bluuebunny/crossref_metadata_2025 huggingface dataset:
The hindlimb in walking horses: 1. Kinematics and ground reaction forces
Authors: HODSON E. , CLAYTON H. M. , LANOVAZ J. L.
Published: April 2007

The objective was to study associations between kinematics and ground reaction forces in the hindlimb of walking horses. Video (60 Hz) and force (2000 Hz) data were gathered for 8 strides from each of 5 sound horses during the walk. Sagittal plane kinematics were measured concurrently with the vertical and longitudinal ground reaction forces. The hindlimb showed rapid loading and braking in the initial 10% stride. The stifle, tarsal and coffin joints flexed and the fetlock joint extended during this period of rapid loading. The vertical ground reaction force showed 2 peaks separated by a dip; this pattern was similar to the fetlock joint angle‐time graph. Peaks in the longitudinal ground reaction force did not appear to correspond with kinematic events. Total braking impulse was equal to total propulsive impulse over the entire stride. Flexion and extension of the hip were responsible for protraction and retraction of the entire limb. Maximal protraction occurred shortly before the end of swing and maximal retraction occurred during breakover. During the middle part of stance the tarsal joint extended slowly, while the stifle began to flex when the limb was retracted beyond the midstance position at 28% stride. Flexion cycles of the stifle and tarsal joints were well coordinated during the swing phase to raise the distal limb as it was protracted. The results demonstrate a relationship between limb kinematics and vertical limb loading in the hindlimbs of sound horses. Future studies will elucidate the alterations in response to lameness.
Risk factors associated with hindlimb lameness and degenerative joint disease in the distal tarsus of Icelandic horses
Authors: AXELSSON M. , BJÖRNSDOTTIR S. , EKSELL P. , HÄGGSTRÖM J. , SIGURDSSON H. , CARLSTEN J.
Published: April 2007

The aim of this study was to evaluate potential risk factors associated with hindlimb lameness and radiographic signs of degenerative joint disease (DJD) in the distal tarsus in Icelandic horses. The material consisted of riding horses (n = 420) age 6–12 years sired by 17 selected sires representing all major breeding lines, and of riding horses (n = 194) in the same age range sired by other sires. The examination protocol included the following: interview with owners/trainers, assessment of conformation, motion evaluation and radiographic examination. At the interview, data related to factors outside the horse (environmental variables) and data associated directly with the horse (intrinsic variables) were obtained. Data analysis was performed in 2 steps: screening using bivariate analysis, followed by testing with a multivariate logistic regression model. In the multivariate analysis, the factors of sire, age when broken to saddle and stud show participation were strongly associated with the prevalence of lameness. Height at the croup and ability to perform different gaits were also associated with the prevalence of lameness, but to a lesser degree. The risk factors of age, tarsal angle and birthplace were significantly associated with radiographic signs of DJD in the distal tarsus. Neither the variation in applied training intensity, the use of a professional oramateurtrainernorthe temperament or front limb action of the individual horse was significantly associated with the prevalence of hindlimb lameness and/or radiographic signs of DJD in the distal tarsus in the Icelandic horse.
Heparinised blood ionised calcium concentrations in horses with colic or diarrhoea compared to normal subjects
Authors: van der KOLK J. H. , NACHREINER R. F. , REFSAL K. R. , BROUILLET D. , WENSING Th.
Published: April 2007

Our objectives were to 1) establish ionised calcium (ICa), C‐terminal PTH and biologically active PTH (intact molecule) concentrations in blood from normal horses, 2) examine the stability of ionised calcium and acid‐base values in stored equine heparinised blood and serum and 3) check the applicability of the formulas based on these parameters in certain disease states.

Mean ± s.d. % ionised calcium in heparinised blood of normal Warmbloods was 51 ± 2.7 (n = 20) of total calcium, range 1.45–1.75 mmol/l (n = 15) at Michigan State University and 1.43–1.69 mmol/l (n = 20) at Utrecht University. Mean ± s.d. EDTA plasma concentration for intact PTH in normal horses measured 0.6 ± 0.3 pmol/l (n = 11). Both mean serum and the heparinised blood ionised calcium concentrations changed (not significantly) after 102 h storage at room temperature. Six cycles of freezing and thawing did not affect serum ionised calcium concentration significantly. Ionised calcium concentration and pH in heparinised blood of 20 normal Warmbloods were used to calculate the regression equation for the prediction of the adjusted ionised calcium concentration to a pH of 7.4. The linear regression equation found was: adjusted plasma ICa at pH 7.4 mmol/l =−6.4570 + 0.8739 × (measured pH) + 0.9944 × (measured ICa mmol/l). By means of this formula, mean adjusted ionised calcium concentration in heparinised blood calculated was 100% of the actual value given by the analyser in the normal horses. When using this formula in horses with colic or diarrhoea, mean adjusted ionised calcium concentration was underestimated by 0.2 and 0.3%, respectively. Furthermore, to adjust the measured ionised calcium concentration in heparinised blood to a pH of 7.4 in healthy as well as in 2 groups of diseased horses 2 formulas with a good prediction are now available.
Treatments to promote colonic hydration: enteral fluid therapy versus intravenous fluid therapy and magnesium sulphate
Authors: LOPES M. A. F. , WALKER B. L. , II N. A. WHITE , WARD D. L.
Published: April 2007

