bluuebunny/crossref_metadata_2025 huggingface dataset:
Narcotic analgesics, their detection and pain measurement in the horse: A review
Authors: KAMERLING S. , WOOD T. , DeQUICK D. , WECKMAN T. J. , TAI C. , BLAKE J. W. , TOBIN T.
Published: April 2010

Narcotic analgesics produce pharmacological effects by interacting with specific opiate receptors. At least five major types of opiate receptors have been recognised. These include μ (morphine) and kappa (ethylketazocine) receptor types. Narcotic analgesics which interact with μ receptors produce locomotor and autonomic stimulation at doses that produce little or no analgesia. Therefore, use of these drugs as analgesics in equine medicine has not been very satisfactory. Theoretical considerations suggested that the role of kappa agonists in equine analgesia be investigated. Using a pure kappa agonist, U‐50. 488H, good analgesia was produced in the horse with little or no locomotor stimulation or autonomic effects. These data suggest that kappa agonists may be superior analgesics for clinical use in the horse. On the other hand, the locomotor stimulant effects of μ agonist analgesics enable their use as illegal medications. Specifically, these agents produce a good running response, signs of central nervous stimulation and analgesia, all potentially useful effects in a racehorse. Regulatory control of most narcotic analgesics can be obtained by high performance thin layer chromatographic screening. However, effective screening for the fentanyls and small doses of etorphine can only be achieved by use of immunoassay.
Comparison of transtracheal aspirate and bronchoalveolar lavage cytology in 50 horses with chronic lung disease
Authors: DERKSEN F. J. , BROWN C. M. , SONEA I. , DARIEN B. J. , ROBINSON N. E.
Published: April 2010

Comparisons were made between transtracheal aspirate (TTA) and bronchoalveolar lavage (BAL) cytology obtained from 50 horses with chronic lung disease and from 10 control horses. There was no significant correlation between the TTA cytology and the BAL cytology, suggesting that the cell population in the trachea is not representative of the cell population in the lower airways. In control horses the range of differential cell counts obtained from TTA fluid was remarkably large, whereas the variability in cell populations observed in BAL fluid was smaller. In the principal horses the total and differential cell counts of the TTA and BAL fluids were within the 95 per cent confidence interval in 38 and 24 per cent of cases, respectively; and an increase in percentage neutrophils was most common. It was concluded that BAL may be a useful diagnostic aid when evaluating horses with chronic lung disease, but that the clinical usefulness of cytological evaluations of TTA fluid may be limited in these cases.
Muscular adaptation of horses during intensive training and detraining
Authors: ESSÉN‐GUSTAVSSON BIRGITTA , McMIKEN D. , KARLSTRÖM K. , LINDHOLM A. , PERSSON S. , THORNTON J.
Published: April 2010

Five horses were studied during a five‐week regime of controlled intensive daily training on a high‐speed treadmill followed by five weeks of detraining. Muscle biopsies were taken weekly from both the right and left gluteus muscle and from the sternocephalicus muscle before, and at the end of, the training and detraining periods. Histochemical and biochemical analyses of the sternocephalicus muscle showed no metabolic adaptation with either training or detraining. No significant differences were observed in any of the analysed parameters in the gluteus muscle between contralateral sites. Glycogen levels decreased by 10 to 15 per cent after one to two weeks of training, remained low during the training period and increased to pretraining levels after one week's cessation of training. Citrate synthase activity increased rapidly and was 27 per cent higher after one week and 42 per cent higher after five weeks of training. Lactate dehydrogenase activity decreased by 15 per cent during this period. The changes seen in these enzyme levels persisted during the detraining period. No alterations were seen in fibre type composition but type IIA fibre areas decreased by 19 per cent after five weeks training and capillary density increased by 17 per cent. It is concluded that a period of intensive training will rapidly increase the oxidative capacity and the capillary density in an actively working muscle, and that these metabolic adaptations are well maintained during a subsequent period of detraining.
Interactions between chloramphenicol, acepromazine, phenylbutazone, rifampin and thiamylal in the horse
Authors: BURROWS G. E. , MacALLISTER C. G. , TRIPP P. , BLACK J.
Published: April 2010

The potential for interactions between chloramphenicol, phenylbutazone, acepromazine and thiamylal and chloramphenicol, rifampin, and phenylbutazone were evaluated in two groups of experiments. In the first, five horses were given thiamylal intravenously (iv) (6.6 mg/kg) after pretreatment with acepromazine, and the time of recumbency was determined. Administration of chloramphenicol iv (25 mg/kg) 1 h prior to anaesthesia significantly lengthened the recumbency time from 21.8 ± 4.8 mins to 36.0 ± 8.3 mins. There was an apparent but not statistically significant decrease in recumbency time when phenylbutazone (4.4 mg/kg) was administered iv daily for 4 days prior to anaesthesia. In the second series of experiments, phenylbutazone (4.4 mg/kg), chloramphenicol (25 mg/kg) and rifampin (10 mg/kg) were administered in various sequences to five different horses. Chloramphenicol pretreatment produced a significant decrease in the elimination rate and rifampin a significant increase in the elimination rate of phenylbutazone. The half‐life of elimination of phenylbutazone alone was about 4 h. Following four days pretreatment with rifampin it was approximately 2.7 h, it was approximately 5.6 h and 9.5 h, respectively, when chloramphenicol was administered in one dose 1 h before or two doses 12 h and 1 h before phenylbutazone.
Effects of season and lower ambient temperature on the structure of the sweat glands in anhidrotic horses
Authors: JENKINSON D. McEWAN , LONEY C. , ELDER H. Y. , MONTGOMERY I. , MASON D. K.
Published: April 2010

