bluuebunny/crossref_metadata_2025_split huggingface dataset:
Headshaking in horses: possible aetiopathogenesis suggested by the results of diagnostic tests and several treatment regimes used in 20 cases
Authors: Newton S. A. , Knottenbelt D. C. , Eldridge P. R. 
Published: April 2007

SummaryTwenty mature horses with typical headshaking of 2 week‐7 year duration were studied. Clinical examinations included radiography of the head and nasopharyngeal endoscopy. All were assessed at rest and at exercise, both before and after fitting an occlusive nasal mask, application of tinted contact lenses and the perineural anaesthesia of the infraorbital and posterior ethmoidal branches of the trigeminal nerve. Infraorbital anaesthesia had no effect in 6/7 cases but 11/17 (65%) cases showed a 90–100% improvement following posterior ethmoidal nerve anaesthesia. Tinted contact lenses had no apparent long‐term benefit, although 2 cases showed a transient improvement. We found no other evidence to suggest a photic aetiology in the current series of cases. Treatment regimens based on the results of the diagnostic investigative methods included sclerosis of the posterior ethmoidal branch of the trigeminal nerve. This was effective in some cases but the benefits were temporary. Cyproheptadine alone was ineffective but the addition of carbamazepine resulted in 80–100% improvement in 80% of cases. Carbemazepine alone was effective in 88% of cases but results were unpredictable at predefined dose rates. The positive response to carbamazepine, combined with the clinical features is consistent with involvement of the trigeminal nerve, particularly the more proximal branches such as the posterior ethmoidal nerve.Headshaking has some clinical features in common with trigeminal neuralgia in humans. As a result of the findings detailed in this paper, we conclude that a trigeminal neuritis or neuralgia may be the basis of the underlying aetiopathology of equine headshaking. Initial observations of the positive response of headshakers to carbamazepine therapy is encouraging. However, future studies will include a more detailed investigation of dosages, duration of effectiveness (in some cases it appears short‐lived) and other effects. In practice there is a realistic possibility of controlling but not curing headshaking with carbamazepine therapy at the present time. Other future investigations will include details of the functional anatomy of the trigeminal nerve and the role of the P2 myelin protein in headshaking and other neurological disease.
Functional adaptation of equine articular cartilage: the formation of regional biochemical characteristics up to age one year
Authors: Brama P. A. J. , Tekoppele J. M. , Bank R. A. , Barneveld A. , Van Weeren P. R. 
Published: April 2007

SummaryBiochemical heterogeneity of cartilage within a joint is well known in mature individuals. It has recently been reported that heterogeneity forproteoglycan content and chondrocyte metabolism in sheep develops postnatally underthe influence of loading. No data exist on the collagen network in general or on the specific situation in the horse.The objective of this study was to investigate the alterations in equine articular cartilage biochemistry that occur from birth up to age one year, testing the hypothesis that the molecular composition of equine cartilage matrix is uniform at birth and biochemical heterogeneity is formed postnatally.Water content, DNA content, glycosaminoglycan content (GAG) and biochemical characteristics of the collagen network (collagen content, hydroxylysine content and hydroxylysylpyridinoline [HP] crosslinks) were measured in immature articularcartilage of neonatal (n = 16), 5‐month‐old foals (n = 16) and yearlings (n = 16) at 2 predefined differently loaded sites within the metacarpophalangeal joint. Statistical differences between sites were analysed by ANOVA (P<0.01), and age correlation was tested by Pearson's product moment correlation analysis (P<0.01). In neonatal cartilage no significant site differences were found for any of the measured biochemical parameters. This revealed that the horse has a biochemically uniform joint (i.e. the cartilage) at birth. In the 5‐month‐old foals and yearlings, significant site differences, comparable to those in the mature horse, were found for DNA, GAG, collagen content and hydroxylysine content. This indicates that functional adaptation of articular cartilage to weight bearing for these biochemical parameters takes place during the first monthspostpartum.Water content and HP crosslinks showed no difference between the 2 sites from neonatal horses, 5‐month‐ old animals and yearlings. At both sites water, DNA and GAG decreased during maturation while collagen content, hydroxylysine content and HPcrosslinks increased.We propose that a foal is born with a uniform biochemical composition of cartilage in which the functional adaptation to weight bearing takes place early in life. This adaptation results in biochemical and therefore biomechanical heterogeneity and is thought to be essential to resist the different loading conditions to which articular cartilage is subjected during later life. As collagen turnover is extremely low at mature age, an undisturbed functional adaptation of the collagen network of articularcartilage at a young age may be of significant importance for future strength and resistance to injury.
Respiratory responses of mature horses to intravenous lobeline bolus
Authors: Marlin D. J. , Roberts C. A. , Schroter R. C. , Lekeux P. 
Published: April 2007

