bluuebunny/crossref_metadata_2025 huggingface dataset:
Enostosis‐like lesions in the long bones of 10 horses: scintigraphic and radiographic features
Authors: BASSAGE L. H. , ROSS M. W.
Published: April 2010

Ten horses admitted for lameness evaluation including bone scintigraphy had enostosis‐like lesions, described scintigraphically as focal or multifocal areas of intense increased radioisotope uptake within the medullary cavity of one or more long bones, and radiographically as one or multiple round to irregularly shaped radiopacities within the medullary cavity, often in close proximity to the nutrient foramen. There were 6 Thoroughbreds, one male, one female and 4 geldings, 3 Standardbreds, all geldings and one Appaloosa gelding; age 3–10 years. Enostosis‐like lesions were seen in the tibia (5 horses), radius (3 horses), humerus (one horse) and third metatarsal bone (MT‐III) (4 horses). The number of affected bones in each horse was 1–3. Of 16 affected limbs, there were 9 hindlimbs and 7 forelimbs. Enostosis‐like lesions were considered a possible cause of lameness in 5 horses, but were considered incidental findings in the other horses. Lesions thought to cause lameness were seen in the tibia (2 horses), MT‐III (one horse) and in the radius (4 horses). Lameness resolved after horses were rested (2–6 months) and given nonsteroidal anti‐inflammatory drugs (4 horses). Follow‐up scintigraphic examination in 3 horses (2, 6 and 9 months later, respectively) revealed normal radioisotope uptake in the affected areas.
Quantification of exercise‐induced pulmonary haemorrhage with bronchoalveolar lavage
Authors: MEYER T. S. , FEDDE M. R. , GAUGHAN E. M. , LANGSETMO I. , ERICKSON H. H.
Published: April 2010

Exercise‐induced pulmonary haemorrhage (EIPH) causes serious economic losses in the horse racing industry. Endoscopic examination indicates that 40–90% of horses exhibit EIPH following sprint exercise, but the limitations of the endoscope prevent diagnosis in many horses. Bronchoalveolar lavage (BAL) was utilised to detect red blood cells (RBCs) in the terminal airways in 6 horses. Two lavages were performed at weekly intervals prior to exercise, one within 90 min after exercise, and 5 at weekly intervals after exercise. The horses were exercised strenuously at 12.5–14.6 m/s on a treadmill (3 degree incline). Heart rates ranged from 192–207 beats/min, and mean pulmonary arterial pressures (mPAP) ranged from 80–102 mmHg. Neither epistaxis nor endoscopic evidence of EIPH was seen in any of the 6 horses following exercise. However, the number of RBCs in the lavage fluid increased significantly over control values immediately after exercise in all horses but returned to control values by one week after exercise.

Haemosiderophages in the BAL fluid did not increase until one week after exercise and remained elevated for 3 weeks after exercise. Twenty per cent of the total population of alveolar macrophages contained haemosiderin. A positive relationship occurred between the number of RBCs in the lavage fluid and mPAP; the amount of haemorrhage increased as the mPAP exceeded 80 to 90 mmHg. The results with BAL used as the diagnostic tool, suggest that all strenuously exercised horses may exhibit EIPH; the amount of haemorrhage appears to be associated with the magnitude of the high pulmonary arterial pressure.
Absence of detectable pharmacological effects after oral administration of isoxsuprine
Authors: HARKINS J. D. , MUNDY G. D. , STANLEY S. , WOODS W. E. , SAMS R. A. , RICHARDSON D. R. , GRAMBOW S. C. , TOBIN T.
Published: April 2010

Isoxsuprine is reported to be a peripheral vasodilator used in human and veterinary medicine to treat ischaemic vascular disease. In horses, it is generally administered orally to treat navicular disease and other lower limb problems. To define the scope and duration of its pharmacological responses after oral administration, 6 horses were dosed with isoxsuprine HCl (1.2 mg/kg bwt) q. 12 h for 8 days and then tested to assess the duration and extent of pharmacological actions. There was no significant difference between isoxsuprine and control treatment values for heart rate, spontaneous activity, sweat production, anal muscle tone, core and skin temperatures, and cutaneous blood flow. The lack of pharmacological effect following oral administration was in sharp contrast to the marked response following i.v. dosing reported in earlier experiments.
Effect of intravenous lidocaine on halothane minimum alveolar concentration in ponies
Authors: DOHERTY T. J. , FRAZIER DONITA L.
Published: April 2010

This study investigated the effect of lidocaine i.v. on halothane minimum alveolar concentration (MAC) in ponies. Six ponies were anaesthetised with thiopentone and succinylcholine, intubated and anaesthesia maintained with halothane. Ventilation was controlled and blood pressure maintained within clinically acceptable limits. Following a 2 h equilibration period, baseline halothane MAC was determined. The ponies were then given a loading dose of lidocaine (2.5 or 5 mg/kg bwt) or saline over 5 min, followed by a constant infusion of lidocaine (50 or 100 μg/kg/min, or saline, respectively). The halothane MAC was redetermined after a 60 min infusion of lidocaine or saline. The baseline halothane MAC for the control group was mean ± s.d. 0.94 ± 0.03%, and no significant decrease occurred following saline infusion. Lidocaine decreased halothane MAC in a dose‐dependent fashion (r = 0.86; P<0.0003). The results indicate that i.v. lidocaine may have a role in equine anaesthesia.
Water and electrolyte intake and output in conditioned Thoroughbred horses transported by road
Authors: van den BERG J. S. , GUTHRIE A. J. , MEINTJES R. A. , NURTON J. P. , ADAMSON D. A. , TRAVERS C. W. , LUND R. J. , MOSTERT H. J.
Published: April 2010

