bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetics of V̇O2 and V̇CO2 in the horse and comparison of five methods for determination of maximum oxygen uptake
Authors: ROSE R. J. , HODGSON D. R. , BAYLY W. M. , GOLLNICK P. D. 
Published: June 2010

SummaryTo determine whether maximum oxygen uptake (VO2max) in the horse is influenced by type of exercise test, five different protocols were evaluated in eight untrained Thoroughbreds exercised on a treadmill. With all protocols, horses were given a 5 min warm‐up on a 10 per cent treadmill slope. Three protocols were at a 10 per cent slope and included: 1) increasing the running speed by 1 to 2 m/sec every 60 sees from 4 m/sec to a maximum of 12 m/sec; 2) running at 12 m/sec until fatigue; and 3) running for 3 to 4 mins at speeds ranging from 6 to 12 m/sec with rest pauses between exercise bouts. The fourth protocol employed a 24 per cent slope where animals exercised for 5 mins at 2 m/sec followed by 3 mins at 5 m/sec, and 2 mins at 6 m/sec. The fifth test involved running at 11 m/sec while the slope of the surface was increased every 2 mins until the horses could not maintain the pace. A plateau in V̇O2 occurred in all protocols except when exercise was performed on a 24 per cent slope. Slow speed exercise at a steep grade (24 per cent) produced the highest V̇O2 (P<0.05) even though there was no plateau in the V̇O2. A steady state for V̇O2 and V̇CO2 existed 90 secs after the onset of exercise with all protocols which involved 2 mins or more at each speed. The V̇O2 and V̇CO2 values at all speeds of the rapid incremental exercise test were not different to those found at steady state in the third exercise protocol.
Some factors influencing plasma AST/CK activities in Thoroughbred racehorses
Authors: HARRIS PAT A. , SNOW D. H. , GREET T. R. C. , ROSSDALE P. D. 
Published: June 2010

SummarySixty‐six Thoroughbred horses in training (2 or 3 years of age) were studied during one flat racing season, to investigate the relationship between age, sex, time of year, dietary electrolyte imbalances and plasma aspartate aminotransferase/creatine kinase (AST/CK) activities. Management and training variations were minimised. Between February to October, monthly 24 h post exercise samples were collected and analysed for AST and CK activities. Sex and/or age were shown to have a significant effect on the occurrence of high CK (>100 iu/litre) and AST (> 300 iu/litre) activities. Fillies were more likely to have elevated CK and AST than colts. Two‐year‐olds tended to have higher AST activities than three‐year‐olds. Time of year had no significant effect on the number of animals with high or low activities. Fourteen animals had consistently raised plasma AST activities (median >300 iu/litre). Eight of these raced and seven won at least one race. The average daily intake of calcium, sodium, phosphorus and potassium was determined at each sampling time. In eight of the horses, the fractional electrolyte excretion (FE) of phosphate (PO4) and sodium (Na) was determined monthly. FE values were also determined in three horses which had suffered repeated attacks of the equine rhabdomyolysis syndrome. The FE, PO4 and Na values reflected dietary intake of calcium, phosphorus and sodium respectively. It was not possible to determine any effect of training or a predisposition to equine rhabdomyolysis. No obvious differences were found between the resting thyroxine values of three animals with consistently low AST activities, six of those with consistently raised AST and three animals which had suffered repeated attacks of rhabdomyolysis.
The effect of an acute angulation of the hind hooves on diagonal synchrony of trotting horses
Authors: CLAYTON HILARY M. 
Published: June 2010

SummaryHigh speed cinematography was used to measure the timing and distance characteristics of the trot in the five sound horses. Two farriery treatments were compared: (1) normal, in which the dorsal hoof wall was aligned with the pastern axis in all four feet and (2) acute hind hoof angulation, in which the hind toes were allowed to grow relatively longer than the heels, so that the angulation was approximately 10° lower than the normal hind hoof angle for the individual animal. Comparison between the two treatments showed that the acute hind hoof angulation was associated with significant increases in hind limb breakover time (P=0.001), overreach distance (P=0.001) and overreach duration (P=0.017), whereas stride length, forelimb breakover and diagonal distance did not change (P>0.05). In the majority of horses, limb movements at the start and end of the diagonal stance phase were slightly asynchronous, so that when the hooves were trimmed normally the hind limb more often preceded the diagonal forelimb at impact and lift off. The prolongation of hind limb breakover due to the acute hind hoof angulation was associated with a tendency for the hind limb to lift off later than the forelimb. The difference in lift off sequence between the two farriery treatments was highly significant (P=0.001). During the swing phase the normal coordination was restored and there was no significant difference in the impact sequence with the normal and acute hind hoof angulations (P>0.05).
Follow‐up of 28 horses with third metacarpal unicortical stress fractures following treatment with osteostixis
Authors: HANIE E. A. , SULLINS K. E. , WHITE N. A. 
Published: June 2010