SummaryThe respiratory stimulant lobeline has been used in equine clinical practice to increase inspiratory and expiratory airflow rates at rest in orderto facilitate investigation of both lower and upper airway function. Some of the responses to lobeline in the pony have been reported, but the detailed time course, effect of dose, possible side effects and reproducibility associated with lobeline administration have not been described in the horse. Respiratory airflow rates and oesophageal pressure were measured with a Fleisch No. 5 pneumotachometer and lightweight facemask and a microtip pressure transducer catheter, respectively. The output of the Fleisch pneumotachometer was calibrated for flow rates up to ± 70 l/s. Seven mature horses with no clinical signs of respiratory disease were studied. Investigations were conducted to determine: (1) the responses to different doses of lobeline (0.15, 0.20, 0.25 and 0.30 mg/kg bwt) as a rapid i.v. bolus (6 horses); (2) arterial blood gases during and after lobeline administration (0.20 mg/kg bwt; 3 horses); and (3) the reproducibility of lobeline‐stimulated hyperpnoea (5 horses; 2 doses of 0.20 mg/kg bwt lobeline, 15 min apart). All horses tolerated the lobeline‐stimulated hyperpnoea well, although one always coughed or snorted at the onset. Mild tremor was noted following the highest dose in several horses. Apnoea of approximately 40 s was common after the hyperpnoea. Both tidal volume (VT) and frequency (fR) increased with lobeline dose. During peak hyperpnoea at a dose of 0.30 mg/kg bwt, peak inspired flow rate (PIF), peak expired flow rate (PEF) and minute ventilation (VE) were mean ± s.e. 41 ± 5 l/s, 61 ± 10 l/s and 920 ± 99 l/min, respectively. The hyperpnoea also caused marked changes in arterial PaO2, PaCO2 and pHa at 90 s after lobeline (0.20 mg/kg bwt) administration (mean ± s.e. 146.0 ± 6.9 mmHg, 20.6 ± 0.8 mmHg and 7.707 ± 0.020, respectively) compared to at rest (mean ± s.e. 104.0 ± 4.0 mmHg, 50.6 ± 2.8 mmHg and 7.432 ± 0.012). Dynamic lung compliance (Cdyn) was unaltered by lobeline administration. The lobeline‐induced hyperpnoea was highly reproducible, with no significant difference in any of the parameters during 2 stimulations 15 min apart. Lobeline induced highly reproducible responses without any apparent adverse effects and may be useful in the investigation of pulmonary function in healthy horses and those with airway disease.
Repeatability of Doppler ultrasound measurements of hindlimb blood flow in halothane anaesthetised horses
Authors: Raisis A. L. , Young L. E. , Meire H. , Walsh K. , Taylor P. M. , Lekeux P. 
Published: April 2007

