bluuebunny/crossref_metadata_2025 huggingface dataset:
A comparison of responses to analgesia of the navicular bursa and intra‐articular analgesia of the distal interphalangeal joint in 59 horses
Authors: DYSON SUE J. , KIDD LISA
Published: April 2010

Analgesia of the distal interphalangeal (DIP) joint and of the navicular bursa was performed independently in the lame or lamer forelimb of 59 horses, in which lameness was significantly improved by perineural analgesia of either the palmar digital or palmar (abaxial sesamoid) nerves.

In 3 horses no improvement was detected. Lameness was improved by analgesia of the DIP joint but there was no response to analgesia of the navicular bursa in 3 horses. In 12 horses, lameness was improved by analgesia of the navicular bursa but intra‐articular analgesia resulted in no change. Forty‐one horses responded both to analgesia of the navicular bursa and intra‐articular analgesia of the DIP joint. Synovial fluid was retrieved from all DIP joints but from only one navicular bursa. It is suggested that a positive response to analgesia of the DIP joint does not necessarily imply that pain arises from the jointper se, but a positive response to intra‐bursal analgesia probably reflects pathology of the bursaper se, the navicular bone and/or supporting ligaments and/or the DDFT.

Radiographic abnormalities of the navicular bone in the lame or lamer limb were detected in 35 horses, all of which showed some response to analgesia of the navicular bursa. In 25 of these horses (71%) changes were only identifiable in the palmaroproximal‐palmarodistal oblique views. There was a higher incidence of radiographic abnormalities of the navicular bone in horses in which the response to intraarticular analgesia of the DIP joint was similar (70%) to, or greater (71%) than analgesia of the navicular bursa, compared with the groups in which there was no response (58%) or a lesser response (62%) to intra‐articular analgesia.

The front feet of 6 horses were examinedpost mortem. All horses had pathological abnormalities of the flexor surface of the navicular bone of the lame or lamer limb and in 5 there was associated fibre damage of the opposing deep digital flexor tendon. No abnormalities of the DIP joint were identified.

We suggest that, when possible, if foot pain is suspected, the following analgesic techniques should be performed in sequence, but on different occasions: (1) perineural analgesia of the palmar digital (and when necessary palmar [abaxial sesamoid]) nerves; (2) analgesia of the DIP joint; and (3) analgesia of the navicular bursa.
Effect of surgical removal of endometrial cups on concentrations of chorionic gonadotrophin and subsequent fertility in the mare
Authors: HUBER M. J. , ROSER JANET F. , RIEBOLD T. W. , SCHMOTZER W. B. , GRUBB T. L. , CRISMAN R. O.
Published: April 2010

Seven pregnant mares underwent general anaesthesia, laparotomy, hysterotomy and removal of a 50‐day conceptus. Eversion of the uterine horn through the hysterotomy site allowed direct visualisation and electrosurgical removal of endometrial cup tissue from 5 randomly selected mares (Nos 1–5), while cup tissue in 2 mares (Nos 6 and 7) was left intact. Two pregnant mares served as unoperated controls (Nos 8 and 9). Efforts to re‐establish pregnancy were initiated 20 days after surgery. Serum samples collected before surgery and during the post‐operative period were analysed for concentration of horse chorionic gonadotrophin (CG) by radioimmunoassay.

Mean (± sd) weight and area of removed tissue was 9.91 ± 4.6 g and 22.4 ± 5.9 cm2, respectively. Concentrations of CG ranging from 3440 to 21,220 ng/ml were highest at the time of cup removal (50 days) and declined thereafter. Peak concentrations of CG at the time of surgery were not linearly correlated (r=−0.59) with mass of excised cup tissue. Individual CG half‐life values for Mares 1–5 ranged from 5.4 to 8.8 days (mean 7.1 ± 1.2 days). Peak CG concentrations occurred 68 days after conception with a rate of disappearance (half‐time) of 13.4 ± 0.4 days in Mares 6 and 7 and at 74 and 78 days after conception with a half‐time of 14.0 ± 5.7 days in Mares 8 and 9.

Mares 1–5 exhibited behavioural oestrus and ovulation 30–44 days after surgery. Pregnancy occurred in 3 mares within 41 days after surgery and was associated with concentrations of CG below 200 ng/ml. Pregnancies developed normally until 120 days when the study was terminated. Sham‐operated control mares failed to exhibit normal oestrous behaviour and ovulation during the 100‐day postoperative period. Uterine tissues from 3 mares examined at necropsy lacked significant gross and microscopic pathology associated with the surgery.
Effects of sodium bicarbonate on cardiorespiratory measurements and exercise capacity in Thoroughbred horses
Authors: LLOYD D. R. , EVANS D. L. , HODGSON D. R. , SUANN C. J. , ROSE R. J.
Published: April 2010

