bluuebunny/crossref_metadata_2025 huggingface dataset:
Iron toxicity in neonatal foals
Authors: MULLANEY T. P. , BROWN C. M.
Published: April 2010

Newborn Shetland foals died of acute hepatic failure following oral administration of approximately 16 mg/kg body weight ferrous fumarate. Lesions in these foals were indistinguishable from lesions in foals given an oral digestive inoculant containing ferrous fumarate and were also similar to the syndrome characterised as ‘toxic hepatopathy’ in foals in the United States in 1983. We conclude that foals are susceptible to toxicity from low doses of iron compounds in the first few days of life. Vitamin E and selenium deficiency may contribute to this susceptibility.
Ruptured inguinal hernia in new‐born colt foals: A review of 14 cases
Authors: van der VELDEN M. A.
Published: April 2010

Over a six year period, 14 new‐born colt foals were treated surgically because of ruptured inguinal hernia. In all cases, the prolapsed intestines, which were jejunal loops, were situated subcutaneously and protruded through a rent in the parietal vaginal tunic at the level of the inguinal canal. After herniorrhaphy and unilateral castration, the prolapsed loops were replaced into the abdomen, and the superficial inguinal ring closed. Seven foals survived.
Effects of xylazine and acepromazine on bronchomotor tone of anaesthetised ponies
Authors: WATNEY G. C. G. , HALL L. W. , JORDAN C. , NOLAN ANDREA M.
Published: April 2010

The effects of xylazine (an α2‐adrenoceptor agonist) and acepromazine (an α‐adrenoceptor antagonist) on bronchomotor tone were investigated in seven anaesthetised, apnoeic ponies using a computer aided forced oscillation technique, which separates changes in bronchial calibre from changes in lung volume. Both agents produced bronchodilatation and a decrease in lung volume.
External balance of water and electrolytes in the horse
Authors: GROENENDYK S. , ENGLISH P. B. , ABETZ INGRID
Published: April 2010

The components of the daily external water and electrolyte balances of five normal Standardbred geldings with a mean body weight of 427 kg, were determined over 14 day periods. The mean value of daily total water intake (a summation of free, combined and metabolic water intake) for the group was 27.6 litres, that is, 64.4 ml/kg body weight, while mean values for ambient temperature and humidity ranged from 16 to 25°c and 55.4 to 75.5 per cent, respectively. the mean daily urine volume of 9.9 litres (23.2 ml/kg) for the group, was found to exceed the mean faecal water output of 7.2 litres (16.9 ml/kg). the mean output of sodium for the five animals, in urine and faeces, was 780 mmol or 79 per cent of the intake. the mean output of potassium, chloride, calcium and magnesium were 3163, 2521, 1824 and 1448 mmol or 95, 84, 74 and 75 per cent, respectively of intake. the sodium and potassium not accounted for in urine and faeces may well have been lost in sweat. results are discussed and compared with those of a previous external balance study in the horse.
Detection of neurectomy by testing skin sensitivity using an electrical stimulus
Authors: MOORMAN G. H. , VAN NOORT J. H. C. , NÉMETH F. , BREUKINK H. J. , GOOTJES P. , VERZIJLENBERG F.
Published: April 2010

A method for detection of neurectomy by electrical stimulation of the skin, distal to the neurectomy site, was tested for accuracy and feasibility. An electrical stimulation device was designed and tested to find the minimum peak voltage that would elicit a response in normal horses. Twenty seven horses were then tested at regular intervals following neurectomy and their responses recorded. Immediately following neurectomy there was an area of insensitivity with sharply defined borders extending in an arc from the back of the pastern down towards the bulbs of the heels. In the months following neurectomy, re‐innervation occurred and this area gradually reduced in size, although it was still possible to detect insensitive areas 14 months after neurectomy in all horses tested. The method proved to be safe, accurate and ethically acceptable.
Detomidine (Domosedan) in foals: sedative and analgesic effects
Authors: OIJALA MARI , KATILA TERTTU
Published: April 2010

Detomidine was administered twice to six foals (14 to 94 days old) using three different doses (10, 20 and 40 μg/kg bodyweight intravenously) in a double blind trial. Sedation, analgesia, heart rate and clinically observed side‐effects were recorded. Detomidine showed strong sedative effects at all doses tested. Sedation deepened very little by increasing the dose from 10 to 40 μg/kg bodyweight, but the duration of the effect was longer. Analgesia was considered good with the largest dose (40 μg/kg), and moderate or non‐existent with the lower doses. Detomidine caused a decrease in heart rate at all doses and other observed side‐effects included ataxia, heavy breathing, arrhythmia, sweating and frequent urination. No adverse effects were observed.
Combined use of detomidine with opiates in the horse
Authors: CLARKE KATHLEEN W. , PATON BARBARA S.
Published: April 2010

The effects of administration of one of four opiates (pethidine 1 mg/kg bodyweight (bwt), morpine 0.1 mg/kg bwt, methadone 0.1 mg/kg bwt, and butorphanol 0.05 mg/kg bwt) given intravenously to horses and ponies already sedated with detomidine (10 μg kg bwt) were investigated. Behavioural, cardiovascular and respiratory effects of the combinations were compared with those occurring with detomidine alone. Addition of the opiate increased the apparent sedation and decreased the response of the animal to external stimuli. At doses used, butorphanol produced the most reliable response. Side effects seen were increased ataxia (greatest following methadone and butorphanol) and excitement (usually muzzle tremors and muscle twitching). Following pethidine, generalised excitement was sometimes seen. Marked cardiovascular changes occurred in the first few minutes after morphine or pethidine injection, but within 5 mins cardiovascular changes were minimal. Following morphine or pethidine there was a significant increase in arterial carbon dioxide tension. Fourteen clinical cases were successfully sedated using detomidine/butorphanol combinations.
The gait of pacers 1: kinematics of the racing stride
Authors: WILSON B. D. , NEAL R. J. , HOWARD A. , GROENENDYK S.
Published: April 2010