SummaryThe purpose of this study was to determine the repeatability of femoral blood flow recorded using Doppler ultrasound in anaesthetised horses. Doppler ultrasound of the femoral artery and vein was performed in 6 horses anaesthetised with halothane and positioned in left lateral recumbency. Velocity spectra, recorded using low pulse repetition frequency, were used to calculate time‐averaged mean velocity (TAV), velocity of component a (TaVa), velocity of component b (TaVb), volumetric flow, early diastolic deceleration slope (EDDS) and pulsatility index (PI). Within‐patient variability was determined for sequential Doppler measurements recorded during a single standardised anaesthetic episode. Within‐patient variability was also determined for Doppler and cardiovascular measurements recorded during 4 separate standardised anaesthetic episodes performed at intervals of at least one month.Within‐patient variation during a single anaesthetic episode was small. Coefficients of variation (cv) were <12.5% for arterial measurements and <17% for venous measurements. Intraclass correlation coefficient was >0.75 for all measurements. No significant change was observed in measurements of cardiovascular function suggesting that within‐patient variation observed during a single anaesthetic episode was due to measurement error. In contrast, within‐patient variation during 4 separate anaesthetic episodes was marked (cv>17%) for most Doppler measurements obtained from arteries and veins. Variation in measurements of cardiovascular function were marked (cv>20%), suggesting that there is marked biological variation in central and peripheral haemodynamics during different anaesthetic episodes.Therefore the results of this study show that Doppler ultrasound is a noninvasive, repeatable method for measuring blood velocity, volumetric flow and indices of peripheral resistance in femoral vessels of anaesthetised horses. However, marked biological variation in haemodynamic measurements between different anaesthetic episodes could limit the ability of Doppler ultrasound to detect differences between anaesthetic agents. Ultimately, detection of differences in central and peripheral haemodynamics associated with different anaesthetic agents depends on the magnitude of the change observed. Further studies are warranted to determine the ability of this technique to detect differences in blood flow during administration of different anaesthetic agents.
Clinical studies on daily low dose oxytocin in mares at term
Authors: Camillo F. , Marmorini P. , Romagnoli S. , Cela M. , Duchamp G. , Palmer E. 
Published: April 2007

SummaryThe aim of this study was to test whether low dose oxytocin i.v. injection once a day to mares diagnosed as being ready for birth by mammary secretion calcium strip test measurements could be used as a reliable method to induce parturition and/or predict the mare would not foal during the following night if parturition did not occur within 2 h of treatment.Fifty‐one near‐term Haflinger mares were used and a single injection of 2.5 iu oxytocin was given between 1700 and 1900 h, including 10 mares used as controls which were administered a placebo. Administration of oxytocin resulted in the delivery of a normal foal within 120 min in 95% of mares. Twenty‐fourout of 38 (63%) treated animals foaled in response to the first oxytocin injection, 9 out of 38 (24%) in response to the second injection and 3 out of 38 (8%) in response to the third treatment. Two out of 38 (5%) treated mares foaled during the night irrespective of treatment whereas 7 out of 10 (70%) control mares foaled during the night. It was concluded that the majoradvantage of injecting a daily low dose of oxytocin appears to be that such a low dose induces delivery only in mares carrying a mature fetus and which are ready to foal.
Transmission ofEhrlichia risticii, the agent of Potomac horse fever, using naturally infected aquatic insects and helminth vectors: preliminary report
Authors: Madigan J. E. , Pusterla N. , Johnson E. , Chae J.‐S. , Pusterla J. Berger , Derock E. , Lawler S. P. 
Published: April 2007

SummaryEhrlichia risticii, the agent of Potomac horse fever (PHF), has been recently detected in trematode stages found in snail secretions and in aquatic insects. Based on these findings, horses could conceivably be exposed toE. risticiiby skin penetration with infected cercariae, by ingestion of infected cercariae in water or via metacercariae in a second intermediate host, such as an aquatic insect. In order to test this hypothesis, horses were challenged with infectious snail secretions and aquatic insects collected from a PHFendemic region in northern California. Two horses stood with their front feet in waterharbouringE. risticii‐infected cercariae, 2 horses drank water harbouringE. risticii‐infected cercariae, and 6 horses were fed pools of different aquatic insects harbouringE. risticii‐infected metacercariae.In this preliminary study, only the one horse infected orally with mature caddisflies (Dicosmoecus gilvipes) developed the clinical and haematological disease syndrome of PHF. The agent was isolated from the blood of the infected horse in a continuous cell line and identified asE. risticiiby characterisation of the 16S rRNA gene. Therefore,E. risticiiis maintained in nature in a complex aquatic ecosystem and transmission to horses can occur through accidental ingestion of insects such as caddisflies containing infected metacercariae. At present, the small number of horses used in this study does not exclude other insects and free trematode stages as potential sources of infection.
The forelimb in walking horses: 1. Kinematics and ground reaction forces
Authors: Hodson E. , Clayton H. M. , Lanovaz J. L. 
Published: April 2007

