bluuebunny/crossref_metadata_2025 huggingface dataset:
Whole blood re‐calcification time in equine colic
Authors: HENRY MICHELLE M. , MOORE J. N.
Published: April 2010

Whole blood re‐calcification times were evaluated as a measure of endotoxin‐associated coagulopathy in horses. First, the effects of endotoxin concentration and duration ofin vitroincubation of citrated whole blood with endotoxin on the whole blood re‐calcification time of blood collected from healthy horses were determined. Increasing concentrations or incubation times of endotoxin accelerated the whole blood re‐calcification time. This effect was attributed mainly to increased monocyte thromboplastin activity. Second, whole blood re‐calcification time, a clotting profile, plasma factor VII activity and plasma endotoxin concentration on blood samples obtained from 35 equine colic patients and 10 healthy horses were determined. Compared with healthy horses, colic patients had a longer mean whole blood re‐calcification and prothrombin time, lower per cent factor VII activity and higher mean fibrin degradation products concentration. Within the colic patient group, horses that did not survive had detectable endotoxin in plasma, longer whole blood re‐calcification and prothrombin times, and lower plasma factor VII activity, compared with colic patients that survived. These data indicate that colic patients with endotoxaemia experience hypercoagulable states, followed by consumptive coagulopathy. Although the cause of endotoxin‐associated coagulopathy is likely multi‐factorial, increased expression of monocyte thromboplastin activity may be involved in the pathogenesis of coagulopathy. The whole blood re‐calcification time is a simple, fast and inexpensive way to detect coagulopathy during endotoxaemia and determine the prognosis for survival.
Changes in some haematological and metabolic indices in young horses during the first year of jump‐training
Authors: JABLONSKA EWA M. , ZIOLKOWSKA SWIETLANA M. , GILL J. , SZYKULA R. , FAFF J.
Published: April 2010

Effects of an 18 min exercise test, on three separate occasions during a one year jump‐training programme, was studied in seven horses. Determinations were carried out on venous blood for packed cell volume, haemoglobin, total protein, lactate and pyruvate, glucose, free fatty acids, insulin, glucagon, blood gases, bicarbonate, pH, aldolase, aspartate aminotransferase and alanine amino‐transferase. Exercise caused a slight increase in lactate and pyruvate, total protein, aldolase, alanine aminotransferase, pO2, bicarbonate and pH. Glucose, free fatty acids and pCO2levels decreased. Training caused no significant difference in these changes. However, during the year, increases in lactate and decreases in pH (resting levels) were observed.
A comparative study of normal equine populations and those with grass sickness (dysautonomia) in eastern Scotland
Authors: DOXEY D. L. , GILMOUR J. S. , MILNE E. M.
Published: April 2010

A retrospective survey was made of premises in eastern Scotland on which at least two cases of grass sickness had occurred between 1970 and 1987. For comparison, a further survey of 49 equine establishments, on which no grass sickness had been recorded, was conducted from 1986 to 1988. The results indicated that younger animals are more susceptible, especially those in good physical condition grazing full‐time in the spring or early summer. Movement to new grazing increases the risk of grass sickness and identifiable stress may contribute. The nature of the establishment governed the animals' condition during the summer, but it did not appear to influence the prevalence of grass sickness. However, riding schools and livery establishments which experienced the disease kept, on average, significantly more animals than unaffected premises of the same type. No relationship was found between supplementary feeding or stage of pasture growth and grass sickness. The results of the survey support the hypothesis that the causal agent of grass sickness is associated with grazing but multiple factors may influence the expression of illness.
Osteomyelitis of the axial border of the proximal sesamoid bones in seven horses
Authors: WISNER E. R. , O'BRIEN T. R. , POOL R. R. , PASCOE J. R. , KOBLICK P. D. , HORNOFF W. J. , POULOS P. W.
Published: April 2010

Destructive lesions of the axial region of the proximal sesamoid bones were identified by radiography in eight fetlocks and seven lame adult horses. Lameness ranged from 2 to 5 (mean 4; scale 1 to 5) at the time of examination, with a duration of 10 days to two years (mean 5.6 months). Destructive lesions involved both proximal sesamoid bones when examined radiographically and were situated primarily at the level of the mid‐body and apical region of the axial borders. Some lesions were cystic, whereas others eroded the axial border more diffusely. Scintigraphy revealed markedly increased activity within the proximal sesamoid bones of the clinically lame limb of four of the five horses examined. In four horses, post mortem computed tomography revealed axial border bone destruction and cavitary lesions within cancellous bone of affected proximal sesamoid bones. Lesions seen by computed tomography were larger than those identified on radiographic examination. Cavitary lesions not seen radiographically were identified in the proximal sesamoid bones of two clinically unaffected fetlocks examined for comparison in two of the seven horses. Evidence of acute, subacute or chronic/reparative osteomyelitis of the axial region of the proximal sesamoid bones was seen in the 10 fetlocks identified as abnormal from radiography or computed tomography. Also, three horses had septic synovitis of the flexor sheath of the clinically affected limb; of these, two had septic arthritis of the fetlock joint.
Radiographic, high detail radiographic, microangiographic and histological findings of the distal portion of the tarsus in weanling, young and adult horses
Authors: LAVERTY S. , STOVER S. M. , BÉLANGER D. , O'BRIEN T. R. , POOL R. R. , PASCOE J. R. , TAYLOR K. , HARRINGTON T.
Published: April 2010