SummaryThe results of 31 intracortical dorsal metacarpal stress fractures in 28 horses following unicortical osteostixis were reviewed. The incidence was predominately in the middle third of the lateral aspect of the left metacarpus, and males were affected more commonly. Approximately half of the surgical procedures were perfomed with the horse in the standing position. The mean times to return to training and racing were 4.25 and 6.9 months respectively. There was no correlation between time taken to return to racing and position of surgery. Complications experienced included lack of suture removal and one case with a seroma.
A comparison of injectable anaesthetic regimens in mules
Authors: MATTHEWS NORA S. , TAYLOR T. S. , SKROBARCEK CINDY L. , WILLIAMS J. D. 
Published: June 2010

SummaryThree combinations of injectable anaesthetic agents were compared in nine adult mules. The combinations were xylazine/ketamine (X/K), xylazine/butorphanol/ketamine (X/B/K), and xylazine/tiletamine‐zolazepam (X/T). Measured variables were heart rate, respiratory rate, systolic blood pressure, arterial blood pH, PCO2and PO2, recumbency time and number of attempts to stand. Quality of induction and recovery, muscle relaxation and response to stimulus were evaluated subjectively. Recumbency time was significantly (P<0.05) longer with X/B/K and X/T than with X/K. Mules required significantly more attempts to stand under the influence of X/T than X/K or X/B/K. No statistically significant (P<0.05) differences in heart rate, respiratory rate, blood pressure or arterial pH, PCO2and PO2were detected between groups.
The pharmacology and pharmacokinetics of high‐dose methocarbamol in horses
Authors: III W.W. MUIR , SAMS R.A. , ASHCRAFT SUSAN 
Published: June 2010

SummaryThe haemodynamic, respiratory and behavioural effects and pharmacokinetics of methocarbamol were studied in eight healthy, adult horses after intravenous (iv) and oral administration of large dosages. Heart rate, cardiac output, mean pulmonary arterial blood pressure, systolic, diastolic and mean aortic blood pressure, respiratory rate and arterial blood gases did not change after either iv (30 mg/kg bodyweight [bwt]) or oral (50 and 100 mg/kg bwt) dosages of methocarbamol. Mild to moderate depression was observed in five of eight horses administered iv methocarbamol, and in all horses administered oral methocarbamol. Plasma methocarbamol concentration declined very rapidly during the initial or rapid disposition phase after iv administration; the terminal elimination half‐life ranged from 59 to 90 mins. Peak plasma methocarbamol concentrations following oral administration occurred within 15 to 45 mins and oral bioavailability ranged from 50.7 to 124 per cent.
Pharmacokinetics and metabolism of intravenous doxapram in horses
Authors: SAMS R. A. , DETRA R. L. , III W. W. MUIR 
Published: June 2010

SummaryThe pharmacokinetics and metabolism of doxapram in horses administered intravenous (iv) doses of 0.275, 0.55 and 1.1 mg doxapram/kg bodyweight (bwt) were investigated. Plasma doxapram concentrations decreased rapidly after drug administration and the disappearance of doxapram from plasma was best described by a polyexponential equation. Median values of total body clearance were 10.9, 10.6 and 10.9 ml/min/kg bwt for the three doses and were independent of dose. The steady‐state volume of distribution was approximately 1,200 ml/kg bwt and the median biological half‐life ranged from 121 to 178 mins. Plasma protein binding of doxapram ranged from 76.0 to 85.4 per cent. The blood:plasma doxapram concentration ratio was approximately 0.8 and the affinity of the red blood cells for doxapram ranged from 2.0 to 2.8 indicating sequestration of doxapram in erythrocytes. Renal clearance of doxapram was a minor route of elimination. Metabolic clearance of doxapram appeared to be a major route of elimination. Four metabolites of doxapram were isolated from urine and were identified. The metabolites were: a) 1‐ethyl‐4‐[(2‐hydroxyethyl) amino]ethyl‐3,3‐diphenyl‐2‐pyr‐rolidinone, b) a glucuronic acid or sulphuric acid conjugate of 1‐ethyl‐3‐(hydroxyphenyl)‐4‐(2‐morpholinoethyl)‐3‐phenyl‐pyr‐rolidinone, c) 3,3‐diphenyl‐4‐(2‐morpholinoethyl)‐2‐pyr‐rolidinone and d) 1‐(2‐hydroxyethyl)‐3,3‐diphenyl‐4‐(2‐morpholinoethyl)‐2‐pyr‐rolidinone. The rapid disappearance of doxapram from plasma immediately after iv administration was attributed to redistribution of the drug from plasma to other tissues. The short duration of clinical effect from doxapram may be attributed to redistribution of the drug from plasma and other well‐perfused tissues, such as the brain, to less well‐perfused tissues such as the skeletal muscles and adipose tissue. Continuous or repeated administration of doxapram could prolong the duration of clinical effect because re‐distribution is less important as steady‐state conditions are approached.
Sympatho‐adrenal activity and the clinical sedative effect of detomidine in horses
Authors: RAEKALLIO MARJA , LEINO ANNE , VAINIO O. , SCHEININ MIKA 
Published: June 2010

