bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationship between ossification of the cartilages of the foot and conformation and radiographic measurements of the front feet in Finnhorses
Authors: RUOHONIEMI MIRJA , RAEKALLIO MARJA , TULAMO RIITTA‐MARI , SALONIUS KARI
Published: April 2010

One hundred Finnhorse cadaver front feet were measured and examined both radiographically and visually to report the incidence of various foot problems and their relationship to ossification of the cartilages of the foot. Ossification extending above the proximal border of the navicular bone and/or separate centres of ossification were found in 36 feet, and the lateral cartilages showed more ossification than the medial cartilages. The feet were generally broad with well developed frogs, but the long toe‐low heel syndrome was a relatively common finding. Ossification of the cartilages correlated with the length of the heels but was not related to any clinically significant foot abnormalities such as contracted or under‐run heels or signs of unequal weightbearing. Ossification of the cartilages did not seem to be either the cause or the result of general conformational adaptations of the front feet.
Flexion test of the metacarpophalangeal and interphalangeal joints and flexion angle of the metacarpophalangeal joint in sound horses
Authors: VERSCHOOTEN F. , VERBEECK J.
Published: April 2010

This paper describes the application of a measuring device ‘Flextest’ to control the effect of traction force and traction time during flexion tests of the distal limb joints of the forelimbs. The optimal force for a flexion test is 100 N, over 1 min. A higher force (150 N) was not harmful. A slightly positive flexion response (100 N/1 min) in a horse with no other clinical signs or radiographic abnormalities is not of clinical significance. Individual left and right flexion and extension angles are almost identical and do not depend on age. Stabled horses which have been rested or horses resting at pasture are less likely to have a positive flexion test than working horses.
Anatomy of the distal interphalangeal joint of the mature horse: relationships with navicular suspensory ligaments, sensory nerves and neurovascular bundle
Authors: BOWKER R. M. , LINDER K. , VAN WULFEN KIMBERLY K. , SONEA IOANA M.
Published: April 2010

The anatomy of the distal interphalangeal (DIP) joint in the adult horse is described in relationship to the suspensory ligaments of the navicular bone, the neurovascular bundle and the sensory nerves to these periarticular regions. Using polymer plastic injections, the synovial cavity of the DIP joint was observed to have a complex relationship to the proximal suspensory or collateral sesamoidean ligament (CSL) of the navicular bone with the cavity forming cranial and caudal compartments around the CSL abaxially. Sensory nerves, as identified by peptide immunocytochemistry and silver/gold chloride axonal impregnation, were present superficially throughout the dorsal and palmar parts of the CSL, the distal sesamoidean impar ligament and in the periarticular connective tissues. These anatomical observations provide support for the idea that a DIP joint injection of local anaesthetic cannot be considered to be selective for only the joint surfaces, but must be considered also to desensitise much of the navicular suspensory apparatus, navicular bone and proximal intramedullary portions of the distal phalanx. However, while a DIP joint injection is not selective for only the joint surfaces, we believe that it is useful in terms of the diagnosis of painful sensations arising from parts of the navicular bone, the suspensory apparatus and proximal positions of the distal phalanx. These anatomical findings are discussed in terms of the potential effects of local anaesthesia injected into the DIP joint with known clinical and necropsy observations of Dyson and Kidd (1993).;
Equine viral arteritis in newborn foals: clinical, pathological, serological, microbiological and immunohistochemical observations
Authors: DEL PIERO F. , WILKINS PAMELA A. , LOPEZ J. W. , GLASER AMY L. , DUBOVI E. J. , SCHLAFER D. H. , LEIN D. H.
Published: April 2010

Clinical, pathological, immunohistochemical, serological and microbiological findings are described for 2 geographically and temporally distinct equine arteritis virus (EAV) epidemics in newborn foals. Outbreak A occurred at a commercial Standardbred breeding facility; Outbreak B began in a group of research animals. Clinical signs were severe and primarily referrable to the respiratory tract. Fever and leucopenia and/or thrombocytopenia were observed in foals surviving for more than 24 h. The most common gross pathological findings were limited to the respiratory tract. Common histopathological findings included interstitial pneumonia, lymphocytic arteritis and periarteritis with fibrinoid necrosis of the tunica media. Renal tubular necrosis was noted in 2 foals. Immunoperoxidase histochemistry combined with virus isolation was diagnostic in all cases.
A light microscopic and ultrastructural examination of calcified dental tissues of horses: 3. Dentine
Authors: KILIC S. , DIXON P. M. , KEMPSON S. A.
Published: April 2010

Ultrastructural examinations of equine dentine found that dentinal tubules extended from the amelodentinal junction towards the pulp forming primary curvatures. The number of dentinal tubules/unit area and their diameters increased significantly from the amelodentinal junction towards the pulp cavities, particularly in regular secondary dentine, but irregular secondary (tertiary) dentine contained no dentinal tubules. Dentinal tubules contained odontoblast processes that appeared to extend as far as the amelodentinal junction, but due to iatrogenic loss during specimen preparation, odontoblasts were seldom found in regular secondary dentine. In primary dentine, the dentinal tubules were surrounded by large amounts of peritubular dentine that increased in diameter from the amelodentinal junction towards the junction of primary and secondary dentine. The site of the dentinal tubule within the peritubular dentine varied at different dentinal sites. Peritubular dentine was present in primary dentine only and was surrounded by a thin layer of intertubular dentine. When acid etched, peritubular dentine gave dentine a honeycomb appearance adjacent to the junction of primary and secondary dentine.
A light microscopic and ultrastructural examination of calcified dental tissues of horses: 4. Cement and the amelocemental junction
Authors: KILIC S. , DIXON P. M. , KEMPSON S. A.
Published: April 2010