Although large intestine impactions are commonly treated with i.v. fluids combined with the osmotic laxative MgSO4, enteral fluids are less expensive and also appear to be efficacious for impactions. Therefore, this study was conducted to compare the systemic and gastrointestinal effects of enteral fluids with the changes produced by i.v. fluids combined with MgSO4. Four horses with a fistula in the right dorsal colon alternately received both treatments in 2 periods one week apart. Sixty litres of fluids were administered continuously (10 l/h) through a venous catheter or a nasogastric tube. Magnesium sulphate (1 g/kg bwt) was administered via nasogastric tube before i.v. fluid therapy. Two horses had mild abdominal discomfort at the end of enteral fluid therapy. Pollakiuria, hypostenuria, increased bodyweight, increased faecal and ingesta hydration, and decreased PCV, plasma protein and plasma magnesium were produced by both treatments. Abdominal distention and more pronounced changes in bodyweight and ingesta hydration were seen with enteral fluids. Intravenous fluids plus MgSO4produced hypocalcaemia and more pronounced changes in plasma protein. These results indicate that enteral fluid therapy is more effective in promoting ingesta hydration and produces less pronounced systemic effects than i.v. fluid therapy plus MgSO4.
High volume continuous venovenous haemofiltration (HV‐CVVH) in an equine endotoxaemic shock model
Authors: VEENMAN J. N. , DUJARDIN C. L. L. , HOEK A. , GROOTENDORST A. , KLEIN W. R. , RUTTEN V. P. M. G.
Published: April 2007

Equine acute abdominal disease is often associated with shock. Important aspects in the onset of this complication include hypovolaemia, the translocation of endotoxins from the gut and the subsequent activation of the cytokine network. The clinical efficacy of high volume continuous venovenous haemofiltration (HV‐CVVH) and the clearance of cytokines were therefore investigated in an equine endotoxaemic model. Ten male Shetland ponies received a slow infusion of LPS (2 μg/kg bwt) under general anaesthesia. The treatment group (n = 5) received HV‐CVVH (2 ml/kg bwt/min) using a 75 kD polymethylmethacrylate (PMMA filter). Haemodynamic, blood variable and cytokine (TNF, IL‐1 and IL‐6) measurements were performed every 30 min for a 6 h period. The ponies showed a typical reaction in mean pulmonary arterial pressure, blood chemical and haematological markers after LPS challenge. No significant differences were found between the treatment group and the control group. Only a slight increase in cardiac index and no marked decrease in mean arterial pressure were seen. A clear cytokine response was found in all ponies, though substantially different in magnitude between individuals. The clearance of cytokines from the blood increased in time, but did not lead to significant decrease in serum levels. In this study, HV‐CVVH with a PMMA filter did not prove to have a significant beneficial effect on the course of experimental endotoxaemia in horses. However, in a more severe model, better efficacy might be obtained. Testing additional filters might lead to a more suitable therapy for horses.
The effects of xylazine, detomidine, acepromazine and butorphanol on equine solid phase gastric emptying rate
Authors: SUTTON D. G. M. , PRESTON T. , CHRISTLEY R. M. , COHEN N. D. , LOVE S. , ROUSSEL A. J.
Published: April 2007

The aim of this study was to measure the effects of specific commonly used sedative protocols on equine solid phase gastric emptying rate, using the13C‐octanoic acid breath test (13C‐OABT). The gastric emptying of a standard13C‐labelled test meal was measured once weekly in 8 mature horses over two 4 week treatment periods. Each horse acted as its own control. In treatmentPeriod 1, saline (2 ml i.v.), xylazine (0.5 mg/kg i.v.), detomidine (0.01 mg/kg i.v.) or detomidine/butorphanol combination (0.01/0.02 mg/kg i.v.) was administered in randomised order after ingestion of the test meal. During treatmentPeriod 2, test meal consumption was followed by saline, xylazine (1.0 mg/kg i.v.), or detomidine (0.03 mg/kg i.v.) administration, or preceded by acepromazine (0.05 mg/kg i.m.) in randomised order. The13C:12C ratio of sequential expiratory breath samples was determined by isotope ratio mass spectrometry, and used to measure the gastric half‐emptying time, t1/2, and duration of the lag phase, tlag, for each of the 64 tests.

In treatmentPeriod 1, detomidine/butorphanol prolonged both t1/2and tlagwith respect to xylazine 0.5 mg/kg and the saline control (P<0.05). InPeriod 2, detomidine 0.03 mg/kg delayed each parameter with respect to saline, acepromazine and xylazine 1.0 mg/kg (P<0.001). Xylazine 1.0 mg/kg also lengthened tlagrelative to the saline control (P = 0.0004), but did not cause a significant change in t1/2. Comparison of treatment periods showed that the inhibitory effect of detomidine on gastric emptying rate was dose related (P<0.05). These findings may have clinical significance for case selection when these agents are used for purposes of sedation and/or analgesia.
In vitroinvestigation of the interaction between nitric oxide and cyclo‐oxygenase activity in equine ventral colon smooth muscle
Authors: VAN HOOGMOED L. M. , HARMON F. A. , STANLEY S. , WHITE J. , SNYDER J.
Published: April 2007