Histological studies of the sweat glands of anhidrotic horses in the Hong Kong summer and under conditions of reduced thermal stress, both natural and controlled, were undertaken to determine if glandular regeneration occurs. Clinical data were collected for comparison with the histological results in each instance. Horses were assigned to one of three categories on the basis of the resulting change in the number of thin glandular profiles in a cooler environment. Group 1, which was classed as normal, had a low initial value, which was maintained. Group 2, typical of mild and moderately affected animals, had a high initial value, which fell markedly after as little as six weeks in the cool environment. Animals in Group 3, classed as severely affected, had a high initial value which remained high even after prolonged exposure to the cool environment. Light microscopical examination of the sweat glands in the heat, and after six weeks in a cool environment, provided a means of predicting the degree of anhidrotic severity and the potential for recovery in a cool climate. This was superior to clinical observation, although a diagnostic test based on glandular function is still required.
Development of an equine nuclear medicine facility for gamma camera imaging
Authors: ATTENBURROW D. P. , PORTERGILL M. J. , VENNART W.
Published: April 2010

A nuclear medicine facility constructed specifically for the application of a gamma camera system to the radioisotope imaging of bone, pulmonary circulation and ventilation in the horse is described. The gamma camera was previously used for human nuclear medicine, and a support for the gamma camera head was specifically designed for this work. Imaging protocols are suggested and the necessary materials for bone and lung studies are described. Images of bone and lung are shown and computer analysis of the data indicated. Imaging times are approximately 1 to 2 mins and typical bone and lung studies can be completed in 20 to 30 mins.
Blood chemistry and skeletal muscle metabolic responses during and after different speeds and durations of trotting
Authors: VALBERG STEPHANIE , GUSTAVSSON BIRGITTA ESSEN , LINDHOLM A. , PERSSON S. G. B.
Published: April 2010

Eight standardbred horses trotted on a treadmill for 55 mins at a sub‐maximal speed of 5m/sec and subsequently performed an exercise test consisting of 2 min intervals at increasing speed. Heart (HR) and respiratory (Rf) rates and venous blood samples were obtained before, during and for 5 mins after exercise. Gluteus medius muscle biopsies and rectal temperatures were taken before and after exercise. The mean HR was 132/min and the mean Rf was 156/min during the 5m/sec trotting. With 5m/sec exercise, plasma free fatty acids (FFA), glucose, creatinine and Cortisol concentrations increased markedly. Blood lactate increased slightly and plasma potassium increased initially and then decreased with a lengthened duration of trotting. Within 5 mins post exercise plasma FFA, glucose and Cortisol concentrations continued to rise, whereas creatinine and lactate levels declined slightly and potassium concentrations declined rapidly to below resting values. The mean intramuscular (im) glycogen utilisation was 86 mmol/kg, no significant changes occurred in creatine phosphate (CP), adenosine triphosphate (ATP) and glucose‐6‐phosphate (G‐6‐P) concentrations and muscle lactate decreased significantly. During the second exercise test mean HR was 215/min and Rf 126/min at top speed. No significant change was seen in plasma glucose whereas Cortisol levels rose to a lesser extent, and creatinine lactate, ammonia and potassium concentrations to a greater extent, compared to 5 m/sec trotting. Post exercise, these parameters continued to increase except for creatinine which declined slightly and potassium which decreased rapidly. The mean im glycogen utilisation was 144 mmol/kg, ATP concentrations were unaltered, CP declined, lactate and G‐6‐P increased during exercise. The rapid changes in concentrations of blood chemistry parameters post exercise emphasise the importance of obtaining blood samples during exercise when studying metabolic response.
Thyroid hormone periodicity in healthy adult geldings
Authors: DUCKETT WENDY M. , MANNING J. P. , WESTON PATRICIA G.
Published: April 2010

Serum samples were collected from 10 healthy geldings every 4 h for three consecutive days and the triiodothyronine (T3) and thyroxine (T4) concentrations determined by radioimmunoassay. There were significant differences in the hormone concentrations related to time. The mean (± sd) T3concentration peaked around 08.00 h at a level (54.06 ± 14.02 ng/dl) significantly (P<.001) higher than the lowest concentration (38.71 ± 10.81 ng/dl) around midnight. Although the highest mean T3level was 08.00 h, this value was not significantly different from the noon and 16.00 h levels. Likewise, the mean T3level at midnight was not significantly different from the 20.00 h and 04.00 h levels, resulting in a plateau from 08.00 h to 16.00 h and a trough from 20.00 h to 04.00 h. The mean (± sd) T4concentration peaked around 16.00 h at a level (2.43 ± .81 μg/dl) significantly (P<.01) higher than the lowest concentration (1.79 ± .63 μg/dl) around 04.00 h.
Twin embryos in mares I: from ovulation to fixation
Authors: GINTHER O. J.
Published: April 2010

