bluuebunny/crossref_metadata_2025 huggingface dataset:
Differential scanning calorimetric studies of superficial digital flexor tendon degeneration in the horse
Authors: MILES C. A. , WARDALE R. J. , BIRCH H. L. , BAILEY A. J.
Published: April 2010

Differential scanning calorimetry (DSC) of equine superficial digital flexor tendons revealed the presence of a small exothermic peak at 23°C of unknown origin, and a large endothermic peak at 70°C due to denaturation of cross‐linked collagen fibres. In the central degenerated core of damaged tendons the denaturation temperature remained at 70°C but the enthalpy decreased in relation to the extent of degeneration of the tendon. We suggest that this reduction in enthalpy is due to depolymerisation and denaturation of the collagen fibres. This contention is supported by the observed increased activity of the degradative enzyme cathepsin B secreted by the fibroblasts. DSC analysis of cultured porcine tendon fibroblasts revealed a multicomponent endotherm, denaturation beginning at 46°C, a temperature capable of being achieved within the tendon during intensive exercise. DSC clearly has considerable potential in complementing morphological and biochemical studies to determine the aetiology and progress of equine tendon degeneration.
Effect of route of administration and age on the pharmacokinetics of amikacin administered by the intravenous and intraosseous routes to 3 and 5‐day‐old foals
Authors: GOLENZ M RENÉE , WILSON W. D. , CARLSON G. P. , CRAYCHEE THERESE J. , MIHALYI JUDITH E. , KNOX LINDA
Published: April 2010

The suitability of the intraosseous (i.o.) route for drug administration to equine neonates was evaluated in a study comparing the pharmacokinetics of amikacin administered by the i.o. and intravenous (i.v.) routes. Using a cross‐over study design amikacin sulphate (7 mg/kg bwt) was administered i.o. or i.v. to 6 healthy foals at 3 and 5 days of age. Amikacin was instantaneously and completely absorbed after i.o. administration, achieving a mean ± sd peak concentration (34.17 ± 3.54 μg/ml) in the first sample collected 3 min after administration which was not significantly different from the mean ± sd peak concentration (32.92 ± 2.63 μg/ml) achieved after i.v. administration. The plasma amikacin concentration‐time profiles for the i.o. and i.v. routes were not different and both were appropriately described by a 2‐compartment open pharmacokinetic model. No significant differences attributable to route of administration were found in values for the major pharmacokinetic variables. The degree of inter‐individual variation in values for indices of clearance was considerably greater than the degree of variation attributable to age. Despite this, values for body clearance (C***lB) were significantly higher (P<0.05) and values for area under the plasma amikacin concentration‐time curve (AUC) and concentration of amikacin in plasma at 8 h [Cp(8h)] were significantly lower in 5‐ than in 3‐day‐old foals, indicating that amikacin was more rapidly cleared by the older foals. Technical difficulties were not encountered during i.o. needle placement in the medial aspect of the proximal tibia. Mild diffuse soft tissue swelling which developed at the i.o. site resolved completely within 1–2 months. Radiographs demonstrated a bony healing process with minor periosteal and endosteal proliferation. The i.o. route appears to be safe, practical and effective for rapid delivery of amikacin to neonatal foals.
Exercise induced ventilation/perfusion inequality in the horse
Authors: SEAMAN J. , ERICKSON B. K. , KUBO K. , HIRAGA A. , KAI M. , YAMAYA Y. , WAGNER P. D.
Published: April 2010

Exercise in normal human subjects causes deterioration of matching of ventilation to blood flow in the lungs, but only in about 50% of those examined. A previous study (Wagner et al. 1989) of 5 horses showed no significant worsening of ventilation/blood flow (V̇a/Q̇) relationships during heavy exercise as determined by multiple inert gas elimination technique (MIGET). Because of the small number of horses in that study and the 50% human incidence of exercise induced V̇a/Q̇ mismatch, we studied an additional 6 Thoroughbreds, comparing V̇a/Q̇ relationships at the walk (1.4 m/s, 0o incline) and during galloping (9.6 ± 0.3 m/s, 7% incline). Such data were collected under 4 different conditions wherein inspired gas was 1) air, 2) 21% O2 in helium, 3) 15% O2 in N2 and 4) 15% O2 in helium. Each horse exercised 4 times (morning and afternoon of 2 days, with inspired gas conditions randomised). There was a small but significant increase in V̇a/Q̇ mismatch (similar under all 4 conditions). The second moment of the V̇a/Q̇ distribution (determined by the MIGET) increased significantly (P < 0.01) from 0.31 ± 0.01 at the walk to 0.38 ± 0.02 during gallop. This increase however is small: 0.38 is well within the range of this parameter for normal human subjects (where the 95% upper confidence limit is 0.60). This study shows that a small amount of exercise induced V̇a/Q̇ mismatch can occur in the horse as in man, but the mechanism remains to be elucidated and its clinical significance remains to be established. It may reflect interstitial pulmonary oedema but effects on arterial oxygenation are minimal.
Distribution of inspired gas to each lung in the anaesthetised horse and influence of body shape
Authors: MOENS Y. , LAGERWEIJ E. , GOOTJES P. , POORTMAN J.
Published: April 2010

