bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of tapered normal and interval training on performance of Standardbred pacers
Authors: SHEARMAN J. P. , HAMLIN M. J. , HOPKINS W. G.
Published: April 2007

Human athletes taper or reduce their training load before a race to enhance performance, apparently because recovery from the effects of fatigue occurs faster than the loss of fitness from the reduced training. However, there appear to be no previous studies of tapering of equine athletes. Our aim in the present study was, therefore, to investigate the efficacy of tapering with Standardbred pacers. We determined the effect of repeated cycles of tapered training on performance of Standardbred pacers. After 8 weeks of jogging and 3 times 2 week cycles of pace work, 19 horses were randomised to a taper and a control group. The taper group completed 5 consecutive 2 week cycles, each incorporating a 7 day taper; some cycles included high‐intensity interval training. The control group continued with 5 more cycles of pace work. All horses completed a 2400 m individual time trial after each cycle. Peak and mean speed of the taper group were faster than those of the control group in all cycles; the differences were clear‐cut in all cycles for peak speed (overall 4.4%, 95% confidence interval 1.7 to 7.1%), but only in one of the interval‐training cycles for mean speed (2.4%, 0.3 to 4.7%). Four horses in the taper group were injured during interval training. Repeated tapering produces a worthwhile enhancement of performance in Standardbreds, but the addition of interval training appears to increase the risk of injury.
Pharmacokinetics of marbofloxacin in mature horses after single intravenous and intramuscular administration
Authors: CARRETERO M. , RODRÍGUEZ C. , ANDRÉS M. I. SAN , FORÉS P. , LUCAS J.J. de , NIETO J. , WAXMAN S. , ANDRÉS M. D. SAN , GONZÁLEZ F.
Published: April 2007

The pharmacokinetic behaviour of marbofloxacin, a new fluoroquinolone antimicrobial agent developed exclusively for veterinary use, was studied in mature horses (n = 5) after single‐dose i.v. and i.m. administrations of 2 mg/kg bwt. Drug concentrations in plasma were determined by high performance liquid chromatography (HPLC) and data obtained were subjected to compartmental and noncompartmental kinetic analysis. This compound presents a relatively high volume of distribution (Vss= 1.17 ± 0.18 l/kg), which suggests good tissue penetration, and a total body clearance (Cl) of 0.19 ± 0.042 l/kg.h, which is related to a long elimination half‐life (t1/2β= 4.74 ± 0.8 h and 5.47 ± 1.33 h i.v. and i.m. respectively). Marbofloxacin was rapidly absorbed after i.m. administration (MAT = 33.8 ± 14.2 min) and presented high bioavailability (F = 87.9 ± 6.0%). Pharmacokinetic parameters are not significantly different between both routes of administration (P>0.05). After marbofloxacin i.m. administration, no adverse reactions at the site of injection were observed. Serum CK activity levels 12 h after administration increased over 8‐fold (range 3–15) compared with pre‐injection levels, but this activity decreased to 3‐fold during the 24 h follow‐up period. Based on the value of surrogate markers to predict clinical success, Cmax/MIC ratio or AUC/MIC ratio, single daily marbofloxacin dose of 2 mg/kg bwt may not be effective in treating infections in horses caused by pathogens with an MIC ≥ 0.25 μg/ml. However, if we use a classical antimicrobial efficacy criteria, marbofloxacin can reach a high plasma peak concentration and maintain concentrations higher than MICs determined for marbofloxacin against most Gram‐negative veterinary pathogens throughout the administration period. Taking into account the fact that fluoroquinolones are considered to have a concentration‐dependent effect and a long postantibiotic effect against Gram‐negative bacteria, a dose of 2 mg/kg bwt every 24 h could be adequate for marbofloxacin in horses.
Deslorelin acetate (Ovuplant) therapy in cycling mares: effect of implant removal on FSH secretion and ovarian function
Authors: FARQUHAR V. J. , McCUE P. M. , CARNEVALE E. M. , NETT T. M. , SQUIRES E. L.
Published: April 2007

Following induction of ovulation with deslorelin acetate (Ovuplant)1, gonadotrophin concentrations are reduced in the subsequent cycle, leading to increased interovulatory intervals in some mares. This study determined whether implant removal after 2 days prevented the decrease in gonadotrophin concentrations and follicular growth during the ensuing cycle. Twenty‐four mares were randomised equally into 3 groups.Group 1ovulated spontaneously,Groups 2and3received the deslorelin implant to induce ovulation. Two days after treatment, the implant was removed fromGroup 3.On Day 10 postovulation, FSH was lower (P = 0.009) inGroup 2, but not different betweenGroups 1and3.Follicular diameter on Day 14 was less (P<0.05) inGroup 2(19.0 ± 2.1 mm) than inGroups 1and3(36.6 ± 2.5 and 30.5 ± 2.0 mm, respectively). Interovulatory interval was longer (P<0.05) forGroup 2(25.8 ± 2.9 days) compared toGroups 1and3(18.5 ± 0.7 and 19.4 ± 0.3 days, respectively). Removal of the deslorelin implant eliminated the decreased FSH secretion and the increased interovulatory interval associated with implant administration. Therefore, it is recommended that the implant be removed after ovulation is detected to prevent the occurrence of a prolonged interovulatory interval.
Evaluation of nebulised hay dust suspensions (HDS) for the diagnosis and investigation of heaves. 3: Effect of fractionation of HDS
Authors: PIRIE R. S. , DIXON P. M. , McGORUM B. C.
Published: April 2007