Recent findings on the origin and development of twins from ovulation (Day 0) to fixation (mean: Day 16) are reviewed. Available data show that almost all twins originate from multiple ovulations. Results of recent ultrasound studies indicate that the number of days between double ovulations does not affect the conception rate per ovum or embryo survival during the first 16 days after each ovulation. Embryo reduction is the natural elimination of excess embryos so that only one embryo enters the foetal stage. In two studies, embryo reduction before or on the day of fixation was not considered an important aspect of the natural correction of twins. Diameters and growth rates on Days 11 to 16 were similar between singletons and twins and the presence of two vesicles did not have a direct effect on their diameter other than that attributable to their age. Twin and singleton embryonic vesicles were mobile within the uterine lumen from the first day of detection (Days 9 to 11) to the day of fixation (mean: Day 16). In one study, the embryonic vesicles were in the uterine body for over 50 per cent of the time during Days 9 to 12 and thereafter were most often in the uterine horns. For twins of dissimilar size, the preference for uterine body versus horns appeared to be an independent function of each vesicle based on its age or size. After Day 12, the number of entries from the uterine body into the horns increased and the vesicles began a maximum mobility phase which continued until fixation. Both members of twin sets were in a given uterine segment more often than would be expected by chance. Results of ultrasound studies indicated that uterine contractions are the propulsive force for conceptus mobility, apparently in response to the production of a stimulant by the conceptuses. Greatest uterine contractility coincided with the period of maximum conceptus mobility. The increase in contractility began four days earlier in pregnant than in nonpregnant mares. Fixation probably occurs when an embryonic vesicle becomes so large and uterine tone so great that the vesicle can no longer move despite the continuation of uterine contractions. Combined data showed that fixation of twins occurred unilaterally more often than would be expected by chance. The incidence of unilateral fixation increased greatly when vesicles were dissimilar in diameter or originated from asynchronous ovulations.
Twin embryos in mares II: post fixation embryo reduction
Authors: GINTHER O. J.
Published: April 2010

Recent findings on the development and natural outcome of twins from Day 17 (immediately after fixation) to Day 40 are reviewed. Incidence of embryo reduction was increased significantly when the vesicles became fixed unilaterally, rather than bilaterally, and when the vesicles were unequal in diameter. Of 68 mares with twins on the day of fixation, post fixation embryo reduction occurred in 41 (60 per cent). The incidence of reduction was 41 of 48 (85 per cent) following unilateral fixation; reduction occurred in all of 22 mares with vesicles of dissimilar size (4 mm or more difference in diameter) and in 19 (73 per cent) of 26 mares with vesicles of similar size (0 to 3 mm difference). Embryo reductions were complete (vesicle no longer visible ultrasonically) by Day 20 (59 per cent of the reductions), during Days 21 to 30 (27 per cent), or Days 31 to 38 (14 per cent). In 80 per cent of the early reductions (by Day 20) the eliminated vesicle disappeared within one day. Reductions that occurred after Day 20 were preceded by a gradual decrease in size. As the number of days after Day 17 increased, the frequency of reduction decreased and the time required for completion of reduction increased. When the twins were dissimilar in diameter (4 mm or more), they were more likely to undergo reduction by Day 20. In summary, dissimilarity in diameter increased the likelihood of unilateral fixation, increased the incidence of reduction for unilaterally fixed vesicles, hastened the day of occurrence of reduction and shortened the interval from initiation to completion of reduction. The deprivation hypothesis proposes that embryo reduction occurs when a major portion of the three walled area of the yolk sac or the vascularised wall of the yolk sac or allantoic sac is in apposition with the wall of the adjacent vesicle rather than with the endometrium; the vesicle is deprived of adequate embryonal‐maternal exchange and therefore regresses.
Pulmonary vascular reactivity of the newborn pony foal
Authors: DRUMMOND W. H. , SANCHEZ I. R. , KOSCH P. C. , WEBB A. I.
Published: April 2010

Adult ponies develop pulmonary hypertension at altitude (Bisgard, Orr and Will 1975), but the neonatal response to acute hypoxaemia is unknown. Seven foals aged five days were instrumented with a systemic and a Swan‐Ganz pulmonary artery catheter while anaesthetised and intubated. Cardiac index, pulmonary (PAP) and systemic (SAP) vascular pressures were measured as the foals breathed gas mixtures with F102 of 8 to 94 per cent. Because foramen ovale or ductus arteriosus shunts might have altered thermodilution cardiac index measurements in the stressed foals, the ratio, PAP/SAP was calculated to define relative circulatory reactivity. Three foals, two of which were full siblings, had very marked elevation of PAP/SAP from 0.6 to 1.41 at low inspired oxygen tensions. Four different foals attained maximal PAP/SAP of only 0.2 to 0.92 at similarly low oxygen tensions (P<0.0001). Thus, pulmonary vascular reactivity to ventilatory hypoxaemia varied greatly in pony foals of the same age. The exaggerated reactivity in related foals suggested that, as in cattle, a genetic predisposition to develop reactive pulmonary hypertension under hypoxaemic stress may exist.
A preliminary investigation of the effect of selected electromagnetic field devices on healing of cannon bone osteotomies in horses
Authors: SANDERS‐SHAMIS MARLENE , BRAMLAGE L. R. , WEISBRODE S. E. , GABEL A. A.
Published: April 2010