The objective of this study was to determine if a correlation exists between the presence of nitric oxide and prostaglandin release in the equine ventral colon smooth muscle, since this relationship may accentuate the inflammatory process during intestinal injury. Tissue was collected from the ventral colon, cut into muscle strips oriented along the circular, longitudinal and taenial layers, and mounted in a tissue bath system. Samples of the bath fluid were collected before, following electrical field stimulation (EFS), and following EFS in the presence of L‐NAME, a nitric oxide synthase inhibitor. Muscle strips were also obtained following systemic administration of a cyclo‐oxygnease inhibitor and samples were collected using the previously described protocol. Concentrations of prostaglandins were determined in the fluid samples using an ELISA. Electrical field stimulated release of nitric oxide produced a significant increase in prostaglandin production which did not occur in the presence of L‐NAME. Systemic administration of flunixin meglumine reduced prostaglandin levels at all sampling periods, although a small increase was present following EFS. The results of this study support the hypothesis that there is a correlation between the release of nitric oxide and the production of prostaglandins in the smooth muscle of the large colon. This association between nitric oxide and prostaglandin may act as an important regulatory mechanism for various physiological mechanisms, such as vascular smooth muscle tone, and may contribute to amplified tissue injury when the induced forms of both enzymes are activated during an inflammatory insult. This suggests that the use and development of COX2 and iNOS inhibitors may help attenuate the inflammatory response following intestinal injury.
Long‐term survival of equine surgical colic cases. Part 1: Patterns of mortality and morbidity
Authors: PROUDMAN C. J. , SMITH J. E. , EDWARDS G. B. , FRENCH N. P.
Published: April 2007

Postoperative complications and mortality can occur many weeks or months after colic surgery. We are interested in the long‐term outcome of these cases. This study documents patterns of mortality and morbidity among 341 horses that recovered from colic surgery March 1998–August 2000. The progress of each horse was rigorously followed by periodic telephone and postal questionnaires. Event time data were recorded for each animal and a total of 321 horse years of survival, together with death from all causes, colic‐related death and various postoperative complications.

Postoperative survival (of all horses excluding grass sickness cases) was triphasic over the first 600 days and there was marked mortality in the first 10 days postoperatively. The probability of survival postoperatively decreased to 0.87 by 10 days, 0.82 by 100 days and declined slowly to 0.75 at 600 days. Horses suffering from epiploic foramen entrapment had a significantly reduced probability of postoperative survival (RR = 2.1, P = 0.033). The causes of death for 104 horses that died postoperatively and the prevalence of postoperative complications are recorded for the study population. Postoperative colic was the most prevalent complication with 100 horses (29%) suffering one or more episodes. However, only 16 horses (4.6%) suffered 3 or more episodes. The incidence of postoperative colic was 0.55 episodes/horse year at risk. This study provides data that will inform the prognosis for postoperative colic cases and identifies epiploic foramen entrapment as carrying a worse prognosis for survival than other strangulating lesions.
Quantitative detection of atropine‐delayed gastric emptying in the horse by the 13C‐octanoic acid breath test
Authors: SUTTON D. G. M. , BAHR A. , PRESTON T. , COHEN N. D. , LOVE S. , ROUSSEL A. J.
Published: April 2007

The13C‐octanoic acid breath test has been correlated significantly to radioscintigraphy for measurement of gastric emptying indices in healthy horses. The objective of this study was to investigate the validity of the test for measurement of equine delayed gastric emptying, prior to its potential clinical application for this purpose. A model of atropine‐induced gastroparesis was used. Gastric emptying rate was measured twice in 8 horses using concurrent radioscintigraphy and/or breath test after treatment i.v. with either atropine (0.035 mg/kg bwt) or saline in randomised order.

Analysis of both data sets demonstrated that the atropine treatment had caused a significant delay in gastric emptying rate. Paired breath test data showed an atropine‐induced delay in gastric half‐emptying time (t1/2), with no overlap in the 99% CI range (P<0.001). Significant correlations were found between scintigraphy and13C‐octanoic acid breath test for calculation of both t1/2(P<0.01) and lag phase duration (P<0.05) in the atropine‐delayed emptying results. The mean (s.d.) bias in breath test t1/2when compared with scintigraphy was 1.78 (0.58) h.

The results demonstrated that the13C‐octanoic acid breath test was an effective diagnostic modality for the measurement of equine delayed gastric emptying. The technique offers advantages to existing methods for clinical investigation, as it is noninvasive, not radioactive, quantitative and requires minimal equipment or training to perform.
Long‐term survival of equine surgical colic cases. Part 2: Modelling postoperative survival
Authors: PROUDMAN C. J. , SMITH J. E. , EDWARDS G. B. , FRENCH N. P.
Published: April 2007

Colic surgery is a frequently performed operation with high postoperative mortality. This study was undertaken to identify variables associated with decreased postoperative survival. We used data from 321 horse years of postoperative survival time to model the probability of survival following recovery from colic surgery. Continuous variables were modelled using a 6 variable, penalised Cox regression model. This demonstrated approximately linear relationships between survival and the following variables: increase in packed cell volume (PCV), intestinal resection length, time to surgery (interval between onset of colic and surgery) and duration of surgery. No significant decrease in survival was demonstrated with increasing age of the patient or with heart rate. The only categorical variable to be significantly associated with decreased survival was epiploic foramen entrapment. The final, fixed effects Cox proportional hazards model of postoperative survival included the variables epiploic foramen entrapment, PCV, resection length and duration of surgery, each variable adjusted for the nonlinear relationship with time to surgery. Residual variation in postoperative survival attributable to professional personnel (referring veterinary surgeon, anaesthetist and surgeon) was explored by fitting each as a random effects term in the model. Little of the residual variation could be attributed to any category of personnel. Model diagnostics indicated little influence by individual outliers on model parameters and little evidence of subjects poorly predicted by the final model. The study highlights factors influencing the long‐term survival of horses recovering from colic surgery and proposes a model that can be used to inform prognosis.
Effects of repeated biopsying on muscle tissue in horses
Authors: LINDNER A. , DAG S. , MARTI‐KORFF S. , QUIROZ‐ROTHE E. , RIVERO J. L. LÓPEZ , DROMMER W.
Published: April 2007

