bluuebunny/crossref_metadata_2025 huggingface dataset:
The forelimb in walking horses: 1. Kinematics and ground reaction forces
Authors: Hodson E. , Clayton H. M. , Lanovaz J. L.
Published: April 2007

Video (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

Electromyographic 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

We 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

The 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

The 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.
Serum markers of lamellar basement membrane degradation and lamellar histopathological changes in horses affected with laminitis
Authors: JOHNSON P. J. , KREEGER J. M. , KEELER M. , GANJAM V. K. , MESSER N. T.
Published: April 2007

In order better to evaluate the extent to which degradation of the lamellar basement membrane (LBM) by matrix metalloproteinases (MMP) occurs in equine laminitis, we determined the concentration of type IV collagen and laminin in normal and laminitic horses, using specific immunoassays. Blood samples were obtained from both the jugular and the cephalic veins of horses (n = 10) before and after the induction of acute alimentary laminitis by carbohydrate overload. Jugular and cephalic venous blood samples were also obtained from horses affected with naturally occurring laminitis (n = 16) and nonlaminitic controls (n = 8). The serum collagen IV concentration was not changed following the induction of laminitis in the experimental group.

Serum collagen IV concentration was increased in jugular venous blood obtained from cases of naturally occurring laminitis (mean ± s.e. 218.04 ± 18.59 ng/ml) compared with nonlaminitic controls (157.50 ± 10.93 ng/ml) (P<0.05). Serum collagen IV concentration was also increased in jugular venous blood obtained from severely laminitic horses (219.50 ± 18.18 ng/ml) compared with nonlaminitic controls (157.50 ± 10.93 ng/ml) (P<0.05). A difference in serum concentration of collagen IV was not identified based on chronicity of naturally occurring laminitis.

Serum laminin concentration did not differ between laminitic and nonlaminitic horses. Differences in serum laminin concentration were not identified based on sampling location (jugular orcephalic vein), severity of laminitic pain, or chronicity of spontaneous laminitis. In conclusion, the circulating concentration of collagen IV was increased in horses affected with naturally occurring laminitis. The potential role for serum collagen IV assay for characterisation of equine laminitis warrants further investigation.
Acrosomal ultrastructure of stallion spermatozoa cryopreserved with ethylene glycol using two packaging systems
Authors: ALVARENGA M. A. , LANDIM‐ALVARENGA F. C. , MOREIRA R. M. , CESARINO M. M.
Published: April 2007

The present experiments aimed to examine the substitution of glycerol (G) by ethylene glycol (E) as a cryoprotective agent for stallion spermatozoa. Two different ethylene glycol concentrations (5% and 10%) and also the association of glycerol (2%) and ethylene glycol (3%) (E/G) were studied (Experiment 1). In Experiment 2, two packing systems (0.5 times 4.0 ml) were evaluated using both cryoprotectors. In both experiments, the sperm membrane integrity after freezing was evaluated using transmission electron microscopy. The mean post‐thaw motility was 34.25, 36.5, 29.25 and 34.75% for G5%, E5%, E10% and E/G, respectively. It was observed that the percentage of motile spermatozoa was significantly smaller (P<0.05) when semen was processed with E10%. A decrease in the acrosome integrity was observed in frozen thawed spermatozoa from all treated groups. It was observed that 28.0, 22.5, 25.5 and 22.5% of the sperm cells had a normal acrosome following freezing with G5%, E5%, E10% and E/G, respectively. Undulation of the outer acrosomal membrane, acrosomal swelling and loss of acrosomal content density and homogeneity were the most evident ultrastructural alterations observed. In Experiment 2, the post‐thaw motility was higher (P<0.05) for sperm frozen in 0.5 ml straws than in 4.0 ml straws, regardless of the cryoprotector used. The ultrastructural evaluation showed 26.7 and 16.0% of intact acrosomes for sperm frozen in 0.5 ml and 4.0 ml straws, respectively. We concluded that ethylene glycol has similar cryoprotective properties to glycerol and that utilisation of 0.5 ml straws improved the ability of horse sperm cells to withstand damage after the cryopreservation process.
In vitro model of equine muscle regeneration
Authors: Byrne K. M. , Vierck J. , Dodson M. V.
Published: April 2007

