bluuebunny/crossref_metadata_2025 huggingface dataset:
Preformed Particle Gel for Conformance Control: Transport Mechanism Through Porous Media
Authors: Bai Baojun , Liu Yuzhang , Coste J. -P. , Li Liangxiong
Published: April 2007

Preformed particle gel (PPG) has been successfully synthesized and applied to control excess water production in most of the mature, waterflooded oil fields in China. This paper reports on laboratory experiments carried out to investigate PPG transport mechanisms through porous media. Visual observations in etched-glass micromodels demonstrate that PPG propagation through porous media exhibits six patterns of behavior: direct pass, adsorption, deform and pass, snap-off and pass, shrink and pass, and trap. At the macroscopic scale, PPG propagation through porous media can be described by three patterns: pass, broken and pass, and plug. The dominant pattern is determined by the pressure change with time along a tested core (as measured at specific points), the particle-size ratio of injected and produced particles from the core outlet, and the residual resistance factor of each segment along the core. Measurements from micromodel and routine coreflooding experiments show that a swollen PPG particle can pass through a pore throat with a diameter that is smaller than the particle diameter owing to the elasticity and deformability of the swollen PPG particle. The largest diameter ratio of a PPG particle and a pore throat that the PPG particle can pass through depends on the swollen PPG strength. PPG particles can pass through porous media only if the driving pressure gradient is higher than the threshold pressure gradient. The threshold pressure depends on the strength of the swollen PPG and the ratio of the particle diameter and the average pore diameter.
Cross‐sectional study of faecal shedding ofGiardia duodenalisandCryptosporidium parvumamong packstock in the Sierra Nevada Range
Authors: Atwill E. R. , Mcdougald N. K. , Perea L.
Published: April 2007

Faecal specimens from 305 horses and mules used as packstock at one of 17 commercial or governmental (National Park Service, US Forest Service) operations were examined forGiardia duodenalisandCryptosporidium parvumusing immunofluorescent microscopy. Fourteen packstock (4.6%) were sheddingG. duodenaliscysts, with herd‐level prevalences ranging 0–22%. Number of packstock in the corral, size of corral and density of packstock in the corral were associated with the odds of sheddingG. duodenaliscysts. None of the horses had detectableC. parvumoocysts. Assuming a sensitivity of at least 43% and a specificity of 100% for our assay, the estimated maximum true prevalence of shedding ofC. parvumfor packstock would be ≤ 2.3% of the population. These data suggest that faecal dispersal ofC. parvumon back country watersheds is unlikely with packstock.
Radiographic and clinical survey of degenerative joint disease in the distal tarsal joints in Icelandic horses
Authors: Björnsdóttir S. , Axelsson M. , Eksell P. , Sigurdsson H. , Carlsten J.
Published: April 2007

The prevalence of degenerative joint disease (DJD) in the distal tarsal joints and the relation between radiographic and clinical signs compatible with the disease were estimated in a population of Icelandic horses used for riding. The material consisted of 614 horses age 6–12 years (mean age = 7.9 years). Radiographs with 3 projections of each tarsus were made and a clinical examination, including palpation of the medial aspect of the distal tarsus and motion evaluation of the hindlimbs before and after a flexion test of the tarsus, was performed. Radiographic signs of DJD in the distal tarsal joints were found in 30.3% of the horses and the prevalence was strongly correlated with age. Hindlimb lameness before and after flexion test and palpation abnormalities were significantly associated with the radiographic findings. The lameness was usually mild and, in most cases, detectable only after the flexion test. The prevalence of lameness was not significantly correlated with age. Lameness could not be predicted by details of the radiographic findings.
Anin vitrostudy to compare 5 different techniques for injection of the navicular bursa in the horse
Authors: Schramme M. C. , Boswell J. C. , Hamhougias K. , Toulson K. , Viitanen M.
Published: April 2007

Numerous different techniques for injection of the navicular bursa have been described but there is little conformity between these descriptions. A literature review was performed and techniques for injection of the navicular bursa were categorised into 5 approaches. This study was performed to evaluate the reproducibility of each technique and to assess which technique was consistently most successful. Five inexperienced operators performed each technique on 5 cadaver forelimbs. Once a needle had been placed, a radiograph was taken to confirm placement was in accordance with the description of the technique. Contrast agent was then injected and another radiograph taken to determine whether the navicular bursa had been injected successfully. The position of the navicular bone was highly predictable as a point 1 cm distal to the coronary band and halfway between the most dorsal and most palmar aspect of the coronary band. The use of this point as a landmark for injection of the navicular bursa allowed a high degree of accuracy and reliability of needle placement, irrespective of foot conformation.
Medical treatment of cholangiohepatitis and cholelithiasis in mature horses: 9 cases (1991–1998)
Authors: Peek S. F. , Divers T. J.
Published: April 2007