The distribution of inspired gas to each lung, time constants of the lungs and parameters of gas exchange were studied in 2 groups of horses (mean bwt 606 kg), anaesthetised using thiopentone and chloral hydrate and breathing room air. One group (n=4) had a downward curved abdominal contour (round‐bellied) and the other group (n=4) had an upward curved abdominal contour (flat‐bellied). An equal distribution of inspired gas between the lungs existed in both groups in dorsal recumbency. Flat‐bellied horses maintained this equal distribution in lateral recumbency whereas in round‐bellied horses an uneven distribution of tidal volume (VT) developed. The percentage of (VT) distributed to the dependent lung was 23% and 38% for left and right lateral recumbency respectively. The distribution of VTagreed with the ratio of time constants of the lungs in flat‐bellied horses but differed markedly from this ratio in round‐bellied horses suggesting that, in the latter, factors other than compliance and resistance play a role in distribution of ventilation. Round‐bellied horses had a lower PaO2and a larger (A‐a)PaO2than flat‐bellied horses in all body positions. The results are compatible with the known hypothesis that pressure exerted by abdominal contents on the dependent lung and diaphragm is an important factor in ventilation/perfusion mismatch of the anaesthetised horse.
Comparison of the anti‐inflammatory actions of flunixin and ketoprofen in horses applying PK/PD modelling
Authors: LANDONI MARIA F. , LEES P.
Published: April 2010

A comparative study in horses of the pharmacokinetics (PK) and pharmacodynamics (PD) of 2 extensively used nonsteroidal anti‐inflammatory drugs (NSAIDs), flunixin (FXN) and ketoprofen (KTP), was carried out applying PK/PD modelling. To evaluate the anti‐inflammatory properties of these drugs a model of acute inflammation, comprising surgically implanted subcutaneous tissue cages stimulated by intracaveal injection of carrageenan, was used.

FXN elimination half‐life (T1/2β) in plasma was 3.37 ± 1.09 h. However, in exudate a much longer T1/2β was obtained (15.99 ± 3.80 h). Apparent volume of distribution (Vdarea) for FXN was 0.317 ± 0.126 1/kg and body clearance (CIB) was 0.058 ± 0.004 1/kg/h. KTP displayed enantioselective pharmacokinetics, the S(+) enantiomer being predominant in plasma, exudate and transudate. T1/2β values for R(‐) and S(+)KTP were, respectively, 1.09 ± 0.19 h and 1.51 ± 0.45 h (plasma) and 19.73 ± 2.72 h and 22.64 ± 4.34 h (exudate), respectively. R(‐)KTP was cleared more rapidly than the S(+) enantiomer. C1B values were 0.277 ± 0.035 1/kg/h and 0.202 ± 0.022 1/kg/h, respectively.

FXN and KTP pharmacodynamics was evaluated by determining their inhibitory effects on serum thromboxane (Tx)B2, exudate prostaglandin (PG)E2, leukotriene (LT)B4and β‐glucuronidase (β‐glu) and intradermal bradykinin‐induced swelling. Both drugs produced marked inhibition of serum TxB2synthesis for up to 24 h, with no significant differences between the drugs. FXN was a more potent inhibitor of exudate PGE2, the EC50 for FXN being lower (P<0.01) than that for KTP (0.019 ± 0.010 μg/ml and 0.057 ± 0.009 μg/ml, respectively). Neither drug had any effect on exudate LTB4concentration. Differences between the 2 drugs were observed for the inhibition of β‐glu, the Emax for KTP being higher (P<0.01) than for FXN. However, no differences were observed in other PD parameters. Both FXN and KTP inhibited bradykinin‐induced swelling. Differences between the drugs were obtained for Emax, which was greater for FXN (P<0.01) than for KTP. Equilibration half‐life (T1/2Ke0) also differed, being much longer (P<0.01) for FXN than for KTP.

PK/PD modelling proved to be a useful and novel analytical technique for studying the pharmacodynamics of NSAIDs, with the advantage over classicalin vitromethods that it provides data in the whole animal. By quantifying action‐concentration interrelationships through PK‐PD modelling, it is possible to shed light on molecular mechanisms of drug action, and establish probable differences in mechanisms of action between structurally similar drugs. In future it should be possible to use PK/PD modelling to provide a rational basis for selecting dosage schedules for clinical use.
Changes in breathing pattern in the normal horse at rest up to age one year
Authors: KOTERBA ANNE M. , WOZNIAK J. A. , KOSCH R C.
Published: April 2010

Changes in pattern of airflow, sequence of respiratory muscle activation and generated pressures were measured serially in a group of foals during the first year post partum, in order to describe the maturation of the equine breathing pattern. In neonatal foals, inspiration and expiration were both primarily active and airflow pattern was essentially monophasic. By age 1 year, foals displayed essentially the same breathing pattern previously described in adult horses, utilising a combination of active and passive inspiration and expiration to breathe around, rather than from, the relaxation volume of the respiratory system (V̇rx). A strong temporal relationship during growth was found between the timing of changes observed in airflow pattern and in the neuromuscular strategy of breathing. The transition to the adult breathing pattern appeared to involve a time delay in activation of both inspiratory and expiratory muscle groups, establishing a passive and active component to both inspiration and expiration. Throughout the study period, concurrent with the increase in delay of abdominal muscle activation, the expiratory flow pattern became progressively more biphasic in appearance. The time of appearance of a consistent biphasic inspiratory flow pattern was considerably later, at approximately age 1 year and coincided with the appearance of a delay in inspiratory muscle activation. From our results, we conclude that the transition from the neonatal to the adult breathing strategy in the horse appears not to be induced by the time course of chest wall stiffening during maturation. While changes in relative body proportions and size of abdominal contents during growth may influence the transition in breathing, our results also indicate that respiratory control mechanisms play an essential role in the expression of the polyphasic breathing pattern.
Effects of glyceryl trinitrate (nitroglycerin) on pulmonary vascular pressures in standing Thoroughbred horses
Authors: MANOHAR M.
Published: April 2010