The objectives of this trial were to measure the water and electrolyte intake and loss, of horses during road transportation in relatively hot environmental conditions. Six mature, Thoroughbred horses in full training were used in a balanced crossover design. The horses were conditioned on a treadmill for 6 weeks before the start of the trial in order to simulate the type of horse that is transported most often over long distances in South Africa. The horses were assigned randomly to one of 2 treatment groups. On a particular day 3 horses were transported, while the other horses served as controls. One month was allowed before the crossover. Horses in the ‘transport group’ were transported by tarred road in a circular route over 600 km. This allowed the standardisation of measurements and use of the same instruments in both groups. Data were collected in each treatment group during transportation that lasted for 8 h (transport phase) and for 6 h after travelling (recovery phase). The following data were collected or calculated: Water and electrolyte (sodium, potassium and chloride) intake and output, changes in bodyweight and feed consumption. Although water was always available, the transport group failed to drink during transit. Based on bodyweight, the transported horses were 3% dehydrated at the end of transit. This bodyweight loss was corrected within one hour after their return due to a significantly higher water intake compared to control horses. The feed intake in the transported horses was unaffected during travelling, but was decreased for 6 h following transportation. Urinary water loss was similar in the 2 treatment groups during and following transportation. The faecal water loss decreased in the transported horses and remained lower than the control group for 6 h following transit. Total sodium and chloride intake were unaffected, while the potassium intake was decreased during transportation. Sodium and potassium loss via the faeces and urine during the transport period were similar in the 2 treatment groups, whereas potassium output in the transport group was significantly decreased during the recovery period of the study. It was concluded that transportation by road affected the water and electrolyte balance of conditioned horses for a period up to 6 h after travelling.
Serum gentamicin concentrations in compromised neonatal foals
Authors: RAISIS A. L. , HODGSON J. L. , HODGSON D. R.
Published: April 2010

Twenty‐one compromised neonatal foals hospitalised at the Rural Veterinary Centre (RVC) during 1993 were studied to determine i) serum gentamicin concentrations obtained when gentamicin was administered at 3.3 mg/kg bwt twice daily i.m.; ii) factors which contributed to inter‐foal variation in serum gentamicin concentrations achieved and iii) clinical efficacy of gentamicin therapy in foals with confirmed septicaemia. Septicaemia was confirmed in 7 foals with positive blood cultures and suspected in 8 foals with a sepsis score >11. Peak serum concentrations (Ps) were >6 μg/ml in all foals and >8 μg/ml in 60% of foals. Trough serum concentrations (Ts) were <2 μg/ml in all foals. Factors found to produce inter‐foal variation in the Ps achieved included age (<24 h; decreased), bodyweight (<38 kg; decreased) and severity of dehydration (8–12% bodyweight; increased). Clinical response was not associated with achievement of Ps >8 μg/ml, but was negatively influenced by the severity of clinical signs of depression. None of the foals in this study developed septic arthritis or pneumonia during or after therapy. No serum biochemical evidence (i.e. elevated serum creatinine concentrations) of gentamicin‐induced nephrotoxicity was noted during therapy.
Effect of cisapride on gastric emptying in horses following endotoxin treatment
Authors: VALK N. , DOHERTY T. J. , BLACKFORD J. T. , ABRAHA T. W. , FRAZIER DONITA L.
Published: April 2010

The effect of cisapride pretreatment on gastric emptying in horses was determined by measuring serum concentrations of acetaminophen, a drug known to be readily absorbed in the small intestine but not in the stomach. The time to reach maximum serum acetaminophen concentrations (Tmax), the maximum serum concentrations (Cmax) and the area under the serum acetaminophen concentration vs. time curves (AUC) were compared among treatment groups. In the first part of the study, the effect of orally administered cisapride (0.1, 0.2 and 0.4 mg/kg bwt) on gastric emptying was examined in 6 normal fasted horses. In the second part of the study, gastric emptying in horses given endotoxin i.v. (n = 6) was compared to those that received cisaprideper osprior to administration of endotoxin (n = 6) and those that received neither compound (n = 6). Cisapride did not alter gastric emptying in normal horses. Endotoxin caused a profound delay in gastric emptying and pretreatment with cisapride significantly attenuated this effect. It is concluded that cisapride may be useful as a prophylactic measure when administered prior to the development of endotoxaemia.
Environmental control to maintain stabled COPD horses in clinical remission: effects on pulmonary function
Authors: VANDENPUT SANDRINE , DUVIVIER DOMINIQUE H. , VOTION DOMINIQUE , ART TATIANA , LEKEUX P.
Published: April 2010

The objective of this study was to test the hypothesis that stabled COPD horses can be maintained in clinical remission by replacing hay by grass silage and bedding made of wood shavings(Period B)and of wheat straw(Period C)during 6 weeks, respectively. At the end of these different periods, the pulmonary function of the horses was assessed by mechanics of breathing and arterial blood analyses. These results were compared to those measured in clinical remission obtained after 2 months in pasture(Period A).No significant difference was observed between these 3 periods neither to values obtained for healthy horses placed during 6 weeks in a hay environment. For all that, COPD horses placed in contact with hay in the same barn developed within mean ± s.d. 8 ± 3 days clinical signs of heaves and significant alterations of pulmonary function parameters.
Equine ulcerative keratomycosis: visual outcome and ocular survival in 39 cases (1987–1996)
Authors: ANDREW S. E. , BROOKS D. E. , SMITH P. J. , GELATT K. N. , CHMIELEWSKI N. T. , WHITTAKER C. J. G.
Published: April 2010