The medical approach to treatment of cholangiohepatitis and cholelithiasis in 9 horses is described. Seven horses were treated successfully and returned to normal use, with a minimum follow‐up period of 12 months. Long‐term antimicrobial therapy was believed to be critical in those cases that survived, with a median treatment duration of 51 days (range 17–124 days). Treatment failure was associated with severe periportal and bridging hepatic fibrosis from biopsy material obtained at admission in 2 horses, one of whom also presented with hyperammonaemic hepatic encephalopathy. Transabdominal ultrasound was used diagnostically in each case to obtain hepatic biopsy material for histopathology and bacterial culture, to evaluate hepatic size and echogenicity and to identify and monitor the dissolution of hepatoliths. Histologically, all horses had evidence of suppurative cholangiohepatitis with varying degrees of periportal and bridging fibrosis. Discrete hyperechoic calculi were identified in 4 cases, but all horses had ultrasonographic evidence of biliary obstruction with numerous dilated bile ducts. Aerobic and anaerobic cultures of liver biopsy material were negative from 7 horses, but 2 different species ofEscherichia coliwere obtained from one horse, andBacteroides vulgatusandEscherichia coliwere isolated from another. In all 7 horses that survived, clinical recovery was seen before normalisation of biochemical indices of hepatobiliary function including gammaglutamyl transaminopeptidase (GGT), alkaline phosphatase (AP), bile acids and serum bilirubin. Serum GGT levels were monitored extensively as a marker of hepatobiliary disease and actually increased during the initial period of clinical improvement in horses that recovered. Supportive medical therapy with i.v. fluids was also a critical part of the therapy of several cases in this report, both acutely and in the management of chronic cases that deteriorated clinically during treatment.

Previous therapeutic failures may well be related to treatment periods of inadequate duration, and the authors recommend that antimicrobial therapy should be continued until GGT values are normal.
Pleuropulmonary and cardiovascular consequences of thoracoscopy performed in healthy standing horses
Authors: Peroni J. F. , Robinson N. E. , Stick J. A. , Derksen F. J.
Published: April 2007

Six healthy, awake, and pharmacologically restrained mature horses were studied in order to define the changes in cardiopulmonary function during and after exploratory thoracoscopy and to determine the presence of postoperative complications occurring 48 hours after thoracoscopy. In a randomised 3 times 3 latin square design with 2 replications, 18 procedures were performed: 6 right (RTH) and 6 left thoracoscopies (LTH) and 6 sham procedures (STH). Prior to each procedure a physical examination and a bronchoalveolar lavage fluid analysis were performed. During thoracoscopy and sham protocols, horses were sedated with a continual drip of detomidine HCl and data were collected at 6 time intervals: T1 (baseline), T2 (10 min detomidine administration), T3 (first 15 min pneumothorax), T4 (5 min recovery from pneumothorax), T5 (second 15 min pneumothorax), and T6 (10 min recovery from the second pneumothorax and detomidine). An endoscopic thoracic examination was conducted during the 2 pneumothorax periods. An identical protocol was followed for sham procedures without surgery or pneumothorax. Data were analysed by ANOVA with time and surgical procedure as main factors. Physical examinations, thoracic radiography and ultrasound, CBC and bronchoalveolar lavage fluid analysis were performed 48 h after thoracoscopy.

Heart rate, respiratory rate, and cardiac output decreased following detomidine administration. There was a trend for cardiac output to be lower during thoracoscopy. Mild systemic hypertension was associated with thoracoscopy although there was no effect on pulmonary arterial pressure. Total and pulmonary vascular resistances were increased following detomidine administration. Thoracoscopy caused a further increase in systemic and pulmonary vascular resistances especially during the second pneumothorax. Arterial O2tension decreased following detomidine administration and was furtherdecreased during the second pneumothorax period. PaO2values were lower when thoracoscopy was performed on the left ratherthan the right hemithorax. No significant complications were found during the 48 h follow‐up evaluation. A subclinical postoperative pneumothorax occurred in 2 horses, one of which had sustained a lung laceration by the trocar. Thoracoscopy performed in healthy, awake, and pharmacologically restrained horses did not have detrimental cardiopulmonary effects and did not cause postoperative complications within the first 48 h period.
Effect of creatine supplementation on muscle metabolic response to a maximal treadmill exercise test in Standardbred horses
Authors: SCHUBACK K. , ESSÉN‐GUSTAVSSON B. , PERSSON S. G. B.
Published: April 2007

The aim of the present study was to investigate the effect of creatine (Cr) supplementation on muscle metabolic response in connection with a maximal treadmill exercise test, known to cause a marked anaerobic metabolic response and adenine nucleotide degradation. First, 6 Standardbred trotters performed a standardised maximal exercise test until fatigue (baseline test). The test used was an inclined incremental treadmill test in which the speed was increased by 1 m/s, starting at 7 m/s, every 60 s until the horse could no longer keep pace with the treadmill. After this baseline test, the horses were separated into 2 equal groups. One half received a dose of 25 g creatine monohydrate twice daily, and the other group were given the same dose of lactose (placebo). The supplementation period was 6.5 days, after which the maximal treadmill exercise test was performed again. A washout period of 14 days was allowed before treatments were switched between groups and a new supplementation period started. After this second supplementation period a new maximal exercise test was performed. After supplementation with creatine or placebo, horses were stopped after performing the same number of speed steps and duration of exercise as they had in the baseline test. Blood samples for analysis of plasma lactate, creatine (Cr), creatinine, hypoxanthine, xanthine and uric acid concentrations were collected at rest, during each speed step and during recovery. The total blood volume (TBV) was also determined. Muscle biopsies for analysis of muscle metabolites (adenosine triphosphate [ATP], adenosine diphosphate [ADP], adenosine monophosphate [AMP], inosine monophosphate [IMP], creatine phosphate [CP], lactate [La] and glycogen) were taken at rest, immediately post exercise and after 15 min recovery. The results showed no significant increase in plasma Cr or muscle total creatine concentration (TCr) after supplementation with Cr. At the end of exercise ATP and CP concentrations had decreased and IMP and lactate concentrations increased in muscle in all groups. Plasma lactate concentration increased during exercise and recovery and plasma uric acid concentration increased during recovery in all groups. No influence could be found in TBV after supplementation with creatine. These results show that creatine supplementation in the dosage used in this study had no influence on muscle metabolic response or TBV.
Evaluation of nasotracheal aspiration as a diagnostic tool forRhodococcus equipneumonia in foals
Authors: HASHIKURA S. , HIGUCHI T. , TAHARAGUCHI S. , ORITA Y. , NANAO Y. , TAKAI S.
Published: April 2007