Ultrastructural examinations showed the diameter of cement lacunae to be greater in infundibular cement than in peripheral cement of upper cheek teeth, which in turn was greater than in the peripheral cement of the lower cheek teeth. However, numbers of lacunae/unit area remained similar in these 3 dentinal region. Two types of cemental hypoplasia were found in equine cheek teeth. The first type was termed central infundibular cemental hypoplasia and was confined to the central region of infundibular cement. The cement adjacent to these frequently large defects was very porous and contained large vascular channels. In recently erupted cheek teeth, these central infundibular cemental defects were filled with connective tissue. The size of these cemental defects, the relationships of such defects with the occlusal surface and the degree of porosity of cement surrounding these defects may be important in the development of cemental caries. The second type of cemental defect was found at the amelodentinal junction of both peripheral and infundibular cement and was termed junctional cemental hypoplasia and appeared as spaces varying from focal, to long narrow defects along the amelocemental junction with the adjacent cement of normal appearance.

Peripheral cement was deposited both directly, i.e. on unresorbed or resorbed enamel surfaces or indirectly, where the cement was separated from enamel by a thin calcified layer. The surface of unresorbed enamel had a pitted appearance, with the bases of the pits formed by enamel prisms and the pit walls by interprismatic enamel. The cemental surface of resorbed enamel contained depressions of variable shapes and sizes. These depressions which are believed to be caused by the resorption of enamel by odontoclasts were both focal and diffuse and were more marked on the cemental surface of infundibular as compared to peripheral enamel.
A survey of reproductive performance in Thoroughbred mares and morbidity, mortality and athletic potential of their foals
Authors: MORLEY P. S. , TOWNSEND H. G. G.
Published: April 2010

A survey was performed to evaluate the reproductive performance of Thoroughbred mares, estimate risks of dystocia and of morbidity and mortality in foals during the first yearpost partumand their physical acceptability at age one year. The study population consisted of registered Thoroughbred mares and their foals owned by residents of 4 Western Canadian provinces. Owners were identified using information obtained from the North American Jockey Club, and questionnaires were mailed regarding mares bred in 1988 and their foals born in 1989. Eighty‐three per cent of mares were reported to be pregnant at some stage following breeding, and 80% of pregnant mares subsequently gave birth to live foals. Estimates of morbidity and mortality were greater than previously reported, 25% of foals had health problems and 5% died during the first 2 weekspost partum. Twenty‐seven per cent of foals surviving 2 weeks were reportedly affected by some health problem between age 15 days and one year, and 6% died during this period. The case fatality rates of horses with upper respiratory tract infections and diarrhoea were much lower than case fatality rates for infectious diseases occurring less frequently. The rate of death or euthanasia among horses with musculoskeletal problems was relatively high after age 2 weeks. Foals with health problems up to age 2 weeks, or between age 15 days and one year were 5 to 7 times more likely to be classified as physically unacceptable for athletic use. Angular limb deformity was the health problem most commonly reported in foals receiving unacceptable physical assessments, and assessments of long‐term athletic potential were apparently not affected by the occurrence of infectious diseases.
Characterisation of equine matrix metalloproteinase 2 and 9; and identification of the cellular sources of these enzymes in joints
Authors: CLEGG P. D. , BURKE R. M. , COUGHLAN A. R. , RIGGS C. M. , CARTER S. D.
Published: April 2010

The cellular production by resident articular cells and infiltrating inflammatory cells of the gelatinase matrix metalloproteinases (MMP) was investigated by tissue culture methods and analysis of cell supernatants by gelatin zymography. Peripheral blood neutrophils in short term culture produced MMP‐9, as did peripheral blood monocytes in culture. Isolated articular chondrocytes in monolayer culture produced both MMP‐2 and MMP‐9, although articular cartilage maintained as explant culture produced MMP‐2 alone. Synovial fibroblasts grown in monolayer culture produced MMP‐2 alone, although synovial membrane in explant culture produced both MMP‐2 and the active form of MMP‐2. Lysis of blood polymorph neutrophils produced large quantities of MMP‐9, but lysis of blood monocytes, synovial fibroblasts and articular chondrocytes produced little enzyme indicating that, unlike the other cell types, polymorph neutrophils store MMPs intracellularly. Equine MMP‐2 was purified from synovial fibroblast cell culture supernatant, and equine MMP‐9 from polymorph neutrophil cell culture supernatant, by gelatin‐sepharose affinity chromatography. The 2 enzymes were identified from their molecular weights and by their respective N‐terminal amino acid sequences which showed homology with the enzymes from other species. The demonstration that invasive cells and resident articular cells can produce enzymes which are capable of digestion of certain component molecules of the articular cartilage matrix, shows that therapeutic targeting of these enzymes could be a valid proposition in the prevention of cartilage destruction in osteoarthritis.
Matrix metalloproteinases 2 and 9 in equine synovial fluids
Authors: CLEGG P. D. , COUGHLAN A. R. , RIGGS C. M. , CARTER S. D.
Published: April 2010