Clinical radiographic (LM and D35L‐P1MO views), high detail radiographic, microangiographic and histological findings of the distal portion of the tarsus of 16 horses (five weanling, four young and six adult), without known clinical histories, were evaluated to determine the sensitivity of clinical radiographs for the detection of abnormalities in the distal tarsus and the prevalence of abnormalities in this population. Clinical radiographic and high detail radiographic abnormalities were observed in at least 30 per cent of the tarsi examined. Statistical agreement between observations from clinical radiographs and corresponding post mortem high detail radiographs was not good for subchondral bone plate irregularities and joint margin changes. Three patterns of sclerosis of the medullary spongiosa were visualised on high detail radiographs: thickening of the subchondral bone plate was seen commonly in the weanling group, whereas arching and bridging patterns were more prevalent in the young and adult groups. Bone production on the dorsal cortex of the central and third tarsal bones did not increase with age. Abnormalities in vascular perfusion and articular cartilage histology were observed in association with subchondral bone plate irregularities and focal regions of osteopenia observed on high detail radiographs.
Bronchoalveolar lavage findings in horses with exercise intolerance
Authors: FOGARTY U. , BUCKLEY T.
Published: April 2010

Significant differences were detected by bronchoalveolar lavage (BAL) between horses racing successfully and those showing exercise intolerance. Neutrophil percentage, haemosiderophage percentage and total bacterial numbers were significantly elevated in horses with exercise intolerance. BAL provided a more accurate indication of the incidence and extent of exercise induced pulmonary haemorrhage (EIPH) than visual inspection.
Risk factors associated with injuries in Thoroughbred horses
Authors: MOHAMMED H. O. , HILL T. , LOWE J.
Published: April 2010

A case‐control study was conducted on Thoroughbred horses to identify factors associated with the risk of breakdown on racetracks. A total of 310 cases (breakdowns) were identified from the Horse Identification Department records kept by the chief examining veterinarian of New York Racing Association. For each case, two control horses were selected randomly from the Daily Racing Form Inc. records. Multiple logistic regression analysis was used to identify and quantify the risk of factors associated with breakdown, while simultaneously controlling for the effect of other putative factors. Factors associated with risk of breakdown were: track (horses raced on Saratoga racetrack were at a lesser risk of breakdown), track composition/condition (turf tracks had a lower risk compared to dirt), number of seasons in race, racing in a later race, number of starts per year, the total number of starts, season (summer had a higher risk than winter or spring) and age of the horse.
Mononuclear cell infiltration of the equine endometrium: immunohistochemical studies
Authors: WAELCHLI R. O. , WINDER N. CHRISTINE
Published: April 2010

Endometrial sections from mares with varying degrees of mononuclear cell infiltration were examined for immunoglobulin (Ig)A‐, IgM‐, IgG(T)‐ and IgG(Fc)‐containing cells, luminal and glandular epithelial cell Igstaining and free interstitial Ig‐staining, using a peroxidase anti‐peroxidase technique. Mares with mild to moderate (Group 2) and mares with severe diffuse mononuclear cell infiltration, superimposed by acute endometritis (Group 3), had significantly higher numbers of Ig‐containing cells than genitally‐normal mares (Group 1). The differences between Groups 1 and 3 were significant for all four isotypes. In Groups 1 and 2, numbers of IgA‐containing cells were significantly larger than numbers of IgM‐ and IgG(T)‐containing cells. Generally, more glandular epithelial cells stained for IgA and IgM than for IgG(T) and IgG(Fc), and Ig‐staining for all isotypes increased from Group 1 to Group 3. Free interstitial staining did not appear to differ among the three groups, but IgG(Fc)‐ and IgG(T)‐staining generally was more intense than IgA‐ and IgM‐staining. The efficiency of uterine defence in the mare does not seem to depend solely on humoral factors, and defects involving other components of the defence system may contribute to failure of the uterus to clear infection.
Pedicle skin flaps in ponies: viable length is related to flap width
Authors: HINCHCLIFF K. W. , MACDONALD DIANE R. , LINDSAY W. A.
Published: April 2010

The relationship between pedicle flap width and viable length was characterised for skin flaps of the flank in ponies. Four dorsally based, pedicle type skin flaps of 20 cm in length and 3, 6, 9 or 12 cm in width were created in a random sequence on one flank in each of 10 ponies. Flap survival length was assessed by skin texture and appearance, depilation of hair and wound healing at 14 days after surgery. There was considerable variation between animals in the viable length of flaps of the same width; however, a significant difference in the viable length of flaps of different widths was detected (P=0.002). The viable length of the 3 cm flaps was significantly different from that of the 12 cm flaps (9.69 ± 1.1 cm vs 12.97 ± 1.0 cm, mean ± se P<0.05). There was a positive correlation between flap width and viable length (r2= 0.141, P=0.017). There was no effect of flap order (cranial to caudal positioning relative to the other flaps) on viable length (P=0.286). The results of this study demonstrate a significant relationship between flap width and viable length, confirming a previously unsupported assumption that flap width and viable length are related. These findings suggest that the clinician should employ broad pedicles when using local flaps to reconstruct skin defects on the flank of the horse.
An evaluation of the effect of reagent modification on routine laboratory coagulation tests
Authors: GENTRY P. A. , FELDMAN B. F. , O'NEILL S. L.
Published: April 2010