The reliability of preparing bacteriological cultures from nasotracheal aspirates of foals routinely in order to diagnoseR. equipneumonia in foals was studied by isolatingRhodococcus equifrom specimens obtained from 96 foals by nasotracheal aspiration with a silicon catheter. Results were compared with specimens obtained from 21 foals by transtracheal aspiration (percutaneous tracheal puncture). These 117 foals showed clinical signs of respiratory tract infection at sampling.R. equiwas isolated from 14 of 21 (66.7%) specimens by transtracheal aspiration and from 59 of 96 (61.4%) specimens by nasotracheal aspiration, 649 of 655 isolates (99.1%) from the 73 positive specimens were virulentR. equi, and the culture‐positive foals were diagnosed as havingR. equipneumonia. To assess the contamination of aspirates by organisms from the nasopharynx, the results ofR. equiisolation from nasal swabs obtained from 56 of the 96 foals were compared to those obtained by nasotracheal aspiration from the same foals.R. equiwas isolated from 2 of the 56 nasal swabs: one from a tracheal aspirate was positive, and the other was not. These results suggest that the nasotracheal aspiration technique, which is noninvasive and not associated with complications, could be used as an alternative to the transtracheal aspiration method, especially for the diagnosis ofR. equipneumonia in foals.
Complications associated with anaesthesia for ocular surgery: a retrospective study 1989–1996
Authors: PARVIAINEN A. K. J. , TRIM C. M.
Published: April 2007

This retrospective study was initiated to identify complications of anaesthesia occurring during ocular surgery. Records of 74 horses anaesthetised for eye enucleation, 65 horses anaesthetised for surgery of the eye and adnexa, and 51 horses anaesthetised for splint bone excision were reviewed. Fifty‐three percent of the horses anaesthetised for eye enucleation moved during surgery which was significantly more frequent than in the other groups (P = 0.001). The incidence of moving was significantly reduced by use of an anaesthetic gas analyser for monitoring (P = 0.001). Transient hypertension was measured in 6 horses during removal of the eye. One horse experienced a momentary decrease in heart rate from 36 to 26 beats/min at the start of surgery involving a mass on the third eyelid. The incidence of unsatisfactory recovery from anaesthesia involving multiple attempts to stand was significantly greater after ocular surgery than after splint bone excision (P = 0.036).

Our conclusions were 1) the oculocardiac reflex was not active in these horses undergoing ocular surgery, 2) increased attention must be paid to provision of analgesia and adequate depth of anaesthesia, which may be facilitated by use of an anaesthetic gas analyser and 3) horses were at greater risk for unsatisfactory recoveries from anaesthesia after ocular surgery.
Reduction of renal function in exercising horses
Authors: GLEADHILL A. , MARLIN D. , HARRIS P. A. , MICHELL A. R.
Published: April 2007

Glomerular filtration rate (GFR) and extracellular volume (ECFV) were measured before, during and after treadmill exercise in 5 trained Thoroughbred horses (mean weight 483 kg). GFR/ECFV was determined by plasma disappearance of Tc‐DTPA and ECFV was measured independently as thiocyanate space. Resting GFR averaged 1.6 l/min (3.3 ml/kg/min) and fell by over 40% during exercise, moreover the fall was severe even during the first walk, prior to trotting. The results suggest that rather than being protected, GFR is allowed to fall, even with mild exercise and that this is probably an adaptation to allow greater perfusion of muscle and skin. In man, GFR appears to be more resistant to the effects of exercise but it is hard to compare intensity of exercise between such different species.
Dynamics of follicle populations and gonadotropin concentrations in fillies age two to ten months
Authors: NOGUEIRA G. P. , GINTHER O. J.
Published: April 2007

Follicle populations and concentrations of circulating gonadotropins were studied during age 2–10 months in 10 spring‐born pony fillies. Blood sampling and ultrasound scanning were done every 4 days and daily for four 30 day periods. During 5–12 weeks, FSH concentrations were lower in 6 fillies with follicles ≥ 6 mm (mean ± s.e. 1.4 ± 0.1 ng/ml) than in 4 fillies with follicles <6 mm (2.8 ± 0.3 ng/ml). The diameters and numbers of follicles and gonadotropin concentrations increased progressively during age 2–4 months. A plateau in follicle activity and reduced levels of gonadotropins occurred during 5–7 months. During 8–10 months, follicles grew to >10 mm and gonadotropin concentrations increased. Waves of follicular growth were identified during the 30 day periods by significant increases in the diameter of the 10 largest follicles. The waves did not partition into dominant and subordinate follicles. Results indicated an initial postnatal period of negative ovarian feedback, temporally related changes in gonadotropins and follicles for months 3–10, and development of follicles in waves.
Haemodynamic response to exercise in Standardbred trotters with red cell hypervolaemia
Authors: Funkquist P. , Nyman G. , Persson S. G. B.
Published: April 2007