Standardbred pacers have been studied under race conditions to describe the gait of the pacer, and to determine relationships between stage of the race, finish order and selected gait kinematics. Overlap increased with the stage of the race while pacing speed decreased marginally for low order pacers and increased for high order finishers. High order finishing pacers appear to have greater stance and stride lengths than do low order finishers. Pacers could be separated into low order and high order groups on the basis of their movement patterns. High order pacers exhibited greater ranges of limb motion than did low order finishers.
The gait of pacers 2: factors influencing pacing speed
Authors: WILSON B. D. , NEAL R. J. , HOWARD A. , GROENENDYK S.
Published: April 2010

Standardbred pacers were studied at four different nominated speeds and selected gait kinematics were analysed to determine factors which contribute to pacing speed. A deterministic model is proposed in which pacing speed is a function of stride length and stride timing variables. Stance length and suspension time remained relatively constant over the different pacing speeds. Variables which discriminated best between pacing speeds were suspension length and overlap time. At near maximal speed, the pacers increased speeds with increased stride length. This was attributed to an increased suspension length with little difference in suspension times. A 22 per cent increase in pacing speed resulted in a 13 per cent increase in stride length, 26 per cent increase in suspension distance, 8 per cent increase in stride frequency, 35 per cent and 16 per cent increases in advanced placement and completion times and a 23 per cent decrease in the period of overlap.
Atypical myoglobinuria: An acute myopathy in grazing horses
Authors: WHITWELL KATHERINE E. , HARRIS PATRICIA , FARRINGTON P. G.
Published: April 2010

Four out of 12 horses grazing a field in Berkshire, England, suffered a prostrating illness and died within 12 to 72h. Serum biochemical abnormalities, including markedly elevated muscle enzymes, were demonstrated and at post mortem widespread myodegeneration was found in both skeletal muscle and myocardium. Urine analysis revealed myoglobinuria, and renal changes were seen histologically. Although similar pathologically, the clinical syndrome and circumstances of the outbreak were not typical of equine exertional rhabdomyolysis (EER). The outbreak bore a striking resemblance to other reported sporadic outbreaks of an atypical myoglobinuria occurring in grazing horses. A number of potential aetiological and contributory factors (including herbicide toxicity) were considered, but the aetiology remains unresolved.
Continuous absorbable suture pattern in the closure of ventral midline abdominal incisions in horses
Authors: TURNER A.S. , YOVICH J.V. , WHITE N.A. , EMBERTSON R.E. , SANTSCHI E.M. , SLONE D.E.
Published: April 2010

A retrospective study was performed to evaluate the healing of ventral midline abdominal incisions, closed with a simple continuous suture pattern using absorbable suture material, in 139 horses and foals. Dehiscence and incisional hernia developed separately in two horses. The low incidence of dehiscence and incisional hernia, compared with their reported incidence following the use of interrupted suture repair, leads the authors to recommend this alternative method of abdominal incision closure in horses. The security of closure is not sacrificed and the advantages of a rapid closure are desirable.
Opsonins in uterine washings influencingin vitroactivity of equine neutrophils
Authors: WATSON ELAINE D.
Published: April 2010

Uterine washings were found to promote neutrophil mediated killing ofStreptococcus zooepidemicus.Depletion of complement and/or specific antibody from the washings significantly reduced bactericidal activity. Phagocytosis of yeast by uterine washings was complement dependent. Inhibition of the classical pathway significantly reduced opsonic activity indicating that, in addition to direct activation via the alternate pathway, antibody may also be involved in yeast phagocytosis.
Sequelae of myelography in the horse
Authors: HUBBELL J. A. E. , REED S. M. , MYER C. W. , MUIR W. W.
Published: April 2010

The records of 131 horses undergoing general anaesthesia and positive contrast cervical myelography with metrizamide were examined to determine the effect of the procedure on the ‘patient’. Three per cent of minimally ataxic and moderately ataxic horses had serious complications after myelography. Thirty‐two per cent of severely ataxic horses died or were destroyed after general anaesthesia and myelography. Although general anaesthesia and myelography are essential components of a complete neurological evaluation of a horse, they impose a significant risk.
The relationship of frog pressure to heel expansion
Authors: COLLES C. M.
Published: April 2010

A study was carried out on five horses and four ponies to assess the effect of altering frog pressure on hoof expansion. Measurements of hoof expansion were made using strain gauges. It was concluded that whereas frog pressure affects hoof expansion, it is only one of several factors. Increasing frog pressure may result in increased expansion, or contraction, or may have virtually no affect. The variable results of changing frog pressure should be taken into account when considering therapeutic shoeing.
Left ventricular function and haemodynamics in ponies during exercise and recovery
Authors: RUGH K. S. , GARNER H. E. , MIRAMONTI J. R. , HATFIELD D. G.
Published: April 2010