The collection of muscle samples in horses to estimate their performance potential, adaptations to training and diagnosis of exertional myopathies is of increasing interest. This study was designed to examine whether repeated biopsying of thegluteus mediusmuscle at 7 week intervals alters morphology and muscle fibre variables in the sampling area. Thegluteushad been biopsied 3 times previously, each biopsy separated by a 7 week interval. Seven weeks after the last biopsy, this study was initiated.

Percutaneous needle biopsies were taken from left and right muscles at 2 depths (2 and 6 cm) and at 2 sites for each depth (22 and 25 cm from thetuber coxae) of 7 mature Thoroughbreds. The 22 cm site was located close (2 cm caudal) to an area of the muscle that had been biopsied previously. The 25 cm site was 5 cm apart from this area. A total of 52 samples were available for histology, electron microscopy and immunohistochemistry. The latter was used to study percentages, sizes and capillaries of muscle fibre types. Most muscle samples collected (75%) had normal morphology, but the remaining 25% showed signs of muscle repair. In some circumstances, they showed regenerative signs of complete muscle repair, while in others ineffective muscle repair (scar formation) was evident. Nevertheless, sufficient normal tissue was always available for measuring routine muscle variables. Samples collected 3 cm laterally apart showed large differences with regard to muscle fibre type variables examined.

These results show that repeated muscle samples in intervals of 7 weeks do not have effects that would impair evaluation of muscle fibre variables for diagnosis of effectivity of conditioning programmes. Furthermore, they emphasise that the only way of keeping variations through sample collection technique small is to standardise all biopsying techniques accurately.
Chronic pulmonary disease with radiographic interstitial opacity (interstitial pneumonia) in foals
Authors: NOUT Y. S. , HINCHCLIFF K. W. , SAMII V. F. , KOHN C. W. , JOSE‐CUNILLERAS E. , REED S. M.
Published: April 2007

Twelve foals, age 3–9 months, examined at The Ohio State University Veterinary Teaching Hospital between 1995 and 2000 were diagnosed with chronic pulmonary disease associated with marked interstitial opacity on radiographic examination. The most characteristic features were a history of respiratory disease of 1–3 months duration, marked clinical signs of respiratory disease, failure to yield a consistent pathogen from tracheobronchial aspirates and a predominantly interstitial pattern on thoracic radiographs. We attributed these signs to chronic interstitial pneumonia. Foals were treated with broad spectrum antimicrobial and corticosteroid drugs. All 12 foals were discharged alive from hospital and, of the 10 available for follow‐up, all were disease‐free and performing to expectation 5 months to 5 years after discharge. We conclude that chronic interstitial pneumonia, occuring in foals, is associated with a good prognosis and that corticosteroid therapy may be useful in its treatment.
Quantitative motor unit action potential analysis of skeletal muscles in the Warmblood horse
Authors: WIJNBERG I. D. , FRANSSEN H. , van der KOLK J. H. , BREUKINK H. J.
Published: April 2007

Motor unit action potential (MUP) analysis in human medicine is a valuable and important diagnostic technique enabling discrimination between myogenic and neurogenic problems. This study establishes normative data in subclavian, triceps and lateral vastus muscles for clinical application of MUP analysis in the Warmblood horse, and examines whether muscle differences are present. Electromyographic (EMG) needle examination and MUP analysis were performed of the triceps, lateral vastus and subclavian muscles in 7 awake, nonsedated, Warmblood horses age 4–10 years. The amplitude, duration, number of phases and turns were calculated from the recorded superimposed MUPs together with intramuscular and rectal temperatures. No significant differences were found in duration of insertional activity between the 3 muscles. The mean ± s.d. duration of the insertional activity was 526 ± 148.3 ms. The MUP amplitude of all 3 muscles differed significantly, with the highest amplitude (427 ± 3.20 μV) in the triceps and the lowest (220 ± 2.08 μV) in the subclavian muscle. The number of turns of the lateral vastus (3.0 ± 1.22) was significantly higher than that of the triceps muscle (2.7 ± 1.51). No differences were found in MUP duration (5.9–6.4 ms).
Diffusion of mepivacaine between adjacent synovial structures in the horse. Part 2: tarsus and stifle
Authors: GOUGH M. R. , MUNROE G. A. , MAYHEW I. G.
Published: April 2007