The purpose of this study was to evaluate the effect of modifying commercial reagents for the laboratory evaluation of several haemostatic parameters in normal, non‐pregnant mares. The routine coagulation screening assays, namely, the activated partial thromboplastin time (APTT) and the one‐stage prothrombin time (PT), and the specific coagulation assays for the determination of the biological activity of Factors VII, VIII:C and IX, are discussed.
Evaluation of the haemostatic profile in the Dre‐ and post parturient mare, with particular focus on the perinatal period
Authors: GENTRY P. A. , FELDMAN B. F. , O'NEILL S. L. , MADIGAN J. E. , ZINKL J. G.
Published: April 2010

Various haemostatic analytes were systematically evaluated for four months pre‐partum and five months post partum in 14 healthy mares. The plasma fibrinogen concentration and both Factor VIII:C and von Willebrand factor activity showed gradual increases from mid‐gestation and reached maximal, or near maximal activity at parturition. These increases were paralleled by an increase in plasma fibronectin concentration, the appearance of fibrinogen degradation products, and a modest rise in antithrombin III concentration. In contrast, the activity of Factor VII and Factor IX, and the one‐stage prothrombin (PT) time and the activated partial thromboplastin (APTT) time remained relatively constant throughout the pre‐ and post parturient period.
Preliminary studies on the vascular anatomy of the equine superficial digital flexor tendon
Authors: KRAUS‐HANSEN ANN E. , FACKELMAN G. E. , BECKER C. , WILLIAMS R. M. , PIPERS F. S.
Published: April 2010

The vascular and microvascular anatomy of normal equine superficial digital flexor tendons was studied by dissection of vinyl‐perfused specimens and by microangiography on high detail film. The presence of an extensive intratendinous vascular latticework was confirmed, and a ‘nutrient artery’ described closely associated with the accessory ligament of the superficial digital flexor tendon (proximal check ligament). Circumferential stripping of the paratenon from the tendon to eliminate afferent vessels was performed bilaterally in three horses and unilaterally in a fourth, followed by a treadmill training regimen. No resulting intratendinous lesions could be documented on gross post mortem and histological examination at three, 10, or 35 days post operatively. There was mild paratendinous proliferation in all instances.

In one horse, four intratendinous ligatures were placed within the medial and lateral borders of the contralateral tendon to isolate further from its blood supply a 10 cm segment. Gross lesions at 35 days post operatively included a marked paratendinous response involving the entire 10 cm segment, and a darkened, soft focus within the core of the tendon. Histopathology and electron microscopy demonstrated focal degeneration.

It was concluded that the blood supply of the normal equine superficial digital flexor tendon is primarily intratendinous, rather than paratendinous as previously thought. The lesions in one horse similar to those in naturally occurring tendinitis supported a vascular aetiology of the disease, and set the groundwork for studies aimed at the development of a clinically relevant tendinitis model.
Inheritance of hydrocephalus in horses
Authors: OJALA M. , ALA‐HUIKKU J.
Published: April 2010

From 1974 to 1979, seven stillborn foals with internal hydrocephalus were encountered from one Standardbred trotter stallion which sired 239 registered foals. An hydrocephalic foal was also aborted by a daughter of the same stallion. One affected foal from Standardbred trotters and one from a Finnish Horses were also reported. In some cases, the condition caused severe dystocia. Based on field data, possible causes of the defect could neither be proved nor specifically overruled in individual cases. Hydrocephalus was obviously not an autosomal recessive single‐locus defect, nor was it X‐linked. A dominant mutation in the germ line in one of the parents or in any embryo seemed the most likely explanation for the occurrence of internal hydrocephalus in horses.
Arrhythmias in newborn Thoroughbred foals
Authors: YAMAMOTO K. , YASUDA J. , TOO K.
Published: April 2010

Foetal electrocardiograms (ECG) were obtained from 39 of 50 Thoroughbred foaling mares close to delivery. The 50 newborn foals were studied electrocardiographically during their adaptive period, immediately after birth. In 48 foals there were paroxysmal arrhythmias or mixed arrhythmias. The most common arrhythmias were sinus arrhythmias including wandering pacemaker (32/50) and atrial premature contraction (30/50). The others observed were atrial fibrillation (15/50), ventricular premature contraction (10/50), partial atrioventricular block (7/50), ventricular tachycardia (4/50), atrial tachycardia (3/50) and idioventricular rhythm (1/50). The duration of the arrhythmias was approximately 5 min, and in all cases the arrhythmia disappeared within 15 min of birth. From foetal ECG recordings, no indication of the likelihood of neonatal arrhythmias was detected. With the exception of 2 cases, all foals have continued to grow and develop normally.

These arrhythmias are considered normal physiological processes in newborn Thoroughbred foals during the adaptive period to extra‐uterine life. High vagal tone and hypoxaemia at birth are probably the main contributing factors.
Pathological aspects of Australian Stringhalt
Authors: SLOCOMBE R. F. , HUNTINGTON P. J. , FRIEND S. C. E. , JEFFCOTT L. B. , LUFF A. R. , FINKELSTEIN D. K.
Published: April 2010