Myocardial and haemodynamic responses to strenuous treadmill exercise were monitored with chronically implanted instrumentation in seven physically untrained ponies. In two other ponies, haemodynamics were monitored using a conventional catheter technique. During exercise (mean ± sem heart rate = 203 ± 3 beats/min), left ventricular peak systolic and end‐diastolic blood pressure significantly increased from 125 ± 2 to 208 ± 6 mmHg and from 29 ± 1 to 58 ± 3 mmHg, respectively (P<0.05). Peak positive first derivative of left ventricular pressure (dP/dt) was also increased significantly, (1397 ± 144 to 6016 ± 325 mmHg/sec), as were myocardial segment velocity of shortening during systole (dL/dtsys) and stroke work (193 and 109 per cent, respectively). Paradoxically, segment systolic shortening was reduced significantly (P<0.05) with respect to resting control values for 10 mins after cessation of exercise, with the maximal reduction of 22 per cent occurring at 2 mins post exercise. In addition, left ventricular segment stroke work decreased significantly to 67 per cent of resting control value at 2 mins post exercise. This study demonstrates that analysis of regional myocardial performance in conjunction with haemodynamic data permits a detailed description of cardiac events during and immediately following exercise, facilitating definition of changes which are not readily reflected by haemodynamics. Based on these findings, the authors conclude that untrained ponies may readily complete short bouts of near‐maximal exercise, yet experience significantly diminished left ventricular function in the immediate post exercise period.
Effect of freeze‐drying on measurements of pH in biopsy samples of the middle gluteal muscle of the horse: Comparison of muscle pH to the pyruvate and lactate content
Authors: HARRIS R. C. , SNOW D. H. , KATZ A. , SAHLIN K.
Published: April 2010

Muscle biopsies taken after exercise, in comparison to those at rest, contain increased amounts of blood and this is a particular problem in studies of the horse. The inclusion of blood in muscle will introduce an upward bias in values of pH measured in muscle homogenates. In an attempt to control this, muscle biopsy samples of the middle gluteal from Thoroughbred horses were freeze‐dried and dissected free of blood before determination of pH. Following exercise, muscle pH measured after freeze‐drying was similar to that measured in homogenates prepared from frozen samples. In contrast, freeze‐drying appeared to increase muscle pH in samples taken at rest. This was probably the result of loss of Co2 during freeze‐drying. Muscle pH determined in freeze‐dried samples taken at rest and after exercise was linearly related to pyruvate and lactate content (P<0.001). It is concluded that muscle samples taken after exercise can be freeze‐dried and dissected free from blood before determination of pH, whereas this procedure will cause an alkaline shift in samples taken at rest.
A rapid, non‐invasive method for measuring total respiratory impedance in the horse
Authors: YOUNG S. S. , HALL L. W.
Published: April 2010

Total respiratory impedance was measured rapidly and non‐invasively in conscious horses over the frequency range 3 to 40 Hz by the forced random noise method. The shape of curve of impedance versus frequency in horses was markedly different from that of humans. Respiratory resistance was readily found as the real part of impedence and both its absolute value and frequency dependence are useful indices of pulmonary function. It was difficult to obtain meaningful results in intubated animals with the method because of the mechanical properties of the endotracheal tube itself.
Muscle glycogen depletion patterns during draught work in Standardbred horses
Authors: GOTTLIEB MARIANNE
Published: April 2010

Muscle fibre recruitment was investigated during draught loaded exercise by studying glycogen depletion patterns from histochemical stains of muscle biopsies from the gluteus and semitendinosus muscles. Three Standardbred trotters performed several intervals of draught loaded exercise on a treadmill with 34 kp at a trot (7 m/sec) and with 34 and 80 kp, respectively at a walk (2m/sec). Exercise was continued until the horses were unwilling to continue. Glycogen depletion was seen in all three fibre types when trotting with 34 kp for 5 or 10 mins. When an equal weight resistance was pulled at a walk, glycogen depletion was first seen in type I fibres only, then followed by a small percentage of type IIA fibres after at least 1 h. When 80 kp was pulled at a walk both type I and IIA fibres showed glycogen depletion, and after at least 30 mins exercise a small percentage of type IIB fibres was also depleted. These results indicate that the muscle fibres are depleted, in order, from type I through IIA to IIB as the intensity or duration of draught work increases.
Predictive utility of pre‐partum temperature changes in the mare
Authors: HALUSKA G. J. , WILKINS KAREN
Published: April 2010

Rectal temperature was recorded from 22 mares at 0700, 1500 and 2300 h daily for seven days pre‐partum and one day post partum. A circadian variation in rectal temperature was present with the lowest temperature recorded at 0700 h. Because of this, the mares were divided into three groups based on time of parturition; those foaling between 0700 and 1500 h (n=2); between 1500 and 2300 h (n=13); and between 2300 and 0700 h (n=7). On the day prior to delivery (Day −1) the circadian pattern was absent because the nocturnal increase did not occur. A significant decrease in temperature was recorded prior to parturition in the group foaling between 1500 and 2300 h. A distinct decrease in temperature occurred in the majority of mares in the other two groups but this was not statistically significant. After parturition, rectal temperature increased to supranormal levels before returning to normal.
Plasma plasminogen concentrations in clinically normal horses: the effect of age, sex and pregnancy
Authors: MORRIS DEBRA DEEM , WARD M. V. , WHITLOCK R. H.
Published: April 2010