The medical records of 39 horses treated for ulcerative keratomycosis over a 10 year period were reviewed. Records were evaluated to determine the medical and/or surgical treatment protocol, visual outcome, globe survival and whether the outcome was influenced by the fungal species isolated. Stromal abscesses and iris prolapses caused by fungi were not included. Twenty of the horses underwent medical treatment only, and 19 horses had combined medical and surgical treatment. Most horses had been treated with topical antibiotics (n = 32) and atropine sulphate (n = 23) prior to referral; topical antifungals had been employed less frequently (n = 14). Fungi were identified by cytology (n = 31), culture (n = 33) and/or surgical histopathology (n = 6).Aspergillus(n = 13) andFusarium(n = 10) were the most commonly isolated fungi. Miconazole (n = 35) was the most common topical antifungal medication utilised. Median duration of treatment was 48 days (range 31–192 days). Associated bacterial infection (n = 13) was frequently encountered. Visual outcome was favourable in 36/39 (92.3%) eyes. All eyes (20/20) retained vision following medical management only, and 16/19 (84%) retained vision following combined medical and surgical therapy. All medically treated horses (20/20), and 17/19 (89%) of those treated medically and surgically retained their globes. Overall ocular survival was favourable in 37/39 (94.9%) eyes.

Aggressive therapy can result in successful results for equine ulcerative keratomycosis.
Measurement of cardiac function by transthoracic echocardiography: day to day variability and repeatability in normal Thoroughbred horses
Authors: YOUNG LESLEY E. , SCOTT G. R.
Published: April 2010

In order to assess the reliability and repeatability of transthoracic echocardiography for detecting serial changes in cardiac function in horses, day to day variability of a number of echocardiographic indices of ventricular function were studied. The variables investigated were, from 2‐dimensional (2‐D) and M‐mode echocardiography ‐ aortic diameter in systole (AoS), pulmonary artery diameter in systole (PaS), left ventricular internal diameter in systole (LLVIDS) and diastole (LLVIDd), and left ventricular fractional shortening (%FS) and estimated ejection fraction (EF). From pulsed Doppler echocardiography ‐ maximum velocity (Vmax) and acceleration (dv/dtmax) of aortic and pulmonary arterial blood flow, left and right ventricular velocity time integral (AoVTI and PAVTI) and estimated cardiac output (COLV, and CORV), left and right ventricular ejection time (LVET and RVET) and pre‐ejection period (LVPEP and RVPEP), and heart rate. Maximum velocity of early rapid right ventricular filling (ETV) and late right ventricular filling due to right atrial contraction (ATV) were measured. Maximum deceleration and time for deceleration of early rapid filling (dv/dtTVand dtTV) were also determined.

Seven healthy mature Thoroughbred horses weighing 490–600 kg were studied. The horses' management regimes and environment were standardised and an echocardiographic examination was carried out on each horse at the same time every day for 6 consecutive days. Two statistical measures of repeatability were calculated for each variable: the intraclass correlation coefficient (rI) and the 95% confidence intervals for error free value of a single measurement.

In general, the dimensions and indices of cardiac function derived from 2‐D and M‐mode echocardiography showed better repeatability for individual horses than did the indices derived from Doppler echocardiography. Overall the 95% confidence intervals for an error‐free value of all variables derived from Doppler echocardiography were wide. This must be appreciated when attributing serial measured changes of Doppler echocardiographic variables in an individual animal to effects of a treatment or disease.
Plasma 5‐hydroxytryptamine constricts equine digital blood vesselsin vitro: implications for pathogenesis of acute laminitis
Authors: BAILEY S. R. , ELLIOTT J.
Published: April 2010

Cumulative concentration response curves to 5‐hydroxytryptamine (5‐HT; 10‐10‐10‐4mol/l) were constructed using isolated rings of equine digital, facial, tail and coronary arteries (endothelium intact). 5‐HT was 17.7 and 41 times more potent as a vasoconstrictor of digital arteries than facial and tail arteries respectively. Removal of the endothelium increased the vasoconstrictor potency of 5‐HT in the facial artery by 3.7‐fold (P<0.05) but did not alter the sensitivity of digital arteries to 5‐HT. Coronary arteries failed to contract to 5‐HT. Coronary arteries pre‐contracted with U44069 showed concentration dependent relaxation to 5‐HT, a response which was partially dependent on the presence of the endothelium. No vasorelaxant effects were found in the digital or facial arteries. The concentration of 5‐HT in platelet poor and platelet rich equine plasma was found to be 6.70 ± 1.1 times 10‐8mol/l and 1.77 ± 0.36 times 10‐6mol/l (mean ± s.e.) respectively by high performance liquid chromatography (HPLC). Plasma which contained no detectable platelets had a 5‐HT concentration of 1.12 ± 0.48 times 10‐8mol/l. Isolated digital arteries constricted when exposed to dilutions of platelet poor and platelet depleted equine plasma. These plasma induced contractions were almost completely inhibited by 5‐HT receptor antagonists, ketanserin and methiothepin. The change in isometric tension in rings of equine digital arteryin vitrowas therefore used as a bioassay for plasma 5‐HT and the results obtained by this method showed an excellent correlation (r2= 97.2%, P<0.001) with the concentration estimated by HPLC. Circulating free concentrations of 5‐HT in normal horses may besufficient to constrict digital blood vessels partiallyin vivobut are well below the threshold for contraction of other peripheral blood vessels examined.
Scintigraphic and clinical findings in the Standardbred metatarsophalangeal joint: 114 cases (1993–1995)
Authors: ROSS M. W.
Published: April 2010