Nine horses with clinical signs of Australian Stringhalt were killed and tissues collected for a detailed pathological study. Lesions were limited to peripheral nerves and muscles. The most severely affected nerves were the superficial and deep peroneal, distal tibial, plantar digital, volar and recurrent laryngeal nerve with changes characterised by a selective loss of large diameter myelinated fibres with various degrees of demyelination, fibrosis, Schwann cell proliferation and onion‐bulb formation. A routine evaluation of the brain and spinal cord by light microscopy failed to reveal any consistent abnormalities. Morphometric analysis of deep peroneal and recurrent laryngeal nerves confirmed the reduced number of large diameter myelinated axons. Teased fibre preparations of these nerves did not show any abnormalities in internodal distance. The most severe muscle lesions were in the long and lateral digital extensors, cranial tibial, dorsal cricoarytenoid, gracilis and lateral deep digital flexor with extensive atrophy of fibres and diffuse fibrosis. Histochemical evaluation of the long digital extensor from 3 affected horses showed an abnormally wide distribution in fibre size and a reduction in type II fibres compared with controls. These lesions are consistent with a distal axonopathy leading to neurogenic muscle atrophy. The distribution of neuromuscular lesions in Australian Stringhalt may be explained by the susceptibility of longer, larger myelinated nerve fibres to injury, but the cause for this distal axonopathy remains unknown.
Contrast‐enhanced computed tomography and myelography in six horses with cervical stenotic myelopathy
Authors: MOORE BONNIE RUSH , HOLBROOK T. C. , STEFANACCI J. D. , REED S. M. , TATE L. P. , MENARD MONICA C.
Published: April 2010

The cervical spines of 6 horses with cervical stenotic myelopathy (CSM) were examined using myelography and contrast‐enhanced computed tomography (CECT). Histopathology of the spinal cord of these horses identified 10 neurologically significant compressive lesions. Myelography and CECT were both able to demonstrate all 10 spinal cord compressive lesions, but myelography falsely identified 2 sites and CECT falsely identified 1 site as compressive lesions of the spinal cord which were not supported by histopathology. Additional qualitative information was obtained by CECT regarding the source, severity and location of spinal cord compression. Computed tomography identified stenosis of the vertebral canal with circumferential loss of contrast agent and documented lateral compressive lesions of the spinal cord due to malformed articular facets. Compression of the peripheral nerve roots by malformed articular facets encroaching on the intervertebral foramen was easily identified by CECT in the axial plane. No compressive lesions were identified in 3 unaffected horses by either method. Minimum sagittal diameter (MSD) values obtained from CECT images were strongly correlated with necropsy measurements, validating CECT as an accurate method of obtaining MSD values. The MSD values in the CSM‐affected horses were significantly narrowed (P<0.05) from C3C6regardless of the site of spinal cord compression, when compared with the unaffected controls. This finding supports previous reports suggesting that generalised stenosis of the vertebral canal is an important feature in the pathogenesis of cervical stenotic myelopathy.
Effects of WEB 2086, an antagonist to the receptor for platelet‐activating factor (PAF), on PAF‐induced responses in the horse
Authors: FOSTER A. P. , LEES P. , ANDREWS M. J. , CUNNINGHAM F. M.
Published: April 2010

Platelet‐activating factor (PAF) causes oedema and neutrophil accumulation when injected into the skin of normal horses. PAF is also known to induce aggregation of horse plateletsin vitro. The selective PAF receptor antagonist WEB 2086 has now been used to determine whether these effects are mediated by PAF receptor activation. Addition of WEB 2086 to equine plateletsin vitroinhibited PAF‐induced aggregation in a competitive reversible manner (pA2= 7.14). Inhibition ofin vivoinflammatory responses to PAF occurred after local administration of WEB 2086: wheal formation induced by 0.1 μg PAF/site was reduced by 1–10 μ WEB 2086/site. PAF (1 μg/site)‐induced neutrophil accumulation was also inhibited by co‐administration of 10 μg WEB 2086/site. Systemic administration of WEB 2086 (3 mg/kg iv) to 4 normal ponies inhibited PAF‐induced wheal formation andex vivoplatelet aggregation. At 30 min after drug administration the concentration of PAF required to produce a half maximal aggregation response was increased 496 ± 137 fold. At 6 h the degree of inhibition was markedly reduced and responses had returned to pre‐treatment values by 24 h. PAF‐induced increases in cutaneous vascular permeability were also reduced by 80% as early as 30 min after iv administration of WEB 2086 in these animals, the inhibition persisting for at least 6 h. These results suggest thatin vitroandin vivoresponses to PAF in the horse are mediated via activation to PAF receptors. WEB 2086 will therefore be a useful agent for studying the role of PAF in the pathogenesis of equine inflammatory conditions.
Plasma potassium and lactate concentrations in Thoroughbred horses during exercise of varying intensity
Authors: HARRIS PAT , SNOW D. H.
Published: April 2010

To investigate the effect of moderate to high intensity exercise of up to 6 min duration on plasma potassium and lactate concentrations, 6 Thoroughbred horses were studied using a treadmill at a 5° incline. Each test consisted of an 8‐min standardised warm‐up followed by an exercise bout at 8, 9, 10 or 12 m/sec. The horses were galloped at each speed for up to a maximum of 6 min or until signs of fatigue were present. The horses were then walked at 0° incline. Carotid arterial blood samples were taken during and after the exercise. At 8, 9 and 10 m/sec there was a general pattern of an initial rise in potassium to a peak around 1.5 min of exercise with the concentration then slowly decreasing. At 12 m/sec there was a continuous rise to a peak at the end of exercise in all horses. Immediately after exercise there was a rapid return (within 3–4 min) to the potassium concentrations recorded at the end of the warm‐up period. Plasma lactate peaked around the end of exercise at all speeds.

