACHMANN I. , AUDIGÉ L. , STAUFFACHER M.
Published: April 2007

Reasons for performing study: Studies on the prevalence of behavioural disorders in horses and on associated risk factors have revealed inconsistent results. There are many studies on the neuropharmacological, surgical ormechanical therapy of stereotypies, but little is known about their causation.

Objectives: To explore risk factors associated with the occurrence of behavioural disorders in horses.

Methods: A sample of horse owners, selected randomly and representative for Switzerland, was contacted in a postal survey. Answers were provided for 622 stables (response rate 35.2%). Individual data of 2341 horses were examined with path analysis (multivariable linear and logistic regression), and adjustment made for possible confounding effects due to age and breed.

Results: Out of 60 possible risk factors, 11 were associated with the outcome at the univariable level (null‐hypothesis path model) and 3 factors remained after the backward logistic regression procedure. Mature Warmbloods and Thoroughbreds, assessed by the owners to be reactive, fed 4 times a day and without daily pasture, had increased odds of displaying crib‐biting, weaving and box‐walking. Furthermore, indirect associations of 5 factors with the outcome were identified.

Conclusions: The final logistic regression model of risk factors leads to the hypotheses that causal prevention of stereotypic behaviours should be based upon housing and management conditions which allow tactile contact with other horses (e.g. mutual grooming), daily free movement (paddock or pasture), as well as the provision of high amounts of roughage but of little or no concentrates.

Potential clinical relevance: It is one of the aims of population medicine to prevent the development of behavioural disorders. Further research is needed to test the concluding hypotheses in experimental studies or to verify them in the context of similar observational studies.
Spasmogenic action of endothelin‐1 on isolated equine pulmonary artery and bronchus
Authors: BENAMOU A. E. M. , MARLIN D. J. , CALLINGHAM B. C. , HILEY R. C. , LEKEUX P.
Published: April 2007

Reasons for performing study: There is currently little published information about the effects of endothelin‐1 (ET‐1), a potent endogenous spasmogen of vascular and airway smooth muscle, on pulmonary vasculature and airways or which ET receptor subtypes mediate ET‐1‐induced vasoconstrictive and bronchoconstrictive action in the horse.

Objectives: To investigate the effect of endothelin‐1 (ET‐1) on smooth muscle from isolated equine pulmonary artery and bronchus. In addition, the roles of ETAand ETBreceptors in ET‐1 mediated contraction in these tissues were assessed.

Methods: The force generation of ring segments from pulmonary arteries or third‐generation airways (obtained from horses subjected to euthanasia fororthopaedic reasons) were studied in an organ bath at 37°C in response to exogenous endothelin and selective endothelin A (BQ123) or B receptor (BQ788) antagonists.

Results: ET‐1 produced concentration‐dependent contractions of the equine pulmonary artery and bronchus. The threshold for contraction was 10−10and 10−9mol/l ET‐1 for pulmonary artery and bronchus, respectively. The maximal contraction induced by the highest ET‐1 concentration (10−7mol/l) was 173 and 194% of the contraction obtained with 100 mmol/l KCl in pulmonary artery and bronchus, respectively. ET‐1 potency was 25 times greater in equine pulmonary artery than in equine bronchus (concentration of ET‐1 producing 50% of maximal contraction [EC50] = 5.6 10−9mol/l and 2.2 10−8mol/l, respectively). In pulmonary artery, ET‐1 induced contractions were significantly inhibited by the ETAreceptor antagonist BQ123 (1 μmol/l; dose‐response curve to ET‐1 was shifted to the right by 5.4‐fold), but not by the ETBantagonist BQ788. In bronchus, dose‐responses curves to ET‐1 were shifted to the right by BQ123 (1 μmol/l; 2.5‐fold), but not by BQ788 (1 μmol/l). In the presence of both antagonists, the dose‐response curve to ET‐1 was shifted to the right by 4.5‐fold.

Conclusions: These functional studies demonstrate that ET‐1 is a potent spasmogen of equine third generation pulmonary artery and bronchus, and that contractions are mediated via ETAreceptors in the former and both ETAand ETBreceptors in the latter.

Potential clinical relevance: Endothelin receptor antagonists may have potential for treating equine pulmonary hypertension or bronchoconstriction.
Investigations into the role of the thyrohyoid muscles in the pathogenesis of dorsal displacement of the soft palate in horses
Authors: DUCHARME N. G. , HACKETT R. P. , WOODIE J. B. , DYKES N. , ERB H. N. , MITCHELL L. M. , SODERHOLM L. V.
Published: April 2007

Reasons for performing study: Contributes to the understanding of the pathogenesis of dorsal displacement of the soft palate during exercise so that management of this condition could be enhanced.

Hypothesis: That the thyrohyoid muscles play an important role in the stability of the laryngo‐palatal relationship and that dysfunction of these muscles leads to dorsal displacement of the soft palate (DDSP) during exercise.