Matrix metalloproteinases (MMPs) may be important in the destruction of cartilage seen in equine osteoarthritis and may be detectable in synovial fluid. Synovial fluids were obtained from normal equine joints and from joints of horses with aseptic and septic joint diseases. The total MMP gelatinase enzyme activities were measured by gelatin zymography and image analysis of the gels. The bioactivity of gelatinase in synovial fluid was determined by a gelatin degradation ELISA. Potential MMP‐2 & MMP‐9 monomer enzyme activities were significantly elevated in both septic and aseptic joint disease synovial fluids in comparison to fluids from normal joints. The dimer form of MMP‐9 enzyme activity was significantly elevated in fluids from septic joint disease cases in comparison to fluids from normal joints, but not fluids from horses with aseptic joint diseases. MMP‐9 monomer and dimer levels in synovial fluids correlated with the synovial fluid white blood cell count. Using the gelatin degradation ELISA to measure net active gelatinases, significant increases in gelatinase bioactivities were seen in synovial fluids from both aseptic and septic joint disease cases. The enzymes in equine joint diseases were present in a bioactive form, in that they were present in the activated form and present in excess of inhibitors, and could therefore be important in the degradation of articular cartilage in joint disease.
Cartilage canals in equine articular/epiphyseal growth cartilage and a possible association with dyschondroplasia
Authors: SHINGLETON W. D. , MACKIE ELEANOR J. , CAWSTON T. E. , JEFFCOTT L. B.
Published: April 2010

Cartilage canals have been described in most mammals and contain the vascular elements necessary for the maintenance of epiphyseal growth cartilage. The presence and longevity of cartilage canals in developing articular/epiphyseal cartilage of horses is described for the first time. Growth cartilages from 30 normal horses (from 130 days gestation to age 2 years) and 6 cases of dyschondroplasia (age <15 months) were examined. Cartilage canals were located in the epiphyses of fetuses as early as 130 days gestation. The secondary centres of ossification had developed by 250 days gestation and, at full term (∼340 days), the articular/epiphyseal cartilage was highly vascularised. Cartilage canals were closely surrounded by small round chondrocytes even when present in the zone of hypertrophic chondrocytes. From late gestation until at least age 10 weeks, blood vessels surrounded by cartilage were found extending beyond the zone of hypertrophic chondrocytes into the secondary centre of ossification. Cartilage canals were absent from normal articular/epiphyseal cartilage of animals age >6 months. Cartilage canals were associated with retained cartilage of dyschondroplastic lesions found in animals age < 15 months. The presence of cartilage canals in association with dyschondroplastic lesions suggests they may have a role in the pathogenesis of this important disease.
Effect of high volume epidural morphine, ketamine and butorphanol on halothane minimum alveolar concentration in ponies
Authors: DOHERTY T. J. , GEISER D. R. , ROHRBACH B. W.
Published: April 2010

This study determined the effects of epidurally administered morphine, ketamine and butorphanol on halothane minimum alveolar concentration (MAC) in ponies. Seven ponies were anaesthetised with thiopentone and succinylcholine, intubated and anaesthesia maintained with halothane. Ventilation was controlled and blood pressure was maintained within normal limits. Following the determination of baseline halothane MAC for the pelvic and thoracic limbs the ponies were given morphine (0.1 mg/kg bwt), ketamine (0.8 or 1.2 mg/kg bwt), butorphanol (0.05 mg/kg bwt) or saline, epidurally, to a final volume of 0.15 ml/kg bwt. The halothane MAC for the pelvic and thoracic limbs was redetermined following each treatment. The baseline halothane MAC for the control group was mean ± s.e. 0.85 ± 0.02% and no significant change occurred after saline administration. Morphine significantly (P = 0.002) decreased MAC from, mean ± s.e. 0.90 ± 0.05% to 0.77 ± 0.06% in the pelvic limb. Ketamine significantly decreased MAC in the pelvic limb from mean ± s.e. 0.86 ± 0.06% to 0.71 ± 0.04%, and 0.82 ± 0.03% to 0.71 ± 0.02%, for the low (P = 0.008) and high dose (P = 0.001), respectively. No significant change in MAC occurred following butorphanol. No treatment reduced halothane MAC for the thoracic limb.
A scoring system for gastric ulcers in the horse
Authors: MACALLISTER C. G. , ANDREWS F. M. , DEEGAN E. , RUOFF W. , OLOVSON S.‐G.
Published: April 2010

Five investigators familiar with gastric ulcer disease in horses met to establish a scoring system that could be utilised in future studies. Slides of gastric lesions were viewed and discussed and a scoring system established that required the nonglandular and glandular portions of the stomach to be graded separately. Each portion of the stomach (glandular and nonglandular) received a score for number of ulcers present and a score for severity of ulcers which resulted in each stomach receiving 4 separate scores. After the grading system was developed, each investigator independently graded 16 horses with gastric ulcer disease that had been previously recorded on video tape. The results of each investigator's scores were then compared. There was a variability between observers in the scores for severity of both nonglandular and glandular lesions but the variability was not significant The variability between observers for the number of glandular lesions was also not significant. This implied that there was consistency between the 5 observers in the way severity of lesions was scored and the number of glandular lesions. However, there was a significant variability between observers for the number of nonglandular lesions which implied agreement on this observation was more variable.
Effects of insulin and insulin‐like growth factors I and II on the growth of equine fetal and neonatal chondrocytes
Authors: HENSON FRANCES M. D. , DAVENPORT CELIA , BUTLER LINDA , MORAN I. , SHINGLETON W. D. , JEFFCOTT L. B. , SCHOFIELD P. N.
Published: April 2010