At the highest intensity of exercise the mechanisms for the re‐uptake of potassium did not appear to be able to match the rate of efflux. In contrast, at less intense work loads, the rate of re‐uptake appeared to be similar to or slightly greater than the rate of efflux. It is possible that a disturbance in this balance between efflux and re‐uptake could result in a disturbance in normal neuromuscular function during exercise.
Standardised imaging technique for guided M‐mode and Doppler echocardiography in the horse
Authors: LONG KAREN J. , BONAGURA J. D. , DARKE P. G. G.
Published: April 2010

Eighteen echocardiographic images useful for diagnostic imaging, M‐mode echocardiography, and Doppler echocardiography of the equine heart were standardised by relating the position of the axial beam to various intracardiac landmarks. The transducer orientation required for each image was recorded in 14 adult horses by describing the degree of sector rotation and the orientation of the axial beam relative to the thorax. Repeatable images could be obtained within narrow limits of angulation and rotation for 14 of the 18 standardised images evaluated.

Twenty‐seven National Hunt horses were subsequently examined using this standardised technique. Selected cardiac dimensions were measured from two‐dimensional and guided M‐mode studies. Satisfactory results were achieved in 26 of the 27 horses. There was no linear correlation between any of the measured cardiac values and bodyweight. There was no significant difference between measurements taken from the left and the right hemithorax. Six horses were imaged on three consecutive days to assess the repeatability of the measurements. No significant difference was found between measurements obtained on different days.

This study demonstrates a method for standardised echocardiographic evaluation of the equine heart that is repeatable, valuable for teaching techniques of equine echocardiography, applicable for diagnostic imaging and quantification of cardiac size, and useful for the evaluation of blood‐flow patterns by Doppler ultrasound.
An association between complete and incomplete stress fractures of the humerus in racehorses
Authors: STOVER SUSAN M. , JOHNSON B. J. , DAFT BARBARA M. , READ D. H. , ANDERSON M. , BARR B. C. , KINDE H. , MOORE JANET , STOLTZ J. , ARDANS A. A. , POOL R. R.
Published: April 2010

Twenty‐one horses had a complete unilateral humeral fracture during race training or racing at a California racetrack during the period 24 February 1990 to 10 July 1991. Fractures occurred approximately equally in left and right limbs, and in males and females. Most fractures occurred during training, and in 2‐ and 3‐year‐old horses. Only 5 of 16 Thoroughbred horses with known racing records had previously raced more than once, and their mean time between races was less than the time between their last race and fracture (P = 0.07). Ten of 13 humeri studied further had gross evidence of periosteal callus bridging one portion of the fracture line, indicative of a pre‐existing stress fracture.
Clinical and radiographic features, treatment and outcome in 15 horses with fracture of the medial aspect of the patella
Authors: DYSON SUE , WRIGHT I. , KOLD S. , VATISTAS N.
Published: April 2010

A sagittal fracture of the medial aspect of the patella was identified in 15 horses, 2 of which had been kicked and 12 of which had hit a fixed fence while jumping. Eight horses showed concurrent fragmentation of the base of the patella, and 2 had sustained a concurrent fracture of the distal end of the lateral trochlear ridge of the femur. A cranioproximal‐craniodistal oblique radiographic view was essential to identify the site of the medial patellar fracture and to determine its configuration. Fourteen horses were treated by surgical removal of the medial patellar fracture fragment(s). Of 12 horses (83%) without evidence of pre‐existing degenerative joint disease, 10 were treated successfully with return to full athletic function.
Videoendoscopic evaluation of the mare's uterus: III. Findings in the pregnant mare
Authors: ALLEN W.R. , BRACHER VERENA
Published: April 2010

During a 5‐year period 65 Pony and 20 Thoroughbred pregnant mares were subjected to videoendoscopic hysteroscopy from 10 to 266 days of gestation. The aims of these examinations were to 1) observe foetal and placental developmentin vivo(60 Pony and 10 Thoroughbred mares); 2) eliminate one of unicornuate twin conceptuses (9 Thoroughbred mares); 3) recover embryonic foetal and placental tissues non‐surgically for experimental purposes (47 Pony mares); 4) induce focal separation of the placenta in late gestation as an experimental model of placentitis (5 pony mares and 1 Thoroughbred mare). It was possible to view the embryo and all constituent extra‐embryonic membranes of the conceptus between Days 10 and 87 of gestation without having to perforate the allantochorion. This allowed study of physiological processes such as the coordinated uterine contractions responsible for conceptus motility between Days 7 and 17, active foetal movements, which began as early as Day 34, and invasion of chorionic girdle cells into the endometrium, which occurred between Days 34 and 38. From Day 90, vision of the foetus was reduced or prevented by the increased thickness of the allantochorion. Transendoscopic recovery of the conceptus was successful in all of 10 mares under 30 days of gestation, whereas only 10 of 18 attempts between Days 30 and 45 produced the conceptus without resorting to uterine lavage after initial rupture of the allantochorion. All 9 attempts to eliminate one of unilateral twin conceptuses were unsuccessful and the technique was abandoned as clinically unsuitable. Nevertheless, 9 of 22 (41%) single conceptuses remained viable after one or more hysteroscopic examinations. This did not seem to be influenced by a variety of anti‐abortion treatments administered.
Milk and water intakes of foals sucking grazing mares
Authors: MARTIN R. G. , McMENIMAN N. P. , DOWSETT K. F.
Published: April 2010