We examined the effects of sodium bicarbonate in 6 Thoroughbred horses during submaximal and maximal treadmill exercise. Cardiorespiratory function was assessed together with the effect on exercise capacity by determining the run time to fatigue at maximal intensities. To discriminate between sodium bicarbonate's alkalinising effects and the fluid shifts that could result from the high osmotic load, we administered an equimolar solution of sodium chloride as a control. The horses were given sodium bicarbonate (1 g/kg bwt) or an equivalent number of moles of sodium chloride by nasogastric tube. Arterial blood samples were collected before exercise and 5 h after treatment, resulting in mean standard bicarbonate values of 39.6 mmol/l in horses treated with sodium bicarbonate compared with 24.2 mmol/l in horses that received saline. The horses were exercised on a treadmill at 40, 60 and 80% of their VO2max for 4, 2 and 2 mins respectively. The horses were walked for 3 mins and accelerated rapidly to a speed approximately equivalent to 110% VO2max and run until fatigued. The horses ran for 170 ± 20 secs (mean ± sem) after administration of sodium bicarbonate compared with 128 ± 13 secs after receiving sodium chloride (P<0.02). At rest and throughout submaximal and maximal exercise, the bicarbonate‐treated horses had significantly lower arterial oxygen tensions and higher arterial carbon dioxide tensions. There were no differences in cardiac output, heart rate, oxygen uptake or carbon dioxide production between the saline and bicarbonate treatments. A second experiment was carried out in which the control group received no treatment. The horses that were given sodium bicarbonate ran for 142 ± 21 secs compared with 182 ± 24 secs for the controls (P=0.05). We conclude that metabolic alkalosis can affect ventilation during exercise and that sodium bicarbonate at an oral dose rate of 1 g/kg bwt significantly affects performance.
Airborne dust and aeroallergen concentration in a horse stable under two different management systems
Authors: WOODS PAMELA S. A. , ROBINSON N. E. , SWANSON M. C. , REED C. E. , BROADSTONE R. V. , DERKSEN F. J.
Published: April 2010

Airborne dust concentration (ADC) was measured in 2 different horse management systems using an Andersen cascade impactor in the box‐stall, and a personal Marple cascade impactor attached to the halter to measure ADC in the breathing zone. The levels of aeroallergens implicated in chronic obstructive pulmonary disease were measured by radioallergosorbent‐inhibition immunoassay. A conventional management system (System C) utilising hay feed and straw bedding, and a recommended environment (System R) utilising wood shaving bedding and a complete pelleted diet were studied. In the stall, total and respirable ADC (geometric mean) were significantly higher in System C (2.55 mg/m3; 0.44 mg/m3, respectively) than in System R (0.70 mg/m3; 0.20 mg/m3, respectively). In System C, the total and respirable ADC in the breathing zone (17.51 mg/m3; 9.28 mg/m3) were much higher than in the stall, but values in both regions were similar in System R (0.52 mg/m3; 0.30 mg/m3). Major aeroallergens were significantly higher in System C than in System R: Micropolyspora faeni (1423 ng/m3 and 705 ng/m3), Aspergillus fumigatus (1823 ng/m3 and 748 ng/m3), and mite allergens (1420 ng/m3 and 761 ng/m3). Measurement of ADC with personal samplers indicates that the very high inhalation challenge in the breathing zone is not reflected in measurements of stall air quality. When compared with System C, System R produced only 3% of the respirable dust burden in the breathing zone and a decreased aeroallergen challenge.
A survey of cardiac auscultatory findings in horses
Authors: PATTESON M. W. , CRIPPS P. J.
Published: April 2010

Auscultation was used to examine 545 horses for cardiac murmurs and some arrhythmias. The most significant finding was the high prevalence of right‐sided holosystolic or pansystolic plateau‐type murmurs compatible with a diagnosis of tricuspid regurgitation in National Hunt racing Thoroughbreds of all ages (16.4%). This condition was found in 4.7% of flat‐racing Thoroughbreds, 3.7% of non‐racing Thoroughbreds and Thoroughbred crosses, and in none of the ponies examined. High prevalences of left‐sided early systolic murmurs (53%), left‐sided early diastolic murmurs (23%), right‐sided early diastolic murmurs (22%) and second degree atrioventricular block (23%) were found in racehorses of both types.
Forelimb lameness associated with radiographic abnormalities of the cervical vertebrae
Authors: RICARDI G. , DYSON SUE J.
Published: April 2010

Eight horses had forelimb lameness which was considered unrelated to primary forelimb pain, but was associated with radiographic abnormalities of one or more cervical vertebrae. There was no evidence of ataxia or weakness. The degree and character of the forelimb lameness varied between horses. In 4 horses, selective local analgesic techniques were used to rule out lameness associated with pain in the forelimb. In the other 4 horses, radiographic examination of the cervical region was performed on the basis of forelimb lameness seen in conjunction with neck stiffness and/or neck pain. Three horses had marked modelling of the synovial articular facet joints in the caudal cervical region; a 4th horse had modelling and a fracture involving the synovial articulation between the 4th and 5th cervical vertebrae. One horse had abnormalities of the intercentral articulation between the 7th cervical and 1st thoracic vertebrae and a discrete mineralised opacity dorsal to it. Two horses had large lucent zones in a vertebral body. One horse had a fracture of the body of the 7th cervical vertebra. Five horses were humanely destroyed, 2 returned to their previous level of activity after a prolonged period of rest and 1 was still being rested at the time of writing.
Familial occurrence of narcolepsy in Miniature Horses
Authors: LUNN D. P. , CUDDON P. A. , SHAFTOE S. , ARCHER R. M.
Published: April 2010

In an investigation of 2 closely related Miniature Horses with a history of excessive sleepiness, depression and episodes of collapse, a diagnosis of narcolepsy was made on the basis of neurological examination and pharmacological testing. Further investigations included electroencephalographic examination (KEG), and analysis of protein content, cell count and monoamine metabolite concentrations of lumbosacral cerebrospinal fluid (CSF). There were no abnormalities noted in the EKGs, and no consistent changes in CSF neurotransmitter metabolites in the narcoleptic horses when compared with 3 normal, unrelated Miniature Horses and 2 related, clinically unaffected animals. The breeding background of the 2 affected horses was investigated and a limited survey of Miniature Horse breeders in North America was conducted. These investigations have shown that narcolepsy is a rare but distinct syndrome in the Miniature Horse, and that the cases described here appear to represent a familial occurrence of the disease.
A study of 118 cases of navicular disease: clinical features
Authors: WRIGHT I. M.
Published: April 2010

The clinical features are reported from 118 horses (mean age 9.2 years) which were diagnosed as suffering from navicular disease using predetermined criteria. The animals were used for a variety of purposes and had been lame for periods between 1 and 72 months. The majority of cases (84.7%) had been treated using various techniques before evaluation. The severity of lameness was related to the duration of clinical signs: 78% of horses were bilaterally affected but there was no left:right limb predominance. Broken foot/pastern axes were recorded in 75% of horses while 45% also exhibited mediolateral foot imbalance. Muscle atrophy was recognised in 77% of animals which appeared to be related to limb affliction.