Plasma concentrations of plasminogen were determined in 28 clinically normal horses, including 13 adult geldings, five nonpregnant mares, five pregnant mares and five yearlings (two fillies, three geldings). Plasminogen was quantitated by a chromogenic assay based on activation of plasmin by excess urokinase. The overall mean plasma plasminogen for these horses was 2.94 ± 0.54 CTA units (casein units, as defined by the Committee on Thrombolytic Agents) per ml. There were no significant differences in mean plasma plasminogen values among adult geldings, non‐pregnant mares, pregnant mares or yearling horses (P>0.05).
Rectal tears in the horse: an analysis of 35 cases
Authors: WATKINS J. P. , TAYLOR T. S. , SCHUMACHER J. , TAYLOR J. R. , GILLIS J. P.
Published: April 2010

The records of 35 horses with Grade 3 or 4 rectal tears, presented to the Veterinary Medical Center at Texas A&M University over a five year period, were reviewed. Grade 3 tears were sub‐classified according to whether the remaining tissue was serosa (Grade 3a) or mesorectum (Grade 3b). Five horses were destroyed on presentation and 30 were treated by primary suture closure (8 horses), faecal diversion alone (9 horses) or in combination with suture closure (11 horses) and packing of the tear with medicated gauze sponges (two horses). Faecal diversion was achieved with a temporary indwelling rectal liner (TIRL) in 19 horses and colostomy in one. Survival was related to classification of the tear, efficacy of first aid measures administered at time of injury and method of treatment. Seventy‐four per cent of horses with Grade 3a tears and 44 per cent of those with Grade 3b tears survived. Grade 4 tears had a grave prognosis. Horses given adequate first aid before admission had a better survival rate. With proper patient selection, primary closure of the tear with sutures yielded excellent results. In horses which were not candidates for suture closure alone, a combination of faecal diversion and suturing gave better results than faecal diversion only. In addition, selected horses were treated successfully by packing the rectal tear with gauze sponges. The results demonstrate the value of a TIRL to divert faeces and appropriate first aid measures in treating rectal tears.
Kinematics of the cervical spine of the adult horse
Authors: CLAYTON HILARY M. , TOWNSEND H. G. G.
Published: April 2010

At least three types of movement, dorsoventral flexion and extension, axial rotation and lateral bending, were shown to occur at each of the intervertebral joints in the cervical spine. Between the first two cervical vertebrae the mean axial rotation was 107.5°, which was 73 per cent of the total axial rotation of the cervical spine. The atlantooccipital joint rotated through a mean of 27°, whereas the remaining cervical joints each had less than 3° of rotatory movement. Dorsoventral flexion and extension were maximal at the atlantooccipital joint, which had an amplitude of 86.4° and accounted for 32 per cent of the total dorsoventral movement of the cervical spine. Lateral bending was relatively more uniform along the length of the neck, with mean values ranging from 25 to 45° for each joint except that between the first two cervical vertebrae, which had a mean of only 3.9° of lateral bending.
The nephrotoxic potential of neomycin in the horse
Authors: EDWARDS DEBORAH J. , LOVE DARIA N. , RAUS J. , BAGGOTT J. D.
Published: April 2010

Neomycin was administered intramuscularly to four normal adult horses at a dose rate of 10 mg/kg bodyweight every 12 h for 10 days (21 doses). The pharmacokinetic behaviour of neomycin with multiple dosing was characterised and a range of blood chemical and urinary parameters examined for evidence of nephrotoxicity. There was evidence of physical renal tubular injury (enzymuria and cylindriuria) within four days of neomycin administration but this subsided following cessation of treatment. No significant functional nephrotoxicity was detected. More severe nephrotoxicity might be expected in ill horses and it is recommended that several clinicopathological results be monitored serially in those horses receiving parenteral neomycin.
Fever of unknown origin in the horse: a review of 63 cases
Authors: MAIR T. S. , TAYLOR F. G. R. , PINSENT P. J. N.
Published: April 2010

Fever of unknown origin (FLO) is a syndrome characterised by prolonged, unexplained fever associated with non‐specific signs of illness such as lethargy, inappetence and weight loss. This paper reviews the details of 63 horses affected by FUO. The cause was found to be infection in 43 per cent of the cases, neoplasia in 22 per cent, immune‐mediated diseases in 6.5 per cent and miscellaneous diseases in 19 per cent the cause remained undiagnosed in 9.5 per cent.
Arterial‐alveolar carbon dioxide tension difference and alveolar dead space in halothane anaesthetised horses
Authors: MOENS Y.
Published: April 2010

Arterial‐alveolar carbon dioxide tension differences (a‐A)PCO2and alveolar dead space were measured during clinical halothane anaesthesia of 110 horses with the help of continuous infra‐red carbon dioxide analysis of expiratory gas. Mean (a‐A)PCO2was 1.6 ± 0.8 kPa. Alveolar dead space expressed as a percentage of alveolar tidal volume had a mean value of 23 ± 13 per cent. Influence on (a‐A)PCO2and alveolar dead space of the following variables was tested statistically: age, weight, body position, respiration mode and duration of anaesthesia. (a‐A)PCO2was influenced positively by weight (P<0.0001) and adoption of dorsal recumbency (P<0.01). Alveolar dead space was influenced positively by weight (P<0.0005), adoption of dorsal recumbency (P<0.01), intermittent positive pressure ventilation (P<0.0001) and duration of anaesthesia (P<0.05).
Postprandial serum gastrin concentrations in normal foals
Authors: SMYTH G. B. , YOUNG DIANE W. , SCHUMACHER J.
Published: April 2010