In order to evaluate the haemodynamic response to exercise in Standardbred trotters with red cell hypervolaemia (RCHV), 12 trotters with RCHV were compared with 9 normovolaemic (NV) trotters. Haemodynamic data were recorded during exercise at 4 different speeds on a treadmill. Oxygen uptake was determined with an open bias flow system. Pulmonary artery pressure (PAP), systemic artery pressure (SAP), heart rate, packed cell volume (PCV) and plasma lactate and haemoglobin ([Hb]) concentrations were measured. Arteriovenous O2content difference, cardiac output, stroke volume, pulmonary vascular resistance (PVR) and total systemic resistance (TSR) were calculated. Oxygen uptake, arteriovenous O2content difference, heart rate, cardiac output, stroke volume, TSR and lactate did not differ between groups. The RCHV horses had significantly higher both mean diastolic and systolic PAP compared to NV horses and this difference increased with higher workload. Further, a higher SAP, PVR, PCV and [Hb] were found in RCHV horses during the course of exercise. Eleven of the RCHV horses, but none of the NV, showed exercise‐induced pulmonary haemorrhage on endoscopic examination. The increase in red cell volume, resulting in a high PCV and high total blood volume, is suggested to be an important contributor to both the increased blood pressures in pulmonary and systemic circulation during exercise and to the development of exercise‐induced pulmonary haemorrhage in RCHV horses.
Superficial digital flexor tendonitis in the horse
Authors: Dowling B. A. , Dart A. J. , Hodgson D. R. , Smith R. K. W.
Published: April 2007

The superficial digital flexor tendon (SDFT) is an elastic structure that during maximal exercise appears to operate close to its functional limits. The biomechanical and biochemical responses to exercise, injury, and healing are still poorly understood but ongoing research is providing valuable new information which is addressed in this review. It appears that the SDFT matures early, after which time it has limited ability to adapt to stress and undergoes progressive degeneration. Focal hypocellularity, collagen fibril degeneration, selective fibril loading and alterations in the noncollagenous matrix occurprimarily within the central core region of the midmetacarpal segment. Current treatment strategies have had equivocal results in returning animals to optimal athletic activity. To date it would seem that progressive rehabilitation programmes coupled with regular ultrasonographic evaluations are a cost‐effective and comparable strategy when compared to surgical treatment methods. Recent interest in pharmacological modulation of intrinsic healing of collagenous structures has led to the investigation of various growth factors as potential therapeutic aids in the healing of tendon injuries. However, one of the major goals in tendon research, and one which holds the most optimism for success in the immediate future, is the prevention of tendon injuries.
Cytological identification and quantification of testicular cell types using fine needle aspiration in horses
Authors: Leme D. P. , Papa F. O.
Published: April 2007

Fifteen stallions of different breeds, age 3–11 years, had their right testicles evaluated by fine needle aspiration cytology (FNAC). Cytological analysis showed the following spermatogenic cell types: spermatogonia (1.6%± 1.1); spermatocyte I (3.4%± 2.2); spermatocyte II (0.8%± 0.7); early spermatids (25.5%± 9.5); late spermatids (37.0%± 9.3). Spermatozoal numbers were expressed as the spermatic index (SI = 31.5%± 8.5) and Sertoli cells were expressed as the Sertoli cell index (SEI = 20.9%± 17.0) (means ± s.d). Identification of cell types was relatively easy and no immediate adverse effects of aspiration were noted. The results suggest that FNAC of testis may assist clinical diagnosis in the study of male equine infertility.
Environment and prednisone interactions in the treatment of recurrent airway obstruction (heaves)
Authors: Jackson C. A. , Berney C. , Jefcoat A. M. , Robinson N. E.
Published: April 2007

Recurrent airway obstruction (RAO) or heaves is a manifestation of a hypersensitivity to dust, moulds, and spores in the environment of a susceptible horse. Although in the majority of RAO‐affected horses, clinical remission can be achieved by keeping horses at pasture to reduce their allergen exposure, this often is not practicable. For this reason, we investigated if changing the environment of a single stall in a 4 stall stable was sufficient to improve lung function and reduce inflammation in RAO‐affected horses. In addition, we determined if addition of oral prednisone provided additional benefit. Twelve RAO‐susceptible horses were stabled, fed hay, and bedded on straw until they developed airway obstruction. At this point, bedding was changed to wood shavings and they were fed a pelleted diet for 2 weeks. Lung function was measured and bronchoalveolar lavage was performed before and 3, 7, and 14 days after environmental modification. In a crossover design, horses were treated for the 14 days with prednisone tablets (2.2 mg/kg bwt, q. 24 h). Horses then returned to pasture for 30 days. Airway obstruction was greatest before environmental modification. Significant improvement in lung function occurred within 3 days of the change in environment and continued to Day 7. Airway function was best after 30 days at pasture. The clinical response achieved by environmental modification was not significantly improved by addition of oral prednisone. The total number of cells, total neutrophils, and percent neutrophils was greatest before environmental modification. In the absence of prednisone, total and percent neutrophils did not decrease until Day 14 and total cell number until 30 days at pasture. In the presence of prednisone, total cells and total and percent neutrophils decreased by Day 3 and again at pasture. The fact that lung function can be improved within 3 days by environmental management alone emphasises the need for allergen reduction as the cornerstone of treatment of RAO. Although prednisone induced a more rapid reduction in airway inflammation, this was not associated with a more rapid improvement in airway function.
Variability of Doppler ultrasound measurements of hindlimb blood flow in conscious horses
Authors: Raisis A. L. , Young L. E. , Meire H. B. , Taylor P. M. , Walsh K. , Lekeux P.
Published: April 2007