To correlate scintigraphic and clinical findings of the metatarsophalangeal joint (MTPJ) in Standardbreds, radiographic findings in horses with confirmed MTPJ lameness, and determine if stress reaction and more advanced bone remodelling occurred in the MTPJ, medical records of 114 Standardbreds admitted between September 1993 and April 1995 in which bone scintigraphy included standing lateral and plantar views of the metatarsophalangeal joint (MTPJ) were reviewed. Images obtained using a large field of view gamma camera were evaluated visually for location, definition and intensity of increased radioisotope uptake (IRU), which was graded as mild, moderate, or intense. Clinical history and lameness examination findings were recorded and, in horses with documented MTPJ lameness, radiographic examination included the 30° (down‐angled) dorsolateral 45° plantaromedial view thought to be useful in evaluation of the plantarolateral condyle of the third metatarsal bone (MtIII).

The most common abnormality, IRU of the plantarolateral aspect of MtIII, was seen in 67 horses, and horses were further classified according to scintigraphic and clinical findings. In 43 horses in which lameness was not localised to the MTPJ, mild (32 horses), moderate (10 horses), and intense (one horse) IRU of MtIII was found. In 24 horses with lameness localised to the MTPJ, moderate (18 horses) and intense (6 horses) IRU was found. Of 18 horses with moderate IRU of MtIII, 9 had radiographic evidence of abnormal bony remodelling of MtIII, whereas 5 of 6 horses with intense IRU had radiographic changes. In 12 horses with MTPJ lameness and radiographic evidence of bony remodelling without fracture, radiographic changes consisted of plantarolateral subchondral radiolucency and sclerosis (7 horses), radiolucency and osteochondrosis (one horse), and plantar MtIII sclerosis without radiolucency (4 horses). In 2 horses with moderate IRU and MTPJ lameness, radiographic evidence of radiolucency and MtIII fracture was found. Of 19 starters with MTPJ lameness and IRU of MtIII, 18 horses raced after diagnosis, but only 13 remained at the same racing class or improved.

The results of this study suggest the most common scintigraphic abnormality of the MTPJ, IRU of the plantarolateral aspect of MtIII, may precede other stress‐related changes, and in some horses is associated with a continuum of stress‐related subchondral bone remodelling which results in lameness and later radiographic changes. Since 24 of 35 horses with moderate or intense IRU of MtIII had MTPJ lameness, and 5 of 7 horses with intense IRU of MtIII had lameness and radiographic evidence of abnormal remodelling, it was concluded that horses with advanced, scintigraphic findings are more likely to have lameness and radiographic evidence of subchondral bone damage.
Behavioural changes in stabled horses given nontherapeutic levels of virginiamycin
Authors: JOHNSON K. G. , TYRRELL J. , ROWE J. B. , PETHICK D. W.
Published: April 2010

Abnormal behaviour commonly develops in intensively managed horses. A possible cause is the change in diet occurring when the horse is stabled. An experiment was performed to examine this possibility by manipulating the diet with the feed supplement virginiamycin, as Founderguard. During 4 weeks, 18 horses were fed diets ranging from hay alone to concentrate plus hay in the ratio of 3:1. The rations of half the horses given concentrate were supplemented with Founderguard. Horses eating high concentrate rations displayed abnormal oral behaviours at a higher frequency than those eating only hay. The incidence of these behaviours was reduced when diets were supplemented with Founderguard. The drop in faecal pH of animals on concentrate diets was also reduced by Founderguard. Animals on concentrate diets had an average of 21 kg less gut fill post mortem. Dietary supplementation with virginiamycin as Founderguard apparently lessens some behavioural problems associated with management of stabled horses and the intake of grain. It may allow concentrate to be fed at higher levels than customary without adverse behavioural side effects. The suggested mechanism for the improved behaviour due to Founderguard supplementation is reduced fermentative acidosis in the hindgut.
Cardiopulmonary changes associated with abdominal insufflation of carbon dioxide in mechanically ventilated, dorsally recumbent, halothane anaesthetised horses
Authors: DONALDSON LYDIA L. , TROSTLE S. S. , WHITE N. A.
Published: April 2010

The use of laparoscopy for the diagnosis or therapeutic management of abdominal disease in the horse has distinct advantages when it allows the horse to remain standing. However, distending the abdomen by insufflation of a biologically active gas in an anaesthetised horse may add to the physiological challenge of general anaesthesia and recumbency. The cardiopulmonary responses to abdominal insufflation with carbon dioxide (CO2) to 15 mmHg pressure were evaluated in 6 horses in dorsal recumbency anaesthetised with halothane in oxygen and subjected to laparoscopic colopexy. Vaporiser settings targeted a fractional expired halothane of 1.5 MAC and a clinically acceptable depth of anaesthesia. Pressure and rate controlled positive pressure ventilation was adjusted to an ETCO2of 35 mmHg before abdominal insufflation and was not changed thereafter. Cardiopulmonary data were collected before, at 30 and 60 min during and 30 min after CO2insufflation. ANOVA for repeated measures followed by Tukey's protectedttest were used to determine differences. Partial pressure of oxygen and pH of arterial blood, tidal volume and systemic vascular resistance decreased during abdominal insufflation and laparoscopic surgery whereas mean arterial blood pressure, right atrial pressure, cardiac index, stroke index, partial pressure of CO2in arterial blood and end tidal respiratory gases, and calculated physiological shunt increased significantly. Only systemic vascular resistance returned to the pre‐insufflation level after de‐sufflation. The hypercapnia, acidosis and apparent increase in cardiac work that accompany CO2pneumoperitoneum for laparoscopic surgery could place the anaesthetised horse at additional risk of perioperative complications.
Effects of inhaled beclomethasone dipropionate on respiratory function in horses with chronic obstructive pulmonary disease (COPD)
Authors: AMMANN V. J. , VRINS A. A. , LAVOIE J.‐P.
Published: April 2010