To investigate the relative importance of inhaled particulates and soluble components in the response to inhaled hay dust suspension (HDS), heaves (previously termed chronic obstructive pulmonary disease; n = 7) and control (n = 6) horses were given inhalation challenges with whole and fractionated HDS. Fractionation was achieved by centrifugation to yield supernatant (SUP) and particulate debris. The particulates were then washed repeatedly in saline to produce a washed particulate (WP) fraction which comprised mainly fungal spores, and a wash fraction (WF) which comprised saline and soluble components washed from the surface of the particulates. Inhalation of HDS and SUP induced a significant airway neutrophilia in both groups, with the magnitude of the response being significantly greater in heaves horses. SUP induced significantly less airway neutrophilia than HDS in both groups, despite the endotoxin and protease content of HDS and SUP being comparable. WP and WF induced only a slight airway neutrophilia in heaves horses. However, a combined challenge with SUP and WP induced a neutrophilic response approaching the magnitude of that following HDS challenge, indicating that dust particulates contribute to the pulmonary recruitment of neutrophils in heaves. Consequently, inhalation challenge with HDS, which contains both particulates and soluble dust components, may be a more useful tool for the diagnosis and investigation of heaves than aqueous dust extracts, which contain only soluble components.
Biochemical development of subchondral bone from birth until age eleven months and the influence of physical activity
Authors: BRAMA P. A. J. , TeKOPPELE J. M. , BANK R. A. , BARNEVELD A. , van WEEREN P. R.
Published: April 2007

Subchondral bone provides structural support to the overlying articularcartilage, and plays an important role in osteochondral diseases. There is growing insight that the mechanical features of bone are related to the biochemistry of the collagen network and the mineral content. In the present study, part of the normal developmental process and the influence of physical activity on biochemical composition of subchondral bone was studied. Water content, calcium content and characteristics of the collagen network (collagen, hydroxylysine, lysylpyridinoline (LP) and hydroxylysylpyridinoline (HP) crosslinking) of subchondral bone were measured in newborn foals, 5‐month‐old foals (pasture‐grown and box‐confined) and 11‐month‐old foals at 2 differently loaded sites of the proximal articular surface of the first phalanx.

During the first 5 monthspostpartum, water and hydroxylysine content decreased significantly while calcium and collagen content and the amount of HP and LP crosslinks increased significantly. The withholding of physical activity during this developmental phase affected the biochemical characteristics of subchondral bone only at the site that is loaded during physical exercise. At this site, calcium content and both HP and LP crosslink levels increased significantly less than in pasture‐raised animals. During development from 5–11 months, measured parameters remained essentially constant, except for water content, which decreased further.

It is concluded that substantial changes, presumed to be largely exercise‐driven, take place during the normal process of development in the biochemical composition of equine subchondral bone. Normal development of subchondral bone is presumably important for the normal functional adaptation of this bone to the loading conditions it is subjected to and therefore essential to resist the future biomechanical challenges the horse will encounter during its athletic career. The findings from this study and the assumed important role of subchondral bone quality in the pathogenesis of osteochondral disease merit more attention to the role of the collagen network in subchondral bone.
Cultivation and characterisation of primary and subcultured equine keratinocytes
Authors: DAHM A. M. , de BRUIN A. , LIMAT A. , von TSCHARNER C. , WYDER M. , SUTER M. M.
Published: April 2007

We describe the establishment and characterisation of equine keratinocyte cultures with maintenance of a high proliferative capacity up to the second passage. Improved attachment and growth were obtained by seeding primary cells on equine feeder layers. Subcultured keratinocytes showed optimal growth when seeded on collagentype I.The proliferation rate of cells on this substrate exceeded that seen for cells seeded on equine feeder layers. By immunohistochemistry, epithelial origin and state of differentiation of the equine keratinocytes were determined. They expressed keratin and desmoplakin I/II, but lacked keratin 10. Electron microscopy revealed typical features of cultured keratinocytes. Purity of keratinocyte cultures was determined by vimentin staining. This is the first report on the establishment of equine keratinocytes derived from lip epithelium. It forms the basis to study equine keratinocyte biology and the pathogenesis of epidermal diseases. Since wound healing represents a severe problem in equine dermatology, our data may be essential for the establishment of new and improved therapy.
The use of magnetic motor evoked potentials in horses with cervical spinal cord disease
Authors: NOLLET H. , DEPREZ P. , van HAM L. , VERSCHOOTEN F. , VANDERSTRAETEN G.
Published: April 2007

The aim of this study was to investigate the use of magnetic motor evoked potentials as an ancillary diagnostic test in horses with cervical cord lesions.

Transcranial magnetic stimulation was performed in 12 ataxic horses and the results of the evoked responses were compared to those found in normal horses. The latency and peak‐to‐peak amplitude of the potentials in the 12 ataxic horses were significantly different from those measured in normal horses. The configuration of the abnormal potentials was also polyphasic. Normalisation of the evoked potentials occurred in none of the horses, presented after a period of clinical improvement. These findings demonstrate that the technique is also able to detect lesions in horses with subtle clinical signs of incoordination.