Postprandial gastrin concentrations were assayed in serum samples from a group of six foals at one day, one week, one month and three months of age. Before sampling, each foal was prevented from feeding for 2 h and was then allowed to suck for 15 mins. Blood samples were taken at the start of the meal and at 30 min intervals for the next 3 h. Feeding increased serum gastrin concentrations at one day, one week and one month, with the greatest increases detected at one day. Mean pre‐feeding gastrin concentrations were 25.2 ± 2.3 pg/ml at one day, 22.8 ± 3.9 pg/ml at one week, 15.2 ± 2.3 pg/ml at one month and 15.6 ± 7.5 pg/ml at three months. Highest mean post prandial concentrations were at 60 mins on Day one (47.4 ± 15.2 pg/ml) and at 30 mins for the one week (44.4 ± 14.2 pg/ml) and one month (25.2 ± 4.1 pg/ml) old foals. There was no apparent post prandial increase in serum gastrin concentrations in foals at three months of age. Precise reasons for changes in postprandial serum gastrin concentrations remain unknown. Factors that could be important include maturation of G cell function, alterations in gastrin metabolism and excretion, and changes in gastrointestinal motility with increasing age.
Development of the navicular bone in foetal and young horses, including the arterial supply
Authors: RIJKENHUIZEN ASTRID B. M. , NÉMETH F. , DIK K. J. , GOEDEGEBUURE S. A.
Published: April 2010

A macroscopic, arteriographic and histological study of the development and the arterial anatomy of the navicular bone of 33 foetuses and 55 young horses is described. After 125 days of gestation the blood supply consists of two routes: one situated in the superficial layer of the fibrocartilage and the other similar to the blood supply of the navicular bone of the normal mature horse. After 270 days gestation, the blood vessels in the fibrocartilage gradually regressed and retracted until they have disappeared at six months after birth. At two months after birth the first macroscopic thinning of the fibrocartilage was noticed. From seven months to one year about 45 per cent of the navicular bones showed a slight thinning of the fibrocartilage. A positive correlation was found between radiographic abnormalities (ie enlargement of the nutrient foramina) and the frequency of thinning of the fibrocartilage. Radiographic abnormalities were first recognised 14 days after birth, whereas the arteriogram showed the first changes such as fewer or no arteries entering distally at the distal extremities at 10 weeks after birth. At four weeks after birth the first arterial wall changes were found, ie intimai thickening with or without splitting of the internal elastic membrane. From that age onward, the number of navicular bones with arterial wall changes gradually increased. Starting at five months after birth only 6 to 20 per cent of the arteries in the navicular bones without radiographic abnormalities showed arterial wall changes. However, the navicular bones with radiographic abnormalities showed arterial wall changes in 25 to 80 per cent of the arteries.
Immunohistochemical investigation of the distribution of immunoglobulins G, A and M within the anterior uvea of the normal equine eye
Authors: MATTHEWS A. G.
Published: April 2010

Distribution of the immunoglobulin (Ig) classes G, A and M within the anterior uvea of eight clinically normal equine eyes was examined using indirect immunoperoxidase labelling. Increased staining intensity of stromal IgG and IgA was observed within the ciliary processes, the iris stroma being relatively free of immunoglobulin. This may reflect anatomical variation in the permeability of the uveal microvasculature to lipid insoluble plasma macro‐molecules. Intracellular IgG and IgA were observed within the non‐pigmented ciliary epithelium in seven and four of the eight eyes respectively, although wide variation between numbers of Ig bearing cells in each eye was noted. It was suggested that these cells may have a role in the removal of Ig from the posterior chamber aqueous. Plasma cells, of IgG isotype, were observed in only one eye, suggesting that intraocular production of Ig is not a feature of the normal equine eye.
The evaluation of isoxsuprine hydrochloride for the treatment of navicular disease: a double blind study
Authors: TURNER A. SIMON , TUCKER C. M.
Published: April 2010

A randomised double‐blind clinical trial of 28 horses was undertaken to evaluate the efficacy of isoxsuprine hydrochloride at four different doses:‐ 0.0 mg/kg bodyweight (bwt) (placebo), 0.6 mg/kg bwt, 1.2 mg/kg bwt and 1.8 mg/kg bwt for treatment of navicular disease. The results showed that horses treated with isoxsuprine hydrochloride (N=22) responded significantly with respect to clinical assessment score (P<0.01) when compared with the control group (N=6). Furthermore, there were no dose‐related differences in the responses of the horses treated with increasing levels of isoxsuprine. No correlation was found between radiological evidence of the extent of navicular disease and severity of lameness or response to treatment.
Iohexol myelography in the horse
Authors: BURBIDGE HILARY M. , KANNEGIETER N. , DICKSON LINDA R. , GOULDEN B. E. , BADCOE L.
Published: April 2010

Iohexol, a water soluble non‐ionic contrast agent, was evaluated for myelography in the horse. Both 300 and 350 mg iodine/ml iohexol gave diagnostic cervical myelograms. Pathological changes were limited to extradural oedema and an increase in the number of white blood cells and specific gravity in the cerebrospinal fluid two days after myelography. This increase in white blood cells in the cerebrospinal fluid was, however, much less than that recorded by other authors using metrizamide and iopamidol contrast media. These findings indicate that iohexol is a less irritant myelographic contrast agent than those previously evaluated in the horse.
Equine mastitis ‐ a review of 28 cases
Authors: McCUE P. M. , WILSON W. D.
Published: April 2010