Equine satellite cells are responsible for muscle healing and regeneration in the mature horse. We describe the in vitro cell culture conditions required for clonal populations of equine satellite cells to undergo both proliferation and differentiation. Our hypothesis is that these in vitro conditions model regeneration of muscle and can be used to evaluate potential therapeutics. In this study, 2 areas of satellite cell response were tested: proliferation of clones induced by growth factors, and fusion induced by culture conditions. Equine satellite cell clones showed differences in their response to growth factors as well as accumulation of cellular protein concentrations. Equine satellite cells proliferate in response to both human and bovine FGF. IGF‐1, a powerful mitogen of other satellite cell culture systems, was not as effective forinducing equine satellite cell proliferation. Protein concentrations were also measured in satellite cell cultures. Clones differed in cellular protein produced depending on growth conditions. Conditions inducing differentiation into myotubes was also determined fora 96 well assay and can be used to study the final stage of functioning muscle production. This in vitro model is the first step in identifying potential therapeutics to speed wound healing and promote muscle regeneration in horses.
Relationship of pulmonary arterial pressure to pulmonary haemorrhage in exercising horses
Authors: Langsetmo I. , Fedde M. R. , Meyer T. S. , Erickson H. H.
Published: April 2007

Exercise‐induced pulmonary haemorrhage (EIPH) is characterised by blood in the airways after strenuous exercise and results from stress failure of the pulmonary capillaries. The purpose of this experiment was to establish a threshold value of transmural pulmonary arterial pressure at which haemorrhage occurs in the exercising horse. Five geldings, age 4–14 years, were run in random order once every 2 weeks at 1 of 4 speeds (9, 11, 13, 15 m/s); one day with no run was used as a control. Heart rate, pulmonary arterial pressure and oesophageal pressure were recorded for the duration of the run. Transmural pulmonary arterial pressure was estimated by electronic subtraction of the oesophageal pressure from the intravascular pulmonary arterial pressure. Within 1 h of the run, bronchoalveolar lavage was performed and the red and white blood cells in the fluld were quantified. Red cell counts in the lavage fluid from horses running at 9, 11 and 13 m/s were not significantly different from the control value, but after runs at 15 m/s, red cell counts were significantly (P<0.05) higher. White cell counts were not different from control values at any speed. Analysis of red cell count vs. transmural pulmonary arterial pressure indicated that haemorrhage occurs at approximately 95 mmHg. Red cell lysis in the lavage fluid was also apparent at transmural pulmonary arterial pressures above 90 mmHg. We conclude that, in the exercising horse, a pulmonary arterial pressure threshold exists above which haemorrhage occurs, and that pressure is often exceeded during high speed sprint exercise.
Surgical treatment of 45 horses affected by squamous cell carcinoma of the penis and prepuce
Authors: Mair T. S. , Walmsley J. P. , Phillips T. J.
Published: April 2007

The medical records of 45 horses treated for suspected squamous cell carcinoma of the penis and/or prepuce were reviewed. The age of 40 horses was known, and these had a mean age of 17.4 years. The duration of neoplasia was known foronly 3 of the 45 horses. The results of histological evaluation of lesions, available for 35 horses, confirmed that the diseased tissue was squamous cell carcinoma. The location of gross neoplastic lesions was recorded for 43 horses; theglans peniswas involved in 24 horses, the body of the penis or the inner lamina of the preputial fold in 27 horses, and the external fold of the prepuce in 10 horses. Surgical treatments of these horses included phallectomy (penile amputation) in 35 horses, segmental posthectomy in 4 horses, phallectomy plus segmental posthectomy in 2 horses, anden blocresection of the penis, prepuce and superficial inguinal lymph nodes with penile retroversion in 4 cases. Short‐term complications in the immediate postoperative period included preputial oedema and haemorrhage at the end of urination. One horse developed acute urinary retention because of severe urethral oedema. Long‐term (>1 year) follow‐up information was obtained for 31 horses. Neoplasia of the penis and/or prepuce recurred in 6 of these 31 horses (19%), and in 5 of these the recurrence necessitated euthanasia of the horse.
Tracheobronchial mucus viscoelasticity during environmental challenge in horses with recurrent airway obstruction
Authors: Gerber V. , King M. , Schneider D. A. , Robinson N. E.
Published: April 2007