Magnetic transcranial stimulation is a valuable ancillary test to assess the integrity of the motortracts. The technique is painless and safe and shows good sensitivity to detect lesions along the descending motor pathways.
The effect of a pectin‐lecithin complex on prevention of gastric mucosal lesions induced by feed deprivation in ponies
Authors: MURRAY M. J. , GRADY T. C.
Published: April 2007

This study examined whether a product containing a pectin‐lecithin complex (Pronutrin)1could prevent gastric lesions induced in the equine gastric squamous epithelial mucosa using a protocol of intermittent feed deprivation that resulted in prolonged increased gastric acidity (Murray and Eichorn 1996). Eight ponies were used and served as theirown controls in 2 trials in which there were 72 h cumulative deprivation (alternating 24 h with no feed, then 24 h free choice hay), with a 4‐week interval between trials. Ponies were assigned randomly to receive either 250 g Pronutrin plus 200 g pelleted feed, or 450 g pelleted feed only. Ponies were conditioned to each treatment for 7 days and received Pronutrin and pellets oronly pellets once daily during the feed deprivation protocol. Gastroscopy was performed at the beginning and conclusion of the feed deprivation protocol. The endoscopist (M.J.M.) was blinded as to treatments, and lesion severity was scored on a scale of 0–5. Gastroscopy revealed normal‐appearing gastric mucosa at the beginning of feed deprivation, with the exception of 2 ponies which had focal squamous mucosal erosion and 1 pony with focal glandularmucosal erosion. After 72 h cumulative feed deprivation, each pony, except 1 pony in one of the trials, developed erosions or ulcers in the gastric squamous mucosa. There was no difference (P = 0.6) in the presence or severity of gastric lesions between treatments. Lesions did not develop in the gastric glandular mucosa as a result of the intermittent feed deprivation with either treatment. In this study, the pectin‐lecithin complex in Pronutrin failed to prevent lesions in the gastric squamous mucosa induced by intermittent feed deprivation.
Inhalation of organic dusts and lipopolysaccharide increases gelatinolytic matrix metalloproteinases (MMPs) in the lungs of heaves horses
Authors: NEVALAINEN M. , RAULO S. M. , BRAZIL T. J. , PIRIE R. S. , SORSA T. , McGORUM B. C. , MAISI P.
Published: April 2007

We report the effects of mouldy hay/straw exposure, inhaled hay dust suspension (HDS) and inhaled lipopolysaccharide (LPS) on bronchoalveolar lavage fluid (BALF) gelatinolytic matrix metalloproteinase (MMP) levels and degree of activation in healthy (n = 6) and heaves‐ (previously termed chronic obstructive pulmonary disease) affected (n = 6 or 7) horses. Gelatinolytic MMPs in BALF were quantified by zymography, and gelatinases were shown by Western immunoblotting to be MMP‐2 and MMP‐9. Hay/straw and HDS challenges increased BALF total gelatinolytic activity only in heaves horses, with the majority of gelatinolytic activity comprising pro‐ and active MMP‐9. The 5 h duration hay/straw challenge increased BALF gelatinolytic MMP activity in heaves horses at 5 and 24 h after the start of this challenge, with activity returning to baseline by Day 4. In contrast to hay/straw and HDS challenges, LPS inhalation increased BALF gelatinolytic MMP activity in both groups. For all challenges, absolute BALF neutrophil counts were highly significantly correlated (P<0.0001) with levels of proMMP‐9 and active MMP‐9, but not with levels of MMP‐2 (P>0.05). As gelatinolytic MMPs are pro‐inflammatory agents, they may contribute to lung dysfunction and tissue destruction in heaves horses exposed to airborne organic stable dusts.
Changes in fibre type composition of gluteus medius and semitendinosus muscles of Dutch Warmblood foals and the effect of exercise during the first year postpartum
Authors: DINGBOOM E. G. , van OUDHEUSDEN H. , EIZEMA K. , WEIJS W. A.
Published: April 2007

In order to obtain broader insights into the equine musculoskeletal system, we studied the fibre type composition of 2 locomotory muscles in biopsies from Dutch Warmblood foals taken at 3 different ages in the first year postpartum. The muscle fibre types were determined histochemically as well as immunohistochemically. ATPase‐characterised IIB fibres appear to express either IId or type IIa plus IId myosin heavy chain (MHC). A high percentage of fibres classified as IIA with ATPase expressed both fast types of MHC. The type I classification by the 2 methods matched almost completely. There was an increase with age of fibres expressing I and IIa MHC in the gluteus medius. At the same time, there was a decrease of fibres expressing IId MHC and fibres co‐expressing MHC IIa and IId. MHC expression of the semitendinosus muscle did not change over time at first, but from age 22–48 weeks there was a decrease in the percentage of type IId fibres. In general, the gluteus medius contained more type I fibres but fewer type IId fibres compared to the semitendinosus. At most ages the fibre type compositions of both muscles correlated with one another. To examine the effect of exercise, one‐third of the foals were given box rest, one‐third received training and one‐third kept at pasture during the first 22 weeks of life. The 3 exercise groups differed in their fibre type composition; however, these differences could not be attributed to the effect of exercise.
Development and application of a scoring system for prognostic evaluation of equine liver biopsies
Authors: DURHAM A. E. , SMITH K. C. , NEWTON J. R. , HILLYER M. H. , HILLYER L. L. , SMITH M. R. W. , MARR C. M.
Published: April 2007

Reasons for performing study: The study was designed to investigate the prognostic value of liver biopsy during investigation of cases of suspected liver disease in mature horses.

Hypothesis: That liver biopsy is the most prognostically useful technique in common usage in the investigation of suspected liver disease.