The effect of electrical stimulation by means of selected electromagnetic field devices on healing of cannon bone osteotomies in horses was examined. The defects were created as 3 cm × 1 mm longitudinal osteotomies through the dorsal cortices of the mid‐metacarpi/metatarsi of adult horses. This type of defect would asses bone healing in a situation similar to an acute, stable fracture of the cortex. Three electromagnetic devices of different design were tested in three different groups of horses. Healing was evaluated radiographically and histologically. Results showed that osteotomies treated with the electromagnetic devices healed similarly to untreated controls. Our conclusion is that the electromagnetic devices studied did not have a local effect on the repair process of an acute, stable, osseous defect.
Body fluid and endometrial concentrations of ketoconazole in mares after intravenous injection or repeated gavage
Authors: PRADES MARTA , BROWN M. P. , GRONWALL R. , HOUSTON ANN ELIZABETH
Published: April 2010

After single oral administration of ketoconazole (30 mg/kg bodyweight [bwt]) in 50 ml of corn syrup to a healthy mare, the drug was not detected in serum. Ketoconazole in 0.2 N HC1 was administered intragastrically to six healthy adult horses in five consecutive doses of 30 mg/kg bwt at 12 h intervals. Ketoconazole concentrations were measured in serum, synovial fluid, peritoneal fluid, cerebrospinal fluid (CSF), urine and endometrium. Mean peak serum ketoconazole concentration was 3.76 μg/ml at 1.5 to 2 h after intragastric administration. Mean peak synovial concentration was 0.87 μg/ml 3 h after the fifth dose. Similarly, mean peritoneal concentration peaked 3 h after the fifth dose at 1.62 μg/ml. Mean endometrial concentrations peaked at 2.73 μg/ml 2 h after the fifth dose. Ketoconazole was detected in the CSF of only one of the six mares at a concentration of 0.28 μg/ml 3 h after the fifth dose. The highest measured concentration of ketoconazole in urine was 6.15 μg/ml 2 h after the fifth dose. A single intravenous injection of ketoconazole (10 mg/kg bwt) was given to one of the six mares; the overall elimination rate constant was estimated at 0.22/h and bioavailability after oral administration was 23 per cent.
Rhodococcus equi foal pneumonia: Protective effects of immune plasma in experimentally infected foals
Authors: MARTENS R. J. , MARTENS JUDY G. , FISKE R. A. , HIETALA SHARON K.
Published: April 2010

The immunoprophylactic capacity of specific immune plasma was evaluated in pony foals infected experimentally withRhodococcus equi.Immune plasma, produced by repeated parenteral administration of viableR. equito adult horses, was harvested and frozen. Group I (six control foals) and Group II (six principal foals) received lactated Ringers solution and immune plasma respectively at three and five days of age.R. equiwere aerosolised into a caudal lung lobe of all foals at seven days of age. Clinical signs, haematological alterations, immune responses, thoracic radiographs and technetium99mpulmonary perfusion scans were monitored. All foals were destroyed and complete post mortem examinations performed. All foals developed pneumonia as evidenced by clinical, radiographic and perfusion alterations, but the survival rate of principal foals was significantly (P < 0.01) greater than that of control foals. Five control foals developed terminal disease, whereas all principal foals recovered. There was no significant (P>0.05) difference in temperature response, or peripheral blood leucocyte, neutrophil or fibrinogen concentrations between groups. ELISA values forR. equiantibody were significantly (P<0.001) greater in principal foals following treatment, but there was no significant (P>0.05) difference in IgG or IgM concentrations between groups. Results of the haemolysis inhibition assay indicated that equi factor neutralising antibodies were transferred by immune plasma to the principal foals. Post mortem examinations of five control foals destroyed at approximately three weeks post infection because of terminal disease, revealed severe pyogranulomatous pneumonia. One control and all principal foals were either free of lesions or had resolving lesions and/or minimal scar formation at three months post infection. The results of this investigation document the importance of humoral factors in controlling the disease process, and the capacity of humoral immunoprophylaxis to alter the clinical progression ofR. equipneumonia.
A retropspective study of 100 pelvic fractures in horses
Authors: RUTKOWSKI J. A. , RICHARDSON D. W.
Published: April 2010

The records of 100 horses with clinical or radiographic diagnosis of a pelvic fracture were reviewed to determine prognostic indicators associated with clinical signs or radiographic fracture characteristics. Degree of lameness, soft tissue swelling, crepitis, muscle atrophy, skeletal external assymetry and palpable assymetry on rectal examination were evaluated. There was no significant relationship between the aforementioned clinical signs and the long‐term case outcome. Fracture sites or presence of an acetabular fracture were not related to prognosis. The positive outcome of 77 per cent of horses that were allowed to survive and were available for follow‐up in this study warrants the effort of salvage of valuable individuals.
Ventilation‐perfusion relationships in the anaesthetised horse
Authors: NYMAN G. , HEDENSTIERNA G.
Published: April 2010

Ventilation‐perfusion relationships were studied by the multiple inert gas elimination technique in seven horses while they were conscious and during inhalation anaesthesia with halothane. A generally good match between ventilation and perfusion was found in the conscious, standing horse. During anaesthesia a huge shunt developed, ie perfusion of completely unventilated lung regions, both in dorsal and left lateral recumbency and whether the horse was breathing spontaneously or mechanically ventilated. The shunt was significantly greater and the arterial oxygen tension (PaO2) significantly lower in dorsal than in left lateral recumbency. Little or no perfusion of low V̇A/Q̇ regions was observed during anaesthesia, whether ventilation was spontaneous or mechanical. Positive end‐expiratory pressure (PEEP) did not significantly improve PaO2or reduce the shunt. Selective mechanical ventilation of dependent lung regions with PEEP reduced the shunt markedly, an effect that was not achieved by conventional mechanical ventilation with general PEEP. The findings seem compatible with alveolar collapse during anaesthesia, causing shunt, whereas the absence of clearly low V̇A/Q̇ regions questions the role of airway closure as the major disturbance of gas exchange.
The arterial supply of the navicular bone in the normal horse
Authors: RIJKENHUIZEN ASTRID B. M. , NEMETH F. , DIK K. J. , GOEDEGEBUURE S. A.
Published: April 2010