The cranial phase of the stride was reduced in 38% and caudal phase shortened in 16% of horses. These abnormalities were related to the degree of lameness. Flexion of the distal joints increased the severity of lameness in 64% of the animals while extension was positive in 41% of instances. Turning in the direction of the lame limb exacerbated lameness in 95% of horses. Only 11% of animals responded to the use of hoof testers and 3% to foot percussion.

A range of responses to local analgesia of the palmar digital nerves was recorded but 91% (of 49) of animals exhibited a positive response to local analgesia of the distal interphalangeal joint, and 92% (of 23) of horses responded to local analgesia of the navicular bursa.
A review of cytological specimens from horses with and without clinical signs of respiratory disease
Authors: FREEMAN KATHY P. , ROSZE J. F. , McCLURE J. M. , MANNSMAN R. , PATTON P. E. , NAlLE S.
Published: April 2010

Thirty‐six transtracheal washing (TTW) and 12 bronchoalveolar lavage (BAL) specimens collected in clinical practice from horses with and without respiratory disease were reviewed. Cytological features were considered in accordance with the presenting complaint, clinical signs, clinical diagnoses, microbiological, radiographic and/or endoscopic findings, therapy, and response to therapy.

The trichrome‐stained TTW and BAL specimens were useful in interpreting the results of concurrent microbiological cultures, and determining whether a condition was present based on occurrence of typical cytological features of patterns (e.g. probable allergy, chronic obstruction, uncomplicated exercise‐induced pulmonary haemorrhage), determining pathological/anatomical diagnoses (e.g. bronchitis, bronchiolitis and/or alveolitis; presence of metaplasia or dysplasia) and possible aetiologies (eg. allergy, bacterial infection). Review of these cases confirmed the practicality of using cytological specimens to evaluate the equine respiratory tract; there were few unsatisfactory specimens and no reported complications.

The importance of cytological evaluation of the equine respiratory system was emphasised by the identification of 13 cases in which clinical signs were not apparent at physical examination. Sequential collections of cytological specimens from foals, young horses before and during early training, and mature horses in training may provide more information about the response of the equine lung to stresses associated with training and/or common environmental exposures.
Metabolic response to standardised exercise test in Standardbred trotters with red cell hypervolaemia
Authors: PÖSÖ A. R. , ESSÉN‐GUSTAVSSON B. , PERSSON S. G. B.
Published: April 2010

Plasma concentrations of lactate, amino acids, ammonia and products of purine catabolism were studied before, during and after a standardised incremental exercise test in 29 Standardbred trotters admitted to the clinic for exercise tolerance testing. According to their red cell volume the horses were divided into red cell normovolaemic and red cell hypervolaemic (polycythaemic) groups. The exercise‐response curve for taurine differed significantly in the two groups, whereas all the other amino acids behaved similarly. The [branched‐chain amino acid]/[alanine] ratio, a proposed indicator for the use of amino acids in gluconeogenesis, was at rest significantly higher in the polycythaemic horses. Post‐exercise concentrations of ammonia and allantoin, both end products of ATP breakdown, were lower in the polycythaemic horses. No differences were observed in the VLA4 and V200 markers for lactate and heart rate responses to incremental exercise, the oxidative capacity of the gluteus medius muscle, the enzyme activities or the post‐exercise concentration of lactate, uric acid and hypoxanthine. It is concluded that horses with red cell hypervolaemia behave in a submaximal standardised exercise test on a treadmill in the same way as do red cell normovolaemic horses. The results suggest that the rate of amino acid utilisation in gluconeogenesis and the ability of amino acids to produce energy aerobically may be elevated in polycythaemic horses.
Training‐induced modifications in cardiorespiratory and ventilatory measurements in Thoroughbred horses
Authors: ART TATIANA , LEKEUX P.
Published: April 2010

The effects of training and detraining on ventilation during a standardised exercise test were investigated.

Ten healthy Thoroughbred horses underwent 5 standardised treadmill exercise tests (SET): SET1, at the start of the experimental period; SET2, after 3 weeks acclimatisation; SET3, after 3 week of aerobic training; SET4 after 3 weeks of anaerobic (i.e. interval) training; and SET5, after 3 weeks of detraining.

The SETs were carried out in an air‐conditioned laboratory on a treadmill inclined at 6°. Respiratory airflow, tidal volume (VT), respiratory frequency (RF) and expired minute volume (VE) were obtained using a face mask and 2 ultrasonic pneumotachographs. Peak oxygen uptake (VO2peak) and carbon dioxide production (Vco2peak) values were calculated on a breath‐by‐breath basis, using a mass spectrometer. Heart rate (HR) was continuously measured with a polar horse tester. Oxygen pulse (Vo2/HR) and ventilatory equivalent for O2were calculated from the collected data. Venous blood was sampled before and after the SET for lactate, pH and haemoglobin determinations.