Strenuously exercising Thoroughbreds exhibit a dramatic increase in pulmonary capillary blood pressure, which contributes to stress failure of pulmonary capillaries resulting in exercise induced pulmonary haemorrhage (EIPH). One strategy to prevent EIPH is, therefore, to lower the pulmonary capillary blood pressure of exercising horses. Recent work in several species suggests that nitric oxide plays a significant role in maintaining low vascular resistance in the pulmonary circulation; however, the effects of nitrovasodilators (which work via the same mechanism as nitric oxide) on equine pulmonary circulation have not been examined. The present study examined the effects of glyceryl trinitrate (nitroglycerin) on right atrial and pulmonary vascular pressures in 7 healthy sound Thoroughbred horses. Freshly prepared nitroglycerin solution was infused for 240 s into the right atrium of quietly standing Thoroughbreds at dose rates of 350, 700, 1400 and 2100 g/min in a randomised manner. All infusions were performed in duplicate. Heart rate, right atrial, pulmonary artery, pulmonary capillary and pulmonary artery wedge pressures were determined preinfusion, at 30 s intervals during nitroglycerin infusions and at 60 s post infusion. Measurements were made using catheter mounted manometers whosein vivosignals had been matched with fluid‐filled systems referenced at the level of the point of the shoulder. It was observed that nitroglycerin infusions caused a dose related increase in heart rate while dose related reductions occurred in the mean right atrial, pulmonary artery, pulmonary artery wedge and pulmonary capillary pressures. At 2100 μg/min, nitroglycerin induced reduction in pulmonary artery wedge pressure was significantly greater than that in the pulmonary artery pressure. It is concluded that (i) pulmonary vascular bed of quietly standing horses has a certain basal vasomotor tone which was unmasked by nitroglycerin infusions (ii) nitroglycerin may have a more potent dilator effect on equine pulmonary veins than on the arteries.
Biokinematic effects of collection on the trotting gaits in the elite dressage horse
Authors: HOLMSTRÖM M. , FREDRICSON I. , DREVEMO S.
Published: April 2010

Trot in hand, working trot, collected trot, passage and piaffe of 6 Grand Prix dressage horses were recorded by high speed film (250 frames/s). Angular patterns and hoof trajectories of the left fore‐ and hindlimbs were analysed and presented as mean and standard deviation (s.d.) curves. Speed and stride length decreased and fore‐ and hind stance phase durations increased with collection resulting in no suspension in piaffe. The diagonal advanced placement was positive in all gaits except for piaffe. Most of the changes in forelimb angular patterns were effects of reduction in forelimb pendulation. The horses did not step under themselves more in collected trot, passage and piaffe than in trot in hand. The stifle and hock joints were more flexed at the start of the stance phase in piaffe and passage than in the other gaits. Flexion of the hock joint at the middle of the stance phase was largest in passage and piaffe. In spite of the limited number of horses the present study confirmed earlier observations of conformation and gaits in dressage horses. Hindlimb pendulation, femur and pelvis inclinations and elbow, carpal, stifle and hock joint angles seem to be the most significant angular measurements for dressage performance.
Clinical features of the 1992 outbreak of equine viral arteritis in Spain
Authors: MONREAL L. , VILLATORO A. J. , HOOGHUIS H. , ROS I. , TIMONEY P. J.
Published: April 2010

During 1992, a widespread outbreak of Equine viral arteritis (EVA) occurred at a riding establishment near Barcelona, Spain. A total of 31 out of 186 horses on the premises displayed clinical signs, most frequently, fever, depression, mild ventral and limb oedema and a vesicular‐erosive stomatitis, with hypersalivation, petechiations and small ulcerations. Affected horses developed illness of varying severity with only a few exhibiting a severe form of the disease and no mortality was recorded. Haematological and blood biochemical examination the most severely affected horses revealed a thrombocytopenia, slight leucocytosis with neutrophilia, lymphopenia and eosinopenia, an increase in plasma fibrinogen and a small rise in serum proteins and indirect bilirubin values. Diagnosis was confirmed by demonstration of seroconversion to equine arteritis virus in acute and convalescent phase sera. Attempted isolation of the virus from citrated blood samples proved unsuccessful.
Ophthalmic cyclosporine in equine keratitis and keratouveitis: 11 cases
Authors: GRATZEK ANN T. , KASWAN RENEE L. , MARTIN C. L. , CHAMPAGNE E. S. , WHITE SUSAN L.
Published: April 2010

Topical cyclosporine A was safely used in a series of 11 cases of equine keratitis and keratouveitis and appeared to be an effective anti‐inflammatory agent in 9 cases. The clinical diagnoses included interstitial keratouveitis, endotheliitis, multifocal punctate keratopathy and a melting stromal ulcer. In most cases, the presence or absence of insidious bacterial infection was not conclusively determined. Topical cyclosporine A had no deleterious effects in this series of cases. The authors suggest that topical cyclosporine in both aqueous and lipid base vehicles should be investigated and evaluated as an alternative mode of achieving ocular immunosuppression.
Harem stability and reproductive success of Misaki feral mares
Authors: KASEDA Y. , KHALIL A. M. , OGAWA H.
Published: April 2010