The effects of beclomethasone dipropionate on pulmonary function and arterial blood gas values were investigated in horses with chronic obstructive pulmonary disease (COPD). Six mature mares, diagnosed as having COPD based on clinical signs, cytological examination of bronchoalveolar lavage and pulmonary function testing, were used. Beclomethasone dipropionate (3750 μg) was administered b.i.d. for a 2 week period with a metered dose inhaler using a mask. Pulmonary function tests and arterial blood gas analyses were performed at weekly intervals, starting before beclomethasone administration and for 4 weeks thereafter. Upper airway endoscopy and nasopharyngeal fungal cultures were performed before and after treatment.

Maximal variations in transpulmonary pressure (ΔPL) were elevated in all horses at baseline. Beclomethasone administration resulted in a significant decrease in ΔPL, in 5 horses, and ΔPL, fell to within the normal range in 4 horses. Two weeks after the end of treatment, ΔPL. was at or above baseline values in all horses. Total pulmonary resistance and elastance decreased significantly during treatment and returned to or above baseline values after the administration of beclomethasone was discontinued. At baseline, PaO2range was 53–90 mmHg. In 4 horses with pronounced laboured breathing, PaO2increased with treatment. One horse became reluctant to inhale the beclomethasone after one week, and only a transient improvement in respiratory function was noted in this animal. One horse developed a mild lower airway infection 24 h after the beginning of treatment, but no other possible side effects were noticed. Pharyngeal fungal cultures were negative before and after treatment.

It can be concluded from the results of this study that inhaled beclomethasone dipropionate causes a marked improvement of respiratory function in horses with COPD.
Reconstruction of the jugular vein in horses with post thrombophlebitis stenosis using saphenous vein graft
Authors: RIJKENHUIZEN A. B. M. , VAN SWIETEN H. A.
Published: April 2010

A surgical technique is described in which a saphenous vein graft is used to reconstruct the jugular vein in horses with facial oedema due to post thrombophlebitic stenosis of the jugular vein. The saphenous vein was harvested from the contralateral limb and implanted in the occluded vein by 2 side‐to‐end anastomoses. Intra‐ and post operatively anticoagulative medication was administered. In 2 out of 3 patients the reconstruction resulted in a permanent patent graft and resolution of the facial oedema. In one patient the graft thrombosed.
Fluid administration attenuates the haemodynamic effect of frusemide in running horses
Authors: HINCHCLIFF K. W. , MCKEEVER K. H.
Published: April 2010

The effect of blood volume repletion after frusemide administration on the right atrial and pulmonary artery pressure responses of horses to exercise has not been reported. We examined right atrial and pulmonary artery pressure and plasma atrial natriuretic peptide concentration (ANP) responses to an incremental exercise test in 6 Standardbred mares. Horses were treated, in a 3 way cross over design, with isotonic saline, frusemide (1 mg/kg bwt, i.v.), and frusemide followed 3 h later by lactated Ringer's solution (12 ml/kg bwt, i.v.). Three and a half hours after saline or frusemide administration the horses completed a standard exercise test. Frusemide significantly affected the right atrial and pulmonary artery pressure and ANP responses to exercise. Fluid administration decreased plasma total protein concentrations at rest and during running and abolished the effects of frusemide on the haemodynamic and ANP responses to exercise. These results suggest that the haemodynamic effect of frusemide in running horses is mediated, in large part, by a reduction in plasma and blood volume.
Electromyographic activity of the long digital extensor muscle in the exercising Thoroughbred horse
Authors: CHEUNG T. K. , WARREN L. K. , LAWRENCE L. M. , THOMPSON K. N.
Published: April 2010

Surface electrodes were used to record electromyographic (EMG) activity of the long digital extensor muscle on the right hindlimb of 8 Thoroughbred horses for 8 s at the walk and 8 s at the trot before (unfatigued) and after (fatigued) an exercise test. The exercise test was performed on a motorised treadmill set on a 10% grade. Each test started at a speed of 6 m/s which was increased by 1 m/s each minute until the horse fatigued as indicated by its inability to keep pace with the treadmill with minimal encouragement. Observations were made on the horses prior to conditioning (untrained state) and after 8 weeks of regular exercise (trained state). The mean root‐mean‐square (rms) values of EMG bursts collected in each experimental trial were determined for each horse and group means were derived from the mean of independent subjects. Statistical comparisons for differences in rmsEMG were related to gait, fatigue and training. Mean rmsEMG at the trot was consistently higher than at the walk (P<0.05). At the walk, mean fatigued rmsEMG tended to be higher than the mean unfatigued rmsEMG in the untrained state and was significantly higher in the trained state (P<0.05). At the trot, mean fatigued rmsEMG was higher (P<0.05) than mean unfatigued rmsEMG in both the untrained and trained states. Training did not have an effect on mean rmsEMG of unfatigued muscles at the walk or the trot (P>0.05). However, fatigued muscles experienced higher EMG activity in the trained state at the walk (P<0.05). A similar tendency was observed at the trot. Results of this study suggest that surface EMG measurement may be useful for evaluating fatigue in exercising horses.
Post traumatic keratouveitis in horses
Authors: MOORE C. P. , HALENDA RUTH M. , GREVAN VICKIE L. R. , COLLINS B. K.
Published: April 2010