The results indicated that trained horses showed significant modifications of all values, except VT, RF and VE. This study suggests that, in horses, the increase in VO2induced by training seems to be mainly due to cardiovascular and haematological changes rather than to ventilatory changes. Consequently, while all the other systems implicated in exercise physiology can be efficiently improved and trained, the ventilatory capacity has only limited ability to adapt to training.
The cross‐sectional areas of normal equine digital flexor tendons determined ultrasonographically
Authors: SMITH R. K. W. , JONES R. , WEBBON P. M.
Published: April 2010

Fifty‐two animals, comprising 22 Irish Draught crosses (Group A), 15 Thoroughbreds (Group B) and 15 ponies (Group C) were examined ultrasonographically using a 7.5 mHz linear array probe and stand‐off pad. All animals were free of tendon disease as determined from clinical and ultrasonographical examination. The superficial (SDFT) and deep (DDFT) digital flexor tendons were scanned at 7 transverse (axial) levels between the carpus and metacarpophalangeal joint. Each transverse image was digitised using a commercially available frame grabber and the cross‐sectional areas of each tendon at each level measured using a dedicated software application.

Excellent accuracy (averaging less than 5%) was demonstrated between the ultrasound generated areas and those measured from the tendonspost mortemin 12 limbs.

The mean, s.d. and tolerance intervals of both SDFT and DDFT cross‐sectional areas at each level were determined for each group of horses. There was no statistically significant difference betweenGroups AandBand these 2 groups were, therefore, combined for further analysis. The cross‐sectional areas of both tendons were statistically smaller forGroup Cwhen compared toGroups AandB.The ratio of SDFT to DDFT cross‐sectional areas was calculated for each level and this demonstrated less variation between groups.

The difference in measurements between limbs of the same horse was analysed. The mean differences for all groups were 9.13 mm2for the SDFT and 11.64 mm2for the DDFT. Upper limits (95% of the population) were 22.67 mm2(SDFT) and 29.22 mm2(DDFT).

Weight (Groups AandC), height and mid‐metacarpal circumference (all groups) were measured and these physical parameters related to the tendon size at each level forGroups AandBcombined andGroup C.Tolerance limits and normograms were calculated. No significant regression was found for the horse group over the range of physical parameters measured while regression was shown for the ponies.

The cross‐sectional areas measured in this study may be useful for determining increased tendon size in cases of bilateral tendonitis or where there is minimal disruption to the internal ultrasonographic architecture of the tendon.
Distribution of Equid herpesvirus‐1 (EHV‐1) in respiratory tract associated lymphoid tissue: implications for cellular immunity
Authors: KYDD JULIA H. , SMITH K. C. , HANNANT D. , LIVESAY GEORGIA J. , MUMFORD JENNIFER A.
Published: April 2010

Twelve adult ponies and 2 conventional foals were exposed intranasal to EHV‐1, strain Ab4 (TCID5010−6.6) and samples of respiratory tract associated lymphoid tissues were recovered between 12 h and 13 days after infection. Infectious virus was detected in tissue homogenates using susceptible cell monolayers and expression of viral antigens was monitored using indirect immunoperoxidase histochemistry on paraffin sections. The results showed both infectious EHV‐1 and viral antigens in respiratory tract associated lymph nodes 12 h after exposure. Infected leucocytes were identified morphologically as lymphocytes, monocytes, macrophages and plasma cells. The rapid intracellular localisation of EHV‐1 in lymph nodes implies that cell mediated immunity is an important aspect of the equine response to this virus.
Regulation of equine fibrinolysis in blood and peritoneal fluid based on a study of colic cases and induced endotoxaemia
Authors: COLLATOS CHRYSANN , BARTON MICHELLE H. , SCHLEEF R. , PRASSE K. W. , MOORE J. N.
Published: April 2010

Much of the pathophysiology associated with equine gastrointestinal diseases is attributed to the effects of endotoxin on haemostasis. Because little is known about the responses of the equine fibrinolytic system to endotoxin, regulation of the system was investigated. Tissue‐type plasminogen activator (t‐PA) and plasminogen activator inhibitortype‐1(PAI‐1) were identified as the primary plasminogen activator and plasminogen activator inhibitor, respectively, in equine blood. Under experimental conditions, the equine fibrinolytic system responded to endotoxin in a manner similar to that reported in man, with an early, transient increase in t‐PA activity followed by an overwhelming and prolonged increase in activity of PAI‐1.

To investigate the response of the equine fibrinolytic system to clinical endotoxaemia, endotoxin concentrations were measured in plasma and peritoneal fluid, and activities of t‐PA and PAI‐1 were compared between healthy horses (n=38) and horses with naturally occurring gastrointestinal diseases (n=150). It was observed thatplasmaPAI‐1 andperitonealt‐PA were increased concurrently in abnormal horses; and that these increases were associated with the presence of endotoxin.