Methods: This study examined the prognostic value of liver biopsy during the investigation of suspected liver disease in 73 mature horses. Histopathological variables comprising fibrosis, irreversible cytopathology, inflammatory infiltration, haemosiderin accumulation and biliary hyperplasia were found to be significant predictors of nonsurvival and were used to formulate a weighted biopsy score representing a prognostically useful broad comparative index of histopathological severity. Minimum and maximum possible scores were 0 and 14 points, respectively.

Results: Retrospective application of the biopsy scoring system to the study population indicated that horses with scores of 0 or 1 were equally likely to survive to 6 months with a combined mortality of 4%. Horses with biopsy scores between 2 and 6 had a combined mortality of 33% and were at a 12‐fold increased risk of nonsurvival within 6 months (hazard ratio = 12.04, 95%CI 1.34–107.81, P = 0.026) compared to horses with a biopsy score of 0. Horses with biopsy scores between 7 and 14 had a combined mortality of 86% and were at a 46‐fold increased risk of nonsurvival (hazard ratio = 46.01, 95%CI 5.92–357.5, P < 0.001) compared to horses with biopsy score 0.

Conclusions: Application of the biopsy scoring system to histopathological findings in liver biopsy specimens was very useful in predicting survival of cases of suspected liver disease.

Potential relevance: Application of the findings in this study may not be directly applicable to other case populations. However, liver biopsy appears to be the most valuable prognostic technique employed during the investigation of suspected cases of liver disease in mature horses.
West Nile virus infection of Thoroughbred horses in South Africa (2000–2001)
Authors: GUTHRIE A. J. , HOWELL P. G. , GARDNER I. A. , SWANEPOEL R. E. , NURTON J. P. , HARPER C. K. , PARDINI A. , GROENEWALD D. , VISAGE C. W. , HEDGES J. F. , BALASURIYA U. B. , CORNEL A J. , MacLACHLAN N. J.
Published: April 2007

Reasons for performing study: West Nile virus (WNV) infection is endemic in southern Africa. With the recent emergence of WNV infection of horses in Europe and the USAthe present study was performed to estimate the risk of seroconversion to WNV in a cohort of 488 young Thoroughbred (TB) horses.

Objectives: To estimate the risk of seroconversion to WNV among a cohort of South African TB yearlings sold at the 2001 National Yearling Sales (NYS) and to determine whetherthe risk varied geographically. Two horses were also infected with a recent South African isolate of WNV to evaluate its virulence in horses.

Methods: Serum samples were collected from the cohort of 488 TB yearlings at the 2001 NYS. Serum samples that were collected from the same horses at the time that they were identified were sourced from ourserum bank. Sera from 243 of the dams that were collected at the time that the foals were identified were also sourced from our serum bank. These sera were subjected to serum neutralisation (SN) tests for antibody to WNV.

Results: Approximately 11% of yearlings seroconverted to WNV on paired serum samples collected from each animal approximately 12 months apart. Studfarms with WNV‐seropositive yearlings were widely distributed throughout South Africa and SN tests on sera from theirdams indicated that exposure to WNVwas even more prevalent (75%) in this population. Neurological disease was not described in any of the horses included in this study and 2 horses inoculated with a recent lineage 2 South African isolate of WNV showed no clinical signs of disease after infection and virus was not detected in their blood.

Conclusions: Infection of horses with WNV is common in South Africa, but infection is not associated with neurological disease.

Potential relevance: In contrast to recent reports from Europe, North Africa, Asia and North America, the results of our field and experimental studies indicated that exposure of horses to the endemic southern African strains of WNV was not associated with neurological disease.
Inclined running increases pulmonary haemorrhage in the Thoroughbred horse
Authors: KINDIG C. A. , RAMSEL C. , McDONOUGH P. , POOLE D. C. , ERICKSON H. H.
Published: April 2007

Reasons for performing study: Capillary stress failure‐induced (exercise‐induced) pulmonary haemorrhage (EIPH) during intense running in horses is thought to involve both intravascular (i.e. mean pulmonary arterial pressure [Ppa] >100 mmHg) and extravascular (e.g. negative inspiratory pressure swings) mechanisms.

Hypothesis: That inclined running would reduce breathing frequency (coupled to stride frequency) and increase tidal volume thus increasing lung volume changes and intrapleural pressure swings resulting in more pronounced EIPH.

Methods: Six Thoroughbred horses were run to volitional fatigue (incremental step test) on a level (L) and inclined (I; 10%) treadmill in random order. Pulmonary minute ventilation, arterial blood gases and mean Ppa were obtained during each run while EIPH severity was quantified via bronchoalveolar lavage (BAL) 30 mins post run.

Results: Time to fatigue did not differ between trials (P>0.05). At end‐exercise, breathing frequency was reduced (L, 127.8 ± 3.0; I, 122.6 ± 2.1 breaths/min; P<0.05) and tidal volume increased (L, 11.5 ± 0.6; I, 13.1 ± 0.5 L; P<0.05) during inclined running. No differences existed in end‐exercise plasma [lactate] between trials (L, 24.5 ± 2.9; I, 26.2 ± 3.4 mmol/l, P>0.05); however, the mean peak Ppa was reduced during the inclined run (L, 105+5; I, 96 ± 4 mmHg, P<0.05). In the face of reduced Ppa, EIPH severity was increased significantly (P<0.05) during the inclined vs. level run (L, 37.0 ± 11.7; I, 49.6 ± 17.0 times106red blood cells/ml BAL fluid).