Methods: Ten horses were exercised on a high‐speed treadmill under 4 different treatment conditions: control conditions (n = 10), after resection of thyrohyoid muscles (TH, n = 10), after sham‐treatment (n = 5), or after restoration of function of the thyrohyoid muscles with surgical sutures (prosthesis‐treatment, n = 6). During trials, the following determinations were made: videoendoscopy of the upper airway, gait frequency and pharyngeal and tracheal static pressures.

Results: None of the 10 horses developed DDSP during 2 separate treadmill‐exercise trials under the control conditions. Seven of the 10 horses developed DDSP after resection of the TH muscles, 4 of 5 of these horses still experienced DDSP aftersham‐treatment, but 5 of 6 horses no longer experienced DDSP at exercise after the prosthesis‐treatment. There were significant anomalies in airway pressures, respiratory frequency, and occurrence of DDSP in both the TH resection and sham‐treatment conditions compared to control conditions. In contrast, no statistical differences were noted in any of the parameters measured between the prosthesis‐treatment and control conditions.

Conclusions: That the function of the TH muscles is important to the stability of the laryngo‐palatal relationship and plays a role in the pathophysiology of exercise‐induced DDSP.

Potential relevance: Management of horses with DDSP could be enhanced by restoring the function of the TH muscles.
The sacroiliac joints: evaluation using nuclear scintigraphy. Part 1: The normal horse
Authors: DYSON S. , MURRAY R. , BRANCH M. , WHITTON C. , DONOVAN T. , HARDING E.
Published: April 2007

Reasons for performing study: Sacroiliac (SI) disease is recognised as a cause of poorhindlimb action but differential diagnosis is often difficult.

Hypotheses: That in clinically normal horses there would be a significant difference in the ratio of radiopharmaceutical uptake (RU) between the fifth lumbar vertebra (L5) and each tuber sacrale (TS) and between L5 and each SI joint; and that these ratios would alter with age, but ratios would be bilaterally symmetrical.

Methods: Dorsal scintigraphic images of the SI region of 15 horses, selected randomly from the clinic database, were analysed by 2 of the authors, comparing noncorrected and motion‐corrected images. To determine scintigraphic anatomy, the scintigraphic images of 10 Thoroughbred horses were superimposed over a ventrodorsal radiographic image of an isolated pelvis.

Dorsal scintigraphic images of 40 clinically normal horses age 3–16 years were evaluated using subjective examination, profile analysis and quantification using regions of interest.

Results: The tubera sacrale were seen as 2 well‐defined oval regions immediately to the left and right of the midline, abaxial to which were larger, approximately oval areas with less RU, representing uptake in the SI joints. The definition between the SI region and the TS was more obvious in younger horses. Nonmotion‐corrected images were often not of diagnostic quality or could be misinterpreted as abnormal. There were significant differences in RU between the TS and SI joints compared to L5, and decreased RU in the tubera sacrale with increasing age, but no change of uptake in the SI joint region and no effect of gender on RU. There was a high degree of left‐right symmetry of the TS and SI joint regions.

Conclusions and potential relevance: The scintigraphic images of horses with suspected sacroiliac joint disease should be compared with images of normal horses of comparable age. In normal horses, there was a high degree of symmetry; therefore, marked left‐right asymmetry is likely to be abnormal.
Validation and clinical utility of a novel immunoradiometric assay exclusively for biologically active whole parathyroid hormone in the horse
Authors: ESTEPA J. C. , GARFIA B. , GAO P. , CANTOR T. , RODRIGUEZ M. , AGUILERA‐TEJERO E.
Published: April 2007

Reasons for performing study: Parathyroid hormone (PTH) plays a critical role in the regulation of mineral metabolism in mammals. Until recently, the standard method for PTH measurement has been the 2nd generation intact‐PTH (I‐PTH) assay. Current evidence indicates that the I‐PTH assay binds to the PTH molecule and to an inactive N‐terminally truncated PTH fragment that tends to accumulate in the blood of uraemic patients. Therefore, a new 3rd generation PTH assay that detects only the whole PTH molecule (W‐PTH; cyclase‐activating PTH [CAP]) has been developed.

Objectives: To validate this more specific W‐PTH assay for measurement of equine PTH and evaluate its clinical utility.

Methods: W‐PTH and I‐PTH were measured in plasma samples from normal horses (adults and foals) and horses with nutritional secondary hyperparathyroidism (N2HPT) and with chronic renal failure (CRF). Replicate measurements and dilutional paralellism were used for assay validation. Changes in blood ionized calcium were induced by EDTA and CaCl2administration.

Results: Performance of the W‐PTH assay (accuracy, sensitivity, specificity and ability to detect changes in PTH in response to changes in calcium) was similar to that of the I‐PTH assay. Surprisingly, the relative W‐PTH concentration in normal horses and foals was higher than the relative I‐PTH concentration. W‐PTH values remained higher than I‐PTH during acute hypo‐ and hypercalcaemia. An increase in both W‐PTH and I‐PTH concentrations was found in horses with N2HPT. In horses with CRF, W‐PTH and I‐PTH values were very low and no increase in I‐PTH was observed.

Conclusions: The W‐PTH assay can be used for measurement of equine PTH.

Potential relevance: The use of W‐PTH assay is likely to improve the diagnosis of mineral metabolism in horses.