SummaryThirty‐nine horses were given detomidine 10 μg/kg bodyweight (bwt) intravenously (iv) and six horses were given a corresponding volume of saline solution before minor procedures. Venous blood samples were collected for catecholamine and cortisol determination immediately before the detomidine or saline injection and 20 mins after it. The behaviour of the horse at the time of detomidine injection and the extent of sedation were evaluated. Plasma adrenaline, noradrenaline and the catecholamine metabolites, 3,4‐dihydroxyphenylglycol (DHPG) and 3,4‐dihydroxyphenylacetic acid (DOPAC), and cortisol concentrations decreased significantly after administration of detomidine, but they remained unchanged in the control group. A high plasma adrenaline concentration before detomidine injection, indicative of a high level of stress, seemed to correspond with a reduced sedative effect of detomidine. The extent of sedation also was related to the concentrations of adrenaline, noradrenaline and DHPG in plasma after the detomidine injection. The reductions in the plasma catecholamine concentrations may have been caused, in part, by decreased secretion of catecholamines due to the sedative effects of detomidine; but detomidine also influences the plasma catecholamine concentrations by reducing directly sympatho‐adrenal activity.
Pharmacokinetics of tolfenamic acid in the horse
Authors: JAUSSAUD P. , GUIEU D. , BELLON C. , BARBIER B. , LHOPITAL M. C. , SECHET R. , COURTOT D. , TOUTAIN P. L. 
Published: June 2010

SummaryThe pharmacokinetics of tolfenamic acid were studied in five ponies after an intravenous (iv) administration (2 mg/kg bodyweight [bwt]) and in four horses after an oral administration (30 mg/kg bwt) of tolfenamic acid. The plasma levels were determined by high pressure liquid chromatography (HPLC) and gas chromatography‐mass spectrometry (GC‐MS). For the iv administration, a three‐compartment model was used to represent the plasma concentration‐time curve of the drug. The elimination half‐life of the compound was 6.1 ± 1.5 h, the total body clearance was 72.4 ± 16.7 ml/kg bwt/h and the steady‐state volume of distribution 0.32 ± 0.11 litres/kg bwt. For the oral administration, absorbtion was delayed with a mean lag‐time to absorption of 32 ± 28 mins. The peak plasma concentration 11.1 ± 0.69 μg/ml was observed after a highly variable delay ranging from 1.9 to 6.5 h post administration. The terminal half‐life (4.2 ± 0.48 h) was very similar; to that obtained after iv administration. Tolfenamic acid could not be detected in equine plasma with the described analytical methods more than 48 h after drug administration.
Investigations into the incidence of field colic
Authors: Uhlinger Christine 
Published: June 2010

SummaryThis investigation was undertaken to compare the accuracy of different methods of collecting data on the incidence of colic. The results of an historical cohort technique and a questionnaire survey were compared with those obtained from a prospective cohort study. In a separate analysis, the practical application of the historical cohort method was used to estimate the incidence of colic in horses owned by regular clients of a general equine practice.Horses from 14 herds were used in Part 1 of the study, to gather the prospective cohort, historical cohort and questionnaire data. The prospective cohort method recorded 91 episodes of colic in 349.1 horse years, generating an incidence of 0.26 cases/horse‐year at risk. The historical cohort method, based on an analysis of billing records, identified 82 colic cases in 370 horse‐years at risk, under‐counting colic cases and overestimating the population at risk. However, the summary estimate of 0.22 cases/horse‐year at risk did not differ significantly from that generated by the prospective cohort study (P / 0.18). The questionnaire based survey identified 112 colic cases in 313 horse‐years at risk, over‐counting cases and under‐counting the population at risk. The incidence estimate was 0.36, which differed significantly from that found in the prospective cohort survey (P = 0.008).The second part of this investigation used the validated historical cohort method to estimate the incidence of colic in animals owned by clients of a University field service practice. The incidence estimated in this population was 0.19 cases/horse year at risk. This incidence may be generalised to groups of mature performance and pleasure horses using veterinary services regularly for herd health activities.
Identification of tumour necrosis factor in the blood and peritoneal fluid of horses with colic
Authors: May S. A. , Spiers Susan , Carter S. D. , Bennett D. , Edwards G. B. 
Published: June 2010