Intakes of milk and milk nutrients were determined for 8 foals at 11–18 days of age and for 10 foals at 30–44 days and 60–74 days of age while sucking grazing mares. Water intakes (sources other than milk) of the foals were determined at 30–44 days and 60–74 days of age. Five of the 10 mares were fed a protein supplement (24% crude protein) in addition to grazing during the stud season. The protein supplement did not influence foal intakes of milk and milk nutrients, milk composition, weight gains of the mares or the growth rate of the foals. Foal milk intakes increased (P<0.05) from 16.9 kg/day at 11–18 days to 18.1 kg/day at 60–74 days of age. The water intakes of the foals increased (P<0.01) from 3.9 kg/day at 30–44 days to 5.5 kg/day at 60–74 days of age. Total fluid intakes per kg foal liveweight were 246, 202 and 172 g at 11–18, 30–44 and 60–74 days of age, respectively. For each kg of weight gain, foals consumed 12.8, 15.7 and 16.4 kg milk at 11–18, 30–44 and 60–74 days of age. Stage of lactation had a significant effect on the total solids, lactose and protein content of milk. The fat and gross energy content of milk remained constant.
Treatment of respiratory infections in horses with ceftiofur sodium
Authors: FOLZ S. D. , HANSON B. J. , GRIFFIN A. K. , DINVALD L. L. , SWERCZEK T. W. , WALKER R. D. , FOREMAN J. H.
Published: April 2010

Ceftiofur sodium was evaluated as a therapy for respiratory infections in horses. This cephalosporin antimicrobial was administered intramuscularly every 24 h and at a dose of 2.2 mg/kg (1.0 mg/lb) of body weight. The efficacy of ceftiofur sodium was compared with that of a positive control drug, ampicillin sodium (recommended dose of 6.6 mg/kg [3 mg/lb], given every 12 h). Both treatments were continued for 48 h after clinical symptoms were no longer evident (maximum of 10 days). Fifty‐five (55) horses with naturally acquired respiratory infections were included in the study; 28 were treated with ceftiofur and 27 with ampicillin. Clinical improvement was recorded for 92.9% of the patients treated with ceftiofur and 92.6% of the animals receiving ampicillin. Both therapies reduced body temperatures to an afebrile level after 2 days of treatment. Complete recovery/cure was noted for 78.6% of the ceftiofur patients and 59.3% of the horses treated with ampicillin. Supporting variables (depression/malaise, respiration/dyspnoea, nasal discharge) were assessed and these also substantiated the effectiveness of the treatments. Both antibiotics were well tolerated. Neither pain nor swelling were noted at the ceftiofur injection site(s). None of the animals developed diarrhoea. Data from this study indicated that ceftiofur sodium is an effective and safe treatment for respiratory infections in horses.
Tearing of the medial palmar intercarpal ligament in the equine midcarpal joint
Authors: McILWRAITH C. W.
Published: April 2010

Tearing of the medial palmar intercarpal ligament is described in 45 intercarpal (midcarpal) joints in 42 horses (37 racehorses, 5 non‐racehorses). Of the 37 racehorses, there were 20 Quarter Horses, 14 Thoroughbreds and 3 Standardbreds. The patients had been referred for arthroscopic surgery for removal of osteochondral chip fragments that had been diagnosed radiographically or diagnostic arthroscopy of a persistent carpal problem. The problem was unilateral in 39 horses and bilateral in 3. The presenting clinical signs were lameness and/or persistent synovial effusion. In one instance, the presenting complaint was haemarthrosis. Osteochondral chip fragments were present in the joint affected with tearing in 23 horses. In 6 horses in which osteochondral fragments were present in other joints, the degree of synovial effusion was greatest in the midcarpal joint with ligamentous tearing. In most of the 22 midcarpal joints where carpal chip fragmentation and ligamentous tearing were present concomitantly, the degree of clinical compromise was greater than normally seen with that degree of osteochondral fragmentation. A ligament was designated as torn when a defect was present in the ligament. This usually took the form of frayed fibres suspended in the irrigating solution, presenting a transverse type of defect in the dorsal aspect of the lateral portion of ligament. However, longitudinal tearing was present in 1 case and tearing was noted in the palmar aspect of the ligament in 2 other cases. The shredded fibres were trimmed in most cases and this allowed better definition of the amount of ligament considered to be torn. The degree of damage ranged from 10% to 100% of the width considered to be torn. A total loss of integrity was diagnosed in 2 cases. The degree of tearing was estimated at 70–90% in 6 joints, 50% in 11 joints, 30% in 7 joints, 20–25% in 7 joints, and 10–15% in 9 joints. Long‐term follow‐up was obtained for 31 horses and 17 had successful and 14 unsuccessful results. Of the horses with successful results, 13 were estimated as having 30% or less damage to the ligament and 3 horses with 50% damage to the ligament raced successfully after treatment with intra‐articular corticosteroids. One horse with >30% damage was considered to be successful without the use of intra‐articular corticosteroids. In the 14 horses with unsuccessful results, all but 2 had 50% or more estimated damage to the medial palmar intercarpal ligament. Of the 2 exceptions, 1 had 30% damage but also had a sagittal fracture of the third carpal bone and the second horse's lack of success was considered to be unrelated to the carpus.
Healing of full‐thickness cartilage compared with full‐thickness cartilage and subchondral bone defects in the equine third carpal bone
Authors: HANIE ELIZABETH A. , SULLINS K. E. , POWERS B. E. , NELSON P. R.
Published: April 2010