This paper tests the hypothesis that the local analgesic agent mepivacaine diffuses between adjacent equine synovial structures in the hindlimb and with greater frequency than latex, gelatine dye or contrast media. We report the incidence of diffusion of mepivacaine between the tarsometatarsal, centrodistal and tarsocrural joints, and the 3 synovial compartments of the stifle in 33 fresh equine cadavers. The tarsometatarsal joint and one synovial compartment of the stifle in the left limb and the centrodistal joint and a different synovial compartment of the stifle in the right limbs were injected with mepivacaine. Following flexion and extension of the limb, synovial fluid was aspirated from the noninjected centrodistal and tarsometatarsal joints and the tarsocrural joints of the hock and the noninjected compartments of the stifle. Concentrations of mepivacaine in these samples were assayed using an enzyme linked immunosorbent assay. For samples obtained by dilution of synovial fluid the concentration of mepivacaine was determined by comparing the concentration of urea in the diluted synovial fluid and the concentrations of the serum urea. Mepivacaine was detected in 25/25 (100%) adjacent tarsometatarsal and centrodistal joints after diffusion in both directions, in 23/25 (92%) of tarsocrural joints after diffusion from tarsometatarsal joints and in 22/25 (88%) tarsocrural joints after diffusion from centrodistal joints in the hocks. Diffusion from the femoropatellar to medial and lateral femorotibial joints and between the medial and lateral femorotibial joints in both directions were 20/20 (100%). Diffusion from the lateral femorotibial to the femoropatellar joint was 18/20 (90%) and from the medial femorotibial to femoropatellar joints 17/20 (85%). Mepivacaine was detected at concentrations >0.3 mg/l in a proportion of samples ranging from 15/25 (60%) in the tarsocrural joint following tarsometatarsal joint injection to 18/20 (90%) in the lateral femorotibial joint after femoropatellar joint injection. At mepivacaine concentrations >100 mg/l, detection ranged from 3/20 (15%) in the lateral femorotibial joint from the medial femorotibial joint to 19/25 (76%) in the centrodistal joint from the tarsometatarsal joint. At mepivacaine concentrations >300 mg/l, detection ranged from 1/25 (4%) in the tarsocrural joint from the tarsometatarsal joint to 16/25 (64%) in the from centrodistal joint the tarsometatarsal joint. The results show greater diffusion of mepivacaine between these adjacent synovial structures than assumed from previous anatomical, latex injection and contrast arthrographic studies. Therefore, commonly performed intrasynovial local analgesic techniques in the hindlimb of the horse are not as specific as first thought.
Diffusion of mepivacaine between adjacent synovial structures in the horse. Part 1: forelimb foot and carpus
Authors: GOUGH M. R. , MAYHEW I. G. , MUNROE G. A.
Published: April 2007

This paper tests the hypothesis that the local analgesic agent mepivacaine diffuses between adjacent equine synovial structures in the forelimb and with greater frequency than latex, gelatine dye or contrast media. We report the incidence of diffusion of mepivacaine between the distal interphalangeal joint (DIPJ) and navicular bursa (NB) of the forelimbs and between the intercarpal (IC) and radiocarpal (RC) joints of 31 fresh equine cadavers. The DIPJ of one forelimb and the NB of the contra lateral forelimb and the RC joint of one forelimb and the IC joint of the contra lateral forelimb were injected with mepivacaine. After flexion and extension of the joints, synovial fluid was obtained from the synovial structures adjacent to the injected synovial structures. The concentration of mepivacaine in these samples was determined using an enzyme linked immunosorbent assay. Forsamples obtained by dilution of synovial fluid, the concentration of mepivacaine was determined by comparing the concentrations of urea in the diluted synovial fluid and the concentration of serum urea. Mepivacaine diffused from the DIPJ to the NB orfrom the NB to the DIPJ in 25/25 (100%) limbs. Mepivacaine diffused from the IC to RC joints in 24/25 (96%) limbs and from the RC to IC joints in 21/25 (84%) limbs. It was detected at concentrations >0.3 mg/l in 9/25 (36%) of IC joints after RC joint injection and in 25/25 (100%) of the NB after DIPJ injection; at concentrations >100 mg/l in 2/25 (8%) of IC and RC joints and 12/25 (48%) of NB following DIPJ injection; and at concentrations >300 mg/l in 1/25 (4%) in the IC joints following RC joint injection and in 11/25 (44%) of DIPJ following NB injection. The results show greater diffusion of mepivacaine between adjacent synovial structures than assumed from previous anatomical, latex injection and contrast arthrographic studies. This study showed that commonly performed intrasynovial analgesic techniques in the forelimb of the horse are not as specific as previously reported.
Efficacy of three corticosteroids for the treatment of heaves
Authors: ROBINSON N. E. , JACKSON C. , JEFCOAT A. , BERNEY C. , PERONI D. , DERKSEN F. J.
Published: April 2007

This study used a cross‐over design to compare the efficacy of 3 corticosteroids for the relief of airway obstruction and inflammation in 9 heaves‐affected horses. The severity of airway obstruction and inflammation was quantified by measurement of lung function and by bronchoalveolar lavage fluid (BALF) cytology, respectively. Airway obstruction was induced by stabling the horses and they remained stabled during the 10 day treatment period. Lung function was measured before treatment (baseline), at Days 3, 7, and 10 of treatment, and after 30 days at pasture. BALF cytology was investigated at baseline, Day 10, and at pasture. All 9 horses received the following 4 treatments in random order: no treatment, daily oral prednisone tablets (1 mg/kg), daily i.v. dexamethasone solution (0.1 mg/kg), and i.m. dexamethasone‐21‐isonicotinate (0.04 mg/kg) every 3 days. When horses received no treatment, lung function did not change significantly during stabling but improved at pasture. In all horses, daily i.v. administration of dexamethasone solution improved lung function within 3 days to levels as good as or better than those measured at pasture. Dexamethasone‐21‐isonicotinate was rapidly effective in 8 of 9 horses. The other horse did not respond to this drug. Prednisone tablets were without effect on Days 3 and 7 of treatment, but by Day 10, 5 of 9 horses showed some improvement in lung function. Dexamethasone i.v. solution decreased the percent neutrophils in BALF at Day 10. Other treatments had no effect on BALF cytology. These results demonstrate that dexamethasone rapidly relieved airway obstruction in heaves‐affected horses. Oral prednisone had inconsistent effects but may be beneficial in some horses after more than a week of treatment.
Plasma and synovial fluid concentrations of calcium pentosan polysulphate achieved in the horse following intramuscular injection
Authors: FULLER C. J. , GHOSH P. , BARR A. R. S.
Published: April 2007