The goal of this study was to compare the rheological properties of mucus from horses with recurrent airway obstruction (RAO) to that from healthy controls during environmental challenge by stabling in stalls with straw as bedding and hay as feed. We determined viscoelasticity (log G*dyn/cm2, at 10 radian/s) and calculated mucociliary clearability index (MCI) and cough clearability index (CCI), which are derivative parameters of G*and the ratio of viscosity and elasticity measured at 1 and 100 radian/s, respectively. We also investigated the solids content of mucus, and cytology of bronchoalveolar lavage fluid (BALF). Samples were obtained before (0 h) and 6, 24 and 48 h after environmental challenge. The central findings were rheological changes in airway mucus, which occurred over time in RAO‐affected animals, but not in controls. Mucus rheology was similar in both groups at 0 and 6 h. In RAO‐affected horses, mucus viscoelasticity, as measured by log G*, increased from 2.49 ± 0.18 dyn/cm2(mean ± s.e.) at 0 h to 3.05 ± 0.13 dyn/cm2at 24 h after environmental challenge, and was accompanied by significant decreases in MCI and CCI. Percent solids of mucus did not differ significantly between the 2 groups, nor over time. Rheological values did not correlate with BALF cytology. We conclude that viscoelastic properties of tracheal mucus samples from RAO horses in remission do not differ from those of normal horses. However, environmental challenge causes clinical signs of small airway disease and a concurrent increase in mucus viscoelasticity only in RAO horses. Therefore, we infer that unfavourable changes in mucus rheology may contribute to stasis and accumulation of mucus in RAO horses in exacerbation, but not in clinical remission.
Melanin affinity: a possible explanation of isoxsuprine retention in the horse
Authors: Törneke K. , Larsson C. Ingvast , Appelgren L.‐E.
Published: April 2007

Isoxsuprine is used in veterinary medicine as a vasodilating agent. The drug has been detected in the urine of horses up to 6 weeks after the cessation of administration. In the present study, the distribution pattern of 3H‐isoxsuprine was investigated using whole body autoradiography in mice to find a possible site of retention. Melanin was the only place of retention identified. Additional in vitro studies showed an affinity of isoxsuprine to both melanin and keratin. The Kd values were 0.02 mmol/l and 1 mmol/l, and the Bmax values were 0.2 μmol/mg and 2 μmol/mg, respectively. A low affinity site with approximately the same Kd and Bmax as keratin was also detected for melanin. 3H‐isoxsuprine was found to have affinity to pigmented horse skin after incubation in vitro and microautoradiography. We believe that affinity to melanin and possibly also to keratin can cause retention of the drug in the body and therefore explain the prolonged excretion of low levels of isoxsuprine in the horse.
Ultrasonography of the equine neonatal kidney
Authors: Hoffmann K. L. , Wood A. K. W. , Mccarthy P. H.
Published: April 2007

Ultrasonography is important in the clinical examination of the foal. The ultrasonographic appearance and size of the neonatal kidneys were defined and an imaging protocol established in 6 normal Thoroughbred foals (mean age ± s.d. 5.0 ± 3.2 days). Characteristically, in both the heart‐shaped right kidney and bean‐shaped left kidney, the renal cortex was more echogenic than the medulla. The terminal recesses, renal crest and pelvis were identified, as was the ureter, which contained anechoic urine in its lumen. The renal, interlobar and arcuate vessels were seen. For the right kidney, the ultrasonographic probe was placed at the 14–17th intercostal spaces and paralumbar fossa. For the left kidney, the probe was at the 16th or 17th intercostal spaces and paralumbar fossa. Perirenal structures, including the caudate lobe of the liver, the dorsal extremity of the spleen, the adrenals, the aorta and caudal vena cava were also identified. An understanding of the ultrasonographic appearance of the normal neonatal kidney, accompanied by a routine imaging protocol to ensure that all regions of each kidney are examined, permit a more informed interpretation of renal images in the first few dayspostpartum.
Ossification of the cartilages in the front feet of young Norwegian coldblooded horses
Authors: Holm A. W. , Bjørnstad G. , Ruohoniemi M.
Published: April 2007

The purpose of the present study was to evaluate the nature of ossification of the cartilages in the front feet of young, about 2‐year‐old Norwegian coldblooded horses, and to compare offspring of different sires in this respect. Dorsopalmarradiographs of the front feet of 392 horses (187 female and 205 male) were evaluated for ossification at the base of the cartilage and for separate centres of ossification. The horses were offspring of 45 different sires. Ossification extending above the navicular bone and separate centres of ossification were considered as significant. Minimal to mild ossification at the base of the cartilages was commonly seen, and significant ossification was present in one or more of the cartilages in 11.5% of the horses. The lateral compared to medial cartilages had more ossification and females had more ossification and more separate centres of ossification than males. The prevalence of horses with significant ossifications was significantly higher (46.3%) among offspring of one frequently used stallion than in the group consisting of offspring of 4 otherpopularstallions (3.5%) and in another group consisting of offspring of other, less frequently used stallions (9.6%). Ossification of the cartilages is considered to have a hereditary background in Norwegian coldblooded horses.
In vitroevaluation of a novel prosthesis for laryngoplasty of horses with recurrent laryngeal neuropathy
Authors: Schumacher J. , Wilson A. M. , Pardoe C. , Easter J. L.
Published: April 2007