The stability of relationships between harem stallions and mares (consort relations) was investigated and the durations ofinter partumintervals were determined in order to establish if there was any correlation between the stability of consort relation and reproductive success of mares in Misaki feral horses. Thirty‐four mares were observed continuously for more than 5 years. The lifetime stability was 80–100% (mean 92.4%) for 16 mares, 60–79% (mean 70.4%) for 10 mares and 0–59% (mean 27.9%) for 8 mares. The continuous length (years) of specific consort relations was 2–10 years and was found to correlate significantly with lifetime stability. There was a significant positive correlation of lifetime stability with lifetime reproductive success for 34 mares observed, and the correlation was higher when the data of 8 wandering mares (<60% in lifetime stability) were omitted. The mean ± s.d. delivery interval of 25 stable mares was 364.5 ± 11.0 days, whereas that of 8 unstable mares and stable mares who changed stallions was 387.0 ± 40.2 days. There was a significant difference between delivery intervals of stable and unstable mares. Significant correlations between the stability of consort relations and both the foaling rates and delivery intervals suggest that mares may obtain major reproductive advantages if they maintain long term and stable consort relations with a particular stallion throughout their reproductive life span.
Ultrastructure of the secretory endometrium during oestrus in young maiden and foaled mares
Authors: TUNÓN A‐M. , RODRIGUEZ‐MARTINEZ H. , HAGLUND A. , ALBIHN A. , MAGNUSSON U. , EINARSSON S.
Published: April 2010

Cyclical accumulation of uterine fluid occurs during oestrus and is often seen in excessive volumes in mares considered susceptible to endometritis. Since the mechanisms behind the formation of free uterine fluid remain to be clarified, the fine structure of the secretory equine endometrium was studied in biopsies collected during videoendoscopy from 14 endometritis‐free, 4–9‐year‐old mares during oestrus. A distinct oedema of thetunica mucosawas evident. The surface epithelium had both ciliated and nonciliated cells and, particularly at the uterine body, often presented intra‐epithelial macrophages. The epithelial cells of the gland duct were similar to the surface epithelium, except that the nonciliated cells lacked secretory vesicles. The mid‐deep glandular segment was, however, loaded with apical secretory vesicles in the nonciliated cells. This glandular epithelium presented clear signs of secretory activity with conspicuous secretory vesicles holding electron‐dense granula in the adluminal cytoplasm and a well developed supranuclear Golgi apparatus. Secretory products as well as cell debris were commonly found in the lumen of the glands. No clear signs of apocrine secretion were found and it seemed therefore, that the mechanism of secretion is merocrine, i.e. by exocytosis. The endometrial oedema and intense secretory activity, both under oestrogenic influence, contribute to the building up of the uterine fluid during oestrus. No differences in morphology of the secretory endometrium could be noticed between nulliparous mares and mares that had had 1 or 2 foals.
Serial measurement of peripheral oestrogen and progesterone concentrations in oestrous mares to determine optimum mating time and diagnose ovulation
Authors: ALLEN W. R. , MATHIAS SUSANNA , LENNARD S. N. , GREENWOOD R. E. S.
Published: April 2010

Rapid enzyme‐based immunoassays were used to measure concentrations of oestradiol‐17ß and progesterone in daily blood samples recovered throughout oestrus and for a few days after ovulation from 34 Thoroughbred and 8 pony‐type maiden, barren and foaling mares. The first dectectable fall in oestradiol‐17ß levels occurred in 88% of the mares within the interval −72 to 0 h with respect to ovulation and in 65% of mares within the interval of −48 to 0 h. The results indicated that serial daily hormone assays of this type could, in a high proportion of animals, predict a correct time for a single mating and diagnose the occurrence of ovulation in Thoroughbred mares at stud in the absence of the present management system which includes repeated veterinary examinations of the ovaries. However, the absolute need for serial daily sampling from all mares to produce interpretable hormone profiles, and the cost of this sampling and the hormone assays, make the method impractical at the present time.
Nitric oxide donors as treatment for grass induced acute laminitis in ponies
Authors: HINCKLEY K. A. , FEARN S. , HOWARD B. R. , HENDERSON I. W.
Published: April 2010

The potential for participation of the arginine‐nitric oxide system in the aetiology of acute equine laminitis has been assessed. Nitric oxide (NO), produced by the action of NO synthase (NOS) on its substratel‐arginine, relaxes vascular smooth muscle to cause vasodilatation. An attenuated normal vasodilatory tone may characterise the pathogenesis of acute equine laminitis. An intravenous infusion of 10%l‐arginine in 0.9% saline caused vasodilatation in the hoof of a normal pony and immediate reperfusion of laminal tissues in an acutely laminitic pony, detected noninvasively by near infrared spectroscopy (NIRS), but the amino acid had little effect on systemic blood pressure. Treatment of acute laminitis with glyceryl trinitrate applied topically to the pasterns reduced the typical ‘bounding pulses’ in treated limbs, reduced lameness and lowered systemic blood pressure. Nitric oxide is likely to participate in the multifactorial pathogenesis of equine laminitis.
Determination of highest no effect dose (HNED) for local anaesthetic responses to procaine, cocaine, bupivacaine and benzocaine
Authors: HARKINS J. D. , MUNDY G. D. , STANLEY S. , WOODS W. E. , REES W. A. , THOMPSON K. N. , TOBIN T.
Published: April 2010

The highest no effect doses (HNEDs) for the local anaesthetic (LA) effects of procaine, cocaine, bupivacaine and benzocaine were determined using the heat lamp/hoof withdrawal model of Kamerlinget al. (1985b) and the abaxial sesamoid block model of local anaesthesia. The heat lamp rapidly (4 or 5 s) increased the temperature of the superficial skin layers of the pastern to about 90°C, at which point the animal sharply withdrew its hoof. Effective LA blockade precluded this response and superficial skin temperatures exceeded 120°C. Thermal stimulus experiments were routinely terminated after 10 s of exposure to prevent undue tissue damage.

Following abaxial sesamoid block with bupivacaine, the HNED for that drug was about 0.25 mg/site. Increasing the dose to 2 mg/site apparently produced complete and prolonged LA blockade.