Results from in vitro studies have indicated that calcium pentosan polysulphate (CaPPS) may be of therapeutic value in osteoarthritis (OA) in the horse. However, no controlled clinical trials using this drug in equine OA have yet been reported. If CaPPS is to be developed for such use, the relationship between the proposed i.m. dose of CaPPS to be used and the concentrations of drug attained in plasma and synovial fluid of the target joint should first be established. An investigation was undertaken to determine these concentrations after a single 2 mg/kg i.m. injection of CaPPS. Blood and synovial fluid samples were taken from 6 healthy, sound horses following i.m. CaPPS administration. Concentrations of CaPPS measured in the synovial fluid were, on the basis of published studies, sufficient to elicit a potential therapeutic effect on synoviocyte metabolism, and possibly also to stimulate proteoglycan synthesis and reduce matrix metalloproteinase activities in articular cartilage. It would therefore seem justified to investigate further the therapeutic effect of CaPPS in OAin the horse.
Physiological variables measured under field conditions according to age and state of training in French Trotters
Authors: COUROUCÉ A. , CHRÉTIEN M. , VALETTE J. P.
Published: April 2007

We hypothesised that the derived physiological variables V2and V4(velocity to achieve a blood lactate concentration of 2 and 4 mmol/l, respectively), HR2and HR4(the corresponding heart rate) and V200(the velocity for a heart rate of 200 beats/min) would improve with training state and age, in French Trotters. A total of 194 French Trotters from one training establishment were followed for 6 years and 1105 standardised field exercise tests performed on a sand training track. The horses were divided into 6 age groups (from 1 to ≥ 6 years) and 4 training groups (beginning, endurance training, sprint training, racing). A 2‐way analysis of variance was performed to evaluate the effects of age, training and the interaction of age and training on these physiological variables with the level of statistical significance set at 5%. The results showed that there was a significant influence of age on HR4, V2, V4and V200, with these variables increasing with age. Also, there was a significant influence of training and both age and training on V2, V4and V200, with these variables increasing with training and age. These results, obtained in a longitudinal study in a reproducible field environment, are consistent with previous laboratory‐based experimental studies. We conclude that objective indices of fitness obtained on the training track can be useful in the commercial training environment.
Impingement of the dorsal spinous processes in two hundred and fifteen horses: case selection, surgical technique and results
Authors: WALMSLEY J. P. , PETTERSSON H. , WINBERG F. , McEVOY F.
Published: April 2007

The surgical treatment of impingement of dorsal spinous processes (DSPs) at 2 equine veterinary hospitals following a similar diagnostic and surgical protocol is described with special reference to the diagnosis and case selection. The diagnosis was made from clinical examination and results of radiography and diagnostic analgesia of the affected sites. Scintigraphy was also used as an aid to diagnosis at one hospital. Surgical treatment was generally recommended when conservative treatment, which included 3–9 months rest, intralesional corticosteroids and physiotherapy, had failed. The DSPs were approached through a midline incision in the skin and supraspinous ligament. They were resected using an oscillating saw. Postoperatively, horses were returned to lungeing work after 2 weeks and riding commenced at 3 months, in most cases, and by 6 months in all successful cases. From one to 6 DSPs between thoracic vertebra (T) 11 and lumbar vertebra (L) 3 were resected in individual horses. T15, 16 and 17 were the spines most commonly treated. Long‐term follow‐up information was obtained in 209 horses. Seventy‐two percent of these horses returned to full work and a further 9% improved sufficiently to be used for some athletic work.
The effect of intra‐articular methylprednisolone acetate and exercise on equine carpal subchondral and cancellous bone microhardness
Authors: MURRAY R. C. , ZNAOR N. , TANNER K. E. , DeBOWES R. M. , GAUGHAN E. M. , GOODSHIP A. E.
Published: April 2007

Dorsal carpal osteochondral injury is a major cause of lameness in horses undergoing high intensity training. Intra‐articular corticosteroid treatment is used commonly to manage exercise‐associated articular pain, but its use remains highly controversial in the equine athlete. This project, therefore, aimed to compare the mechanical properties of intra‐articular MPA and diluent‐treated middle carpal subchondral and cancellous bone in horses undergoing a short‐term treadmill exercise programme. It was hypothesised that subchondral and cancellous bone mechanical properties are influenced by intra‐articular administration of methylprednisolone acetate (MPA). Eight 2‐year‐old female horses had MPAor diluent administered into contralateral middle carpal joints at 14 day intervals, for a total of 4 treatments per horse. Horses underwent a standard treadmill exercise protocol until euthanasia (Day 70). Standard sites were located on the dorsal aspect of third, radial and intermediate carpal bones. Osteochondral samples from each test site were divided into subchondral bone and cancellous bone portions. These were dried, resin‐embedded and gold‐coated. Microhardness measurements were obtained at each test site. No significant effect of intra‐articular treatment was detected. At each site, cancellous bone trabecular struts had an 18–19% higher microhardness value than the overlying subchondral bone. These findings indicate that intra‐articularadministration of MPA at this dose has no effect on subchondral or cancellous bone adaptation to short‐term exercise and, therefore, on the propensity of carpal bones to injury. Further investigation into the calcified cartilage layer, effect of different corticosteroid preparations and diffusion of medication are required.
A study of the ultrastructure and staining characteristics of the ‘dental star’ of equine incisors
Authors: MUYLLE S. , SIMOENS P. , LAUWERS H.
Published: April 2007