Mastitis was diagnosed in 28 mares. Cytological evaluation of milk samples showed large numbers of neutrophils in 72 per cent and bacteria in 33 per cent. Aerobic bacteria were cultured from 71 per cent of samples.Streptococcus zooepidemicuswas the most common isolate (37 per cent). Gram‐negative species accounted for 42 per cent. Determination of the probability for antimicrobial susceptibility of bacterial isolates from mares with mastitis indicated that a trimethoprim‐sulphonamide combination would be active against more than 75 per cent of isolates while penicillin would be active against less than 60 per cent. Systemic antibiotics, frequent milking, hotpacks and/or hydrotherapy and, if possible, infusion of an intramammary antibiotic preparation is recommended for treatment of equine mastitis.
Injuries to the cranial cruciate ligament and associated structures: summary of clinical, radiographic, arthroscopic and pathological findings from 10 horses
Authors: PRADES MARTA , GRANT B. D. , TURNER T. A. , NIXON A. J. , BROWN M. P.
Published: April 2010

The clinical, radiographic, arthroscopic and pathological findings of 10 horses with injury to the cranial cruciate ligament are presented. The most consistent clinical signs included moderate to severe distension of the femoropatellar joint and a Grade III to a Grade V out of V lameness. Craniocaudal instability could be elicited in five horses under general anaesthesia and in one conscious horse. Radiographic evaluation of the stifles revealed that avulsion fracture of the medial intercondylar eminence was the most common finding in six out of 10 horses. Arthroscopic examination of the affected femorotibial joints were performed in five horses. This confirmed the presumptive diagnosis of cranial cruciate ligament injury or rupture. Post mortem examinations were performed on two horses which documented partial tears of the cranial cruciate ligament.
Fluorometric evaluation of large and small intestinal ischaemia in the horse
Authors: BRUSIE R. W. , SULLINS K. E. , SILVERMAN D. G. , ROSENBERGER J. L.
Published: April 2010

Arteriovenous (ischaemic strangulating obstruction, ISO) and venous obstructions (haemorrhagic strangulating obstruction, HSO) were created for 70 min in the small intestine of eight anaesthetised horses, and ISO was created in four horses for 2 h and four horses for 3 h at the sternal and diaphragmatic flexures of the large colon. Five minutes following release of the occlusions, sodium fluorescein 20 per cent (0.5 mg/kg bodyweight intravenously) was administered. Serial quantitative measurements of serosal surface fluorescence of the injured segments and a control segment were made at 2, 10, 15, 20 and 30 mins using a fibreoptic perfusion fluorometer. Significant differences in fluorescence were seen in small intestine segments between HSO vs control, ISO vs HSO, but not ISO vs control segments. In the large colon, significant differences were seen between the fluorescence in the ischaemic 3 h ventral colon and control segments, and a trend for difference in fluorescence between the 2 and 3 h ischaemic segments. Differences in fluorescence between 2 vs 3 h dorsal colon segments and 2 or 3 h dorsal colon vs control segments were not significant.
Prevalence of gastric lesions in foals without signs of gastric disease: An endoscopic survey
Authors: MURRAY M. J. , MURRAY CORINNA M. , SWEENEY H. J. , WELD J. , DIGBY N. J. WINGFIELD , STONEHAM SARAH J.
Published: April 2010

Gastroendoscopic examinations were conducted on 75 Thoroughbred foals aged two to 85 days on seven breeding farms in England and Ireland. The foals showed no signs of gastric disease. There was no significant difference between lesion prevalence in foals in England (16 of 28 foals; 57 per cent) or Ireland (22 of 47 foals; 47 per cent). Neither was there any sex predilection (18 of 36 males; 20 of 39 females). Lesions were most prevalent in foals under 10 days old (8 of 9) and least prevalent in foals older than 70 days (3 of 10). Lesions occurred most frequently in the squamous mucosa immediately adjacent to the margo plicatus along the greater curvature (34 foals), whereas lesions in the squamous fundus, the glandular fundus, and the lesser curvature were observed in 11, six and three foals, respectively. Lesions were not observed in the squamous mucosa surrounding the cardia. Gastric lesions were more prevalent in foals with a previous disorder than in those without (68 vs 43 per cent) and particularly with a history of recent or concurrent diarrhoea (9 of 14).
Haemodynamic, pathological, haematological and behavioural changes during endotoxin infusion in equine neonates
Authors: LAVOIE J. P. , MADIGAN J. E. , CULLOR J. S. , POWELL W. E.
Published: April 2010

The purpose of this study was to evaluate the effects of experimentally induced sublethal endotoxaemia in equine neonates. Four foals, between two and five days of age, were infused intravenously with 0.5 μg/kg bodyweight ofSalmonella typhimuriumendotoxin (LPS) over a 5 h period. A four‐day‐old and a five‐day‐old foal, similarly infused with sterile isotonic saline, served as controls. Clinical signs were monitored, blood samples obtained for evaluation of selected haematological and biochemical parameters; and haemodynamic parameters were recorded hourly during the infusion, as well as 6 and 24 h post infusion. Depression, anorexia, increased rectal temperature, leucopenia followed by leucocytosis, hypoglycaemia, increased prothrombin time, partial thromboplastin time (APTT), pulmonary artery pressure, pulmonary artery wedge pressure, right atrial pressure, pulmonary and systemic vascular resistance and mild hypoxaemia were consistent findings in the foals receiving endotoxin. There was marked variation over time in the above parameters, during the infusion. Shock was not induced, and the foals appeared to be healthy shortly after the infusion was discontinued. The return to baseline values of body temperature (3 of 4 foals), APTT (1 of 4 foals) and neutrophil count (2 of 4 foals), during endotoxin infusion, suggests induction of early tolerance. The control foals remained alert and the temperature, prothrombin time and fibrinogen remained stable during the study. Hyperglycaemia, transient increased APTT and variations in selected haemodynamic parameters were recorded in the control foals during the infusion.
Effects of intravenous xylazine hydrochloride on blood glucose, plasma insulin and rectal temperature in neonatal foals
Authors: ROBERTSON S. A. , CARTER S. W. , DONOVAN M. , STEELE C.
Published: April 2010