A prosthesis, composed of a steel cable and stress‐reducing washers, was developed to prevent failure of laryngoplasty, a common treatment for horses affected by recurrent laryngeal neuropathy. Laryngoplasties were performed on 15 cadaveric larynges using a polyester suture on one side and the cable prosthesis on the other. Each prosthesis was distracted at a displacement rate of 20 mm/s using a servohydraulic materials testing machine until laryngoplasty failed. Distraction force and actuator displacement were recorded and analysed. All 15 laryngoplasties performed with a suture failed at the muscular process at a mean ± s.d. force of 55.8 ± 13.1 N. Six laryngoplasties performed with the cable prosthesis failed at the muscular process at mean force 219.6 ± 125.0 N. In the other 9, the arytenoid cartilage was avulsed from the larynx at mean force 206.4 ± 75.3 N, and the cable then tore through the muscular process at mean force 357.0 ± 32.0 N. The difference in force required to cause failure of laryngoplasty was significant (P<0.0001). Although the prosthesis resisted substantially higher forces than did the suture, the effects of the prosthesisin vivomust be evaluated.
Topographical mapping of biochemical properties of articular cartilage in the equine fetlock joint
Authors: Brama P. A. J. , Tekoppele J. M. , Bank R. A. , Karssenberg D. , Barneveld A. , Van Weeren P. R.
Published: April 2007

The aim of this study was to evaluate topographical differences in the biochemical composition of the extracellular matrix of articular cartilage of the normal equine fetlock joint. Water content, DNA content, glycosaminoglycan (GAG) content and a number of characteristics of the collagen network (total collagen content, levels of hydroxylysine‐ (Hyl) and the crosslink hydroxylysylpyridinoline, (HP) of articular cartilage in the proximal 1st phalanx (P1), distal 3rd metacarpal bone (MC), and proximal sesamoid bones (PSB) were determined in the left and right fetlock joint of 6 mature horses (age 5–9 years). Twenty‐eight sites were sampled per joint, which included the clinically important areas often associated with pathology. Biochemical differences were evaluated between sampling sites and related with the predisposition for osteochondral injury and type of loading.

Significant regional differences in the composition of the extracellular matrix existed within the joint. Furthermore, left and right joints exhibited biochemical differences. Typical topographic distribution patterns were observed for each parameter. In P1 the dorsal and palmar articular margin showed a significantly lower GAG content than the more centrally located sites. Collagen content and HP crosslinks were higher at the joint margins than in the central area. Also, in the MC, GAG content was significantly lower at the (dorsal) articular margin compared with the central area. Consistent with findings in P1, collagen and HP crosslinks were significantly lower in the central area compared to the (dorsal) articular margin.

Biochemical and biomechanical heterogeneity of articular cartilage is supposed to reflect the different functional demands made at different sites. In the present study, GAG content was highest in the constantly loaded central areas of the joint surfaces. In contrast, collagen content and HPcrosslinks were higherin areas intermittently subjected to peak loading which suggests that the response to a certain type of loading of the various components of the extracellular matrix of articular cartilage are different. The differences in biochemical characteristics between the various sites may help to explain the site specificity of osteochondral lesions commonly found in the equine fetlock joint. Finally, these findings emphasise that the choice of sampling sites may profoundly influence the outcome of biochemical studies of articular cartilage.
Equine dental disease Part 3: a long‐term study of 400 cases: disorders of wear, traumatic damage and idiopathic fractures, tumours and miscellaneous disorders of the cheek teeth
Authors: Dixon P. M. , Tremaine W. H. , Pickles Kirstie , Kuhns Lorna , Hawe Carlyn , Mccann Jacqui , Mcgorum B. C. , Railton D. I. , Brammer Stephanie
Published: April 2007

Of 400 horses referred because of dental disorders, 349 cases were diagnosed as suffering from primary disorders of their cheek teeth. Details of 104 of these cases are presented, including 44 cases with abnormalities of wear, 26 cases with traumatic damage, 24 cases with idiopathic fractures and 10 cases with miscellaneous cheek teeth disorders including oral tumours. The long‐term response to treatment was excellent in most cases, even in cases with residual secondary periodontal disease.
Evaluation of IgG concentration and IgG subisotypes in foals with complete or partial failure of passive transfer after administration of intravenous serum or plasma
Authors: McCLURE J. T. , DeLUCA J. L. , LUNN D. P. , MILLER J.
Published: April 2007