An arteriographic and histological study of the arterial blood supply of 35 navicular bones, from 19 adult horses with no clinical or radiographical signs of navicular disease, is described. The arteries enter the navicular bone from four directions: distal, proximal, medial, and lateral. The navicular bone can be divided into areas which receive arteries from one, two, or three directions, whereas the distal supply covers the largest part of the navicular bone. The distal arteries enter the navicular bone through the nutrient foramen which contains loose connective tissue, nutrient vessels and myelinated nerves. At least 77 per cent of the nutrient foramina contains synovial membrane. Twelve per cent of the arteries in the navicular bone show histological changes. Thickening of the intima with or without splitting of the internal elastic membrane and hyalinisation, fibrosis and hypertrophy of the media were observed.
The effect of unilateral resection of segments of both palmar digital arteries on the navicular bone in ponies: An experimental study
Authors: RIJKENHUIZEN ASTRID B. M. , NÈMETH F. , DIK K. J. , GOEDEGEBUURE S. A. , VAN DEN BROM W. E.
Published: April 2010

Clinical, radiographical, scintigraphical and histological effects on the navicular bone after resection of the medial and lateral palmar digital arteries in the pastern of one forelimb in ponies are evaluated. The acute disruption of the main blood supply of the distal extremity causes lameness due to the suddenness of the resection in which the collateral circulation is insufficiently developed. Because of the compensatory collateral circulation, no permanent symptoms of ischaemia occur despite the partial resection of both palmar digital arteries. Histologically the percentage of relative osteoid volume of the operated limb was significantly higher than in the control limb.
The effect of artificial occlusion of the Ramus navicularis and its branching arteries on the navicular bone in horses: An experimental study
Authors: RIJKENHUIZEN ASTRID B. M. , NÉMETH F. , DIK K. J. , GOEDEGEBUURE S. A. , VAN DEN BROM W. E.
Published: April 2010

The clinical, radiographic, arteriographic, scintigraphic and histological effects of experimental occlusion of the Ramus navicularis (R. Navicularis) and its branching arteries are evaluated. Occlusion of the R. navicularis and its branching arteries creates changes, arteriographically and histologically, which resemble those of navicular disease. The increased bone remodelling, the shift in arterial pattern, the formation of collaterals and the increased connective tissue in the synovial membrane and nutrient foramina, as a reaction to the reduction of the distal arterial supply of the navicular bone, are also pathological features in the navicular bones of horses with navicular disease. The results of the present study support the theory that a reduced distal arterial supply of the navicular bone is important in the pathogenesis of navicular disease.
Changes in circulating equine erythrocytes induced by brief, high‐speed exercise
Authors: SMITH J. E. , ERICKSON H. H. , DEBOWES R. M. , CLARK MARGARET
Published: April 2010

Five horses were exercised at 10m/sec at a 3° incline for 2 mins. Packed cell volume, erythrocyte count, haemoglobin concentration, mean corpuscular volume, plasma protein, total white cell count and lymphocytes increased significantly in blood samples taken after exercise, compared with those taken before exercise; but mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration decreased. Erythrocytes were more resistant to osmotic stress after exercise, but their shape and degree of deformity were unaffected by exercise.
A computer‐derived protocol to aid in selecting medical versus surgical treatment of horses with abdominal pain
Authors: DUCHARME N. G. , PASCOE P. J. , LUMSDEN J. H. , DUCHARME G. R.
Published: April 2010

In order to determine which variables are useful in identifying horses with abdominal pain requiring surgery, data were analysed from 219 horses presented at one veterinary teaching hospital. Using multiple stepwise discriminant analysis with a recursive partitioning algorithm, we obtained a decision tree that identifies surgical and non‐surgical patients. The prevalence of surgical patients was 79 per cent in this population. The sensitivity, specificity, and positive and negative predictive values of this decision tree were 99 per cent, 55 per cent, 90 per cent and 99 per cent respectively. Compared to the clinical decision, this decision tree yielded more false positives (11 per cent) but almost eliminated false negatives (1 per cent). This decision tree was validated by the jack‐knife method and also by evaluation using a new sample in a second veterinary teaching hospital in which the prevalence of surgical patients was 55 per cent. This led to sensitivity, specificity and positive and negative predictive values of 93 per cent, 73 per cent, 81 per cent and 89 per cent respectively.
Induction of peritoneal adhesions with small intestinal ischaemia and distention in the foal
Authors: LUNDIN CANDACE , SULLINS K. E. , WHITE N. A. , CLEM M. F. , DEBOWES R. M. , PFEIFFER C. A.
Published: April 2010