The effect of lesion depth on the quality of third carpal bone cartilage repair was examined. A 1‐cm diameter articular defect penetrating the calcified cartilage in one limb and the subchondral bone plate in the opposite limb was created in the radial facet of the third carpal bones. Clinical and xeroradiographic examinations were performed every 4 weeks until 4 months (3 horses) and 6 months (3 horses) after surgery. The synovial membrane, non‐opposing articular surfaces and articular defects were examined grossly, histologically and histochemically. Grossly, deeper defects contained thicker, whiter tissue, but both joints contained generalised degenerative changes. Defects extending through calcified cartilage were filled deeply by fibrocartilage and superficially by fibrous connective tissue. Defects extending through subchondral bone were consistently filled with hyaline‐like cartilage in the depths of the lesion, fibrocartilage in the intermediate layer and fibrous connective tissue superficially. The results indicate that subchondral bone is the source of hyaline‐like cartilage repair tissue and suggest that quality of healing of cartilage defects may be improved by penetrating the subchondral bone plate. It also appears that the synovitis associated with the procedure must be controlled before the procedure can be advocated for treatment of clinical cases.
Intravenous catheterisation of foetus and mare in late pregnancy: management and respiratory, circulatory and metabolic effects
Authors: TAYLOR POLLY M. , SILVER MARIAN , FOWDEN ABIGAIL L.
Published: April 2010

The uterine and umbilical vessels of 12 pregnant ponies were catheterised to study foetal metabolism. The effects of this procedure on maternal and foetal cardiovascular, respiratory, metabolic and adrenocortical activity were monitored during and after surgery. Premedication with acepromazine ‐butorphanol‐detomidine was followed by induction of anaesthesia with detomidine and ketamine and maintenance, using mechanical ventilation, with halothane in oxygen and nitrous oxide. Mean maternal arterial blood pressure was >70 mmHg during anaesthesia and arterial oxygen tension remained over 100 mmHg. The foetuses were adequately oxygenated but were hypercapnic and lacticacidaemic. Most maternal and foetal blood gases and metabolites had returned to normal by 24 h, although foetal plasma lactate fell more slowly. The maternal adrenocortical discharge was less severe than reported previously and plasma Cortisol had fallen to basal levels by 48 h after surgery. Foetal plasma Cortisol remained low and did not change during or after surgery. Arterio‐venous metabolite and gas tension differences across the uterine and umbilical circulations were slightly greater at operation than in the recovery period, suggesting that uteroplacental perfusion may have been impaired during surgery. Post‐operative recovery of the mare and foetus was satisfactory and subsequent problems associated with the foetal catheters were not related to the anaesthesia or surgery.
Fractures of the lateral malleolus of the tibia in 16 horses
Authors: WRIGHT I. M.
Published: April 2010

Clinical and radiological features of 16 horses with fractures of the lateral malleolus of the tibia are reported. The paper describes surgical techniques used, results obtained and discusses justification for removal. Fourteen fractures were unilateral and two bilateral. There was no left:right disparity. The history included a known traumatic incident in 14 cases. All animals had a tarsocrural joint effusion and 10 had palpable thickening of the lateral collateral ligaments. Crepitus was also palpable in 10 horses. The fracture was identified in all dorsoplantar and 14 of 18 dorsomedial‐plantarolateral oblique radiographic projections. Nine fractures were simple and 9 comminuted. All fractures were removed via a tarsocrural arthrotomy. Approaches were dorsolateral in 14 joints, plantarolateral Ural in 3 and dorsolateral and plantarolateral in 1. After an ascending exercise programme horses returned to work 6 months after surgery: 15 horses were free of lameness after 17–62 months, with 13 animals performing at a level similar to pre‐injury standard.
Effects of hypoxia and azotaemia on the pharmacokinetics of amikacin in neonatal foals
Authors: GREEN S. L. , CONLON P. D. , MAMA K. , BAIRD J. D.
Published: April 2010

The effects of hypoxia and azotaemia on the pharmacokinetics of amikacin were evaluated in 20 full‐term neonatal critically ill foals which required 24‐h supportive care, antibiotics and dextrose‐supplemented polyionic fluids given intravenously, nasal insufflation with oxygen and nutritional supplementation. There was no association between sepsis score or survival and pharmacokinetic parameters. Concurrent hypoxia and azotaemia were associated with significantly decreased clearance and increased peak and trough serum concentrations of amikacin; however, peaks or troughs did not exceed toxic values. Derangements in serum peak, trough and clearance values, which were present on admission, persisted over the 6‐day duration of this study. Daily monitoring of serum amikacin concentration revealed a tendency to underdose (particularly in foals receiving aggressive fluid therapy), which necessitated increasing the dose/kg body weight (9–12 mg/kg) and increasing the dose interval (10–12 h) in 40% (8/20) of the cases, so that blood concentrations of amikacin could be maintained within the target range of 3–15 μg/ml. Amikacin‐induced nephrotoxicity was not indicated by conventional laboratory testing, nor was it strongly suspected after examination of post mortem lesions.
Nutrient utilisation by the hindlimb of Thoroughbred horses at rest
Authors: PETHICK D. W. , ROSE R. J. , BRYDEN W. L. , GOODEN J. M.
Published: April 2010