Conclusions: Although inclined running lowered peak Ppa, EIPH severity was increased. It is likely that this effect resulted, in part, from an altered ventilatory pattern (i.e. increased tidal volumes and associated intrapleural pressure changes).

Potential relevance: This conclusion supports an important role for extravascular factors in the aetiology of EIPH.
Estimates of heritability for ossification of the cartilages of the front feet in the Finnhorse
Authors: RUOHONIEMI M. , AHTIAINEN H. , OJALA M.
Published: April 2007

Reasons for performing study: Ossification of the cartilages in the foot is common in coldblooded horses, but prevalence as well as ossification pattern varies between breeds; research on estimation of heritability for the condition has been limited.

Objectives: Our purpose was to calculate estimates of 1) heritability for ossification parameters of the cartilages in the front feet of the Finnhorse and 2) genetic correlations between the different ossification parameters.

Methods: Estimates of heritability for different ossification parameters of the cartilages in the front feet and of genetic correlations between different parameters were evaluated in data consisting of dorsopalmar radiographs of the front feet and pedigree up to the fourth generation of 964 Finnhorses (age ≥2 years; 345 females and 619 males). Ossification at the base of the cartilages and total ossification, including separate centres of ossification, were graded 0–5 according to the most proximal point of ossification and the presence of separate centres of ossification was recorded separately. The data were analysed using a model including a fixed sex‐age subclass effect and a random animal effect. Variance and covariance components were estimated with the restricted maximum likelihood (REML) method assuming an animal model.

Results: Females had more ossification than males and this difference increased with age. The ossification in the medial cartilages progressed significantly with age in females but not in males. In the lateral cartilages, the increase in ossification with age was evident in both sexes. Separate centres of ossification were an incidental finding. Estimates of heritability for the ossification parameters varied slightly between the cartilages as well as between the front feet. For total ossification, the estimates of heritability varied between 0.31 (right lateral) and 0.50 (left medial) and were slightly higher for ossification at the base of the cartilages. High genetic correlations were found for total ossification between the medial and lateral cartilages in the foot and for parallel ossification parameters between the right and left foot.

Conclusions: The estimates of heritability were relatively high, and both cartilages and front feet have a similar genetic tendency to ossify.

Potential relevance: This information is useful in further studies assessing other factors contributing to the ossification process and also in the planning and modifying breeding programmes.
Dystocia in a referral hospital setting: approach and results
Authors: BYRON C. R. , EMBERTSON R. M. , BERNARD W. V. , HANCE S. R. , BRAMLAGE L. R. , HOPPER S. A.
Published: April 2007

Reasons for performing study: Dystocia in the mare is an emergency in which duration has a profound effect on survival of the foal. Specific examination of the effects of dystocia duration on foal survival provides information to enable horse care personnel and veterinarians to manage these cases more effectively and maximise the chances of obtaining a live foal.

Hypothesis: Dystocia duration would have a negative impact on foal survival while method of dystocia resolution would not have an effect on foal survival. Additionally, we were interested in determining the effects of dystocia on subsequent fertility.

Methods and results: In the years 1986–1999, 247 dystocias were admitted. Of these, 91% resulted in survival and discharge of the mare, 42% in delivery of a live foal, and 29% of foals survived to discharge. Period from hospital arrival to delivery for foals alive at discharge (23.0 ± 14.1 mins) was not significantly different than for foals not surviving (24.8 ± 10.6 mins) (P>0.05); and from chorioallantoic rupture to delivery for foals alive at discharge (71.7 ± 34.3 mins) was significantly less than for foals not surviving (85.3 ± 37.4 mins) (P<0.05). Average predystocia live foaling rates for all mares with available records was 84%. Overall post dystocia live foaling rates over the entire period of this study were 67%. Of mares bred in the year of the dystocia, 59% had a live foal in the year following.

Conclusions: Based on these results, dystocia duration has a significant effect on foal survival and resolution methods should be chosen to minimise this time, as the difference between mean dystocia duration for foals that lived and those that did not in this study was 13.6 mins. Post dystocia foaling rates reported here are higher than previously reported for both same‐season and overall breedings, indicating same‐season breeding may be rewarding for select dystocia cases.

Potential relevance: Dystocia resolution methods that minimise delivery time may maximise foal survival. Post dystoicia breeding may be rewarding in select cases.
Validation of the 13C‐octanoic acid breath test for measurement of equine gastric emptying rate of solids using radioscintigraphy
Authors: SUTTON D. G. M. , BAHR A. , PRESTON T. , CHRISTLEY R. M. , LOVE S. , ROUSSEL A. J.
Published: April 2007

Reasons for performing study: Disordered gastric motility may be a significant factor in the pathogenesis of many equine conditions. Although tests for liquid phase emptying rate have been validated in the horse, there are no effective tests for solid phase emptying measurement that can be performed routinely in the field.

Objectives: The objective of this study was the assessment of a novel stable isotope technique, the13C‐octane acid breath test (13C‐OABT), for the measurement of gastric emptying of solid ingesta, by direct comparison with the optimum method of gastric scintigraphy.

Methods: To facilitate dual measurement of gastric emptying, a test meal was used containing baked egg yolk labelled with both13C‐octanoic acid and99mtechnetium sulphur colloid. Simultaneous, serial lateral gastric scintigraphs and expiratory breath samples were obtained in 12 healthy horses after voluntary ingestion of the test meal. Analysis of breath13CO2:12CO2ratio was performed by continuous flow isotope ratio mass spectrometry. Power regression was used to determine the gastric emptying coefficient, the gastric half‐emptying time (t1/2) and duration of the lag phase (tlag).