Analogous work showed that the HNED for procaine was about 2.5 mg/site. Similarly, the dose response curve for procaine was parallel with that of bupivacaine but was shifted 10‐fold to the right The duration of the LA response following procaine injection was less than for bupivacaine with the statistically significant response following 40 mg/site injection lasting less than 45 min.

Cocaine was less potent than procaine, showing a shallower dose response curve. The HNED for cocaine was less than 5 mg/site, although at this dose the duration of action was extremely short (<7.5 min). Benzocaine had no significant LA action when a dose of 800 mg was applied topically as a 5% preparation.

These results show that the HNEDs for bupivacaine and procaine are remarkably low, that cocaine is somewhat less potent as a LA than might be expected, and that 5% topical benzocaine has no significant pharmacology. The small doses of bupivacaine and procaine producing effective local anaesthesia suggests that developing plasma thresholds for these agents is likely to be very challenging.
Basement membrane pathology: a feature of acute equine laminitis
Authors: POLLITT C. C.
Published: April 2010

Thirty‐two dorsal, mid‐hoof wall, lamellar sections from 8 Standard bred horses, humanely killed 48 h after the administration of an alimentary carbohydrate overload, were sectioned and examined by light microscopy. Sections were stained with the connective tissue and basement membrane stains periodic acid‐Schiff (PAS), Azan and periodic acid silver methanamine (PASM) and with routine haematoxylin and eosin (H&E). Lesions of the epidermal lamellae, attributable to laminitis, were graded in order of increasing severity fromGrade N(normal),Grade 1(mild),Grade 2(moderate) toGrade 3(severe and extensive). The grading system was based principally on changes to lamellar basement membrane (BM) which were clearly visible when the connective tissue stains PAS and PASM were used. Earliest changes were rounding of the basal cell nuclei and elongation of secondary epidermal lamellae (SELs). Secondary epidermal lamellae tips were pointed instead of round and the basement membrane had separated from the lamellae. In earlyGrade 1lesions, this was obvious at the tips of the SELs where the BM had lifted to form teat‐shaped bubbles. The absence of BM at the tips of secondary dermal lamellae, along with varying amounts of connective tissue, was considered a progression in severity and classified asGrade 2. Eventually, even the primary epidermal and primary dermal lamellae separated from each other and the empty shells of isolated BM, in what was once the tip of the primary epidermal lamella, signified that a global separation of the epidermal and dermal lamellae had occurred (Grade 3lesion). The histopathological grading system correlated well with the degree of lameness at the time of euthanasia, (r2= 0.94) and apparently described the severity of laminitis accurately. Disintegration of the BM and failure of its attachment to the basal cells of the epidermis appears to be one of the earliest pathological events to occur in acute laminitis and could be the change that initiates the collapse of the lamellar architecture. Histopathological diagnoses of laminitis are strengthened when based on sections stained with at least PAS, in addition to routine H&E and should exhibit evidence of the BM pathology described here.
Ultrasonographic anatomy of the dorsal and abaxial aspects of the equine fetlock
Authors: DENOIX J. M. , JACOT STEPHANIE , BOUSSEAU B. , PERROT PATRICIA
Published: April 2010

This paper describes normal ultrasound images of the soft tissues of the dorsal and abaxial aspects of the equine fetlock. The palmar aspect of the fetlock is not discussed because it is related to the suspensory apparatus and flexor tendon anatomy which has been previously described. Ultrasound scanning was performed with 7.5 MHz linear or 10 MHz sector probes and recorded on 7.5 cm U‐matic videocassettes allowing further retrospective data analysis, computer manipulation and good image reproducibility. Sagittal, parasagittal, frontal and transverse ultrasound scans of 13 lameness free mature horses were compared to anatomically dissected leg specimens, anatomical sections and Magnetic Resonance Imaging scans of isolated limbs. The results are focused on the comparison between anatomical sections and ultrasonograms performed on the legs of nonlame horses. Ultrasonography was demonstrated to be a very accurate imaging procedure for soft tissue structures at the dorsal and abaxial aspects of the equine fetlock. Under clinical conditions, a thorough knowledge of normal ultrasonographic anatomy is critical for an accurate diagnosis of fetlock soft tissue injury.
Retinal detachment in horses
Authors: Mätz‐Rensing Kerstin , Drommer W. , Kaup E‐J. , Gerhards H.
Published: April 2010

Ten horses with partial or total retinal detachment were investigated using light and electron microscopy (TEM, SEM). Several lesions were observed and compared with normal retinal morphology. Three weeks after the initial retinal detachment, hypertrophy of the pigment epithelium with transformation of the apical microvilli could be observed. The lesions were accompanied by progressive degeneration and atrophy of the sensory retina, starting at the photoreceptor outer segments. Hypertrophy of Müller cells was a concomitant finding. Retinal detachment represents a sequel either to inflammatory processes or trauma.
Regulatory significance of procaine residues in plasma and urine samples: preliminary communication
Authors: HARKINS J. D. , MUNDY G. D. , STANLEY S. , WOODS W. E. , BOYLES J. , ARTHUR R. A. , SAMS R. A. , TOBIN T.
Published: April 2010

Plasma and urinary concentrations of procaine and the duration of response to procaine after its administration as a local anaesthetic to horses were studied. Following injection of a clinical dose of procaine HCl (80 mg), the concentration of procaine in plasma was less than the lower limit of quantitation and unsuitable for threshold determination. Therefore, the urinary concentration of procaine was determined after injection of a dose of 5 mg procaine HCl, the highest no‐effect dose (HNED) of this agent. Free unconjugated procaine in equine urine reached a peak concentration of 23.7 ng/ml, while total (unconjugated plus conjugated) procaine peaked at 37.9 ng/ml (mean urine pH of 8.5). Because a basic drug may concentrate substantially in acidic urine, a threshold concentration of 25 ng/ml of unconjugated procaine is a reasonable and conservative threshold for procaine at this time.