The effects of intravenous xylazine hydrochloride on blood glucose, plasma insulin and rectal temperature were investigated in six foals at 10 and 28 days of age. These variables were also measured in three foals at 19 days of age when saline alone was injected. Rectal temperature fell significantly after 30 mins in both groups of xylazine treated foals and was still depressed after 120 mins. Hypothermia did not occur in the saline control group. There was no significant change in blood glucose or plasma insulin concentrations during the 120 mins following either xylazine or saline administration and no significant differences between the three groups of foals. When foals were allowed to suckle after being away from their dams for 2 h, there was a significant (P < 0.01) rise in plasma insulin levels in all the groups. Blood glucose showed a concomitant rise but this was only significant in the saline group. Unlike adults, intravenous xylazine (1.1 mg/kg) does not produce hypoinsulinaemia and hyperglycaemia in foals. This study suggests that the inhibition of insulin release from pancreatic ß‐cells by xylazine, which in adults is α2‐adrenoceptor mediated, is immature or absent in foals under one month of age.
A scanning electron microscopical study of the dermal microcirculation of the equine foot
Authors: POLLITT C. C. , MOLYNEUX G. S.
Published: April 2010

The microcirculation of the dermal laminae and papillae of the equine foot from seven clinically normal Australian ponies was studied using an improved microvascular casting corrosion technique and scanning electron microscopy. Casts of veins, arteries, capillaries and arteriovenous anastomoses (AVAs) were readily identified by their characteristic surface morphology. Arteries entered the laminar circulation axially, between pairs of axial veins, and were connected to each other by smaller calibre interconnecting arteries. Short abaxial branches of the axial interconnecting arteries gave rise to tufts of predominantly, proximodistally orientated, capillaries arranged abaxially in rows. The laminar veins anastomosed with each other extensively (the axial venous plexus) and formed most of the vascular skeleton of casts of the dermal laminae. AVAs were found throughout the laminar circulation but the largest and longest (40μ diameter) were found clustered close to the origin of the axial arteries. The density of the laminar AVAs was estimated to be 500 AVAs/cm2. Blood vessels of the dermal papillae of the periople, coronary band, distal laminae, sole and frog shared a basic structural organisation. The cast of each papillary unit consisted of a central artery and vein enmeshed in a sheath of fine capillaries. At intervals along the length of the central artery were short branches which gave rise to tufts of capillaries. The capillaries formed a tortuous anastomosing plexus which encircled the papillary unit and drained into the central vein at intervals along its length. AVAs were always present at the base of the papillary units and anastomoses connected the central artery and vein. AVAs are important components of the dermal microcirculation of the equine foot and their distribution and density is compatible with their proposed role in the pathophysiology of equine laminitis.
Equine urine pH: normal population distributions and methods of acidification
Authors: WOOD T. , WECKMAN T. J. , HENRY P. A. , CHANG S.‐L. , BLAKE J. W. , TOBIN T.
Published: April 2010

Our investigation of the urine of grazing horses at the University of Kentucky shows that the mean pH level is about 7.9, and if their diet is supplemented with grain, it is about 7.4. There appears to be no significant effect of time of day or year on urine pH levels in horses. However, horses taken from pasture and supplemented with grain in a stalled environment show a slight decrease in urine pH. Additionally, we investigated the effects of storage on pH levels. Equine urine samples appear to be quite stable with regard to pH for 48h, but then show a marked increase. Urine pH can have a great effect on the urine concentration of some drugs and therefore, uncertainties can arise when data generated in grazing horses are compared or extrapolated to racing horses whose urine pH can be quite low.

In an effort to simulate the drop in urine pH seen in some racing horses, we examined the effects of ammonium chloride, ascorbic acid, lactic acid and methionine on urine pH in research horses. Both oral and intravenous routes of administration were used. Although all agents tested showed varying degrees of efficacy, oral administration of ascorbic acid proved to be the safest and most effective agent to model the rapid acidification of urine seen in post race samples.
A comparison between chromium‐mordanted hay and acid‐insoluble ash to determine apparent digestibility of a chaffed, molassed hay/straw mixture
Authors: CUDDEFORD D. , HUGHES DENISE
Published: April 2010