Traumatic keratouveitis in horses is characterised by a unilateral, aseptic, vascularising keratitis accompanied by moderate to severe anterior uveitis. In a series of 9 cases of post traumatic keratouveitis, topical and systemic nonsteroidal drugs and atropine were used to control the anterior uveitis while allowing spontaneous corneal healing. Among the 9 cases reported, 6 affected eyes previously treated with local corticosteroids took significantly longer to resolve when compared to 3 eyes in which corticosteroids had not been administered. It was concluded that, in cases of equine post traumatic keratouveitis, locally administered corticosteroids inhibit healing of damaged corneal stroma and, by prolonging the keratitis, perpetuate the concurrent anterior uveitis.
Stress fractures of the vertebral lamina and pelvis in Thoroughbred racehorses
Authors: HAUSSLER K. K. , STOVER SUSAN M.
Published: April 2010

Thirty‐six Thoroughbred racehorses that died at California racetracks between October 1993 and July 1994 were evaluated for stress fractures in the caudal portion of the thoracic and lumbosacral regions of the spine and the pelvis. The lumbosacral spine and pelvis were collected, debrided of soft tissues and examined visually for the presence of an incomplete fracture line and focal periosteal proliferation, characteristic of a stress fracture.

Sixty‐one per cent of specimens had evidence of stress fracture in the caudal portion of the thoracic and lumbosacral regions of the spine and the pelvis. Vertebral lamina stress fractures were found in 50% of specimens and were positively associated with the severity of dorsal spinous process impingement and overall severity of articular process degenerative changes. Pelvic stress fractures affected 28% of specimens and occurred more frequently in older horses. Pelvic stress fractures were positively associated with the severity of lumbar transverse process impingement and several ilial articular surface degenerative changes.

A high prevalence of vertebral and pelvic stress fractures was noted in this sample of Thoroughbred racehorses that died because of unrelated injuries. Vertebral and pelvic stress fractures need to be considered in the clinical evaluation of horses with back problems or hindlimb lameness. Undiagnosed stress fractures of the vertebrae or pelvis could be a significant cause of poor performance and lameness in Thoroughbred racehorses.
Net joint moments and powers in the equine forelimb during the stance phase of the trot
Authors: CLAYTON HILARY M. , LANOVAZ J. L. , SCHAMHARDT H. C. , WILLEMEN M. A. , COLBORNE G. R.
Published: April 2010

The objective of this study was to provide normative data describing the net joint moments and joint powers for the stance phase of the forelimb in trotting horses. Kinematic and force plate data, synchronised in time and space, were collected for the right forelimb of 6 Warmblood horses moving at a trot. The 3‐D kinematic data were collapsed onto a sagittal plane, and were combined with the vertical and longitudinal ground reaction forces and with segment morphometric data to calculate net joint moments in the sagittal plane across the distal interphalangeal (coffin), metacarpophalangeal (fetlock), carpal, elbow and shoulder joints. The joint mechanical power was calculated as the product of the joint moment and the joint's angular velocity. Major peaks on the moment and power curves were identified.

Each joint showed consistent and repeatable patterns in the net joint moments and joint powers. During most of stance the net joint moment was on the caudal/palmar side of all joints except the shoulder. At the coffin joint the power profile indicated an energy absorbing function that peaked at 74% stance, which coincided with the maximal longitudinal propulsive force. The fetlock joint behaved as an elastic spring; energy was absorbed in the first half of stance as the flexor tendons and SL stored elastic energy, which was released in the second half of stance as a result of elastic recoil. The carpus did not appear to play an important role in energy absorption or propulsion. Both the elbow and shoulder joints showed what appeared to be phases of elastic energy storage and release in the middle part of the stance phase, followed by a propulsive function at the shoulder in the later part of stance. The fetlock, carpus and elbow showed virtually no net generation or absorption of energy. The net energy generation at the shoulder joint was approximately equal to the energy absorption at the coffin joint.

In human subjects specific gait pathologies produce characteristic alterations in the shape of the power profile as well as changes in the amount of energy absorbed and generated at the joints. In horses evaluation of net joint moments and joint powers will further our understanding of the mechanics and energetics of lameness, and may prove to be a useful diagnostic tool. An understanding of the function and dysfunction of different anatomical structures will facilitate the interpretation of clinical findings in terms of mechanical deficits.
Maintenance of anaesthesia with sevoflurane and oxygen in mechanically‐ventilated horses subjected to exploratory laparotomy treated with intra‐ and post operative anaesthetic adjuncts
Authors: CARROLL GWENDOLYN L. , HOOPER R. N. , RAINS C. B. , MARTINEZ ELIZABETH A. , MATTHEWS NORA S. , HARTSFIELD SANDEE M. , BELEAU M. H.
Published: April 2010