The purpose of this study was to evaluate the ability of an equine plasma product i.v. and a concentrated serum product i.v. to deliver antibodies to 46 foals with failure of passive transfer (FPT). Treatment of FPT was as per manufacturers recommendations, using plasma (950 ml/unit) or a concentrated serum product (250 ml/unit). Significant variables affecting the 3 day post‐transfusion serum immunoglobulin G (IgG) concentration of foals included body weight, pretransfusion IgG concentration, number of product units transfused, foaling season and product administered. Plasma treatment had a greater increase in post‐transfusion serum IgG concentrations compared to the serum product treatment mainly because plasma contained approximately twice the amount of IgG per unit as the serum product. The change in equine influenza virus and tetanus toxoid‐specific IgGa, IgGb, and IgG(T) titres was measured in foals from pretransfusion to 3 days post‐transfusion. For each gram of IgG transfused, the change in antigen‐specific IgG subisotypes were similar for both treatment groups. The results of this study suggest that similar foal serum IgG concentrations can be achieved 3 days post‐transfusion by administering 1 unit of plasma or 2–3 units of serum product.
A new modified live equine influenza virus vaccine: phenotypic stability, restricted spread and efficacy against heterologous virus challenge
Authors: CHAMBERS T. M. , HOLLAND R. E. , TUDOR L. R. , TOWNSEND H. G. G. , COOK A. , BOGDAN J. , LUNN D. P. , HUSSEY S. , WHITAKER‐DOWLING P. , YOUNGNER J. S. , SEBRING R. W. , PENNER S. J. , STIEGLER G. L.
Published: April 2007

Flu Avert IN vaccine is a new, live attenuated virus vaccine for equine influenza. We tested this vaccinein vivoto ascertain 1) its safety and stability when subjected to serial horse to horse passage, 2) whether it spread spontaneously from horse to horse and 3) its ability to protect against heterologous equine influenza challenge viruses of epidemiological relevance. For the stability study, the vaccine was administered to 5 ponies. Nasal swabs were collected and pooled fluids administered directly to 4 successive groups of naïve ponies by intranasal inoculation. Viruses isolated from the last group retained the vaccine's full attenuation phenotype, with no reversion to the wild‐type virus phenotype or production of clinical influenza disease. The vaccine virus spread spontaneously to only 1 of 13 nonvaccinated horses/ponies when these were comingled with 39 vaccinates in the same field. For the heterologous protection study, a challenge model system was utilised in which vaccinated or naïve control horses and ponies were exposed to the challenge virus by inhalation of virus‐containing aerosols. Challenge viruses included influenza A/equine‐2/Kentucky/98, a recent representative of the ‘American’ lineage of equine‐2 influenza viruses; and A/equine‐2/Saskatoon/90, representative of the ‘Eurasian’ lineage. Clinical signs among challenged animals were recorded daily using a standardised scoring protocol. With both challenge viruses, control animals reliably contracted clinical signs of influenza, whereas vaccinated animals were reliably protected from clinical disease. These results demonstrate that Flu Avert IN vaccine is safe and phenotypically stable, has low spontaneous transmissibility and is effective in protecting horses against challenge viruses representative of those in circulation worldwide.
Detection of IgG and IgE serum antibodies to Culicoides salivary gland antigens in horses with insect dermal hypersensitivity (sweet itch)
Authors: WILSON A. D. , HARWOOD L. J. , BJÖRNSDOTTIR S. , MARTI E. , DAY M. J.
Published: April 2007

We postulated that all horses exposed to the bites of Culcoides (midges) would have an antibody response to the antigen secreted in Culcoides saliva, but that IgE antibody would be restricted to allergic individuals. Using immunohistology on sections of fixed Culicoides, we have demonstrated the presence of antibodies in horse serum which recognise Culicoides salivary glands. Antibodies were detected in the serum of horses with insect dermal hypersensitivity and in the serum of normal horses exposed to Culicoides bites. In contrast, no antibodies were detected in serum from native Icelandic ponies which had not been exposed to Culicoides. Anti‐salivary gland IgG antibodies were detected in serum from both allergic and healthy horses exposed to Culicoides. IgE antibodies were only detected in horses with signs of insect dermal hypersensitivity, they were not found in serum of healthy controls nor in the serum of horses with a history of hypersensitivity but in remission at the time of sampling. Using western blotting we confirmed the presence of antibodies to Culicoides antigens and demonstrated that individual horses react to different numbers of antigens. This paper demonstrates the ability of serum from allergic horses to detect Culcoides antigens and will enable further studies to isolate and characterise the allergens.
Passive transfer of maternal immunoglobulin isotype antibodies against tetanus and influenza and their effect on the response of foals to vaccination
Authors: WILSON W. D. , MIHALYI J. E. , HUSSEY S. , LUNN D. P.
Published: April 2007