The results of this study suggest that 1) fibrinolysis is regulated in horses in a manner similar to that in man; 2) regulation of fibrinolysis is altered in endotoxaemic horses with gastrointestinal diseases; 3) events occurring in the vascular system may not reflect those in the peritoneal cavity; and 4) t‐PA activity is increased in the peritoneal fluid of endotoxaemic horses with gastrointestinal diseases.
Effect of central or marginal location and post‐operative exercise on the healing of osteochondral defects in the equine carpus
Authors: BARR A. R. S. , WOTTON S. F. , DOW S. M. , WATERMAN A. E. , GOODSHIP A. E. , DUANCE V. C.
Published: April 2010

The effects of osteochondral defect location and postoperative walking exercise on structural repair and recovery of joint function were examined in the midcarpal joints of ponies. Functional recovery was monitored by measuring ground reaction forces using a force plate. Structural repair was evaluated histologically and by measuring the total collagen and uronic acid content and relative proportions of Type I and II collagen in the repair tissue. Central defects tended to cause a more marked functional disturbance but were repaired with fibrocartilage rather than fibrous tissue in 3 out of 6 ponies while marginal defects were repaired almost exclusively with fibrous tissue. There was no significant difference between defect locations with regard to the biochemical measures evaluated. Exercise produced no beneficial effect on structural repair of the defects. Secondary ‘kissing’ lesions in the third carpal bones opposite the defects appeared grossly more severe in the exercised ponies which also showed a trend to more marked functional disturbance.
Influence of intra‐articular sodium hyaluronate and polysulphated glycosaminoglycans on the biochemical composition of equine articular surface repair tissue
Authors: BARR A. R. S. , DUANCE V. C. , WOTTON S. F. , WATERMAN A. E.
Published: April 2010

The influence of repeated intra‐articular injections of sodium hyaluronate and polysulphated glycosaminoglycan on the repair of full‐thickness osteochondral defects was examined in the midcarpal joints of ponies. The study showed no significant difference between treated and control groups with regard to total collagen content, uronic acid content or the relative proportions of Type I and Type II collagen in the repair tissue, indicating that the drugs did not affect the biochemical composition of the repair tissue 11 weeks after defect induction.
Proteolytic enzymes in equine joints with infectious arthritis
Authors: SPIERS SUE , MAY S. A. , HARRISON LUISE J. , BENNETT D. , EDWARDS G. B.
Published: April 2010

Significant amounts of collagenase and caseinase activity were detected in infected synovial fluid samples. Partial characterisation of the enzymes by gel filtration suggested that synovial fluid from cases of infectious arthritis may contain enzymes from both the synovial cells and neutrophils. This finding was also supported by analysis of sequential synovial fluid samples from 4 infected joints. In 3 joints the concentration of caseinase and in 1 joint collagenase paralleled the decline in total nucleated cell count. However, in 3 joints the concentration of collagenase remained high after the total nucleated cell count had returned to normal, suggesting that this enzyme originated from resident articular cells.
Frusemide attenuates the exercise‐induced rise in pulmonary capillary blood pressure in horses
Authors: MANOHAR M. , HUTCHENS E. , CONEY E.
Published: April 2010

Catheter mounted micro‐tip‐manometers (the signals from which were matched with fluid‐filled pressure signals from same cardiovascular sites and zeroed at the point of the shoulder), were used to study pulmonary haemodynamics in 8 healthy sound horses at rest and during exercise performed at 8, 10, 12 and 14 m/s on a treadmill. Measurements were made without frusemide (control) and 4 h after iv administration of 250 mg frusemide. Post‐frusemide data were also obtained on a separate day, and these observations were not significantly different from those made on the same day as controls. Pre‐frusemide values of heart rate, mean right atrial pressure, mean pulmonary artery pressure, mean pulmonary artery wedge pressure and mean pulmonary capillary pressure at 14 m/s were 214 ± 5 beats/min, 54 ± 4, 92 ± 4, 65 ± 6 and 79 ± 5 mmHg, respectively. Exercise at 14 m/s after frusemide resulted in a similar heart rate (216 ± 4 beats/min), but the mean right atrial, pulmonary arterial, pulmonary artery wedge and pulmonary capillary pressures were all significantly lower, i.e. 34 ± 5, 79 ± 4, 45 ± 4, and 62 ± 3 mmHg, respectively. Attenuation, by frusemide, of the exercise‐induced rise in pulmonary capillary pressure would lower the magnitude of the transmural force exerted on the pulmonary capillaries. If, therefore, exercise‐induced pulmonary haemorrhage (EIPH) is caused by stress failure of pulmonary capillaries, frusemide pretreatment has the potential for reducing/limiting the extent of EIPH.
Measurements of urethral pressure profiles in the male horse
Authors: RONEN N.
Published: April 2010

Urinary tract pressure profiles were evaluated in 6 clinically normal geldings over 3 consecutive days. This was performed by introducing a 1.3 m‐long cuffed catheter into the urinary tract, under xylazine sedation (0.8 mg/kg, iv). The method was reproducible. The mean (±sd) intra‐vesicular pressure (IVP) and maximal urethral closure pressures (MUCP) were 10.3 (±1.7) and 129.8 (±19.6) cmH2O, respectively, and the ratio between MUCP and IVP was 13.2 (±2.5). A gelding with urinary incontinence showed a significantly lower MUCP (73.4 cmH20), and an MUCP to IVP ratio of 8.0. It was concluded that the day‐to‐day variation was non‐significant, and that the technique may be useful in the differential diagnosis of urinary incontinence in male horses.
Fracture of the wing of the ilium, adjacent to the sacroiliac joint, in Thoroughbred racehorses
Authors: PILSWORTH R. C. , SHEPHERD M. C. , HERINCKX B. M. B. , HOLMES M. A.
Published: April 2010

During a two year period, sagittal fractures of the wing of the ilium were diagnosed in 10 Thoroughbred horses. All were spontaneous fractures sustained during normal exercise in training and racing, with no history of inciting trauma.

When ultrasound scans of the surface of the pelvis were performed, the fracture was clearly visible as a discontinuity of the sacral wing of the ilium. In 3 horses, an irregular contour suggestive of periosteal callus was seen in the vicinity of the acute fracture. All horses examined by gamma scintigraphy had a focal increase in uptake of isotope just lateral to the tuber sacrale.