Twenty‐two foals were divided into groups of intestinal distension and intestinal ischaemia as methods to induce peritoneal adhesions. In the first group, the lumen of a segment of distal small intestine was occluded without extramural vascular compromise and distended with lactated Ringer's solution to a constant pressure of 25 cm H2O for 2 h within the abdomen. The ischaemic group underwent 70 mins total vascular occlusion of identical segments of bowel. Serosal biopsies were obtained before and after each experimental procedure and following 60 mins of reperfusion. Similar biopsies were harvested from a control group of foals with no bowel occlusions. The foals were destroyed 10 days after surgery and tissues collected for histological and ultrastructural evaluation. Experimental and control mesothelial surfaces were denuded histologically immediately after experimental occlusions. Serosal oedema and cellular infiltration were observed following reperfusion of the ischaemic segments but were present immediately after 2 h of distension. All foals had developed bowel‐to‐bowel and bowel‐to‐mesentery adhesions of the experimental segments. Control foals under 30 days old exhibited mesenteric contraction and thickening of the isolated segment whereas those older than 30 days had little or no mesenteric thickening or contraction. Histologically, in the experimental segments, fibrous tissue had formed on the outer boundary of the original serosa, and new mesothelial‐like cells were present on the surface of fibrous tissue in some areas. Some serosal fibrosis was also seen in most of the control segments.
Sequential clinical and synovial fluid changes associated with acute infectious arthritis in the horse
Authors: TULAMO RIITTA‐MARI , BRAMLAGE L. R. , GABEL A. A.
Published: April 2010

Infectious arthritis was induced experimentally in one tarsocrural joint of six horses by intra‐articular injection of 1 ml Staphylococcus‐saline suspension containing 9 times 104to 3 times 106organisms. The corresponding contralateral joint was injected with 1 ml of saline and served as a control. The progression of the induced infectious arthritis was assessed over a nine‐day period by clinical examination and sequential synovial fluid analysis with pH and lactate measurements. Changes in synovial fluid were present before clinical signs of infectious arthritis were manifested. The diagnostic value of different synovial fluid parameters at various stages of infection was determined. Cellular changes initially preceded the biochemical changes. Total leucocyte counts showed a significant increase within 24 h (up to 100 times 109/litre) with great variability in subsequent measurements. Neutrophilia over 90 per cent and pH under 6.9 were the most consistent findings in the infected synovia. Increased total protein was also significant and was progressive throughout the experiment. Serum and synovial glucose difference and synovial lactate had more diagnostic value in the acute stages than in the chronic stages. The control joints elicited an inflammatory response manifested by increased leucocyte count, moderate neutrophilia, slightly increased total protein concentration, and slightly decreased pH, but all reactions were minor in comparison to those in the infected joints.
High frequency jet ventilation in horses: an experimental study
Authors: DUNLOP C. I. , HODGSON D. S. , WATSON J. W. , GILLESPIE J. R. , STEFFEY E. P. , JACKSON A. C.
Published: April 2010

High frequency jet ventilation (HFJV) is a recently developed mode of ventilation that delivers small tidal volumes at frequencies greater than 60 cycles per min via an injection catheter to the animal's airway. The construction of a high frequency jet ventilator suitable for use in adult horses is described. The effectiveness of this ventilator in maintaining normal arterial blood ‐ gas tension was evaluated in five healthy adult horses. The horses were anaesthetised with intravenous acetylpromazine, guaifenesin, and thiamylal, positioned in lateral recumbency and baseline measurements were made during spontaneous ventilation. The horses were then paralysed with succinylcholine and ventilated for at least 20 mins with HFJV. Air was delivered from the ventilator to the animal by a polyethylene tube. The tip of this tube remained within and approximately 30 cm from the cuffed end of a standard 30 mm internal diameter large animal orotracheal tube. Frequency of flow interruption was 3 Hz with a constant source pressure of 275 kPa and an inspiratory to expiratory ratio of approximately 1:2.6. Gas delivery to the horse, as estimated with a resonator system was approximately 2 litres/breath. During HFJV, arterial carbon dioxide tension was significantly reduced and arterial oxygen tension significantly increased above measurements made when the horses were spontaneously breathing air.
Treatment of solar prolapse using the heart bar shoe and dorsal hoof wall resection technique
Authors: EUSTACE R. A. , CALDWELL M. N.
Published: April 2010

This paper describes the treatment of 10 horses suffering from acute laminitis using the heart bar shoe and a dorsal hoof wall resection technique. All cases had progressed to prolapse of the tip of the pedal bone covered by solar corium through the horny sole; in one case the exposed tip of the distal phalanx became visible. Nine cases of distal phalangeal rotation and one case of distal displacement of the distal phalanx (sinking) are described. Two animals were destroyed because of the degree of lameness, one remains slightly lame at the trot and the remaining seven have returned to their previous use at comparable levels of performance.
Visceral prolapse after castration in the horse: a review of 18 cases
Authors: VAN DER VELDEN M. A. , RUTGERS L. J. E.
Published: April 2010

During a 10 year period, 18 horses were treated surgically because of visceral prolapse after castration. Surgery was successful in six cases of omental prolapse and in eight out of 12 cases of intestinal prolapse. To minimise the risk of visceral prolapse, the authors prefer half‐closed castration, with proper ligation of the parietal vaginal tunic, to open castration. If adequate treatment is started promptly, prognosis in cases of visceral prolapse is favourable.
Pharmacokinetics of amikacin in critically ill neonatal foals treated for presumed or confirmed sepsis
Authors: ADLAND‐DAVENPORT PAMELA , BROWN M. P. , ROBINSON J. D. , DERENDORF H. C.
Published: April 2010