Influenza and tetanus‐specific antibodies of the IgG sub‐isotypes are posively transferred to foals via colostrum and inhibit their response to inactivated influenza vaccines and tetanus toxoid. High titres of influenza antibodies of IgGa and IgGb subisotypes and tetanus antibodies of the IgGa, IgGb and IgG(T) subisotypes were detected in postsucking serum samples collected from foals born to mares that had received booster doses of multicomponent vaccines during the last 2 months of gestation. Thereafter, titres declined in an exponential manner but were still detectable in all foals at age 26 weeks, regardless of whether they had been vaccinated prior to age 26 weeks. Mean ± s.e. half‐life of decline of influenza IgGa antibodies (27.0 ± 2.3 days) was significantly shorter than that of influenza IgGb antibodies (39.1 ± 2.7 days; P<0.005). Tetanus IgGa and IgGb antibodies declined with half‐lives of 28.8 ± 3.0 and 34.8 ± 5.1 days, respectively. Titres of tetanus IgG(T) antibodies were substantially higher than those of influenza IgG(T) antibodies in postsucking samples and remained so through age 26 weeks, declining with a half‐life of approximately 35 days. Postsucking titres of tetanus and influenza antibodies of the IgA isotype were low and declined rapidly to undetectable levels.

Yearlings showed significant increases in titre of influenza IgGa, IgGb and IgG(T) subisotype antibodies but no increase in influenza IgA antibodies in response to 2 doses of multicomponent vaccines containing tetanus toxoid and inactivated influenza A‐1 and A‐2 antigens. Yearlings also showed strong tetanus IgGa, IgGb and IgG(T) subisotype responses to one dose of vaccine and a substantial further rise in titre in response to administration of a second dose 3 weeks later, but failed to show an increase in titre of tetanus IgA antibodies. The influenza and tetanus IgGa, IgGb and IgG(T) subisotype responses of 6‐month‐old foals to vaccination followed the same pattern as those shown by yearlings but titres were generally lower. In contrast, 3‐month‐old foals failed to show increases in titre of either influenza or tetanus IgG subisotypes in response to 2 doses of vaccine and generally needed 1–3 additional booster doses of vaccine to achieve titres similar to those achieved by yearlings after 2 doses. Based on the finding that maternal antibodies exert a significant inhibitory effect on the response of foals to tetanus toxoid and inactivated influenza antigens, it is recommended that primary immunisation of foals born to vaccinated mares should not commence before age 6 months.
Endothelin in the equine hypoxic pulmonary vasoconstrictive response to acute hypoxia
Authors: BENAMOU A. E. , MARLIN D. J. , LEKEUX P.
Published: April 2007

Elevated concentrations of endothelin (ET), a potent endothelium‐derived vasoactive peptide, have been reported in a number of pathophysiological conditions associated with pulmonary hypertension, both in the horse and other species. We have previously shown, both in vitro and in vivo, that the pulmonary and systemic vascular response to exogenous ET is mediated predominantly via ETA receptors. Our hypothesis in the present study was that ET is involved in the equine hypoxic pulmonary vasoconstrictive response to acute hypoxia. In this study, we investigated the effects of a selective ETA receptor antagonist on hypoxic pulmonary hypertension in the mature horse. Horses were exposed to a 10 min period of hypoxia (FIO2∼0.11) on 2 occasions, with and without pretreatment with the selective ETA receptor antagonist TBC11251 (10 mg/kg bwt i.v.). Hypoxia increased mean pulmonary artery pressure (PAP) from 18.3 ± 0.9 (mean ± s.e. normoxia) to 28.0 ± 0.8 mmHg (hypoxia) in the session without ETA receptor antagonism. Carotid arterial pressure (CAP) also increased progressively throughout the period of hypoxic challenge and at the end was 153 ± 5 mmHg (hypoxia) compared to during normoxia (140 ± 5 mmHg). There was no significant overall effect of ETA receptor antagonism on the haemodynamic or ventilatory responses to acute hypoxia. However, between 5 and 10 min of hypoxia there was a trend for the mean PAP to diverge in the 2 treatments, which just failed to reach significance at 10 min of hypoxia (P = 0.053). In conclusion, this study describes the haemodynamic and ventilatory changes in response to a period of acute hypoxia in the adult horse. The results do not support a role for ET as a mediator of acute HPV in the horse, but suggest that it may be involved as a modulator or in the slower (>10 min) phase of HPV.
Effects of phlebotomy on haemodynamic characteristics during exercise in Standardbred trotters with red cell hypervolaemia
Authors: FUNKQUIST P. , SANDHAGEN B. , PERSSON S. G. B. , HEDENSTIERNA G. , ESSÉN‐GUSTAVSSON B. , NYMAN G.
Published: April 2007