SummaryVideo (60 Hz) and force (2000 Hz) data were collected from 5 sound horses during walking. Forelimb data were analysed for 8 strides (4 left, 4 right) per horse to determine sagittal plane kinematics and ground reaction forces (GRFs). The results suggested that brachial rotation was responsible for protraction and retraction of the limb as a whole, while rotations of the scapula and antebrachium elevated the distal limb during breakover and early swing then lowered it in preparation for ground contact. The coffin joint was flexed maximally at the time of peak longitudinal braking force, which occurred during breakover of the contralateral forelimb. The metacarpus was vertical at 28% stride. This was considerably earlierthan the change from a braking to a propulsive longitudinal force (34% stride), which coincided with maximal extension of the fetlock joint. The longitudinal propulsive force peaked just aftercontact of the contralateral forelimb. During the swing phase the joints distal to the shoulder showed a single flexion cycle that peaked at 76% stride at the carpus, 81% stride at the fetlock and 84% stride at the elbow and coffin joints. The coffin and shoulder joints began to extend in the terminal swing phase and continued to extend through ground contact and early stance. The results provide normative data that will be applied in detecting changes in kinematics and ground reaction forces that are associated with specific lamenesses.
The effects of treadmill inclination and speed on the activity of two hindlimb muscles in the trotting horse
Authors: Robert C. , Valette J. P. , Denoix J. M. 
Published: April 2007

SummaryElectromyographic activity (EMG) was used to determine how hindlimb muscle activation patterns vary with speed and incline in the horse. EMG was recorded using surface electrodes over thegluteus mediusandtensor fasciae lataemuscles during treadmill locomotion at trot for different combinations of speed (3.5 to 6 m/s) and inclination (0, 3 and 6%). Raw EMG signals were processed to determine stride duration, activity onset and end, and integrated EMG (IEMG). Stride and stance phase duration decreased linearly with increasing speed. Stride duration was not influenced by the slope. Onset and end of muscle activity came significantly earlier in the stride cycle when speed increased and later when inclination changed from 0 to 6%. The relative duration of the burst (percentage of stride duration) increased as running speed increased, but tended to decrease with increasing slope. The IEMG of the muscles increased with increasing speed and slope, the largest increase being observed in thetensor fasciae latae.It is concluded that both increases in speed and inclination lead to an increase in the integrated electromyographic activity and hence to a higher workload of the 2 hindlimb muscles investigated.
Cytotoxicity of stimulated equine neutrophils on equine endothelial cells in culture
Authors: Benbarek H. , Grülke S. , Deby‐Dupont G. , Deby C. , Mathy‐Hartert M. , Caudron I. , Dessy‐Doize C. , Lamy M. , Serteyn D. 
Published: April 2007