Nine of the horses were treated conservatively by rest. The other horse had bilateral fractures and was subjected to euthanasia at the time of the injury. Six horses returned to full training, and 2 subsequently won, without recurrence of lameness.
Scintigraphic measurement of uterine clearance in normal mares and mares with recurrent endometritis
Authors: LeBLANC M. M. , NEUWIRTH L. , ASBURY A. C. , TRAN T. , MAURAGIS D. , KLAPSTEIN E.
Published: April 2010

The percentage of Technetium 99m‐albumin colloid (99mTc‐μAA), a radiocolloid, cleared from the uterine lumen within 4 h of intrauterine infusion, was measured in 15 mares during 2 consecutive cycles, on Day 3 of oestrus and 48 h after ovulation. Four nulliparous (Group 1) and 4 multiparous (Group 2) mares were classified as resistant and the remaining 7 multiparous mares were classified as susceptible (Group 3) to endometritis. Mares in Groups 1 and 2 cleared more99mTc‐μAA from their uteri than did mares in Group 3 during oestrus (P<0.01) and 48 h after ovulation (P<0.001). In the Group 1 + 2 mares, >50% of the colloid was cleared in 7 and none in the remaining mare, apparently related to lack of cervical relaxation. Mean percentage of99mTc‐μAA cleared by Group 3 mares was negligible (<5%), but some99mTc‐μAA was cleared by 3 of the 7 mares during 4 of the 6 studies conducted. Clearance of radiocolloid infused into the uterus of 3 reproductively normal mares during dioestrus was negligible.99mTc‐μAA infused into the uterus did not adversely affect endometrial integrity as determined by endometrial biopsy. Mares tolerated the procedures well. We conclude that scintigraphy can be used to detect impaired mechanical clearance of the uterus: reproductively normal mares clear >50%99mTc‐μAA within 2 h of infusion whereas those susceptible to endometritis or mares with poor cervical dilatation may exhibit delayed uterine clearance.
Studies on the transportin vitroof lysine, histidine, arginine and ammonia across the mucosa of the equine colon
Authors: BOCHRÖDER BRITTA , SCHUBERT R. , BÖDEKER D.
Published: April 2010

Discs of stripped mucosa from the proximal ventral colon were prepared immediately after slaughter of 8 Shetland cross‐breed ponies. The mucosae were fixed in incubation chambers and used in incubation experiments to study the transmucosal fluxes of the amino acids lysine, histidine and arginine (150 min) and of ammonia (90 min). When the amino acid concentrations in the mucosal solution were in the physiological range (2.8–3.0 mmol/l) no transport to the serosal side of the tissue was found. When the concentrations were raised 10‐fold, less than 2% of the mucosal amino acid pool was recovered in the serosal solution. Ammonia was transported across the mucosa at significant rates although only 63% of the ammonia that disappeared from the mucosal solution was found in the serosal solution. The findings show that the equine proximal colon is virtually impermeable to luminal free amino acids whereas ammonia is transported at rates equal to, or higher than those observed with rumen mucosa from sheep.
Identification of 2 stallion sperm‐specific proteins and their autoantibody response
Authors: TEUSCHER CORY , KENNEY R. M. , CUMMINGS MARGARET R. , CATTEN M.
Published: April 2010

In this study, 2 stallions were immunised with their own spermatozoa to ascertain whether an antisperm autoantibody response could be mounted. The results demonstrated that the stallion can recognise and respond to sperm autoantigens by producing circulating antisperm antibodies, primarily of the IgG class. Such autoantibodies appeared 2–4 weeks after inoculation and persisted for 6–20 weeks. Immunochemical characterisation by western blot identified two major sperm autoantigens, with molecular weights of 70 kD and 62 kD. Control pony stallions immunised with adjuvants alone failed to exhibit such antibodies. IgA antisperm antibodies were measurable in seminal plasma of both stallions. We suggest that, as in other species, autoimmunity to spermatozoa may play a role in idiopathic subfertility in stallions.
Comparison of the stride kinematics of the collected, working, medium and extended trot in horses
Authors: CLAYTON HILARY M.
Published: April 2010

Highly‐trained dressage horses were studied to test the hypothesis that stride length is altered independently of stride duration in the transitions between the collected, working, medium and extended trot. Six well‐trained dressage horses were filmed at a frame rate of 150 frames/s performing the collected, working, medium and extended trots in a sand arena. Temporal, linear and angular data were extracted from the films, with 4 strides being analysed for each horse and gait type. There were no significant asymmetries between the left and rights limbs or diagonals when data from the whole group were pooled, but 3 horses showed asymmetries in one or more variables (P<0.01). Analysis of variance and post‐hoc tests indicated that the speed increased significantly (P<0.01) from the collected (3.20 m/s) to the working (3.61 m/s) to the medium (4.47 m/s) to the extended (4.93 m/s) trot. The increases in speed were associated with a significant increase in stride length from 250 cm in the collected trot, to 273 cm in the working trot, 326 cm in the medium trot and 355 cm in the extended trot (P<0.01). The lengthening of the stride was a result of increases between each gait type in the over‐reach distance, whereas the diagonal distance was significantly longer in the extended than the collected trot only (P<0.01). The stride duration tended to decrease as speed increased, and the difference became significant between the collected and extended trots (P<0.01).
Oxytocin enhances clearance of radiocolloid from the uterine lumen of reproductively normal mares and mares susceptible to endometritis
Authors: LeBLANC MICHELLE , NEUWIRTH L. , MAURAGIS D. , KLAPSTEIN E. , TRAN T.
Published: April 2010