The apparent digestibility of a molassed, chaffed grass hay/straw mixture was determined using four mature horses (mean weight 606 kg). Animals were stalled individually and kept on rubber mats. A preliminary feeding period of 18 days was followed by a 10 day collection period. Chromium‐mordanted hay was given before the first feed at 08.00 h and subsequent meals were at 12.00, 16.00 and 20.00 h. On Days 3 and 10 of the collection, all faeces were sampled over a 24 h period. In addition, throughout the 10 day collection, faecal material was sampled at 10.00 and 16.00 h. The mean (± se) chromium recovery was 96.5 per cent ± 0.76 and the hay/straw mixture contained 7 MJDE/kg dry matter and 15.1 g DCP/kg dry matter. There was no significant difference between the methods used to estimate apparent digestibility although chromium measurements consistently underestimated whilst acid‐insoluble ash consistently overestimated digestibility values. There was a large variation in faecal chromium concentration for each horse over a 24 h period compared to acid‐insoluble ash concentrations and, consequently, indirect estimates of apparent digestibility of nutrients in the equine are prone to large errors if chromium is used as a marker. If total faecal collection is impractical, acid‐insoluble ash is the preferred indirect marker for the estimation of apparent digestibility coefficients for nutrients in horses.
Failure to demonstrate reperfusion injury following ischaemia of the equine large colon using dimethyl sulphoxide
Authors: REEVES J. , VANSTEENHOUSE J. , STASHAK T. S. , YOVICH J. V. , COCKERELL G.
Published: April 2010

A study was undertaken to evaluate the significance and mechanism of reperfusion injury in the equine large colon following 1 h of haemorrhagic strangulation obstruction (HSO) or ischaemic strangulation obstruction (ISO) and to assess the effect of treatment with dimethyl sulphoxide (DMSO). ISO or HSO were created 40 cm from the pelvic flexure and maintained for 60 mins under general anaesthesia. Normal saline or 20 per cent DMSO (1g/kg bodyweight) was administered intravenously 10 mins prior to the end of the ischaemic period. Four groups of four horses in a 2 times 2 factorial design were used. Treatments of HSO or ISO and DMSO given (yes or no) were utilised. Intestinal wall biopsies and right colic arterial and venous blood samples were taken at 0, 60, 90 and 120 mins following initiation of the obstructions. Histological evaluation of the intestine using haematoxylin and eosin stained sections and immunohistochemical staining for albumin were performed. Mucosal and serum reduced glutathione (GSH) and oxidised glutathione (GSSG) levels and the amount of lymphatic dilatation with albumin and submucosal pooling of albumin were used as indirect measures of oxygen free radical production. Histopathological changes were minimal after 1 h of either type of ischaemia. Progressive changes during the post ischaemic period were minimal for ISO and moderate for HSO. Serum GSH and GSSG levels were not detectable. There was no demonstrable benefit of DMSO treatment as assessed by histology, immunohistochemistry or preservation of GSH levels in the mucosa. In conclusion, a reperfusion injury following 60 mins of ischaemia could not be detected in this study.
Prolonged luteal activity in mares ‐ a semantic quagmire
Authors: GINTHER O. J.
Published: April 2010

Prolonged luteal activity is one of the most formidable terminology challenges in mare reproductive biology. Prolonged luteal activity can be a result of persistence of an individual corpus luteum or the sequential development of luteal glands, each of which may have a normal life span. Luteal tissue can originate from an unovulated follicle or from an ovulation occurring during either follicular or luteal dominance. These complexities, together with ambiguous and inconsistent terminology, have resulted in confusion regarding those conditions which can be grouped broadly under the term prolonged luteal activity. Persistence of an individual corpus luteum can occur in association with severe damage to the endometrium resulting in loss of the uterine luteolytic mechanism. Spontaneous (no known uterine pathology) persistence of the corpus luteum from the follicular‐phase ovulation has not been documented adequately as a clinical entity. The occurrence of ovulation towards the end of dioestrus may cause confusion about the origin of prolonged luteal activity. Such immature dioestrous corpora lutea may not respond to the release of uterine luteolysin, thereby leading to prolonged luteal activity even though the original corpus luteum regressed at the normal time. In the absence of critical monitoring of the corpus luteum (eg by ultrasound) the prolonged activity could be attributed erroneously to persistence of the corpus luteum from the follicular‐phase ovulation. Pseudopregnancy is another confusing term that is sometimes used to describe persistence of the corpus luteum, especially when the luteal persistence is caused by embryonic loss after the embryo has blocked the uterine luteolytic mechanism. Careful attention to terminology, reliable technology and critical experimentation are needed to clarify the nature of those conditions that can be grouped under the term prolonged luteal activity. Terminology advanced in this review includes primary corpus luteum, secondary corpus luteum, luteinised follicle, idiopathic persistence and uteropathic persistence.
Evaluation of a bronchoalveolar lavage technique
Authors: FOGARTY URSULA
Published: April 2010

The bronchoalveolar lavage (BAL) technique described produced no detectable gross or histopathological lesions. Airway fluid accumulation was observed for up to 4 h post lavage. There was good qualitative correlation between BAL cytopathological and diffuse pulmonary pathological changes. The technique provided an accurate assessment of the presence and extent of exercise induced pulmonary haemorrhage.
Jugular thrombophlebitis resulting from an anaesthetic induction technique in the horse
Authors: DICKSON LINDA R. , BADCOE L. M. , BURBIDGE HILARY , KANNEGIETER N. J.
Published: April 2010

Forty‐eight hours after general anaesthesia was induced by glycerol guaiacolate and thiopentone sodium in 10 horses, the jugular veins were dissected out at post‐mortem and examined visually and histologically. All veins showed a marked thrombophlebitis involving the media and intima at the site of injection. The influence of catheter composition, catheter placement and chemical composition on the occurrence of the thrombophlebitis is discussed. It is concluded that the thrombophlebitis was chemically induced.