Fourteen foals less than four days of age were treated with the aminoglycoside, amikacin sulphate, and either penicillin or ampicillin for septicaemia, pneumonia, and/or failure of passive immunoglobulin transfer. Serum amikacin concentrations were determined at three times during an 8 or 12 h dosing interval. A 7.0 mg/kg bodyweight dose of amikacin every 8 h was appropriate. Prematurity did not influence mortality. All seven premature foals survived, whereas four of the seven full term foals died. Uraemia in three foals was caused by urinary bladder rupture; amikacin‐induced nephrotoxicity was not recognised by clinical chemistries (elevations in serum creatinine or blood urea nitrogen concentrations) or post‐mortem findings.
Effect of strenuous exercise stress on chemiluminescence response of equine alveolar macrophages
Authors: WONG C. W. , THOMPSON H. L. , THONG Y. H. , THORNTON J. R.
Published: April 2010

Bronchoalveolar lavage samples were collected using a fibreoptic endoscope from horses at specified times before and after single bouts of exercise. Lucigenin‐dependent phagocytic chemiluminescence was used to assess the effect of exercise on the alveolar macrophage metabolic activity in response to stimulation by opsonised zymosan. A profound suppressive effect on the chemiluminescence production was present throughout the first three days after exercise. However, the cellular composition of lavage fluids was not altered by the exercise. It is suggested that strenuous exercise may jeopardise the antimicrobial function of alveolar macrophages which may lead to an increase in susceptibility to infection.
Prolonged effect of a single injection of human chorionic gonadotrophin on plasma testosterone and oestrone sulphate concentrations in mature stallions
Authors: COX J. E. , REDHEAD PATRICIA H.
Published: April 2010

The long term effect of a single injection of 6,000 iu of human chorionic gonadotrophin (hCG) was studied in two pony stallions. Peripheral plasma samples were anlaysed for testosterone and oestrone sulphate. Testosterone concentrations were markedly elevated for five days after injection in both stallions. No adverse effects of these high concentrations were observed on concentrations later in the experiment. There was an initial increase in oestrone sulphate in one stallion, after which concentrations decreased to below pre‐injection levels. The other stallion (whose initial oestrone sulphate concentrations were somewhat higher) showed no rise in response to hCG but did show a significant decline from five days after injection. Whether this suppression is an effect of the high testosterone concentrations remains to be determined.
Pharmacokinetic studies of cimetidine hydrochloride in adult horses
Authors: SMYTH G. B. , DURAN S. , RAVIS W. , CLARK C. R.
Published: April 2010

Histamine type II (H2) antagonists inhibit gastric acid secretion and are useful in treating gastric and duodenal ulcer disease. To provide some information on the pharmacokinetics of the H2 antagonist cimetidine, adult horses were given 3.3 mg/kg cimetidine intravenously (iv) or 3.3 and 10 mg/kg orally. Plasma cimetidine concentrations after 3.3 mg/kg orally were too low to measure. Following 33 mg/kg iv, cimetidine displayed two‐compartment characteristics with a t1/2 of 0.083±0.039 h and t1/2 of 2.23±0.64 h. The total body clearance was 0.443±0.160 litre/h/kg and the mean residence time was 2.74±1.11 h. This clearance and t1/2 are similar to that in man. The volume of distribution (VSS) and volume of the central compartment (VC) were 1.138±0.230 and 0.276±0.102 litre/kg, respectively. After a single oral dose of 10 mg/kg as crushed tablets, peak plasma concentration of 1.81±0.82 μg/ml occurred at approximately 1.4 h. Oral absorption of cimetidine appeared variable and slow with an extent of absorption of 0.296±0.183 and a mean residence time for absorption of 1.99±0.79 h. This was less than in man. Based on a desired average steady state plasma concentration of 1.0 μg/ml, 11.0 mg/kg/day iv and 48 mg/kg/day orally can be recommended in adult horses.
Pharmacokinetics of trimethoprim‐sulphamethoxazole in two‐day‐old foals after a single intravenous injection
Authors: BROWN M. P. , McCARTNEY J. H. , GRONWALL R. , HOUSTON A. E.
Published: April 2010

Six healthy two‐day‐old foals (3 pony foals and 3 horse foals) were given a single intravenous (iv) injection of trimethoprim (TMP) ‐ sulphamethoxazole (SMZ) at a dosage of 2.5 mg of TMP/kg bodyweight (bwt) and 12.5 mg of SMZ/kg bwt. Serum TMP and SMZ concentrations were measured serially during a 24 hour period. The overall elimination rate constant (K) for TMP in the pony and horse foals was 0.45/h, whereas the K values for SMZ for the pony and horse foals were 0.12/h and 0.07/h, respectively (no significant difference; P > 0.05). Based on published minimum inhibitory concentration values for equine pathogens (Adamsonet al1985), the primary indication for the use of TMP/SMZ in foals may be in the treatment of infections caused by gram‐positive bacteria. A dosage of 2.5 mg of TMP/kg bwt and 12.5 mg of SMZ/kg bwt, given iv at 12 h intervals would be appropriate.
Ancient origins of horsemanship
Authors: McMIKEN D. F.
Published: April 2010