Results: Significant correlations (P<0.001) were found between the 2 techniques for measurement of both t1/2and tlag. In addition, scintigraphic left t1/2was correlated significantly to breath test gastric emptying coefficient (P<0.001).

Conclusions: It was concluded that the13C‐octanoic acid breath test is a reliable diagnostic procedure to measure gastric emptying rate of solids in the horse.

Potential relevance: Being safe, noninvasive and easy to perform, this test has potential value as both sensitive diagnostic modality and humane research tool for motility studies.
Thoracic trauma in foals:post mortemfindings
Authors: SCHAMBOURG M. A. , LAVERTY S. , MULLIM S. , FOGARTY U. M. , HALLEY J.
Published: April 2007

Reasons for performing study: Thoracic trauma occurs in newborn foals and may cause associated clinical signs; this condition remains poorly documented.

Objectives: The purpose of this study was to describe the pathological features of thoracic trauma in newborn foals presented for necropsy examination between 1990 and 2000.

Methods: Necropsy reports of foals with thoracic trauma from 1990–2000 were reviewed. Subject details, clinical signs, thoracic and abdominal lesions were noted and analysed statistically.

Results: Sixty‐seven (9%) of 760 necropsied foals had thoracic trauma. In 19 foals, fractured ribs were considered to be the cause of death (Group A). The remaining foals had fractured ribs (Group B, n = 20) or rib contusions (Group C, n = 28) that were incidental findings. Ribs 3 to 8 accounted for 86% of the traumatised bones. The most common site of injury was the costochondral junction and an area immediately above it (94%). InGroup A, all but 2 foals died within the first 8 dayspost partum.Haemothorax and subsequent pulmonary collapse was cited most commonly as the cause of death (53%). Diaphragmatic rupture and hernia (n = 2) also occurred.

Conclusions: The focal site, consistent location and presence of lesions during the first weekpost partum, all suggest that thoracic trauma in newborn foals probably occurs during parturition.

Potential relevance: The description of lesions and site of occurrence of thoracic trauma in foals will increase awareness and improve the diagnosis and treatment of this life threatening condition.
Potentiation of the extracellular release of equine neutrophil elastase and alpha‐1‐proteinase inhibitor by a combination of two bacterial cell wall components: fMLP and LPS
Authors: DAGLEISH M. P. , BRAZIL T. J. , SCUDAMORE C. L.
Published: April 2007

Reasons for performing study: Lipopolysaccharide (LPS) and N‐formyl‐methionyl‐leucyl‐phenylalanine (fMLP)‐like peptides are Gram‐negative bacterial cell wall components which, when released into the peripheral circulation in endotoxaemia, have the potential to activate leucocytes. In vitro, equine neutrophils require priming with LPS in order to generate reactive oxygen intermediates (ROI) in response to fMLP.

Objectives: The aim of this study was to examine whether the release of other neutrophil products is similarly dependent on priorpriming with LPS. In particular, neutrophil elastase (NE), a potent proteolytic enzyme, and its major inhibitor, alpha‐1 proteinase inhibitor, were investigated.

Methods: Neutrophils were isolated from equine peripheral blood (n = 5) by discontinuous Percoll gradient preparative centrifugation and primed with LPS prior to stimulation with fMLP. ROI were measured by lucigenin dependent chemiluminescence (LDCL). Concentrations of NE and API were determined by ELISA on cell free supernatants taken at 0, 2, 10, 30, 60 and 90 mins post stimulus. Data was analysed by Kruskal‐Wallis and Mann‐Whitney Tests.

Results: Sequential exposure of Percoll purified equine blood neutrophils in vitro to LPS followed by fMLP resulted in the greatest release of NE from equine neutrophils and was required for ROI generation. However, LPS or fMLP stimulation alone resulted in an in crease in NE release compared to unstimulated control cells. In contrast, significant API release was only induced by LPS stimulation or fMLP stimulation only after LPS priming, not fMLP on its own.

Conclusions: These results suggest that different stimuli (fMLP or LPS) are capable of invoking similar responses from equine neutrophils with respect to NE release yet different ones with respect to API release.

Potential relevance: In addition, demonstration of elastase release induced by LPS and/or fMLP suggests that monitoring serum elastase levels is a potential diagnostic tool for detecting the early onset of endotoxaemia in the horse.
Differential distribution of cathepsins B and L in articular cartilage during skeletal development in the horse
Authors: GLÄSER K. E. , DAVIES M. E. , JEFFCOTT L. B.
Published: April 2007

Reasons for performing study: This study was designed to examine a new role for cysteine proteinases in the process of endochondral ossification.

Objectives: The aim of the present study was to investigate the presence and distribution of cathepsin B and cathepsin L in equine articular cartilage during development.

Methods: Full‐depth cartilage samples from a total of 40 horses (age range: 4 month fetuses to 2 years) were examined and enzymes detected by immunocytochemical localisation.

Results: Observations on the presence of cathepsins B and L revealed significant age‐related differences, resulting in clear division of the animals into 2 age groups: i) fetuses and neonates; ii) young growing horses (age 4 weeks to 2 years). Cathepsin B was not detected in cartilage from the majority of fetuses and neonates but was located characteristically in chondrocytes at the articular surface and hypertrophic zone in all growing horses. In contrast, cathepsin L was predominantly present in fetal and neonatal cartilage, located primarily in proliferating chondrocytes.