Ultrasonography of the left and right femoral artery and vein was performed in 5 conscious horses. Velocity waveforms, 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) and volumetric flow. Waveform analysis included calculation of early diastolic deceleration slope (EDDS) and pulsatility index (PI) and subjective description of the waveform. Measurements were recorded at monthly intervals for 6 months. The repeated measurements were used to determine the within‐horse variation. Horses were then anaesthetised with halothane and the same measurements recorded 60 min afterinduction. Differences between measurements recorded in conscious and anaesthetised horses were determined.

Within‐horse variability fordiameters of femoral arteries and veins was small (CV<10%). Within variability for all other measurements was marked (CV>11%), with within‐horse variability being the largest for femoral venous flow (CV>35%). Source of variability was measurement errorand biological variation. Despite variability in conscious horses it was possible to detect changes in blood flow during anaesthesia. In the femoral arteries, volumetric flow was lower and EDDS and PI was higher in anaesthetised horses. In the femoral veins, volumetric flow was also lower in anaesthetised horses. Therefore Doppler ultrasound appears to be a useful technique for studying blood flow in conscious and anaesthetised horses.
Postexercise and positional variation in mechanical properties of the radius in young horses
Authors: Batson E. L. , Reilly G. C. , Currey J. D. , Balderson D. S.
Published: April 2007

The metacarpal of the horse is severely loaded during vigorous exercise. Metacarpal specimens have a greater impact strength in young horses that have been exercised than in those that have only been walked. We did not find a corresponding difference in the radius of the same horses.

We show that cranial (anterior) cortical bone from the radius, which is loaded in tension during locomotion, has a greater Young's modulus, and tensile and bending strength, than bone from the caudal (posterior) cortex, which is loaded in compression. Caudal bone is, however, stronger in compression. The differences can be explained by differences in the histological structure developed by the 2 cortices and are presumably adaptive. This work confirms the work of others.

Furthermore, we demonstrate that the impact energy absorption of cranial bone is nearly twice as great as that of caudal bone. The caudal cortex has apparently paid a heavy price in its reduction in resistance to accidental impact loading for being stronger than the cranial cortex in compressive loading.
Analysis of right ventricular function in the exercising horse: use of the Fourier Transform
Authors: Weigle G. E. , Langsetmo I. , Gallagher R. R. , Dyer R. A. , Erickson H. H. , Fedde M. R.
Published: April 2007

The objective of this study was to develop and test a technique to allow dynamic cardiac function to be studied during exercise in the horse. Blood pressure waveforms in the exercising horse are difficult to interpret because of the large influence of stride and respiration. A method has been devised to study dynamic right ventricular variables during high‐speed exercise in the horse. A Fast Fourier Transform was performed on the digitised pressure waveforms and the frequency components associated with stride and respiration were removed. An inverse Fourier Transform was then performed to generate a time‐domain pressure signal. Several dynamic right ventricular variables were calculated using the derived signal. Various parameters associated with removing frequencies from the frequency‐domain pressure signal were changed to determine their influence on the variables. Most of the variables were not sensitive to these parameters. When compared during separate exercise bouts, some variables differed among runs, while others were not significantly different. Using the signal separation technique described here, right ventricular function of an exercising horse can be critically analysed.
The effect of oxytocin on contractility of the equine oesophagus: a potential treatment for oesophageal obstruction
Authors: Meyer G. A. , Rashmir‐Raven A. , Helms R. J. , Brashier M.
Published: April 2007

This study was performed to determine the effect of administration of i.v. oxytocin on the contractility of the musculature associated with the equine oesophagus. Nine clinically normal horses were fitted with a nasogastric tube modified with inflatable latex cuffs. These cuffs were connected to piezoelectric pressure recording devices. Oxytocin in 3 different doses or saline controls were administered i.v. in a randomised block pattern. Systolic blood pressure, ECG, heart rate and nasogastric tube cuff pressures were then measured for 60 min. Administration of oxytocin i.v. at 0.11 and 0.22 iu/kg bwt, resulted in a short‐term statistically significant relaxation of the musculature of the equine oesophagus. When oxytocin was administered at 0.11, 0.22 and 0.44 iu/kg bwt, no clinically significant cardiovascular changes were seen. In approximately 5% of the oxytocin administrations, signs of mild short‐term abdominal discomfort were observed. In clinical cases of noncomplicated oesophageal obstruction, it is suggested that reduction in tone of oesophageal musculature may result in passage of oesophageal obstructions with reduced risk of oesophageal injury when compared to other traditional treatments.
The effect of replacing nonstructural carbohydrates with soybean oil on the digestibility of fibre in trotting horses
Authors: Jansen W. L. , Van Der Kuilen J. , Geelen S. N. J. , Beynen A. C.
Published: April 2007