SummaryTumour necrosis factor was detected both in the blood and peritoneal fluid of 14 horses with various types of gastrointestinal obstruction. In comparison, tumour necrosis factor was not present in these fluids in 6 normal horses and ponies. The median endotoxin concentration was increased in the blood of horses with colic, but the median interleukin‐1 concentration was not altered in the blood and peritoneal fluid of colic cases in comparison with the normal horses and ponies. This preliminary work supports the hypothesis that tumour necrosis factor is involved in the endotoxaemia which is a consequence of severe gastrointestinal obstructions, and that it is a potential target for medical therapy in such cases.
Duration of antisecretory effects of oral omeprazole in horses with chronic gastric cannulae
Authors: Jenkins Christine C. , Blackford J. T. , Andrews F. , Frazier Donita L. , Mattsson H. , Olovsson S.‐G. , Peterson A. 
Published: June 2010

SummaryEight female horses with chronic gastric cannulae were given omeprazole as enteric‐coated granules (1.4 mg/kg bwt) via nasogastric tube once daily for 6 days. The effects on basal and pentagastrin‐stimulated gastric acid secretion were determined 5 h after dosing on Days 1 and 5 ofadministration. A third gastric secretion test was done on Day 7, 24 h after the dose on Day 6. Gastric juice volume, pH, acidity, and acid output were determined during a 1‐h basal secretion test followed by a 2‐h pentagastrin‐stimulated (6 μg kg−1 h−1) test.When compared with placebo controls, omeprazole significantly inhibited basal gastric acid output by 72% and pentagastrin‐stimulated acid output by 86% on Day 5. Gastric juice pH was also significantly increased. On Day 7, basal gastric acid output was significantly decreased by 90% and pentagastrin‐stimulated secretion was decreased by 72%. The effect of omeprazole administration on gastric juice volume was variable.Once daily administration of 1.4 mg omeprazole/kg bwt significantly inhibited basal and stimulated gastric acid secretion in horses by the 5th dose. Gastric acid secretion was significantly inhibited for at least 27 h after omeprazole treatment, indicating a long duration of antisecretory effect of the drug in horses.
Placentas and foetal health
Authors: COLLINS MARGARET H. 
Published: June 2010

SummaryThe placenta provides many critical services to the developing foetus. Proper placental implantation, growth and function are necessary for normal foetal growth and development. Placental structure varies widely among species but all mammalian placentas have a convoluted materno‐foetal interface that may be quite simple or highly complex; the more complicated interdigitations tend to characterise smaller placentas that have limited areas of contact between the placenta and the endometrium. The intimacy of the contact between maternal and foetal tissue varies from apposition only, as in the equine placenta, to invasion of maternal vessels by foetal cells, as in man. Abnormalities identified in the human placenta provide insight into maternal and foetal diseases that affect pregnancy outcome.
Endoderm cells of the equine yolk sac from Day 7 until formation of the definitive yolk sac placenta
Authors: ENDERS A. C. , SCHLAFKE S. , LANTZ K. C. , LIU I. K. M. 
Published: June 2010