Conclusions: This study is the first to demonstrate differential and site‐specific roles for cathepsin B and cathepsin L in skeletal development in the horse.

Potential relevance: The demonstrated involvement of cathepsins B and L in endochondral ossification is of relevance to developmental orthopaedic diseases such as osteochondrosis in which there is a focal failure of bone formation.
Ultrasonographic abnormalities detected in the sacroiliac area in twenty cases of upper hindlimb lameness
Authors: TOMLINSON J. E. , SAGE A. M. , TURNER T.A.
Published: April 2007

Reasons for performing study: The pelvis is covered with extensive musculature and often presents a challenge in diagnostic imaging. Ultrasonography provides diagnostic information about soft tissue, articular cartilage and bone surfaces, although little information exists about the normal ultrasonographic appearance of the equine sacroiliac region.

Objectives: To determine the clinical applicability of ultrasonographic examination in horses with sacroiliac pain.

Methods: Horses presented to the University of Minnesota Veterinary Teaching Hospital for hindlimb lameness were evaluated and lower limb lameness was ruled out with examination and local anaesthesia. Twenty cases were diagnosed with sacroiliac pain, characterised by response to palpation over thetuber sacrale.Seven of the 20 had visible a symmetry of thetuber sacrale.Ultrasonography was performed percutaneously andper rectum.Structures imaged were measured and compared to normal reference measurements. Other methods used to confirm diagnoses included thermography, scintigraphy and radiology.

Results: All 20 cases with sacroiliac pain showed ultrasonographic abnormalities of the sacroiliac area. Abnormalities were detected in the dorsal sacroiliac ligaments. Ligament size was significantly different from the normal ranges (P<0.01). Malalignment of the sacroiliac area and sacral fractures were also imaged.

Conclusions: Ultrasonography of the sacroiliac region aided diagnosis of ligament damage and displacement of bone surfaces; and may aid in monitoring the progression of healing.

Potential relevance: Diagnostic ultrasound is readily available to most practitioners. Therefore the findings of this study show that diagnosis of sacroiliac injuries is possible in the field.
Effects of dosage titration of methylprednisolone acetate and triamcinolone acetonide on interleukin‐1‐conditioned equine articular cartilage explantsin vitro
Authors: DECHANT J. E. , BAXTER G. M. , FRISBIE D. D. , TROTTER G. W. , McILWRAITH C. W.
Published: April 2007

Reasons for performing study: Osteoarthritis is a frequent sequela of joint disease, especially with severe injuries or if attempts at therapy are unsuccessful. Negative and positive effects of corticosteroid treatment of articular cartilage have been demonstrated byin vitroandin vivostudies.

Objectives: To assess the metabolic effects of varying dosages of methylprednisolone acetate (MPA) and triamcinolone acetonide (TA) on interleukin‐1α (IL‐1) conditioned equine cartilage explants. Our hypothesis was that lower dosages of corticosteroids would be less detrimental to cartilage metabolism than higher dosages. TA would be less detrimental to cartilage metabolism than MPA.

Methods: Treatment groups included articular cartilage explants with no IL‐1 (control), IL‐1 alone, and IL‐1 plus 10, 5, 1 and 0.5 mg/ml MPA or 1.2, 0.6, 0.12 and 0.06 mg/ml TA. Explants were labelled with35SO4priorto the beginning and end of the experiment to assess glycosaminoglycan (GAG) degradation and synthesis, respectively. Total GAG content in media and explants and total cartilage DNA were also analysed.

Results: MPA and TA reduced GAG synthesis compared to control and IL‐1 alone. The highest dosage of MPA (10 mg/ml) reduced GAG synthesis less than lower dosages of MPA and all dosages of TA Compared to IL‐1 alone, all dosages of TA and lower dosages of MPA increased GAG degradation. MPA at 10 mg/ml reduced GAG degradation. Both MPA and TA increased media GAG content compared to control and IL‐1 explants. Total cartilage GAGs were unchanged with MPA, but reduced with TA, compared with IL‐1 alone. Total cartilage DNA was decreased with MPA and increased with TA compared to IL‐1 and control explants.

Conclusions: MPA and TA did not counteract the negative effects of IL‐1 and did not maintain cartilage metabolism at control levels. Lower dosages of MPA and TA were not less detrimental to cartilage metabolism than higher dosages. TA did not appear to be less harmful than MPA on cartilage metabolism. The results of this study differ from the findings of comparablein vivostudies.

Potential relevance: The low numbers of horses used in this study limits extrapolation of these findings to the equine population; however, this study also questions the clinical relevance of thisin vitromodel.
Clostridium difficile: prevalence in horses and environment, and antimicrobial susceptibility
Authors: BÅVERUD V. , GUSTAFSSON A. , FRANKLIN A. , ASPÁN A. , GUNNARSSON A.
Published: April 2007

Reasons for performing study: Clostridium difficilehas been associated with acute colitis in mature horses.

Objectives: To surveyC. difficilecolonisation of the alimentary tract with age, occurrence of diarrhoea and history of antibiotic therapy; and to study the occurrence and survival ofC. difficilein the environment and antimicrobial susceptibility of isolated strains.

Methods: A total of 777 horses of different breeds, age and sex were studied. Further, 598 soil samples and 434 indoor surface samples were examined. Antimicrobial susceptibility of 52 strains was investigated by Etest for 10 antibiotics.