Horses were administered abaxial sesamoid blocks containing 2% procaine HCl (40, 80, 160 and 320 mg) and 2% procaine HCl (40 and 320 mg) with epinephrine (1:100,000) in local anaesthetic experiments. There was a significant local anaesthetic (LA) effect for all doses of procaine HCl with the duration of effect ranging from 30 min (40 mg) to 60 min (320 mg). The addition of epinephrine significantly increased the duration of local anaesthesia to 180 min for a 40 mg dose and 420 min for a 320 mg dose. Because epinephrine may extend the duration of local anaesthesia beyond a reasonable period of confinement for horses before the starting time of a race, the increased LA effect following the addition of epinephrine to procaine has regulatory significance.
Influence of shoeing on ground reaction forces and tendon strains in the forelimbs of ponies
Authors: Riemersma D. J. , van den Bogert A. J. , Jansen Margot O. , Schamhardt H. C.
Published: April 2010

Strains in the superficial digital flexor tendon (SDFT), deep digital flexor tendon (DDFT), accessory ligament of the deep digital flexor muscle (inferior check ligament [ICL]) and theinterosseus mediusmuscle (suspensory ligament [SL]) in the right forelimb of 5 ponies were measured using mercury‐in‐silastic strain gauges a few hours after implantation. Tendon strains were recorded at the walk with normal flat shoes, egg‐bar shoes, a 7° increased hoof angle accomplished by application of a heel‐wedge and a 7° decreased hoof angle using a toe‐wedge, consecutively. Ground reaction forces were recorded with all 4 shoe types preoperatively and with flat shoes post operatively.

The strain patterns of the SDFT, DDFT and SL showed a rapid increase at the beginning of the stance phase, followed by a plateau with a small incline or decline and a rapid decrease at the end of the stance phase. The SDFT had its maximal strain in the first half of the stance phase in all ponies. The DDFT and SL reached their maximal strain in the first half of the stance phase in 2 ponies and in the second half of the stance phase in the other 3 ponies. The ICL was strained maximally in the second half of the stance phase in all ponies.

Averaged over all 5 ponies, the maximal strains in the SDFT, DDFT, ICL and SL with normal flat shoes were 2.4, 1.3, 5.4 and 3.7%, respectively. If an egg‐bar was applied the mean peak strain in the DDFT was 0.13% lower and strain in the SL was 0.22% higher. With a heel‐wedge, strain decreased in the DDFT and ICL (0.19% and 0.4%, respectively) and increased by 0.24% in the SL. A toe‐wedge increased strain in the ICL by 0.8%. All changes mentioned were statistically significant (P<0.1).

The changes in tendon strain as a result of different types of shoeing correlated with changes in calculated torque's of the ground reaction force acting on the coffin joint.
Surgical treatment for colic in the foal (67 cases): 1980–1992
Authors: VATISTAS N. J. , SNYDER J. R. , WILSON W. D. , DRAKE CHRISTIANA , HILDEBRAND SUSAN
Published: April 2010

Sixty‐seven foals age <150 days underwent a ventral celiotomy for colic. Of the 67 foals, 51 foals (82%) recovered from anaesthesia and 42 (63%) were subsequently released from the hospital. Three (6%) of the 51 foals were subjected to a repeat celiotomy. Long term follow‐up was available on 36 foals. Twenty‐nine (57%) of the 51 foals recovered from anaesthesia, were alive at least 2 years following surgery. Adhesions were identified in 8 (17%) of the foals which recovered from general anaesthesia but were subsequently subjected to euthanasia due to recurrent colic. Strangulating lesions were associated with a lower survival rate. Nineteen per cent of foals with strangulating intestinal lesions survived >2 years following surgery, compared to 69% of foals with nonstrangulating lesions. The age of foals on admission had a significant effect on survival. Only 10% of foals less than 14 days of age survived, compared to 45.8% of foals between age 15 and 150 days.
Clinical and pathological studies in horses with hepatic disease
Authors: West Hilary J.
Published: April 2010

In horses with hepatic necrosis, lipidosis, neoplasia and cirrhosis, progression of the disease was studied by serial measurements of total serum bile acid concentrations and of plasma glutamate dehydrogenase (GD) and γ glutamyl transferase (γGT) and by liver biopsy. Plasma ammonia concentrations were significantly elevated compared to clinically normal horses, but such changes were not always accompanied by a decline in plasma urea concentration. A fall in plasma glucose concentration carried a guarded prognosis. These were all invaluable aids in early diagnosis and throughout the disease course. The study suggests that other factors, such as hypokalaemia, alkalosis, short chain volatile fatty acids, false and true neurotransmitters, may be important in the pathogenesis of hepatic coma in the horse.
Linear assessment of the Thoroughbred horse: an approach to conformation evaluation
Authors: MAWDSLEY A. , KELLY E. P. , SMITH F. H. , BROPHY P. O.
Published: April 2010

A linear assessment trait evaluation system is proposed to allow quantitative description of the static conformation of the horse. Measurements were made on 27 selected traits. The system was tested initially for repeatability of measurements on 4 horses. Twenty‐one of the selected traits were satisfactory and 6 proved unsatisfactory in terms of reproducibility. A population of 101, superior 2‐ and 3‐year‐old Thoroughbreds and 19 premium Thoroughbred stallions were similarly assessed. More than 65% of the traits exhibited large (CV>10%) phenotypic variation within the sampled population. It is proposed that such a system of static conformation assessment, in conjunction with a similar system for dynamic linear assessment, would provide useful quantitative selection criteria in the description and breeding of horses.
Variation of an epitope of keratan sulphate and total glycosaminoglycans in normal equine joints
Authors: FULLER C. J. , BARR A. R. S. , DIEPPE P. A. , SHARIF M.
Published: April 2010