The effects of insulin and insulin‐like growth factors (IGFs) I and II on fetal and foal chondrocytes were investigated in vitro. Chondrocytes from the lateral trochlear ridge of the distal femur were obtained from 2 fetuses (280 and 320 days gestation) and one 4‐day‐old foal and cultured. Membrane proteins consistent with type 1 and type 2 IGF receptors were demonstrated by radioligand cross linking and equilibrium binding analysis. It was demonstrated that both IGF‐I and IGF‐II acted as mitogens for isolated equine chondrocytes when present as the sole mitogenic factor in monolayer culture. It was further shown that whereas insulin was able to promote the survival and expansion of cell populations of chondrocytes in culture there was significantly reduced mitogenic stimulation compared to the IGFs. These results suggest that the role of insulin in growth cartilage may be to promote chondrocyte survival, or to suppress differentiation/apoptosis. This supports the hypothesis that relative hyperinsulinaemia may be a contributory factor to equine dyschondroplasia (osteochondrosis). Understanding of contributory, and possibly triggering factors such as this may allow the development of modified methods of husbandry which minimise the risk of disease in populations with a known predisposition.
Severe mitral regurgitation in horses: clinical, echocardiographic and pathological findings
Authors: REEF VIRGINIA B. , BAIN F. T. , SPENCER PAMELA A.
Published: April 2010

Forty‐three horses with mitral regurgitation (MR) and congestive heart failure were examined, using M‐mode, 2‐dimensional real‐time and Doppler echocardiography. There was no breed or sex predisposition when compared to the general hospital population. The mean ± s.d. age of affected horses was 7.6 ±8.1 years. Horses with MR and congestive heart failure had significant increases in mean values for left ventricular chamber size, left atrial size and heart rate and significant decreases in interventricular septal and left ventricular free wall thickness. Significant increases in pulmonary artery diameter were detected compared to aortic diameter. Mean values for fractional shortening were not significantly different from normal.

All horses had aGrade 3–6/6holosystolic or pansystolic murmur with its point of maximal intensity in the mitral to aortic valve area. Atrial fibrillation was found at presentation in 24 horses with MR and congestive heart failure. One horse presented with atrial tachycardia and subsequently developed atrial fibrillation. Seven horses had ventricular premature contractions. Exercise intolerance (n = 34), respiratory signs (n = 31), and fever (n = 21) were the most common presenting signs. Thickening of the left atrioventricular valve leaflets, endocarditis, flail valve leaflets, rupture of achorda tendineae, and mitral valve prolapse were detected echocardiographically. Doppler echocardiography confirmed the presence of a large systolic regurgitant jet in the left atrium in all horses in which it was used, and in many horses, concurrent tricuspid and pulmonary regurgitation was detected. All horses died or were subjected to euthanasia due to the severity of their MR and/or lack of response to therapy.Post mortemexaminations were performed in 35 horses and confirmed the echocardiographic findings. The echocardiographic detection of a flail mitral valve leaflet was significantly associated with the detection of a rupturedchorda tendineaeatpost mortemexamination. There was a significant association between echocardiographic detection of a dilated pulmonary artery and its presence atpost mortemexamination.

M‐mode, 2‐dimensional real‐time, and Doppler echocardiography should be used to accurately characterise the valvular abnormalities and assess the severity of mitral regurgitation. Pulmonary artery dilatation, an echocardiographic indication of severe pulmonary hypertension, should be considered a grave prognostic indicator and may indicate impending pulmonary artery rupture.
Post exercise changes in compartimentai body temperature accompanying intermittent cold water cooling in the hyperthermic horse
Authors: MARLIN D. J. , SCOTT CAROLINE M. , ROBERTS C. A. , CASAS I. , HOLAH G. , SCHROTER R. C.
Published: April 2010

Whereas the efficacy of cold water cooling of horses has been demonstrated by several studies, the dynamics of temperature changes within and between compartments (primarily muscle, blood [core], skin and deep core [rectal]) have not been investigated. Changes in body temperature associated with cold water cooling were investigated in the hyperthermic horse. Muscle (TMU), pulmonary artery (TPA), rectal (TREC), tail‐skin (TTSK) and coat surface (TCOAT) temperatures, were monitored continuously in 5 Thoroughbred horses during and after exercise in hot humid (30°C and 80% RH) conditions on a treadmill. Horses were cooled in the hot humid environment with cold water (∼6°C) for 6 30 s periods. Between each 30 s cooling period the horses stood for 30 s. A total of 180 1 of cold water was applied. Horses were monitored for a further 4 min following the final cooling period. From the end of exercise to the end of the final cooling (6.5 min), mean (± s.e.) rates of decrease for TTSK and TPA were similar (0.8 ± 0.1 and 0.8 ± 0.1°C/min, respectively). The effects on TMU and TREC were less marked, with average rates of 0.2 ± 0.1 and 0.0 ± 0.1°C/min, respectively. During the first 4 min of cooling, TPA fell during the 30 s period of water application and rose during each 30 s period of standing. When TPA fell below ∼36.5°C, these variations were suppressed and TPA rose steadily, despite continued applications; TREC and TMU continued to fall, although less rapidly than before. These observations are consistent with the onset of skin vasoconstriction at low TPA. The mechanism is mediated through a cooling of circulating blood volume providing a greater capacity for heat transfer between muscle and circulation. Intermittent application of cold water (∼6°C) improves heat removal without apparent deleterious effects and is well tolerated. Even when hypothermia develops (based on TPA), muscle and rectal temperatures continue to fall.
Effects of osteochondral fragmentation and intra‐articular triamcinolone acetonide treatment on subchondral bone in the equine carpus
Authors: KAWCAK C. E. , NORRDIN R. W. , FRISBIE D. D. , TROTTER G. W. , MCILWRAITH C. W.
Published: April 2010