The hypothesis tested was that the intake of extra fat at the expense of an isoenergetic amount of nonstructural carbohydrates reduces fibre utilisation in horses. In a crossovertrial with feeding periods of 42 days each, 6 mature trotting horses (age 4–12 years, bodyweight 340–476 kg) were given either a control or test diet. The test concentrate was formulated to contain 37% of net energy in the form of soybean oil. The control concentrate contained an isoenergetic amount of corn starch plus glucose. The concentrates were fed in combination with the same amount of hay so that the control and test diet contained 25.13 and 86.66 g crude fat/kg dry matter, respectively. Apart from the amounts of fat and nonstructural carbohydrates, the 2 diets were identical. The test diet reduced the apparent total tract digestibilities of crude fibre, neutral and acid detergent fibre by 8.0 (P = 0.007), 6.2 (P = 0.022) and 8.3 (P = 0.0005) percentage units, respectively. It is suggested that a high fat intake by horses may increase the amount of fat entering the large intestine to levels that depress fermentation by cellulolytic bacteria. The observed interaction between fat content of the diet and fibre utilisation may have consequences for practical horse feeding in that calculating the energy content of test diets on the basis of feedstuff tables leads to overestimating the amount of energy provided by the high‐fibre ingredients of the diets.
Cartilage oligomeric matrix protein (COMP) levels in digital sheath synovial fluid and serum with tendon injury
Authors: Smith R. K. W. , Heinegård D.
Published: April 2007

Cartilage oligomeric matrix protein (COMP) is a noncollagenous extracellular matrix protein found predominantly in cartilage, but also in tendon, ligament and meniscus. Studies in man have demonstrated that it may be used as a prognostic marker in rheumatoid arthritis and osteoarthritis. The present study investigated whether tendon injury contributes to serum and tendon sheath synovial fluid levels of COMP in horses. COMP levels, analysed by competitive ELISA, in the digital sheath synovial fluid were more than 10‐fold higherthan in the serum. Levels were significantly raised when tendon damage or sepsis was present within the tendon sheath but showed only mild, statistically insignificant, elevation in cases of tenosynovitis alone. COMP concentrations in serum were found to vary with age. Foals (age ≥ 1 year) had significantly (P<0.001) higher levels in comparison to older control horses. Total COMP concentrations in an age‐matched group with tendinitis were not significantly different from the control group. Measurements of COMP levels in tendon sheath synovial fluid are therefore useful in depicting processes in tendon tissue, while elevated serum levels are likely to be more representative of joint disease than tendinitis.
Clinical and neuropathological features of West Nile virus equine encephalomyelitis in Italy
Authors: Cantile C. , Di Guardo G. , Eleni C. , Arispici M.
Published: April 2007

West Nile (WN) virus infection is a mosquito‐borne flavivirosis endemic in Africa and Asia. Clinical disease is usually rare and mild and only in a few cases the infection causes encephalomyelitis in horses, fever and meningoencephalitis in man. We report here the clinical and pathological findings in an epidemic of the disease involving 14 horses from Tuscany, Italy. All cases were observed from August to October 1998. Affected horses showed ataxia, weakness paresis of the hindlimbs and, in 6 cases, there was paraparesis progressing to tetraplegia and recumbency within 2 to 9 days. Eight animals recovered without any important consequences. Serological investigations revealed positivity to WN virus in all the 14 horses and the agent was isolated from the cerebellum and spinal cord of an affected horse. Postmortem examination was carried out on 6 horses. The neuropathological pattern was that of a mild to moderate, nonsuppurative polioencephalomyelitis with constant involvement of the ventral horns of the thoracic and lumbar spinal cord, where focal gliosis and haemorrhage were also apparent in some cases. Differential diagnoses with other equine viral encephalomyelitides are discussed. Climatological and environmental characteristics of the geographic area in which the outbreaks occurred suggest the existence of suitable conditions for the development of the disease. This is the first report of WN virus equine encephalomyelitis in Italy.
An immunodeficiency in Fell ponies: a preliminary study into cellular responses
Authors: BELL S. C. , SAVIDGE C. , TAYLOR P. , KNOTTENBELT D. C. , CARTER S. D.
Published: April 2007

A putative immunodeficiency, causing mortality in UK Fell pony foals (Fell pony syndrome), was studied in affected foals and compared with healthy, age‐matched foals. Differential cell counts of peripheral blood indicated that the syndrome foals were lymphopenic (P<0.05). Flow cytometric analysis of circulating leucocytes showed a reduced MHC II expression (P<0.01) on lymphocytes but not on polymorphonuclear cells in affected foals. There were no changes in the percentages of CD4+ or CD8+ T cells. There was an increased (P<0.05) expression of CD11a/18 by the lymphocytes of the syndrome foals, compared to the control foals, which is probably a response to systemic bacterial infections. The syndrome foals' lymphocytes responded to mitogens (PHA, ConA, PWM) at normal levels. The data do not conform to any known immunodeficiencies identified in any other species. Further analyses will be required, particularly on bone marrow function.
Efficacy of a cold‐adapted, intranasal, equine influenza vaccine: challenge trials
Authors: TOWNSEND H. G. G. , PENNER S. J. , WATTS T. C. , COOK A. , BOGDAN J. , HAINES D. M. , GRIFFIN S. , CHAMBERS T. , HOLLAND R. E. , WHITAKER‐DOWLING P. , YOUNGNER J. S. , SEBRING R. W.
Published: April 2007