Nutrient uptake by the hindlimb was investigated utilising the arteriovenous difference technique in 5 Thoroughbred horses fed to maintenance a diet of 100% roughage or 52% oat grain and 48% roughage. Arterial blood was obtained from a catheter inserted into the carotid artery while venous blood was simultaneously collected from a catheter placed into the iliac vein via the medial saphenous vein. The arteriovenous difference for glucose was significant and represented a mean extraction of 10 ± 1% with no effect of diet. If fully oxidised, glucose uptake (corrected for lactate and pyruvate arteriovenous difference) was sufficient to account for 78 ± 13% or 107 ± 15% of the oxygen consumed by the hindlimb in horses fed a roughage or 52% oat grain diet respectively. Acetate was also a major metabolite of the hindlimb, showing a 39 ± 5% extraction with no effect of diet. However, the 52% oat grain diet did induce a significant decline in the concentration of acetate in arterial blood. The potential contribution to oxidation in the hindlimb was significantly reduced from 32 ± 4% in horses fed roughage to 21 ± 3% when fed 52% oat grain. D‐3‐Hydroxybutyrate uptake could account for 9 ± 1% of the oxidation by the hindlimb with no effect of diet. The technique for measuring nutrient uptake across the hindlimb using the arteriovenous difference is relatively simple and would be valuable in investigating fuel use by muscle during exercise.
Effect of carnitine supplement to the dam on plasma carnitine concentration in the sucking foal
Authors: BENAMOU AGNES E. , HARRIS R. C.
Published: April 2010

The changes in carnitine in plasma and milk during the first 3 months of lactation were studied in 14 broodmares and their foals. Six of the mares (Group S) were given a supplement of 10 g carnitine split between the morning and evening feeds, starting 2 weeks before birth.

At birth the plasma carnitine concentration in Group S mares was about twice that in Group NS mares (no supplement). In both groups the concentration initially declined in the days after birth. Whilst this trend was reversed in Group S mares, the concentration in Group NS mares remained at a reduced level for the remainder of the study. Milk concentrations declined continuously over the monitoring period in both groups. There was no apparent relationship between milk and plasma concentrations. Despite this the milk concentration tended to be higher in Group S than in Group NS mares although differences were not significant. There was an immediate drop in the plasma concentration in foals after birth which was reversed in foals of Group S mares but not in those of Group NS mares. There were no apparent side effects of carnitine supplementation.
The correlation of running ability and physiological variables in Thoroughbred racehorses
Authors: HARKINS J. D. , BEADLE R. E. , KAMERLING S. G.
Published: April 2010

The running abilities of 25 Thoroughbred racehorses were measured at distances of 1200, 1600 and 20000 m. Various physiological variables were measured subsequently on the treadmill and correlated with running speed. There was a negative correlation for running speed with the velocity (VLa4) and work rate (WLa4) at which blood lactate reaches a steady‐state concentration of 4 mmol/litre and a positive correlation with peak plasma lactate, suggesting that plasma lactate concentrations of faster horses rise more rapidly and to higher levels than do those of slower horses. The correlation between running speeds and heart rates (HR) was stronger for unfit than fit horses, suggesting that cardiovascular effects of training are more beneficial to slower horses. The significant correlation between running speeds and V200 suggests that the HR of faster horses increases more rapidly than in slower horses performing similar exercise. The correlation of running speeds and O2max suggests that the HR of faster horses increases more rapidly than in slower horses performing similar exercise. The correlation of running speeds and VO2max suggests that faster horses utilise more oxygen during maximal intensity exercise. The correlation of running speeds with minimum pH and minimum HCO3− suggests that faster horses maintain speed at higher hydrogen ion (H+) concentrations. Correlations between running speeds and the measured variables were consistently stronger for the longer distance runs. Because VLa4 and WLa4 were obtained during sub‐maximal exercise, these variables were determined to be the best correlates of running performance.
Advancing the time of ovulation in the mare with a short‐term implant releasing the GnRH analogue deslorelin
Authors: MEINERT C. , SILVA J. F. S. , KROETZ I. , KLUG E. , TRIGG T. E. , HOPPEN H. O. , JÖCHLE W.
Published: April 2010

A small, biocompatible and short‐term implant releasing 1.5 mg or 2.25 mg of the GnRH analogue deslorelin was evaluated in 140 Hanoverian (warm blooded) mares during the 1990 breeding season (Study I). Mares in oestrus and with a follicle 40 ± 2 mm in diameter were assigned alternately to treatment (70) or remained as untreated controls. Implants were administered subcutaneously, and intervals to ovulation determined by rectal examination and ultrasound at 12‐h intervals. Since results with both doses of deslorelin were similar, data were pooled. Deslorelin implantation resulted in ovulations in 65 of 70 mares within 48 h (93%), while only 5 of 70 control mares ovulated within the same time period (7%) (P<0.01). Most induced ovulations (63%) occurred 36–48 h after implantation. In Study II, 4 groups of 12 Hanoverian mares each were treated with 3,000 or 5,000 iu hCG, or a 2.25 mg deslorelin implant, or received placebo. All treatments resulted in 100% ovulations within 48 h, versus 25% ovulations in controls (P<0.01), and 63%, 75% and 86% of these ovulations occurred 36–48 h after treatment with 3,000 and 5,000 iu hCG and deslorelin respectively.

Hormonal response to deslorelin in treated mares, sampled every 12 h, consisted of elevations of FSH and LH concentrations of >200% and >300% baseline values at 12 h (P<0.001), of 67% and 79% at 24 h (P<0.01) and of 35% and 49% at 48 h (P<0.05), respectively. No local reactions at the implantation site were observed.