To determine the effects of osteochondral fragmentation and intra‐articular corticosteroid treatment on dynamics of bone remodelling and fragility, 12 horses each had a unilateral, 8 mm osteochondral fragment created in the distal aspect of one radiocarpal bone. Six of the horses were treated in the fragmented joint, and the other 6 were treated in the nonfragmented joint with 12 mg of triamcinolone acetonide (TA) 14 and 28 days after surgery. All horses were exercised on a high‐speed treadmill starting 15 days, and ending 72 days after surgery. Horses treated with TA in the fragmented joints were significantly less lame than those treated in the nonfragmented joints. Third carpal bones from joints with fragments showed significantly more vascularity, single labelled surface, total labelled surface and mineralising surface in subchondral and subjacent trabecular bone. Trends were also seen towards higher vascular canal volume and osteochondral junction remodelling sites in third carpal bones from fragmented joints. No significant differences were seen in microdamage density or size between fragmented and nonfragmented joints. No significant influence of TA treatment was seen on any parameter measured. The results from this study show that osteochondral fragmentation induces significant changes in remodelling of opposing bones, and that the administration of corticosteroids into joints with fragmentation does not significantly alter bone remodelling or fragility.
Effect of exercise on erythrocyte β‐adrenergic receptors and plasma concentrations of catecholamines and thyroid hormones in Thoroughbred horses
Authors: GONZÁLEZ O. , GONZÁLEZ EMA , SÁNCHEZ C. , PINTO J. , GONZÁLEZ I. , ENRÍQUEZ O. , MARTÍNEZ R. , FILGUEIRA G. , WHITE A.
Published: April 2010

The effects of exercise stress on erythrocyte β‐adrenergic receptor characteristics and plasma concentrations of adrenaline, noradrenaline and thyroid hormones were studied in Thoroughbred racehorses during rest and after exercise.

Five minutes after a maximal speed race of 1200 ± 200 m (mean ± s.d.), both plasma adrenaline and noradrenaline concentrations increased with respect to basal values (from 2.48 ± 0.15 to 3.83 ± 0.27 and from 2.13 ± 0.11 to 3.53 ± 0.27 nmol/1 respectively). The increment of adrenaline was greater in high performance (HP) as compared to low performance (LP) horses (76.9 vs. 43.5%), in accordance with the contribution of the adrenal medulla in the sympathoadrenal response to exercise.

Triiodothyronine (T3), but not thyroxine (T4) levels increased 5 min after exercise (from 55.6 ± 2.9 to 81 ± 3.7 ng/dl and from 0.67 ± 0.04 to 0.70 ± 0.05 pg/dl respectively). No differences were observed in basal values of thyroid hormones or in the percentage of T3 increment, when comparing HP vs. LP horses.

Erythrocyte membranes obtained 5 min after racing showed decreased concentrations of β‐adrenergic receptors (β‐AR) and dissociation constant as compared to basal values (50.1 ± 7.0 vs. 95.7 ± 12.0 fmol/mg protein and 0.97 ± 0.24 vs. 2.04 ± 0.3 nmol/l respectively). This temporal pattern suggest that the observed changes in β‐AR characteristics could be mediated by catecholamines, but not by thyroid hormones, in this model. This down regulation of β‐AR may act as a protecting mechanism preventing the erythrocytes from the decrease in membrane fluidity known to be provoked by adrenergic agonists.

The accomplished study showed that, in the Thoroughbred horse, there is a homeostatic response to race stress, characterised by a sudden increase in plasma catecholamines and T3 and a parallel decrease in β‐AR concentration on the erythrocyte membrane. In this way the racing horse could rapidly adjust its metabolism to the exercise stress, but at the same time override one possible undesirable side‐effect caused by these hormonal changes. Further studies will be required to establish performance‐related differences occurring in endocrine changes.
Cardiovascular effects of surgical castration during anaesthesia maintained with halothane or infusion of detomidine, ketamine and guaifenesin in ponies
Authors: TAYLOR POLLY M. , KIRBY J. J. , SHRIMPTON D. J. , JOHNSON C. B.
Published: April 2010