An epitope of keratan sulphate (KS) and total glycosaminoglycans (GAG) were measured in synovial fluid samples from joints of 53 horses immediately following humane destruction. Internal examination of the jointspost mortemensured that there was no gross evidence of osteoarthritis or other joint disease. Joints sampled were distal interphalangeal (DIP), proximal interphalangeal (PIP), metacarpophalangeal (MCP), metatarsophalangeal (MTP), tarsometatarsal (TMT), tarsocrural (TC), femoropatellar (FP) and antebrachiocarpal (ABC) joints. The age of each horse was assessed by examination of the teeth. Samples were analysed for the KS epitope using a monoclonal antibody 5D4 and an inhibition ELISA and for total GAG level by a direct dye binding technique.

There was no significant correlation between KS or GAG concentration and age. However, there were significant differences in the concentrations of KS and GAG in different joints. The median level (+ semi interquartile range) of KS:GAG ratio in the MCP was significantly lower than the PIP (0.25 [0.05] vs. 0.35 [0.08]; P<0.007) and also the DIP joints (0.25 [0.05] vs. 0.47 [0.09] P<0.001). This study provides information which is both valuable in the investigation of normal joint metabolism and essential in the interpretation of synovial fluid KS and GAG values in their potential role as aids in the evaluation of joint disease.
Radiological appearance of air introduced during equine regional limb anaesthesia
Authors: KIRBERGER R. M. , GOTTSCHALK R. D. , GUTHRIE A. J.
Published: April 2010

Twelve horses were injected intra‐articularly into the metacarpophalangeal joint and extra‐articularly in the region of the lateral palmar digital nerve with 1 ml air and local anaesthetic to simulate gas accidentally introduced during regional anaesthesia. Half the horses underwent limited exercise after which all horses were radiographed at 15 and 45 min and then every 24 h until all evidence of gas had disappeared. Intra‐articular gas appeared as gas capped radiolucencies (GCR) in the proximal aspect of the joint. Extra‐articular gas appeared as linear radiolucencies (LR) which initially tended to migrate proximally. There was no significant difference in gas resorption in exercised and nonexercised horses. All gas was resorbed within 96 h with most of the gas already gone at 48 h.
Use of a hand‐held, metered‐dose aerosol delivery device to administer pirbuterol acetate to horses with ‘heaves’
Authors: DERKSEN F. J. , OLSZEWSKI M. , ROBINSON N. E. , BERNEY C. , LLOYD J. W. , HAKALA J. , MATSON C. , RUTH D.
Published: April 2010

Aerosol administration of bronchodilators to horses is recommended for treatment of certain airway diseases such as ‘heaves’. We have developed a novel, hand‐held, metered‐dose inhaler and we sought to determine the bronchodilator efficacy of the (β2adrenoceptor agonist pirbuterol delivered by this device to horses affected with ‘heaves’. To induce airway obstruction, 6 heaves‐susceptible horses were stabled, bedded on straw and fed hay. When the maximum change in pleural pressure during tidal breathing (ΔPplmax) was greater than 20 cmH2O on 2 consecutive days, pulmonary function was measured before and 5, 10 and 30 min, as well as 1, 2, 3, 4, 5, 6 and 7 h after administration of aerosol pirbuterol. Pirbuterol was administered using a metered canister and the hand‐held delivery device that was inserted into the left nostril. Either vehicle or pirbuterol acetate (400, 600, 800, 1200 or 1600 μg) was administered to each horse. Relief of airway obstruction indicated by changes in pulmonary function was observed within 5 min after administration of both vehicle and pirbuterol. Significant decreases in ΔPplmaxand pulmonary resistance (RL) and an increase in dynamic compliance (Cdyn) persisted for the 7 h duration of the experiment. Comparison of the effect of vehicle and pirbuterol at each time period showed that pirbuterol decreased K, and ΔPplmaxsignificantly for up to 1 h. The optimal dose was determined to be 600 μg. Immediate response to treatment, magnitude of drug effect and lack of side effects indicated that aerosol pirbuterol is an effective and safe bronchodilator in horses with 'heaves'. The hand‐held, metered‐dose aerosol delivery device was very convenient and extremely effective and is, therefore, recommended for delivery of therapeutic aerosols to horses.
Daily fluctuations of haematology and blood biochemistry in horses fed varying levels of protein
Authors: GREPPI G. F. , CASINI LUCIA , GATTA D. , ORLANDI M. , PASQUINI MARINA
Published: April 2010

Changes in the plasma biochemistry of 12 stallions were studied over seven 24 h periods. Twelve healthy male horses of 4 different breeds (Thoroughbred [TB], Anglo‐Arabo‐Sardo [AAS], Avelignese [Av] and Maremmano [M]) were divided into 3 experimental groups and fed with an isoenergetic maintenance ration with different protein levels. The same amount of food was given daily at 0730 and 1930 h. After 20 days of pretrial, a series of 6 blood samples were collected daily from the jugular vein every 4 h for 7 days. The samples were analysed for packed cell volume (PCV), haemoglobin, plasma glucose, free fatty acids, cholesterol, total plasma protein, urea, creatinine, calcium, phosphorus and enzymatic activities: aspartate aminotransferase (AST), alanine aminotrasferase (ALT), creatine kinase (CK) and lactate dehydrogenase (LDH). The data were analysed following the armonic analysis (Fourier) in order to define the pattern of biorhythm. Many parameters showed a biorhythmical pattern. Protein levels of the diet failed to influence haematology, blood biochemistry and biorhythm. Thoroughbreds showed the highest values of PCV, haemoglobin and creatinine and the lowest total protein, phosphorus and enzymatic activities.
Anatomy of the ocular arteries in the horse
Authors: SIMOENS P. , MUYLLE S. , LAUWERS H.
Published: April 2010