Eight healthy horses premedicated with xylazine and induced with ketamine were used to evaluate sevoflurane in oxygen for maintenance of anaesthesia during elective exploratory laparotomy. After orotracheal intubation, horses were hoisted, placed in dorsal recumbency on a padded surgery table, and received sevoflurane in oxygen for maintenance of anaesthesia. The horses were allowed to breathe spontaneously until instrumented; then, they were mechanically ventilated to maintain the PaCO2between 35 and 45 mmHg. Systolic (SAP), diastolic (DAP), and mean (MAP) arterial blood pressures, heart rate (HR), ECG, respiratory rate, an estimation of the saturation of haemoglobin with oxygen in peripheral arterial blood (SpO2), nasal temperature, end‐tidal CO2(ETCO2), end‐tidal sevoflurane (ETSEVO), and vaporiser concentration were recorded every 5 min post induction; arterial blood samples were obtained soon after induction, at 30 min after induction, and every hour thereafter until surgery was completed. Recovery data including times from the sevoflurane vaporiser being turned off to first movement, to sternal recumbency, and to standing, number of attempts to stand, and recovery score (between 1 = safe, smooth and 6 = stormy, major injury to horse) were collected. Analysis of variance was performed using physiological data collected over 195 min of anaesthesia, the longest time period during which all 8 horses were instrumented. Time effects (P<0.05) for HR, SAP, DAP, MAP, and nasal temperature were identified. Heart rate peaked at 45 min and declined over the course of the procedure. Arterial blood pressure generally decreased over time. Body temperature decreased over time. From 15 to 195 min mean ETSEVOconcentration ranged from 2.0 to 3.3%, while mean vaporiser settings ranged from 3.7 to 5.5%. Three horses received intra‐operative ketamine; all horses received dobutamine infusions; and 2 horses received intra‐operative calcium‐dextrose. Total anaesthesia time was 222–316 min (mean ± s.d. 269 ± 31 min). Time from turning the sevoflurane vaporiser off to first movement was mean ± s.d. 18 ± 15 min; to sternal recumbency was 54 ± 22 min; to standing was 65 ± 27 min; and to returning the horse to the stall in the ward was 78 ± 24 min. Six horses stood on the first attempt; 2 horses stood on the second attempt. The median recovery score was one (1–3). In conclusion, sevoflurane provided a stable, easily controllable anaesthetic plane during prolonged exploratory laparotomies; horses experienced smooth, safe recoveries after maintenance of anaesthesia with sevoflurane following routine anaesthetic induction and post operative xyalzine administration.
Thoracoscopy in the horse: diagnostic and therapeutic indications in 28 cases
Authors: VACHON ANNE M. , FISCHER A. T.
Published: April 2010

Thirty‐two thoracoscopies were performed in 28 horses. Sixteen horses were affected with pleuropneumonia whereas 12 were affected with various other thoracic conditions. The indications for thoracoscopy was diagnostic in 19 cases, therapeutic in 11 cases and both diagnostic and therapeutic in 2 cases. Twenty‐six thoracoscopies were done standing whereas 6 were performed under general anaesthesia. The specific procedures performed during thoracoscopy were exploratory only (7), biopsy of the lung and lymph nodes (10), drain placement into pleural effusions (2) and abscesses (5), exploration prior to thoracotomy (2), transection of pleural adhesions and decortication (1) and window pericardectomy (2). Diaphragmatic hernia repair (2) and partial pneumonectomy (1) were initiated thoracoscopically but conversion to thoracotomy was necessary for completion. Standing thoracoscopy was well tolerated in most horses. Transient exacerbation of pulmonary compromise evidenced by tachypnoea was readily alleviated by reinflation of the lung. Standing thoracoscopy provided good visualisation of the dorsal and lateral structures of the thorax. The ventral thoracic structures and the cranial ventral diaphragmatic surfaces of the lungs were best visualised in dorsal or lateral recumbency under general anaesthesia. Thoracoscopy is a safe and useful diagnostic and therapeutic tool in horses with thoracic diseases.
Measurement of parathyroid hormone in horses
Authors: ESTEPA J. C. , AGUILERA‐TEJERO E. , MAYER‐VALOR R. , ALMADÉN Y. , FELSENFELD A. J. , RODRÍGUEZ M.
Published: April 2010

Measurement of parathyroid hormone (PTH) in horses was performed on plasma samples using 2 immunoradiometric assays: a human intact PTH assay and a rat amino‐terminal PTH assay. The assays were validated by assessment of their precision, sensitivity and specificity, and also by evaluating PTH changes in the horse in response to variation in blood ionised calcium. Intra‐ and inter‐assay variance, precision and sensitivity were similar for both human and rat assays; however, the rat assay was slightly more precise and sensitive than the human assay. Both assays detected an increase in PTH levels in the horse when blood ionised calcium was decreased and a decline in PTH concentration with hypercalcaemia. Measurement of PTH concentration in samples from healthy horses with the human assay yielded a mean (± s.e.) value of 31.3 ± 4.1 pg/ml. When using the rat assay, PTH values were 44.1 ± 5.3 pg/ml. Plasma samples held for up to 3 months at −20°C did not show a significant change in PTH concentration. In conclusion, the human intact PTH and the rat amino‐terminal assays detected equine PTH and can be used for measurement of this hormone in horses. Quantification of equine PTH using these assays will allow more precise diagnosis of a variety of disorders affecting mineral metabolism in horses.
Clostridium difficileassociated with acute colitis in mares when their foals are treated with erythromycin and rifampicin forRhodococcus equipneumonia
Authors: BÅVERUD V. , FRANKLIN A. , GUNNARSSON A. , GUSTAFSSON A. , HELLANDER‐EDMAN A.
Published: April 2010