The effects of oxytocin on the percentage of technetium99malbumin colloid (99mTc‐μAA), cleared from the uterine lumen was measured in 13 mares. Scintigraphy was performed during 4 consecutive oestrous cycles, on Day 3 of oestrus during Cycles one and 3 and 48 h after ovulation during Cycles 2 and 4. Oxytocin (20 iu) was given i.v. after the initial scintigraphy image during Cycles 3 and 4. Seven multiparous mares(Group 1)were classified as ‘susceptible’ and 6 mares (2 nulliparous and 4 multiparous;Group 2) were classified as ‘resistant’ to endometritis. All mares cleared >90% of99mTc‐μAA within 30 min of oxytocin injection. When no drug was given,Group 1mares cleared negligible amounts of radiocolloid (<5%) andGroup 2mares cleared 50–80%. No mares showed signs of colic after oxytocin administration. It is concluded that oxytocin enhances uterine clearance of radiocolloid and may be useful for treating mares exhibiting impaired uterine clearance.
An investigation of the proteoglycan metabolism of mature equine articular cartilage and its regulation by interleukin‐1
Authors: PLATT D. , BAYLISS M. T.
Published: April 2010

The effect of human recombinant interleukin‐1ß (rhIL‐1ß) on proteoglycan metabolism was investigated in cultures of full thickness explants of articular cartilage from horses 3–21 years of age. Proteoglycan synthesis was inhibited at all ages but no alteration in the hydrodynamic size or electrophoretic heterogeneity was observed in proteoglycan isolated from rhIL‐1ß stimulated cartilage. The sulphation pattern of the newly synthesised proteoglycan molecules was, however, significantly affected by the presence of the peptide regulatory factor. Interleukin‐1 had no effect on the rate of turnover of newly synthesised or endogenous proteoglycans in mature equine articular cartilage and did not influence the structure of proteoglycan fragments released into the culture medium. These observations suggest that IL‐1, released into synovial fluid during inflammation, may modify the proteoglycan composition of normal equine cartilage not by stimulating catabolic enzymes capable of degrading the resident proteoglycans but by promoting the deposition of a reduced number of newly synthesised proteoglycan molecules of abnormal composition.
The structure, innervation and location of arteriovenous anastomoses in the equine foot
Authors: MOLYNEUX G. S. , HALLER C. J. , MOGG K. , POLLITT C. C.
Published: April 2010

In the foot of the horse, arteriovenous anastomoses (AVAs) of epithelioid type occurred in the dermis of the coronary band, in the coronary and terminal papillae, in neurovascular bundles and at the entrance to and along the length of the dermal laminae. A particular feature of the epithelioid segment of AVAs in the horse, compared with that of other species, was the height and surface complexity of many of the endothelial cells. They extended into the lumen, forming undercut and tunnel‐like areas which correlated with the characteristic surface marking of AVAs observed in vascular casts. The number of cell organelles, including the concentration of vesicles in the luminal cytoplasm, suggested cells with a high metabolic activity. The luminal surface possessed numerous microvilli and long cytoplasmic cell processes which appeared to surround material in the lumen.

The innervation of AVAs was more dense than that of the arteries and consisted of adrenergic and peptidergic nerves. Noradrenaline‐ and neuropeptide Y‐containing nerves were identified as the vasoconstrictor components of the nerve supply and occurred along arteries and formed dense plexuses around AVAs. Calcitonin gene‐related peptide, substance P and vasoactive intestinal polypeptide are vasodilators and were present in single nerve fibres which accompanied arteries and AVAs along the length of the dermal laminae. In this study the distribution, density and innervation of AVAs in the equine foot are correlated with their proposed role in the development of acute laminitis. The release of vasoactive peptides from diseased organs remote from the foot may induce inappropriate prolonged dilatation of AVAs and thus contribute to the laminar ischaemia of acute laminitis.
Causes of death in racehorses over a 2 year period
Authors: JOHNSON B. J. , STOVER SUSAN M. , DAFT BARBARA M. , KINDE H. , READ D. H. , BARR B. C. , ANDERSON M. , MOORE JANET , WOODS L. , STOLTZ J. , BLANCHARD P.
Published: April 2010

Necropsies were performed on 496 horses that had a fatal injury or illness at a California racetrack during the period February 20th 1990 to March 1st 1992. The primary cause of death was categorised by breed, activity at time of injury or illness and organ system affected. Most of the submissions were Thoroughbred horses (432) and Quarter Horses (46). Most of the injuries occurred while racing (42%) and in training sessions (39%); with fewer non‐exercise (12%) and accident (7%) related injuries or illnesses. Musculoskeletal injuries accounted for 83% of the Thoroughbred and 80% of the Quarter Horse submissions. The Thoroughbred horses incurred 306 fractures with 263 in the limbs and 90% of those in the forelimbs. The proximal sesamoid bone(s), third metacarpal bone and humerus were the most common bones fractured in Thoroughbred horses and Quarter Horses. Other major causes of death included respiratory, digestive and multi‐organ system disorders.
Clinical efficacy and safety of clenbuterol HCl when administered to effect in horses with chronic obstructive pulmonary disease (COPD)
Authors: ERICHSEN DEBORAH F. , AVIAD ANITA D. , SCHULTZ R. H. , KENNEDY T. J.
Published: April 2010

A field study of 239 horses was conducted to determine the efficacy and safety of clenbuterol HCl, a ß2‐adrenergic bronchodilator, when administered incrementally to effect in the treatment of chronic obstructive pulmonary disease (COPD). The severity of COPD (heaves) and response to treatment was determined by clinical evaluation; an overall ‘heaveiness rating’ (OHR) was assigned at each observation. The horses were treated orally b.i.d. with clenbuterol (as Ventipulmin Syrup), beginning with the lowest dosage of 0.8 μg/kg. On Day 10 of treatment at the effective dose (0.8, 1.6, 2.4 or 3.2 μg/kg), treatment was either withdrawn(Schedule A)or continued for an additional 20 days(Schedule B).