The objective of this study was to examine the diameter, extent, orientation and contents of dentinal tubules in order to validate the hypothesis of pigment penetration into the dental star of equine incisival occlusal surfaces. The time of appearance and the configuration of the dental star on the incisival occlusal surface are macroscopically visible features that, along with other more reliable parameters, are used for the determination of horses' age. Although dental stars are an integral part of the equine incisor occlusive surface, the exact nature and microstructure of the dental star are poorly documented. Therefore, equine incisor dentine was examined macroscopically and by scanning electron microscopy to elucidate numerical density, diameter and 3‐dimensional organisation of the dentinal tubules in the dental star.

The dental star is surrounded by primary dentine and consists of a central core of tertiary dentine, an intermediate ring of pale secondary dentine and a peripheral rim of darker, yellowish‐brown secondary dentine. The central core of tertiary dentine contains relatively few dentinal tubules (<8000/mm2) that have small diameters (mean ± s.d. 1.67 ± 0.34 μm) and are arranged in an irregular pattern. The surrounding pale ring of secondary dentine comprises manifestly more and wider tubules that lie almost parallel to the occlusal surface. The dark peripheral rim of the dental star contains high numbers of tubules (28,000–58,000/mm2) that have wide luminal diameters (mean ± s.d. 3.09 ± 0.31 μm) and open perpendicular to the occlusal surface. In contrast, the primary dentine surrounding the dental star is made up by a lower number of dentinal tubules (<25,000/mm2). The tubules of primary dentine, which are initially mean ± s.d. 5.15 ± 0.80 μm wide, are narrowed by circumferential deposits of peritubular dentine and are obliquely exposed at the occlusal surface.

From these observations, it was concluded that the regional differences in numerical density, diameterand spatial orientation of the dentinal tubules may influence the penetration of food pigments into the equine occlusal surface and result in the particular staining of the dental star.
Retrospective study of primary intention healing and sequestrum formation in horses compared to ponies under clinical circumstances
Authors: WILMINK J. M. , HERTEN J. van , WEEREN P. R. van , BARNEVELD A.
Published: April 2007

In accidental wounds, trauma and infection can result in dehiscence of primarily closed wounds and in sequestrum formation when cortical bone is exposed. In experimental studies, it has been shown that second intention healing is faster and occurs with less complications in ponies than in horses. Also, a greater initial inflammatory response was seen in ponies. Based on these experimental data, it was hypothesised that accidental wounds in ponies would heal with a lower incidence of wound dehiscence and/or sequestrum formation compared to horses.

A retrospective study of 89 ponies and 422 horses with traumatic wounds was performed. The animals, wounds and treatments were categorised and related to the success rate of primary closure and to the incidence of sequestrum formation. The ponies and horses were of similar age and sex. The wounds that were treated were comparable for localisation, duration, degree of contamination and depth in both groups of animals, but there were significantly more cases with ruptured extensor tendons in ponies. Antibiotics and NSAIDs were administered significantly less often to ponies. The success rate of primary closure was significantly higher in ponies than in horses, and sequestra were formed significantly less often in ponies.

It was concluded that the results of healing were better in ponies although the external conditions were less favourable. This may be associated with the differences in the initial inflammatory response after injury as found in earlier experimental work, which may result in a betterlocal defence against wound infection.
Prednisoneper osis likely to have limited efficacy in horses
Authors: PERONI D. L. , STANLEY S. , KOLLIAS‐BAKER C. , ROBINSON N. E.
Published: April 2007

Based on its efficacy for the treatment of human asthma, the corticosteroid prednisone is commonly used in horses for treatment of recurrent airway obstruction. However, recent studies have failed to show any benefit of prednisone tablets for the treatment of this condition. The purpose of this study was to determine why oral prednisone has poor efficacy for the treatment of heaves in horses. In a crossover study, 5 horses were given the following treatments: prednisone tablets, prednisone liquid, prednisolone tablets, prednisolone liquid and i.v. prednisolone sodium succinate (positive control). Blood samples were taken before drug administration and at selected time points during a 24 h period. Serum concentrations of prednisone and prednisolone were determined in order to evaluate gastrointestinal absorption and hepatic metabolism. Serum concentrations of the endogenous glucocorticoid hydrocortisone were also determined as an indicator of the biological activity of the drugs. Both prednisolone tablets and liquid were absorbed rapidly, with prednisolone detectable in serum within 15 min of administration and with peak concentrations occurring within 45 min. Small amounts of prednisone were detected in the serum samples after administration of both prednisone tablets and liquid. Prednisolone was not detected in serum samples after administration of prednisone liquid and was detected in serum samples from only one horse after administration of prednisone tablets. Endogenous hydrocortisone production was suppressed when horses received prednisolone. The results of these studies indicate that prednisone has poor efficacy for the treatment of heaves because it is poorly absorbed and the active metabolite prednisolone is rarely produced. In contrast, prednisolone tablets have excellent bioavailability and should be useful as a therapeutic agent in horses.
Cytological analysis of equine bronchoalveolar lavage fluid. Part 1: Comparison of sequential and pooled aliquots
Authors: PICKLES K. , PIRIE R. S. , RHIND S. , DIXON P. M. , McGORUM B. C.
Published: April 2007