A randomised, controlled, double‐blind, influenza virus, aerosol challenge of horses was undertaken to determine the efficacy of a cold‐adapted, temperature sensitive, modified‐live virus, intranasal, equine influenza vaccine. Ninety 11‐month‐old influenza‐naïve foals were assigned randomly to 3 groups (20 vaccinates and 10 controls per group) and challenged 5 weeks, 6 and 12 months after a single vaccination. Challenges were performed on Day 0 in a plastic‐lined chamber. Between Days 1 and 10, animals were examined daily for evidence of clinical signs of influenza. Nasal swabs for virus isolation were obtained on Day 1 and Days 1 to 8 and blood samples for serology were collected on Days 1, 7 and 14. There was no adverse response to vaccination in any animal. Following challenge at 5 weeks and 6 months, vaccinates had significantly lower clinical scores (P = 0.0001 and 0.005, respectively), experienced smaller increases in rectal temperature (P = 0.0008 and 0.0007, respectively) and shed less virus (P<0.0001 and P = 0.03, respectively) over fewer days (P<0.0001 and P = 0.002, respectively) than did the controls. After the 12 month challenge, rectal temperatures (P = 0.006) as well as the duration (P = 0.03) and concentration of virus shed (P = 0.04) were significantly reduced among vaccinated animals. The results of this study showed that 6 months after a single dose of vaccine the duration and severity of clinical signs were markedly reduced amongst vaccinated animals exposed to a severe live‐virus challenge. Appropriate use of this vaccine should lead to a marked reduction in the frequency, severity and duration of outbreaks of equine influenza in North America.
Opsonic capacity of foal serum for the two neonatal pathogensEscherichia coliandActinobacillus equuli
Authors: GRÖNDAHL G. , STERNBERG S. , JENSEN‐WAERN M. , JOHANNISSON A.
Published: April 2007

Two of the most commonly isolated foal pathogens areEscherichia coliandActinobacillus equuli.The hypothesis tested in this study was that young foals carry a lower opsonic capacity for these bacteria compared to adult horses. A flow‐cytometric method for the phagocytosis of these by equine neutrophils was established. The opsonic capacity of serum from healthy foals from birth to age 6 weeks was evaluated and related to the concentrations of IgGa and IgGb. Phagocytosis of yeast was used as a control. Serum was required for phagocytosis, with higher concentrations forE. colithan forA. equuli.Ingestion of colostrum led to a significantly higher serum opsonic capacity. After that, there was no consistent age‐related trend for opsonic capacity for the different microbes. Foal serum showed similar or higher opsonisation ofE. coliandA. equulicompared to serum from mature individuals. During the studied period, the predominance among IgG subisotypes switched from IgGb to IgGa. Although the overall correlation between concentrations of IgG subisotypes and serum opsonic capacity was poor, sera with IgGb levels below 1.9 mg/ml induced lower opsonisation ofE. coliand yeast, but not ofA. equuli.Complement activation was important for opsonisation of all tested microbes. The results of this study are significant to the understanding of a key immunological facet in the pathophysiology of equine neonatal septicaemia in clinical practice.
Concentration of collagen, aggrecan and cartilage oligomeric matrix protein (COMP) in synovial fluid from equine middle carpal joints
Authors: SKIÖLDEBRAND E. , LORENZO P. , ZUNINO L. , RUCKLIDGE G. J. , SANDGREN B. , CARLSTEN J. , EKMAN S.
Published: April 2007

The aim of the present investigation was to study the metabolic activity of the third carpal bone and the release of COMP, aggrecan and collagentype IImolecules in the synovial fluid as a result of injury. Cartilage oligomeric matrix protein (COMP), aggrecan and collagentype IIor fragments of these molecules released to the synovial fluid and serum (COMP) were quantified in samples from 73 left equine middle carpal joints from 2 breeds with different activity profiles (52 Standardbred trotters [STB] and 21 Swedish Warmblood riding horses [SWH]) and different articular cartilage lesions. Synovial and serum samples were analysed using inhibition ELISA for COMP and aggrecan. An ELISA that combines features of both the competitive and capture ELISAs was used for collagentype II.COMP and aggrecan concentrations decreased in synovial fluid from the joints with moderate lesions of STB compared with the normal joints; COMP from 16.6 to 12.0 μg/ml and aggrecan from 93.0 to 68.1 μg/ml. In serum, COMP concentrations were also lowered in the STB with moderate lesions compared with the normal joints, while in the SWH, the COMP concentration in synovial fluids from joints with moderate lesions was somewhat increased at 19.6 μg/ml compared with the normal joints (17.6 μg/ml). The ratio between aggrecan/COMP in the synovial fluid from joints with moderate lesions was higher in the STB (6.2) than in the SWH (3.4). The level of collagentype IIin synovial fluid was higher in the SWH (8.8 μg/ml) than the STB (1.6 μg/ml), but there was no correlation between joint damage and collagen concentrations in synovial fluids (10.0 and 1.8 μg/ml in joints with moderate lesions from SWH and STB, respectively). A marked difference in COMP synthesised upon metabolic labelling between the normal and osteoarthritic cartilage was seen and the synthesis of COMP in the articular cartilage of the third carpal bone with moderate articular lesions (from an STB) was lower than in the joint with mild lesions.