Orbital and intrabulbar arteries were studied in 20 equine eyes by means of latex injections and methylmethacrylate casts. The orbital branches of the external ophthalmic artery arise far caudal to the posterior pole of the eyeball and present a variable topographic arrangement. The intrabulbar arteries are supplied by ciliary and choroidoretinal arteries. Dependent on their entrance into the eyeball, the ciliary arteries are subdivided into a posterior and an anterior group. The posterior ciliary arteries perforate the sclera post equatorially and consist of 4 major vessels that penetrate in the lateral, medial, dorsal and ventral meridian of the eyeball, respectively. The lateral and medial of these arteries follow a long intrabulbar trajectory after having supplied several short posterior ciliary arteries to the choroid. The anterior ciliary arteries consist of a dorsal and a ventral vessel which penetrate the eyeball in the pericorneal area. The choroidoretinal arteries form an arterial network around the optic nerve at the posterior pole of the eyeball. They give rise to all retinal arterioles and some peridiscal choroidal branches. The larger part of the choroid is supplied by branches of the posterior ciliary arteries. Additionally, the anterior choroid receives recurrent branches from an arterial circle that lies externally in the ciliary ring. The iris contains a major arterial circle formed by the lateral and medial long posterior ciliary arteries and both anterior ciliary arteries. A minor iridic arterial circle nor central retinal artery could be found in the equine eyes examined.
Factors associated with gastric lesions in Thoroughbred racehorses
Authors: MURRAY M. J. , SCHUSSER G. R. , PIPERS F. S. , GROSS SHEILA J.
Published: April 2010

Gastroscopic examinations were performed on 67 Thoroughbred horses in training at a race track and repeat examinations performed in 35 horses, 2 to 3 months later. Horses were age 2–9 years and included 16 two‐year‐olds, 32 three‐year‐olds and 19 horses ≥ 4‐years‐old. Forty‐two of the 67 horses had raced within the 2 months before the initial examination and the remaining 25 horses were in training. Sixty‐two of the 67 horses (93%) had one or more lesions present in the gastric mucosa and lesions were present in all of the 42 horses that had raced. Thirty‐two of the 35 horses, examined twice (91%), had gastric lesions on the first examination and all had lesions on the second examination. Four sites of the gastric squamous epithelium were graded for lesion severity on a scale of 0 to 10 and the mean maximum squamous mucosal lesion score was significantly (P<0.01) greater for the second examination (4.89) than for the first examination (3.63). Maximum lesion scores were greater in 24 horses, no different in 5 horses and less in 6 horses on the second examination. The difference in mean maximum lesion scores between examinations was greatest in horses age 2 years, increasing from 1.75 to 4.00 (P = 0.014). Lesions in the gastric glandular mucosa also were scored on a scale of 0 to 10 and there was no difference in mean lesion scores in the glandular mucosa between the first and second examinations (1.89 vs. 1.90).

Lesion scores were compared for gender, racing history and medication with nonsteroidal anti‐inflammatory drugs, systemic corticosteroid or ACTH, or frusemide within the previous 2 months. Except for racing history, there were no significant differences in mean lesion scores for squamous or glandular mucosa based on these comparisons, indicating that there was no effect of gender or medication history on ulcer severity in the horses of our study. Mean maximum gastric squamous mucosal lesion score was significantly (P<0.01) greater in horses that had raced (4.51) than for horses that had not raced (2.36) in the 2 months before the endoscopic examination. There was no difference in mean glandular mucosal lesion scores between horses that had raced (1.93) compared to horses that had not raced (1.13).
Accuracy of Accusport for measurement of lactate concentrations in equine blood and plasma
Authors: EVANS D. L. , GOLLAND LORRAINE C.
Published: April 2010

The aim of this study was to investigate correlations between lactate concentrations in equine whole blood and plasma measured with Accusport1 and Yellow Springs Instruments (YSI2) (2300) methods. The effect of packed cell volume (PCV) on the accuracy of Accusport was also investigated. Blood samples were collected from Thoroughbred horses at 5–10 min intervals after a treadmill exercise test. Blood was added to NaEDTA (for PCV measurement) and to 2 tubes containing lithium heparin anticoagulant (for lactate assays). At concentrations greater than 10 mmol/1, Accusport1 greatly underestimated the blood lactate concentration. Accusport1 also underestimated blood lactate concentration when PCV were greater than 53%. Accusport1 accurately measured plasma lactate concentration in the range 0.8–20 mmol/1.
Pharmacokinetics and tolerance of florfenicol in Equidae
Authors: MCKELLAR Q. A. , VARMA K. J.
Published: April 2010

Florfenicol was administered to horses and ponies at a dose rate of 22 mg/kg bwt by i.v., i.m. and oral routes. Following i.v. administration it had an elimination half‐life of 1.8 ± 0.9 h, a body clearance of 0.4 ± 0.11/h.kg and a volume of distribution at steady‐state of 0.7 ± 0.2 1/kg. It was highly bioavailable following i.m. (81%) and oral (83%) administration. Less than 15% of the administered dose was excreted unchanged in the urine during the 30 h following administration. Animals treated with florfenicol had elevated bilirubin concentrations. Florfenicol was well tolerated by animals in the present study although all animals had loose faeces following administration by each route. At present, florfenicol cannot be recommended for clinical use until multiple dose studies have been carried out to confirm its safety.