Sixteen colts were premedicated with acepromazine and anaesthesia was induced with detomidine and ketamine. Ponies were randomly allocated to receive halothane (HAL) or infusion of detomidine, ketamine and guaiphenesin (DKG) to maintain anaesthesia. Heart and respiratory rate, ECG, mean arterial blood pressure (MABP), cardiac index (CI), blood gases and plasma Cortisol, ketamine and guaiphenesin were measured. Surgical castration took place between 45 and 75 min and anaesthesia lasted 90 min. MABP with DKG was significantly higher than with HAL, and, with HAL, MABP increased from pre‐surgery (64 ± 6 mmHg) to mid‐surgery (80 ± 5 mmHg) but did not change with DKG. At 30 min, CI was similar in both groups (57 ± 7 ml/kg bwt/min); it decreased during surgery with HAL and remained low, but it increased slightly with DKG, and was higher than with HAL at 60 and 90 min. Plasma Cortisol decreased in both groups until 40 min then increased with HAL only during surgery. Ketamine concentration reached a plateau (1.3‐1.8 μg/ml) between 20 and 90 min and guaiphenesin concentration between 60 and 90 min (99–101 μg/ml). Recovery was generally smooth in both groups. This study demonstrated that during HAL the increase in blood pressure associated with surgical stimulus is accompanied by decreased CI; this did not occur during DKG which is likely to lead to better tissue perfusion than HAL. The adrenocortical activity seen during HAL was absent during DKG which may result from pituitary depression, analgesic effects of total intravenous anaesthesia (TIVA) or better perfusion.
Glomerular filtration rate, effective renal plasma flow, blood pressure and pulse rate in the equine neonate during the first 10 dayspost partum
Authors: HOLDSTOCK NICOLA B. , OUSEY JENNIFER C. , ROSSDALE P. D.
Published: April 2010

The aim of this study was to determine glomerular filtration rate (GFR), effective renal plasma flow (RPF) and filtration fraction (FF) values in Pony foals during the first 10 dayspost partumin order to assess any age‐related changes and the reliability of the single injection inulin/p‐aminohippurate (PAH) method. Arterial blood pressure and pulse rate were determined in Pony and Thoroughbred (TB) foals during the first 10 dayspost partumto establish age‐related changes, differences between breeds and possible interrelationships with GFR and RPF.

Inulin and PAH were injected intravenously (i.v.) in healthy Pony foals (n = 6) on Days 1, 2, 4, 7 and 10post partum.Blood samples were collected via the contralateral jugular catheter over a 4 h period. Plasma clearances of inulin and PAH showed that GFR and RPF, respectively, remained relatively constant throughout the post natal period, and were similar to values reported for mature horses. The GFR measurements obtained using the inulin method gave clearance values that were significantly higher (P<0.01) than those of creatinine clearance performed in a separate group of Pony foals (n = 7).

Blood pressure and pulse rates were measured using an electronic sphygmomanometer in TB (n = 6) and Pony foals (n = 7) on Days 1,2,3,4,7 and 10post partum.There were no significant differences in these measurements between the breeds, and both cardiovascular parameters increased during the first 3 dayspost partum.Values remained unchanged for the rest of the study period. Although measurements of GFR, RPF, blood pressure and pulse rates were not determined in the same animals, blood pressure and pulse rates did not appear to correlate with either GFR or RPF in the Pony foals during the post natal period.
Inhibin secretion in the stallion
Authors: NAGATA S. , MIYAKE Y‐I. , NAMBO Y. , NAGAMINE N. , WATANABE G. , TSUNODA N. , TANIYAMA H. , HONDO E. , YAMADA J. , TAYA K.
Published: April 2010

To examine the physiological role of inhibin in the stallion, a heterologous radioimmunoassay (RIA) based on a bovine RIA was validated and used to measure immunoreactive (ir)‐inhibin concentrations in plasma and testicular homogenates. The bioactivity of equine testicular inhibin was also examined using an assay for suppression of FSH secretion from rat anterior pituitary cells. In addition, to identify the cell responsible for secreting testicular inhibin, the localisation of inhibin in the testis was investigated by an immunohistochemical method using a polyclonal antibody against (Tyr30)‐porcine inhibin α(1–30) NH2. In the RIA, parallel dose response curves were obtained for the bovine inhibin standard and serial dilutions of stallion plasma and equine testicular homogenates. Parallel FSH inhibition curves were also observed for the bovine inhibin standard and serial dilutions of equine testicular homogenates in the bioassay. The inhibition of FSH secretion from rat pituitary cells by equine testicular homogenates was neutralised by an antiserum against bovine inhibin in vitro. Plasma concentrations of ir‐inhibin, testosterone and oestradiol‐17ß in stallions decreased abruptly after bilateral gonadectomy and FSH and LH concentrations in the plasma subsequently increased. Therefore, circulating inhibin in the stallion appeared to be largely of testicular origin. The histochemical results showed for the first time that strong immunopositive staining for inhibin occurred in the Leydig cells of the testes. Sertoli cells were also stained by the inhibin antibody but the reaction was weaker than that in Leydig cells. These results indicate clearly that both Leydig and Sertoli cells are potential sources of testicular inhibin in the stallion. A clear increase in plasma ir‐inhibin concentrations was observed during the natural breeding season. Similar seasonal changes in the plasma concentrations of testicular steroid hormones and pituitary gonadotrophins occurred throughout the year.

In conclusion, the testes appear to be the main source of inhibin, and testicular inhibin is secreted by Leydig and Sertoli cells in stallions. The positive correlations between plasma ir‐inhibin and testicular activity during both the breeding and nonbreeding seasons indicate that plasma irinhibin is a useful indicator of reproductive activity in the stallion.
Pulmonary vascular pressures of strenuously exercising Thoroughbred horses after administration of phenylbutazone and frusemide
Authors: MANOHAR M. , GOETZ T. E. , SULLIVAN EILEEN , GRIFFIN R.
Published: April 2010