SummaryOn Day 7 of pregnancy, when the inner cell mass coalesces to one side of the blastocyst, a discontinuous layer of cells is present underlying the inner cell mass and isolated cells were found around the mural trophoblast. As early as Day 8, these cells that were scattered around the blastocyst cavity unite to form a continuous endodermal layer, resulting in a bilaminar blastocyst. The endodermal cells have slightly bulging apical surfaces towards the cavity of the blastocyst, but in many areas have flanges and projections that form complex basolateral compartments within the endoderm and especially between the endoderm and trophoblast. These cells also develop an extensive series of unusual apical ridges. With the development of the primitive streak and the trilaminar blastocyst, angiogenesis proceeds from the forming embryo into the yolk sac. At first the anastomotic vessels form a simple mesh, but by Day 20, erythroblasts are present in the newly formed sinus terminalis. The loss of the capsule (Day 21) and the development of the embryonic circulation establish the relationships of the definitive yolk sac. There is a bilaminar region with endodermal cells showing basolateral compartmentalisation and a specialised sinus terminalis region bordering the choriovitelline placenta. The largest endodermal cells are associated with the choriovitelline placenta, but a substantial cuboidal lining also covers the splanchnopleuric portion of the vascular yolk sac. The allantochorion rapidly assumes predominance in respiratory exchanges, and the choriovitelline placenta not only decreases in relative area but increases in thickness. However, the 3 major regions of the yolk sac persist for several weeks after their formation, and both the vasculature and especially the endodermal cells remain robust despite the decrease in size of the yolk sac. It is concluded that the pleomorphic endodermal cells of the equine yolk sac differentiate in response to local signals. By Day 25 the allantochorion is an increasingly significant exchange unit, and the continued robustness of the vascular portions of the yolk sac and especially its endodermal layer suggests that synthetic and metabolic activities of the endodermal cells will be the dominant function of the yolk sac subsequently.
Embryonic and early foetal development in donkeys
Authors: GASTAL E. L. , SANTOS G. F. , HENRY M. , PIEDADE H. M. 
Published: June 2010

SummaryEmbryo and early foetal development was studied until Day 60 (ovulation = Day 0) in 25 Brazilian jenny donkeys. The occurrence of ovulation and embryonic development was assessed by daily examinations using realtime ultrasonography. An embryonic vesicle, first detected at Day 10.9 ± 0.1 after ovulation, remained mobile within the uterine lumen until Day 16.0 ± 0.5 when it had a diameter of 21.8 ± 1.5 mm. Until immobilised the vesicle was detected in the left horn, right horn and body of the uterus 49.2, 41.8 and 9% of the time respectively. There was a temporal relationship between vesicle expansion, increase in uterine tone and immobilisation of the vesicle.The mean diameter of the embryonic vesicle or conceptus was 3.5, 28.0, 30.9, 45.3 and 59.2 mm on Days 10, 20, 30, 40 and 50, respectively, after ovulation. The vesicle remained spherical up to Day 17.8 ± 0.4 but thereafter became irregular in outline. The embryo was first detected on Day 19.9 ± 0.2 and heart beats were noted on Day 21.8 ± 0.3. The mean values for width x crown‐rump length of the embryo/foetus were 3 times 4, 8 times 12, 11 times 17, 13 times 32 and 19 times 47 mm on Days 20, 30, 40, 50 and 60, respectively. The allantoic sac was first detected between Days 19 and 23 and it occupied approximately 25, 50 and 75% of the embryonic vesicle on Days 30, 33 and 38 respectively. The embryo was situated in the dorsal pole of the vesicle by Day 34.8 ± 0.7 and an umbilical cord was first observed on Day 41.1 ± 0.8, coincident with descent of the foetus.
PGE2 secretion by the conceptus and binding by non‐pregnant endometrium in the horse
Authors: VANDERWALL D. K. , WOODS G. L. , WEBER J. A. , LICHTENWALNER A. B. 
Published: June 2010

SummaryConceptus PGE2secretion was determined by incubating equine conceptuses (7/day)in vitrofor 24 h. Day‐11, ‐13 and ‐15 conceptuses secreted (mean ± sem) 91.2 ± 23.7, 92.8 ± 15.9 and 170.8 ± 24.9 ng PGE2/24 h, respectively. Day‐15 conceptuses secreted more (P<0.05) PGE2than Day‐11 or Day‐13 conceptuses. Conceptus diameter and PGE2secretion were positively correlated (R2= 0.52; P<0.001). Endometrial membrane preparations from non‐pregnant mares (6/day) were incubated with [3H]PGE2and nonradioactive PGE2. The concentrations of unoccupied endometrial PGE2binding sites on Days 11, 13 and 15 were 116.2 ± 17.7, 93.3 ± 12.4 and 57.2 ± 7.3 fmol/mg protein, respectively. The binding site concentration was higher (P<0.05) on Day 11 than Day 15. The dissociation constant of the binding reaction on Days 11, 13 and 15 was 1.94 ± 0.35, 1.55 ± 0.11 and 1.64 ± 0.25 nM, respectively. There was no difference (P>0.10) in the dissociation constant between days. These results demonstrate that equine conceptuses secrete PGE2, and non‐pregnant equine endometrium specifically binds PGE2during the period of maintenance of the corpus luteum.