In Sweden, mares sometimes develop acute, often fatal, colitis when their foals are treated orally with erythromycin and rifampicin forRhodococcus (R.) equiinfection.Clostridium (C.) difficile, or its cytotoxin, was demonstrated in faecal samples from 5 of 11 (45%) mares with diarrhoea. By contrastC. difficilewas not found in the faecal flora of 12 healthy mares with foals treated forR. equiinfection or in 56 healthy mares with healthy untreated foals. No other enteric pathogen was isolated from any diarrhoeic mare. Of 7 investigated treated foals, 4 had a high (1651.0, 1468.3, 273.0 and 88.8 μg/g) faecal concentration of erythromycin. The dams of those 4 foals developed acute colitis, whereas the dams of 3 foals with a lower (26.3, 4.6 and 3.7 μg/g) faecal erythromycin concentration remained healthy, indicating that there might have been an accidental intake of erythromycin by mares. The foals treated with antibiotics were regarded as asymptomatic carriers and potential reservoirs, asC. difficilewas found in 7 of 16 foals investigated, while 56 untreated foals proved negative. The isolatedC. difficilestrains proved resistant to both erythromycin (MIC >256 mg/l) and rifampicin (MIC >32 mg/l), a fact that may have favoured the growth ofC. difficilein the foal intestine. All mares found positive forC. difficilewere, or had recently been, hospitalised together with their foals, indicating thatC. difficilemay be a nosocomial infection, in horses. The results emphasise that routine testing forC. difficileand its cytotoxin is recommended when acute colitis occurs in mares when their foals are treated with erythromycin and rifampicin. Preventive measures in order to avoid accidental ingestion of erythromycin by mares from the treatment of their foals are suggested.
Effect of moderate exercise on the severity of clinical signs associated with influenza virus infection in horses
Authors: GROSS DIANE K. , HINCHCLIFF K. W. , FRENCH P. S. , GOCLAN SALLY A. , LAHMERS K. K. , LAUDERDALE MARGARET , ELLIS J. A. , HAINES DEBORAH M. , SLEMONS R. D. , MORLEY P. S.
Published: April 2010

The purpose of this experiment was to determine if exercising horses, infected with influenza virus, exacerbates the severity of clinical disease. Eight horses were trained on a treadmill for 42 days and then challenged with aerosolised influenza A/equine/Kentucky/91 (H3N8). Following challenge, 4 horses (exercise group) continued training for 28 days, while the other 4 horses (nonexercise group) were confined to their stalls. All horses developed clinical signs within 36 h of challenge (fever, coughing, and mucopurulent nasal discharge) and clinical scores were greater in the exercise group. Horses developed fever from Days 1–11 post challenge (PC) and were tachypnoeic and tachycardic from Days 1–14 PC. All horses lost weight within 4 days PC, but the exercise group lost an average of 20 kg more than the nonexercise group. All horses developed pneumonia, and ultrasonography revealed pulmonary consolidation and oedema by Day 7 PC that was resolving by Day 14 PC. Endoscopy and transtracheal aspirates showed airway inflammation for up to 21 days PC. While the exercise group exhibited more severe signs of clinical disease, resolution occurred for both groups on approximately Day 14 PC, and no adverse effects were noted at the end of the study. However, the potential long term effects of exercising horses acutely infected with influenza virus are unknown. Until further research is conducted in this area, it appears prudent not to exercise affected horses.
Muscle anaerobic response to a maximal treadmill exercise test in Standardbred trotters
Authors: SCHUBACK KATARINA , ESSÉN‐GUSTAVSSON BIRGITTA
Published: April 2010

The purpose of this study was to develop a standardised maximal treadmill exercise test performed until fatigue in order to find reproducible markers for anaerobic metabolism, specifically adenine nucleotide degradation. Six Standardbred trotters performed an incremental maximal treadmill exercise test in 1 min steps (starting with 7 m/s) until they could no longer keep pace with the treadmill. The test was performed twice with at least one week between the tests. Heart rate was recorded and venous blood samples were obtained during the test and in the recovery period for determination of plasma lactate, hypoxanthine, xanthine and uric acid. Muscle biopsy samples (m. gluteus) were collected at rest, immediately post exercise, and after 15 min recovery and analysed for their concentrations of glycogen, creatine phosphate (CP), adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP), inosine monophosphate (IMP) and muscle lactate (MLa). Significant decreases in glycogen, CP and ATP and significant increases in IMP and MLa were seen immediately post exercise. None of these metabolites had returned to resting levels after 15 min of recovery. A marked increase in plasma lactate (PLa) occurred during exercise and the peak concentration (mean value = 27.2 mmol/l) was reached within 5 min of recovery. Plasma uric acid concentration did not increase during exercise but rose markedly immediately post exercise, reaching the highest level (mean value = 121.5 pmol/l) at 20–30 min recovery. The duration of the maximal test was related to peak PLa and the uric acid concentration at 30 min of recovery. A correlation was also found between the ATP and IMP concentrations immediately post exercise and the plasma uric acid concentration at 30 min of recovery. The results show that this treadmill test triggered anaerobic metabolism and also that uric acid concentration post exercise seems to be a marker for the adenine nucleotide degradation that occurs during intense exercise. No significant differences were seen in metabolic response between the 2 test occasions.