The present study was carried out to examine the effects of phenylbutazone treatment on the pulmonary haemodynamic effects of frusemide in strenuously exercising horses. Using catheter mounted manometers, whosein vivosignals were referenced at the point of the shoulder, heart rate, right atrial, right ventricular and pulmonary vascular pressures were measured in 3 different sets of experiments. Seven Thoroughbreds were subjected to 1) control (no medications), 2) frusemide control and 3) phenylbutazone + frusemide. The experiments were carried out in random order and were separated by 7 days. Measurements were made at rest and during incremental exercise performed on a treadmill set at 3.5% uphill grade. In the frusemide control experiment, horses received frusemide 250 mg i.v., 4 h pre‐exercise. In the phenylbutazone + frusemide experiment, horses received 4 i.v. injections of phenylbutazone (4.4 mg/kg bwt) at 12 h intervals. Twenty‐four hours after the last phenylbutazone injection, horses received frusemide 250 mg i.v. and exercise was performed 4 h later. This latter regimen mimics prevailing veterinary practice at Illinois racetracks. The highest work intensity (14.2 m/s, 3.5% uphill grade) elicited maximal heart rate of horses. Significant right atrial, as well as pulmonary arterial, capillary and venous hypertension occurred with exertion in all 3 experiments. However, in the frusemide‐control and the phenylbutazone + frusemide studies, the exercise induced rise in mean right atrial and pulmonary vascular pressures was significantly (P<0.05) attenuated in comparison with that in the control experiments. Statistically significant differences were not found between the frusemide control study and the phenylbutazone + frusemide study either at rest or during any level of exertion. Therefore, it was concluded that the phenylbutazone treatment in our study did not mitigate the pulmonary haemodynamic effects of frusemide in strenuously exercising Thoroughbred horses.
Impact of mixed strongyle infections in foals after one month on pasture
Authors: THAMSBORG S. M. , LEIFSSON P. S. , GRØNDAHL C. , LARSEN M. , NANSEN P.
Published: April 2010

Twelve Standardbred foals (age 3–6 months), with little previous exposure to parasites, were allocated to 2 groups and put onto pasture with low (Group L) or high (Group H) levels of larval contamination of large strongyles and cyathostomes. After 4 weeks grazing in September, the foals were housed indoors until necropsy 15 weeks later. Foals in Group H became clinically more affected than those of Group L in that they showed loss of vigour, weight gain depression, intermittent soft faeces and inappetence. One foal of Group H had persistent diarrhoea and was subjected to euthanasia 12 weeks after housing. Signs of colic were not observed. Faecal egg counts were significantly higher in Group H than in Group L (P<0.05). At necropsy, the mean number of S. vulgaris and cyathostomes was 20 and 18,000, respectively, in Group L, and 167 and 25,000 in Group H. Routine blood chemistry did not specifically reveal presence of S. vulgaris in pre‐patency. A transient neutrophilia and eosinophilia, most prominent in Group H, was seen 2–8 weeks after start of exposure and anaemia was observed later in Group H. Serum albumin and albumin/globulin ratio were reduced, particularly in Group H, and a marked hyperbetaglobulinaemia was observed at 16–20 weeks in Group H. In conclusion, heavy infections with strongyles including S. vulgaris may become established in weaned foals after a brief period on pasture. Infections may be expressed clinically as debilitation, inappetence and intermittent diarrhoea without colic, and the need for control is imperative.
Quantitative assessment of motor neuron loss in equine motor neuron disease (EMND)
Authors: POLACK EVELYNE WEBER , KING J. M. , CUMMINGS J. F. , DE LAHUNTA A. , DIVERS T. J. , MOHAMMED H. O.
Published: April 2010

The mean number of motor neurons was assessed in the C7 spinal cord segment of 5 EMND and 5 control horses. Mean number per section in EMND horses was reduced significantly (P<0.001). The mean neuronal loss was estimated at 31%. Each of the 5 affected horses had a mean neuronal count below the 95% confidence interval for control horses. The statistically significant difference between the 2 groups was consistent in the cranial, middle and caudal thirds of the C7 segment (P<0.001). The results of regression analysis indicated an association between neuronal reduction in EMND horses and the duration of the disease when adjusted for age (P<0.001). This is the first quantitation of the neurodegenerative loss in EMND and it provides a clearer explanation for residual deficits in horses that survive EMND.
Bone scintigraphy in the diagnosis of sacroiliac injury in twelve horses
Authors: TUCKER R. L. , SCHNEIDER R. K. , SONDHOF A. H. , RAGLE C. A. , TYLER J. W.
Published: April 2010

Nuclear bone scintigraphy was used to diagnose sacroiliac injury in 12 horses presented for nonspecific rear limb lameness. The most common history was decreased performance and/or a mild chronic rear limb lameness which could not be localised by routine lameness examination. The scintigraphic patterns of the 12 affected horses were compared to 5 normal horses and 10 horses with lameness not related to the pelvic region. Subjective and quantitative evaluation of the bone scans clearly separated the 12 affected horses from the S normal horses and the 10 horses with lameness from causes other than the sacroiliac joint disease. The 12 affected horses had a scintigraphic pattern of moderate to marked increased uptake of the radiopharmaceutical within the sacroiliac joint region on the side of lameness. In contrast, the 5 normal horses and 10 horses scanned for other causes of lameness, had a symmetric, or only slightly asymmetric pattern of radioisotope uptake. Although nonspecific for the type of injury, nuclear bone scintigraphy is considered sensitive for the detection of sacroiliac injuries in horses.
Clinical assessment of gas exchange in mature horses
Authors: DAVIS M. S. , MURRAY M. J. , DONALDSON LYDIA L.
Published: April 2010