SummaryWe studied the interactions of isolated equine neutrophils with endothelial cells in culture, mimicking a situation of acute inflammation. Our main purpose was to demonstrate that the supernatant of activated neutrophils was sufficient to damage endothelial cells. Equine endothelial cells (from carotid arteries) were covered either with increased numbers of equine neutrophils stimulated by phorbol myristate acetate, or with the supernatant collected after anin vitrostimulation of the neutrophils. Cytotoxicity was estimated by the release of preincorporated51Cr, and by light microscopy observations. To assert the specific role of reactive oxygen species, endothelial cells were treated by the hypoxanthine/xanthine oxidase (X/XOx) system (production of superoxide anion and hydrogen peroxide), and by hypochlorite (product of the activity of myeloperoxidase). A strong cytotoxicity was found with stimulated neutrophils; microscopic observations indicated a loss of 50% of the endothelial cells and morphological alterations in the remaining cells. The supernatant of stimulated neutrophils was cytotoxic, in correlation with the number of neutrophils used to obtain the supernatant, and with the supernatant concentration of myeloperoxidase. The cytotoxicity of the X/XOx system was weak, but was increased by myeloperoxidase. Hypochlorite was highly toxic. We concluded that the supernatant of stimulated neutrophils was sufficient to obtain cytotoxic effects on the endothelium, in the absence of a direct contact between endothelium and neutrophils, and that this cytotoxicity was mainly linked to the activity of myeloperoxidase. From thesein vitroresults, it can be extrapolated that in pathologies characterised by an important activation of neutrophils, damage can spread to cells and tissues away from the inflammation focus.
Effects of maternally administered Depot ACTH1–24on fetal maturation and the timing of parturition in the mare
Authors: OUSEY J. C. , ROSSDALE P. D. , PALMER L. , GRAINGER L. , HOUGHTON E. 
Published: April 2007

SummaryThe aims of this study were to ascertain 1) whether fetal maturation could be induced precociously by maternal administration with adrenocorticotrophic hormone (ACTH) and 2) whether maturation could be achieved without significant risk to mare or fetus. Twenty‐two mares received either 1 mg (low dose, LD, n = 6) or 4 or 5 mg (higher dose, HD, n = 16) synthetic Depot ACTH1–24at 300, 301 and 302 days gestation. Because, during the course of the study, ACTH appeared to have a greaterinfluence on mares mated during the later part of the breeding season, the HD group were divided retrospectively into those mated before (HDE, n = 6), or after (HDL, n = 10), 1st July. All LD mares were mated before 1st July. Control injections were not performed but gestational data were compared retrospectively with 64 untreated, spontaneously foaling pony mares mated between May and October.Plasma progestagen and cortisol concentrations increased significantly (P<0.05) following ACTH administration in all groups, but progestagens were higher and cortisol elevated for longer in HD mares. ACTH stimulated mammary development and milk electrolyte changes in HD mares. Mean ± s.e. gestation period (days) was significantly (P<0.01) shorter in HDLmares (318 ± 1.8) compared with LD (335 ± 3.7), HDE (340 ± 4.3) and untreated mares mated after 1st July (327 ± 1.3). All foals were mature except 2 HDLfoals which were stillborn. HDL foals had a higher MCV and lower mean bodyweight, indicating they were delivered before full term. In conclusion, maternal ACTH administration appears to accelerate fetal maturation and delivery in pony mares given high doses and mated late in the breeding season.Further work is required to establish the optimal gestational age and dosage for maternal ACTH administration before clinical recommendations can be given for this therapy.
Qualitative and quantitative documentation of the racing performance of 461 Thoroughbred racehorses after arthroscopic removal of dorsoproximal first phalanx osteochondral fractures (1986–1995)
Authors: COLÓN J. L. , BRAMLAGE L. R. , HANCE S. R. , EMBERTSON R. M. 
Published: April 2007

SummaryThe purpose of this study was to examine the longevity of postoperative careers and quality of performance of 461 Thoroughbred racehorses after arthroscopic removal of dorsoproximal first phalanx (P1) osteochondral fractures. Six hundred and 59 dorsoproximal P1 chip fractures were removed arthroscopically from 574 joints in 461 horses presented forlameness or decreased performance attributed to the chip fractures. Radiological and arthroscopic examination revealed an average of 1.43 fragment sites/horse, 1.15 fragment sites/joint and 1.25 affected joints/horse. Eighty‐nine percent of the horses (411/461) raced after surgery and 82% (377/461) did so at the same or higher class. Fifty horses did not race after surgery. Sixty‐eight percent of the horses raced in a Stake or Allowance race postoperatively. Data, previously undocumented, establishes that the quantity and quality of performance is not diminished after arthroscopic treatment of dorsoproximal P1 fragmentation. Surgical removal of chip fractures is a means of preserving the economic value of an injured Thoroughbred, allowing a rapid and successful return to racing at the previous level of racing performance.