Horses onSchedule Ademonstrated a significant improvement in the mean OHR on treatment Day 10 compared to the baseline overall heaveiness rating (BOHR) and a significant increase in the mean OHR (relapse) after the drug was withdrawn.Schedule Bhorses showed significant improvement (compared to BOHR) on treatment Days 10, 20 and 30.

Incremental dosing with clenbuterol provided clinical improvement in 75% of the horses with a lower 95% confidence limit of 71%. Twenty‐five percent were nonresponders. A greater percentage of the more severely affected horses required the 3.2 μg/kg dosage or were nonresponders compared to horses with a lower BOHR.

Side effects of sweating, muscle tremor, and nervousness were of low intensity (mild to moderate) and frequency (<7% of all observations) due to the regimen of incremental dosing to effect.
Evaluation of the thoraco‐laryngeal reflex (‘slap test’) as an indicator of laryngeal adductor myopathy in the horse
Authors: NEWTON‐CLARKE M. J. , DIVERS T. J. , VALENTINE B. A.
Published: April 2010

A study was conducted over a 12 month period to assess the accuracy of the ‘slap test’ in the diagnosis of laryngeal adductor myopathy. The thoraco‐laryngeal reflexes of 15 horses with no clinical signs of idiopathic laryngeal hemiplegia (ILH) were recorded using a video‐endoscope. These ‘slap test’ responses were examined independently by 3 assessors. The horses were subsequently subjected to euthanasia and samples taken from the cricoarytenoideus lateralis (CAL) muscles for histopathological examination and assessment of denervation atrophy. Despite normal adductory responses, moderate to severe atrophy of the left CAL muscles was seen in 5 horses. The remaining horses had varying degrees of adductor myopathy, invariably worse in the left side of the larynx. The ‘slap test’ as performed in this study was therefore unable to differentiate between horses with moderate to severe muscle changes and those without, making it useless as a diagnostic test for adductor myopathy. The reason for the preservation in adductor function despite advanced histological atrophy of the muscle may lie in the degree of reinnervation found in the muscles.
ß‐glucuronidase and trypsin inhibitor capacity of tracheal lavage fluid as indicators of seasonal airway irritation in the horse
Authors: MAISI P. , KOIVUNEN A.‐L. , RANTALA A.‐R. , TURGUT K.
Published: April 2010

The health of the respiratory tracts of 19 horses was studied for 11 months. The horses were placed into 3 groups (healthy, periodically diseased and continuously diseased) based on the measurements of blood gases, intrapleural pressure and on neutrophil content of tracheal mucus. Lysosomal enzymes (N‐acetyl‐ß‐D‐glucosaminidase and ß‐glucuronidase) and reflectors of the proteolytic system (plasmin, plasminogen, trypsin inhibitor capacity) were determined.

ß‐glucuronidase appeared to be a good indicator of the presence of disease of the respiratory system. High ß‐glucuronidase values were seen in horses with elevated numbers of neutrophils, elevated arterial alveolar and intrapleural differences as well as in diseased horses during the stabling period. Trypsin inhibitor capacity seemed to be lower in the diseased respiratory system, probably due to the increased consumption of trypsin inhibitors.
The basement membrane at the equine hoof dermal epidermal junction
Authors: POLLITT C. C.
Published: April 2010

In the equine hoof, the basement membrane connects the heavily keratinised hoof wall to the dense connective tissue of the distal phalanx, a region able to withstand considerable mechanical stress. This study investigated the properties of this important anatomical and physiological structure. In contrast to haematoxylin and eosin, the connective tissue stains, periodic acid Schiff, periodic acid silver methenamine and Azan showed good resolution of lamellar basement membrane. The lamellar basement membrane cross‐reacted with mouse monoclonal antibodies raised against human laminin, thereby providing evidence that laminin is a component of the equine basement membrane. The ultrastructure of the equine hoof basement membrane was essentially the same as in other animals but appeared to have many anchoring fibrils and extensions of the lamina densa into the adjoining connective tissue, an arrangement interpreted to convey extra strength to the region. Large areas of the surface of the hoof wall basement membrane could be exposed to examination with the scanning electron microscope by treating tissue blocks with detergent/enzyme or sodium bromide. When epidermal lamellae were separated from their dermal counterparts the basement membrane stayed with the dermis and the dermal lamellae retained their natural shape despite the absence of an adjacent epidermis. The exposed surface of the lamellar basement membrane was generally smooth and unbroken, marked with small indentations and fine wrinkles. At the cut edges of the lamellae, a mesh of fine connective tissue fibres were attached to the inner surface of the basement membrane. The basement membrane of both the coronary and terminal papillae was folded into numerous longitudinal ridges, all parallel to the long axis of the papillae. Like the folds in the basement membrane of the lamellae (the so‐called secondary lamellae) the longitudinal ridges of the papillae are probably an adaptation to increase the surface area of attachment of the dermis to the inner hoof wall. The architecture of the equine basement membrane and the tissues adjacent to it is severely disrupted as the pathology of laminitis develops. A study of the basement membrane using the techniques described in this study may add to our understanding of the pathophysiology of equine laminitis.