Results: In horses that developed acute colitis during antibiotic treatment, 18 of 43 (42%) were positive toC. difficileculture and 12 of these (28%) were positive in the cytotoxin B test Furthermore,C. difficilewas isolated from a small number of diarrhoeic mature horses (4 of 72 [6%]) with no history of antibiotic treatment, but not from 273 healthy mature horses examined or 65 horses with colic An interesting new finding was that, in normal healthy foals age <14 days,C. difficilewas isolated from 1/3 of foals (16 of 56 [29%]). All older foals (170) except one were negative. Seven of 16 (44%) nondiarrhoeic foals treated with erythromycin or gentamicin in combination with rifampicin were also excretors ofC. difficile.

On studfarms, 14 of 132 (11%) outdoorsoil samples were positive forC. difficilein culture, whereas only 2 of 220 (1%) soil samples from farms with mature horses were positive forC. difficile(P = <0.001). By PCR, it was demonstrated that strains from the environment and healthy foals can serve as a potential reservoir of toxigenicC. difficile.The experimental study conducted here found thatC. difficilesurvived in nature and indoors for at least 4 years in inoculated equine faeces. The susceptibility of 52 strains was investigated for 10 antibiotics and all were susceptible to metronidazole (MIC≤4 mg/l) and vancomycin (MIC≤2 mg/l).

Conclusions: C. difficileis associated with acute colitis in mature horses, following antibiotic treatment. Furthermore,C. difficilewas isolated from 1 in 3 normal healthy foals age <14 days.

Potential relevance: Strains from healthy foals and the environment can serve as a potential reservoir of toxigenicC. difficile.
Comparison of unfractioned and low molecular weight heparin for prophylaxis of coagulopathies in 52 horses with colic: a randomised double‐blind clinical trial
Authors: FEIGE K. , SCHWARZWALD C. C. , BOMBELI TH.
Published: April 2007

Reasons for performing study: Unfractioned heparin (UFH) is widely used for prophylaxis of coagulation disorders, especially in colic‐affected horses. However, it is accompanied by certain side effects.

Objectives: To compare the efficacy and side effects of unfractioned and low molecular weight heparin (LMWH) in horses with colic.

Methods: The study was carried out as a randomised, double‐blind, controlled clinical trial. Fifty‐two horses with colic were treated subcutaneously with either UFH (heparin calcium, 150 iu/kg bwt initially, followed by 125 iu/kg bwt q. 12 h for 3 days and then 100 iu/kg bwt q. 12 h) or LMWH (dalteparin, 50 iu/kg bwt q. 24 h). All horses underwent daily physical examination including assessment of jugular veins, local reaction to heparin injections, haematological evaluation and coagulation profiles over up to 9 days.

Results: The type of heparin used did not affect the general behaviour and condition. There were significantly more jugular vein changes in horses treated with UFH. Packed cell volume decreased significantly within the first few days of UFH treatment, but did not change significantly in horses treated with LMWH. Activated partial thromboplastin time (aPTT) and thrombin time (TT) were prolonged in horses treated with UFH but not in those treated with LMWH.

Conclusions: It was concluded that, in comparison to UFH, LMWH has markedly fewer side effects in horses.

Potential relevance: Therefore, LMWH is recommended for prophylaxis of coagulation disorders in colic patients.
Lysosomal storage disease in Sida carpinifolia toxicosis: an induced mannosidosis in horses
Authors: LORETTI A. P. , COLODEL E. M. , GIMENO E. J. , DRIEMEIER D.
Published: April 2007

Reasons for performing study: This study reports a neurological disease unrecognised until now in ponies in southern Brazil.

Hypothesis: Epidemiological data strongly suggests that the ingestion of Sida carpinifolia is involved in the aetiology. We tested the hypothesis that it is an acquired lyosomal storage disease.

Methods: Following the death of 3 ponies, all ponies from the premises were closely monitored; epidemiological data and clinical findings carefully recorded. Fragments of several organs, including CNS, were fixed in neutral formalin and embedded in paraffin‐wax. Sections were stained with haematoxylin and eosin. Representative sections of the cerebellum and trigeminal ganglia were submitted to lectin histochemical procedures.

Results: The neurological disorder, characterised by stiff gait, muscle tremors, abdominal pain and death, was observed on a farm with 3 hectares of pasture. Three of 11 ponies died 15–20 days after they had been introduced into a new paddock heavily infested by the plant Sida carpinifolia. No significant gross lesions were observed.

The main histological findings included multiple cytoplasmatic vacuoles in swollen neurones in the brain, cerebellum, spinal cord, autonomic ganglia (trigeminal and celiac ganglia), and submucosal and myenteric plexus of the intestines. In the kidneys, there was marked vacuolation of the proximal convoluted tubular cells. Sections of cerebellum and trigeminal ganglion were submitted to lectin histochemistry. The vacuoles in different cerebellar and ganglion cells reacted strongly to the following lectins: Concanavalia ensiformis, Triticum vulgaris and succinylated‐Triticum vulgaris.

Conclusions: The pattern of staining coincides with that of both swainsonine toxicosis and inherited mannosidosis reports. The histopathological changes were similar to those described in S. carpinifolia spontaneous and experimental poisoning in goats. This disease seems to be similar to Swainsona, Oxytropis and Astragalus toxicosis.

Potential relevance: S. carpinifolia should be evaluated as a possible cause in the diagnosis of equine neuropathies.