The aim of this study was to investigate whether initial equine bronchoalveolar lavage fluid (BALF) aliquots were more representative of bronchial cytology that bronchiolar and alveolar cytology. Cell viability and total nucleated (TCC), differential (DCC) and absolute cell counts of cytocentrifuged preparations of 3 sequentially collected BALF aliquots (Aliquots 1–3) were compared with those of pooled BALF (Aliquot 4) to assess whetherall aliquots were representative of the lavaged lung segment. BALF samples (n = 21) were collected from control horses (n = 5) orheaves‐affected horses (n = 5). There were nonsignificant trends of increasing TCC and absolute macrophage count fromAliquot 1toAliquot 3and significant differences in macrophage (P<0. 05) and lymphocyte (P<0.01) DCC among aliquots of all horses; however, no linear trend in this DCC data was observed. There was a significant decrease in mast cell DCC (P<0.01) fromAliquot 1toAliquot 3in control horses. Cell viability did not differ significantly among aliquots. There was no diagnostically significant difference in TCC, DCC, absolute cell counts or cell viability, among sequential and pooled BALFaliquots and, therefore, all aliquots can be considered to represent the cytology of the lavaged lung segment. This indicates that even if BALF recoveries are very low, cytological analysis of samples will be of diagnostic value.
Development of biochemical heterogeneity of articular cartilage: influences of age and exercise
Authors: BRAMA P.A. J. , TeKOPPELE J. M. , BANK R. A. , BARNEVELD A. , van WEEREN P. R.
Published: April 2007

The objective of this study was to document the development of biochemical heterogeneity from birth to maturity in equine articular cartilage, and to test the hypothesis that the amount of exercise during early life may influence this process. Neonatal foals showed no biochemical heterogeneity whatsoever, in contrast to a clearbiochemical heterogeneity in mature horses. The process of formation of site differences was almost completed in exercised foals age 5 months, but was delayed in those deprived of exercise. For some collagen‐related parameters, this delay was not compensated for after an additional 6 month period of moderate exercise.

It is concluded that the functional adaptation of articular cartilage, as reflected in the formation of biochemical heterogeneity in the horse, occurs forthe most part during the first 5 monthspostpartum. A certain level of exercise seems essential forthis process and withholding exercise in early life, may result in a delay in the adaptation of the cartilage.
Cytological analysis of equine bronchoalveolar lavage fluid. Part 2: comparison of smear and cytocentrifuged preparations
Authors: PICKLES K. , PIRIE R. S. , RHIND S. , DIXON P. M. , McGORUM B. C.
Published: April 2007

The aim of this study was to develop a diagnostically useful smear method for preparation of equine bronchoalveolar lavage fluid (BALF) for use by practitioners. A smear method for equine BALF preparation which included the addition of serum was developed, and cell morphology, differential cell counts (DCC) and repeatability of counting DCC compared with those of cytocentrifuged BALF preparations. BALF samples (n = 21) were collected from 5 control horses and 5 heaves‐susceptible horses. Smear preparations of BALF produced smaller, darker, staining cells, making cytological identification more difficult than on cytocentrifuged preparations. There was a significantly higher (P<0.0 1) macrophage DCC and lower lymphocyte DCC on cytocentrifuged compared to smear preparations. Mast cell and eosinophil DCC were significantly higher (P<0.05) on cytocentrifuged compared to smear preparations of BALF. Smear preparations were shown to be reliable for the cytological diagnosis of equine neutrophilic pulmonary disease and offerpractitioners an alternative to sending equine BALF to a laboratory for processing and cytological analysis.
Evaluation of nebulised hay dust suspensions (HDS) for the diagnosis and investigation of heaves. 1: Preparation and composition of HDS
Authors: PIRIE R. S. , McLACHLAN G. , McGORUM B. C.
Published: April 2007

Currently, heaves is investigated by exposing susceptible horses to dusty hay. Consequently, the response will be dependent on the organic dust content and composition of the hay. It was hypothesised that the use of a hay dust suspension (HDS) would reduce the variability of the challenge and therefore standardise experimental protocols. Furthermore, analysis of HDS would also permit further investigation of the organic dust components responsible for the response. Three hay dust suspensions (HDS‐1, 2 and 3) were prepared for use in the diagnosis and investigation of heaves. HDS were produced from fine dust particles, comprising mostly fungal spores, collected from 3 batches of dusty hay. HDS‐1 and 3 were analysed for endotoxin, β‐D‐glucan and protein concentrations, general protease activity and enumeration and size distribution of particulates. Protease activity was mainly attributable to a 28kDa serine protease and to 85kDa and 160kDa metalloproteases. The particulate and soluble components of HDS could be aerosolised by jet nebulisation. We therefore conclude that detailed analysis of HDS is possible, that such a challenge system provides a method of standardising experimental protocols and that all components of HDS (both soluble and particulate) can be delivered to the lung using standard nebulisation techniques. For the above reasons, nebulised HDS offers considerable advantages over conventional hay/straw challenge for the diagnosis and investigation of heaves.