Five Standardbred trotters with red cell hypervolaemia (RCHV) were compared before and after removal of approximately 22% (36 ml/kg bwt) of the total blood volume in order to evaluate the haemodynamic responses, haemorheological alterations and oxygen transport during exercise to fatigue. Data were recorded during submaximal exercise at 4 different speeds on a treadmill and then during continued running at the highest speed step until fatigue. Oxygen uptake (V̇O2), pulmonary artery pressure (PAP), systemic artery pressure (SAP), heart rate (HR), haematocrit and haemoglobin concentrations (Hb) were measured. Arteriovenous O2content difference (C(a‐v̄)O2), pulmonary vascular resistance (PVR) and total systemic resistance (TSR) were calculated. Whole blood and plasma viscosity and erythrocyte aggregation tendency were determined with a rotational viscometer. Endoscopy was performed after exercise. ANOVA was used for statistical analysis.

Phlebotomy resulted in a decrease in haematocrit and Hb during the course of exercise. Blood and plasma viscosity were lower and erythrocyte aggregation tendency was higher after phlebotomy. Throughout exercise, including submaximal work and continued running to fatigue, PAP, SAP, PVR, TSR and C(a‐v̄)O2were lower after phlebotomy. HR was higher after phlebotomy during submaximal exercise. Oxygen delivery and VO2were lower after phlebotomy in the period from submaximal exercise to fatigue. Run time to fatigue was shorter after phlebotomy. Four horses showed exercise‐induced pulmonary haemorrhage (EIPH) before phlebotomy and the degree of bleeding was diminished but not abolished after phlebotomy.

The reductions in PVR, TSR, PAP and SAP after phlebotomy were probably a result of reduced blood viscosity. In conclusion, although a 22% reduction in blood volume improved the haemodynamic and haemorheological parameters and the degree of EIPH, it was found that RCHV trotters have to rely on high oxygen delivery to the working muscles for maintenance of maximal performance.
A cross‐sectional study of colic in horses on Thoroughbred training premises in the British Isles in 1997
Authors: HILLYER M. H. , TAYLOR F. G. R. , FRENCH N. P.
Published: April 2007

The aim of this study was to estimate the incidence of colic in horses in Thoroughbred training premises in 1997 in the British Isles. The seasonal pattern and outcome of colic episodes were also investigated, together with any association between premises level variables and colic. Data were collected by a postal questionnaire.

The results showed a colic incidence density of 7.19/100 horse years (s.e. 0.42) and a cumulative incidence of colic of 5.80% (s.e. 0.30). Premises were grouped according to whether they had more Flat than National Hunt horses (Flat premises) or more National Hunt than Flat horses (NH premises). A similar rate of colic episodes was found in each group. However, significantly higher cumulative incidences of one episode of colic were found in the Flat premises and of multiple episodes in the NH premises, respectively. The outcome of each episode of colic showed spontaneous recovery in 28.7%, medical recovery in 63.1%, surgical recovery in 2.0% and death in 6.2% of cases. This indicated an overall mortality rate from colic of 0.45 deaths/100 horse years. The seasonal pattern of episodes of colic showed a spring and autumn peak, with significant differences in the seasonal pattern between the Flat and NH premises. Relative risk analysis and logistic regression modelling with random effects showed significant associations between the number of episodes of colic and the number of horses on the premises (allowing for the number of horses on each premises, the larger premises had a decreased risk of colic). After adjusting for the number of horses, 3 other variables were associated with colic; Flat premises (with an increased risk), the owner being the sole person looking after the horses (a decreased risk) and the premises being a combined training and breeding establishment (a decreased risk).
Recovery from transport and acclimatisation of competition horses in a hot humid environment
Authors: MARLIN D. J. , SCHROTER R. C. , WHITE S. L. , MAYKUTH P. , MATTHESEN G. , MILLS P. C. , WARAN N. , HARRIS P.
Published: April 2007