This difference between breeds may reflect different load characters, in release of macromolecules in osteoarthritic and normal joints. This a novel finding that should be considered in studies of equine traumatic arthritis.
Proximal interphalangeal arthrodesis in 22 horses
Authors: SCHAER T. P. , BRAMLAGE L. R. , EMBERTSON R. M. , HANCE S.
Published: April 2007

The purpose of this study was to evaluate a new method of internal fixation technique for pastern arthrodesis. Pastern arthrodeses are performed commonly in horses with chronic osteoarthritis of the pastern joint or, in cases of acute traumatic injury to the pastern, in which the weightbearing bony column must be restored. Chronic osteoarthritis of the pastern is a frequent cause of lameness in the equine athlete and is evidenced by chronic lameness localised to the pastern joint, and supported radiographically by periosteal proliferation and loss of joint space. Nonsurgical and surgical treatments have both been described in the literature. Complications following pastern arthrodesis have been reported on several occasions and appear to focus on excessive periarticularexostoses and increased time in a cast due to prolonged time to bony fusion.

The hospital records of horses presenting for pastern arthrodesis to the Rood and Riddle Equine Hospital in Lexington, Kentucky, were reviewed and 22 met criteria for inclusion in the study. Horses with chronic osteoarthritis of the proximal interphalangeal joint or horses with an acute traumatic injury to the pastern undergoing pastern arthrodesis with one of the following techniques were included in the study. Horses with severe comminution of the middle phalanx were excluded. Three 5.5 mm cortical bone screws placed in lag fashion alone or in combination with a 4 or 3 hole dynamic compression plate affixed with 4.5 mm cortical bone screws were compared. A lower limb fibreglass cast was applied in all cases. Period in cast, time to return to intended use, complications encountered and outcome were evaluated.

Seven of the 8 hindlimbs treated with the combination technique became sound. Three out of 6 of the front limbs treated with the combination technique became sound. Four of the 5 horses with hindlimbs, and one of the 2 with front limbs, treated with screws only returned to their intended use.

The type of internal fixation did not appear to influence the overall number of horses returning to the intended level of performance. The period spent in cast and the time to return to soundness were decreased in horses operated on using the combination technique. We concluded that, in the immediate postoperative period, the combination of the parallel screw technique with a dorsally‐applied dynamic compression plate provides the most stable and secure fixation, minimising motion, expediting bone remodelling and therefore favouring rapid fusion of that joint.
Postprandial arterial vasodilation in the equine distal thoracic limb
Authors: HOFFMANN K. L. , WOOD A. K. W. , GRIFFITHS K. A. , EVANS D. L. , GILL R. W. , KIRBY A. C.
Published: April 2007

The effects of feeding on blood flow to the equine foot are poorly understood. In a temperature‐controlled room, duplex Doppler ultrasonographic observations were made pre‐ and postprandially of the lateral proper palmar digital artery of 5 horses, randomly assigned to twice and 4 times daily feeding in an unbalanced 2 period crossover design. Arterial diameter and blood velocity were measured over 4 h and additional observations made of heart rate, blood pressure, total plasma protein, packed cell volume, plasma glucose and insulin. There was no effect of the feeding regimen on any variable. Postprandially, there were significant increases in arterial diameter, blood velocity, total plasma protein, plasma glucose and insulin; the other variables were unchanged. It appeared that the normal postprandial response was an increase in blood flow to the foot. The value of ultrasonography for noninvasive investigation of the peripheral vasculature of the conscious horse was established; and in the future it may have a role in the diagnosis of vascular diseases of the foot.
Effects of training on resting peripheral blood and BAL‐derived leucocyte function in horses
Authors: RAIDAL S. L. , ROSE R. J. , LOVE D. N.
Published: April 2007

In this study, the effects of prolonged, high intensity training on aspects of peripheral blood and bronchoalveolar lavage (BAL)‐derived leucocyte function were evaluated in 8 horses. All horses undertook a 7 week endurance training programme, followed by 5 weeks of high intensity training (HIT). Thereafter, horses were divided into control (C) and overtraining (OT) groups. The frequency and intensity of training were increased more substantially for horses in the OT group. Training was terminated in week 32 when horses in the OT group demonstrated a significant performance reduction. Peripheral blood and BAL samples were collected from 4 horses in C and OT groups in training weeks 7, 11, 14, 18, 22, 28 and 32. Flow cytometric techniques were used to assess phagocytosis by peripheral blood neutrophils and pulmonary alveolar macrophages (PAM), and oxidative burst activity of neutrophils, PAM, peripheral blood and BAL‐derived lymphocytes. Peripheral blood neutrophil phagocytosis (internalisation) increased during the initial HIT period and decreased from week 16 when the training workload was increased forboth groups. The oxidative burst activity of peripheral blood neutrophils and lymphocytes similarly increased and then decreased in response to training. The oxidative burst activity of PAM was reduced towards the end of the overtraining phase of the programme. Pulmonary alveolar macrophage phagocytosis and oxidative burst activity of BAL‐derived lymphocytes demonstrated no change throughout the course of the study. There was no difference in results obtained from C or OT group horses, suggesting that protracted HIT, rather than overtraining, was associated with impaired cell function.

The detrimental effects observed in peripheral blood neitrophil and PAM function may indicate impaired nonspecific immunity which may adversely affect the health and performance of horses undergoing protracted periods of intense training.