Archaeological evidence of horse domestication dates from 4000 BC in the Eurasian Steppes of the Ukraine. There, Indo‐Europeans rode horses and herded them for meat. This had profound social and economic consequences which led to the development of nomadic equestrian cultures. The earliest direct evidence of riding is from Mesopotamian plaques, and correspondence of the Kings of Mari (2000 BC). Indo‐Europeans brought the horse to the Near East and there, outside its natural habitat, used specialised knowledge to raise and train horses on a large scale for military use. Hittite instructions on training chariot horses are contained in the Kikkuli text from Anatolia (1350 BC). Systematic conditioning, grain feeding and elements of ‘interval training’ are notable. Equine prescriptions were also recovered from Ugarit (Syria) which indicate a rational approach to veterinary medicine in the same era. With the evolution of effective training and tools, chariots, metal bits, and the recurve bow, horses became formidable weapons of war. Mounted bowmen succeeded chariots in warfare, particularly nomadic Scythians who dominated Central Asia (1000‐500 BC). In the Middle East (Iraq), Assyrians assembled a powerful military empire and employed a vast and skilled cavalry (900‐612 BC). The first surviving text on training cavalry mounts is by the Athenian General Xenophon (400 BC) who reveals a sensitive understanding of the horse. Although the horse has been used for herding, transportation and sport, a recurring stimulus for horsemanship throughout history has been its military role.
Ultrasound as an aid to diagnosis of granulosa cell tumour in the mare
Authors: HINRICHS KATRIN , HUNT P. R.
Published: April 2010

The ultrasonic appearance of seven cases of granulosa cell tumour is described, and compared with an ovarian haematoma and an ovarian serous cystadenoma. The granulosa cell tumours varied from being uniformly dense to having one or several large fluid filled cysts. Some tumours resembled the haematoma or cystadenoma and also, in some aspects, normal ovarian structures such as corpora haemorrhagica or follicles in early pregnancy. There was no typical ultrasonographic appearance of the granulosa cell tumours which enabled definitive diagnosis. However, ultrasound may be a diagnostic aid when used in conjunction with the history and findings on rectal palpation.
Changes in plasma progesterone concentrations from Days 17 to 42 of gestation in mares maintaining or losing pregnancy
Authors: IRVINE C. H. G. , SUTTON P. , TURNER J. E. , MENNICK P. E.
Published: April 2010

Plasma progesterone concentrations were measured in 179 mares bled on alternate days commencing with a positive pregnancy diagnosis on Days 17 to 18 after ovulation and concluding on Days 42 to 45. During this period 17 mares (10 per cent) lost their pregnancies, 11 before Day 25. In 15 mares the timing of the pregnancy loss could be determined with adequate accuracy; in only one did a decline in progesterone precede the loss. Thus pregnancy loss between Days 17 and 42 was rarely caused by a fall in plasma progesterone.
Arthrography of the equine shoulder joint
Authors: NIXON A. J. , SPENCER C. P.
Published: April 2010

Techniques and normal radiographic anatomy for positive and double contrast shoulder arthrography in horses were evaluated. General anaesthesia was used for most radiographic projections of the shoulder. The mediolateral projection provided the most information during arthrography, although the supinated mediolateral view occasionally allowed better definition of the cartilage surfaces on the medial aspects of the humeral head. The craniocaudal mediolateral oblique and caudocranial projections provided limited additional information. Water soluble non‐ionic contrast agents, such as metrizamide and iohexol, were suitable for shoulder arthrography; iohexol resulted in less synovitis and lameness. Arthrography in cases of osteochondrosis and osteochondritis dissecans allowed better evaluation of cartilage attachment to subchondral bone, better evaluation of the length and depth of cartilage lesions and more accurately defined the site and shape of osteocartilaginous free bodies. Cartilage thickening without detachment from the subchondral bone could only be determined by arthrography. Although these thick cartilage regions may later dissect from the subchondral bone, most cases where the cartilage was firmly adherent were not candidates for surgical debridement and carried a favourable prognosis. The determination of a free flap by arthrography indicated the need for surgery. Extensive humeral and glenoid cavity lesions were better defined by arthrography, allowing a rational decision between surgical debridement or euthanasia. Using arthrography, evaluation of the size and patency of the communicating canal to a subchondral cystic defect better separated cases with long, narrow and poorly patent canals for conservative rather than surgical therapy.
Osteochondral fragmentation of the distal aspect of the patella in horses
Authors: MclLWRAITH C. WAYNE
Published: April 2010

A condition characterised by osteochondral fragmentation of the distal aspect of the patella in 15 horses is described. The problem was unilateral in six horses and bilateral in nine. There were eight Quarterhorses, three Thoroughbreds, two American Saddlebreds, one American Paint and one Warmblood‐Thoroughbred cross. A previous medial patellar desmotomy had been performed on 12 of the 15 horses. The condition manifested as hindlimb lameness and stiffness ranging from mild to severe. There was fibrous thickening in the stifle area in the 12 cases with a previous medial patellar desmotomy, and synovial effusion in seven of 12 cases. Synovial effusion was present in two of the three cases in which a previous medial patellar desmotomy was not performed. The radiographic changes included bony fragmentation, spurring (with or without an associated subchondral defect), subchondral roughening and subchondral lysis of the distal aspect of the patella. All horses were treated with arthroscopic surgery. The lesions at arthroscopy varied from flaking, fissuring, undermining or fragmentation of the articular cartilage to fragmentation or lysis of the bone at the distal aspect of the patella. The subchondral bone was involved in all cases that had a previous medial patellar desmotomy. Of the 12 horses that had a previous medial patellar desmotomy, eight became sound at their intended use, one was sold in training without problems, one is in early training without problems, one never improved and one is in convalescence. Of the three that did not have a patellar desmotomy, two performed their intended use well but one was unsatisfactory.