The aims of the present field‐based study were to investigate changes in fit horses undergoing acclimatisation to a hot humid environment and to provide data on which to base recommendations for safe transport and acclimatisation. Six horses (age 7–12 years) were flown from Europe to Atlanta and underwent a 16 day period of acclimatisation. Exercise conditions during acclimatisation (wet bulb globe temperature index 27.6 ± 0.0 [mean ± s.e.]) were more thermally stressful compared with the European climate from which the horses had come (22.0 ± 1.8, P<0.001). Following the flight, weight loss was 4.1 ± 0.8% bodyweight and took around 7 days to recover. Water intake during the day was significantly increased (P<0.05) compared with night during acclimatisation. Daily mean exercise duration was 72 ± 12 min and the majority of work was performed with a heart rate below 120 beats/min. Respiratory rate (fR) was increased (P<0.05) throughout acclimatisation compared with in Europe, but resting morning (AM) and evening (PM) rectal temperature (TREC), heart rate (fC) and plasma volume were unchanged. White blood cell (WBC) count was significantly increased at AM compared with in Europe on Days 4 and 10 of acclimatisation (P<0.01), but was not different by Day 16. In conclusion, horses exposed to hot humid environmental conditions without prior acclimatisation are able to accommodate these stresses and, with appropriate management, remain fit and clinically healthy, without significant risk of heat illness or heat‐related disorders, provided they are allowed sufficient time to recover from transport, acclimatisation is undertaken gradually and they are monitored appropriately.
A prospective study of the roles ofClostridium difficileand enterotoxigenicClostridium perfringensin equine diarrhoea
Authors: WEESE J. S. , STAEMPFLI H. R. , PRESCOTT J. F.
Published: April 2007

Faecal samples from adult horses and from foals with diarrhoea or with normal faeces were evaluated for the presence ofClostridium difficile, C. difficiletoxins,C. perfringensenterotoxin (CPE) andC. perfringensspore counts.Clostridium difficilewas isolated from 7/55 horses (12.7%) and 11/31 foals (35.5%) with colitis, but from 1/255 normal adults (0.4%) and 0/47 normal foals (P<0.001).Clostridium difficiletoxinsAand/orBwere detected in 12/55 diarrhoeic adults (21.8%) and 5/30 diarrhoeic foals (16.7%) but in only 1/83 adults (1.2%) and 0/21 foals with normal faeces (P<0.001 and P<0.05, respectively).Clostridium perfringensenterotoxin was detected in 9/47 diarrhoeic adults (19%) and 8/28 diarrhoeic foals (28.6%), but was not detected in 47 adult horses (P<0.002) or 4 foals (P = 0.22) with normal faeces. The positive predictive value of isolation ofC. perfringenswith respect to the presence of CPE was only 60% in adult horses and 64% in foals. There was no association between totalC. perfringensspore count and CPE in the faeces. The overall mortality rate from colitis was 22% for adult horses and 18% for foals.Clostridium difficiletoxin‐positive adult horses with colitis were less likely to survive thanC. difficile‐negative horses with colitis (P = 0.03). This study provides further evidence thatC. difficileand enterotoxigenicC. perfringensare associated with equine enterocolitis.
A study of ten cases of focal peritarsal infection as a cause of severe lameness in the Thoroughbred racehorse: clinical signs, differential diagnosis, treatment and outcome
Authors: PILSWORTH R. C. , HEAD M. J.
Published: April 2007

The differential diagnoses of tarsal joint infection, fracture and peritarsal focal infection are of particular importance in practice. The objective of the present report is to provide additional clinical data to assist in the understanding of one of these conditions. The haematological parameters, clinical signs, treatment and outcome of 10 cases of severe lameness associated with peritarsal infection are reviewed. All horses had a significant rise in rectal temperature. The majority of cases (6/10) had haematological changes consistent with acute bacterial infection on the day of first examination. In the remaining cases these changes were not apparent on a blood sample taken on the first examination, but became so after 24 h. Nine out of 10 cases made a complete recovery on a regimen of i.v. antibiotic therapy, in conjunction with administration of nonsteroidal anti‐inflammatory drugs and repeated forced exercise. One case developed osteomyelitis of the third and fourth metatarsal bones, but made a full recovery in due course. It is concluded that, in the majority of cases, prompt treatment with antibiotic therapy, analgesics and forced exercise results in complete resolution of the condition.