There are limited methods of assessing pulmonary function in horses at rest. We developed clinical techniques to measure gas exchange efficiency in horses and evaluated 3 groups of horses that were 1) asymptomatic based on auscultation with rebreathing, transtracheal aspirate cytology, and thoracic radiographs (n = 6), 2) asymptomatic at rest but symptomatic with rebreathing (n = 11) and 3) symptomatic at rest (n = 9). Blood samples were obtained from the transverse facial artery and jugular vein. Maximal end‐tidal CO2tension (PETCO2) was measured by an infrared capnograph through a facemask. Alveolar O2tension, dead space fraction (VD/VT), and physiological shunt fraction (QS/QT) were calculated using standard formulae. Arterial O2tension inGroup 1horses (mean ± s.d. 103 ± 3 mmHg) was significantly higher than inGroup 2orGroup 3horses. QS/QTinGroup 1horses (0.37 ± 0.98%) was significantly lower than inGroup 2andGroup 3horses. Mean ± s.d.VD/VTinGroup 1horses (‐18.2 ± 3.1) was significantly lower thanGroup 3horses but notGroup 2horses.
Prevalence and characteristics of foal rejection in Arabian mares
Authors: JUARBE‐DÍAZ SORAYA V. , HOUPT KATHERINE A. , KUSUNOSE R.
Published: April 2010

Separate surveys of Thoroughbred, Paint, and Arabian mare owners revealed a higher than expected rate of foal rejection in Arabian mares. A behavioural history form was submitted by owners of foal rejecting and nonrejecting Arabian mares, and maternal behaviour and management practices compared. Four generation pedigrees of rejecting and nonrejecting Arabian mares were also examined. Foal rejecting mares were more likely to avoid, threaten, squeal at, chase, bite, and kick their foalspost partumthan nonrejecting mares. Nonrejecting mares were more likely to lick, nicker and defend their foalspost partumthan rejecting mares. No statistically significant relationship was found between foal rejection and the type of breeding method (natural vs. artificial insemination), the presence of people at birth, the presence of nearby horses at birth, or assistance of the first nursing bout. The presence at least once of 1 of 2 related sires was statistically higher in the pedigrees of rejecting vs. nonrejecting mares. Inherited and learned or environmental factors are likely to affect the expression of foal rejection behaviour.
Cytology of 100 samples of abdominal fluid from 100 horses with abdominal disease
Authors: GARMA‐AVIÑA A.
Published: April 2010

A total of 100 samples of abdominal fluid (AF) from 100 horses with abdominal disease were evaluated by cytology. Cytology results were subsequently correlated with the final outcome of the disease. The horses were classified into 4 groups: Group I, horses that were treated with conventional (nonsurgical) therapy and recovered; Group II, horses that had surgery and survived; Group III, horses that had surgery but died; and Group IV, horses that were subjected to euthanasia prior to surgery. Statistical analysis showed that both nucleated cell count and total neutrophils were significantly higher in Group III than in Group I; and that the total mesothelial cells were significantly higher in Group III than in Groups I and II. No significant differences were found for erythrocyte counts and fluid total protein levels among the 4 groups. The findings suggest that classifying AF as transudate, modified transudate and exudate, as well as grading of inflammation as mild, moderate and severe on the basis of nucleated cell count (NCC) and fluid total protein (AFTP) can be greatly misleading. Differential identification of the nucleated cells was found to be far more reliable than the NCC alone, with or without the AFTP, and rendered valuable information, which overuled many times a diagnosis of transudate or modified transudate. Bands, metamyelocytes, toxic changes, plasma cells, and neutrophils penetrating rafts or fronds of mesothelial cells, supported a diagnosis of inflammation, even when the NCC, and the AFTP (interpreted according to currently accepted values) suggested otherwise. Several morphological features were found, including some cell types for which little or no mention was found at all in 22 major studies of this fluid in horses. Among these were ‘reddish neutrophils’, large granular lymphocytes (LGL), plasma cells, Mott cells, blasts, and a unique hitherto undescribed granular mesothelial cell.
Angular kinematic patterns of limbs in elite and riding horses at trot
Authors: MORALES J. L. , MANCHADO M. , VIVO J. , GALISTEO A. M. , AGÜERA E. , MIRÓ F.
Published: April 2010

Normal speed videography was used to determine the angular parameters of 28 Spanish Thoroughbreds at trot. Horses were divided into 3 groups:Group UT, comprising 9 animals (provided by the VII National Stud, Córdoba, Spain) which had undergone no specific training programme and which were hand led at the trot;Group T, formed by 19 horses considered to be highly bred and trained, and which were also hand led; andGroup RT, comprising the same horses as the latter group but this time trotted by a rider. Each animal was filmed 6 times from the right‐hand side, using a Hi8 (25 Hz) video camera. Angular parameters for fore‐ and hindlimb joints were measured in each stride from computer‐grabbed frames and entered into a spreadsheet for calculation; parameters included maximum and minimum angles, range of motion, and angles at landing, lift off and maximum hoof height; the times at which maximum angle, minimum angle, lift off and maximum hoof height occurred were calculated as percentages of total stride duration. Stride velocity (mean [s.d.]) was 4.01 (0.62), 3.60 (0.34) and 3.07 (0.36) m/s forGroups UT, TandRT, respectively. Data were then compared betweenGroups UT‐TandGroups T‐RT.

Compared withGroup UT, horses fromGroup Tfeatured a shorter stance percentage (P<0.001) in both fore‐ and hindlimbs. The range of motion in forelimbs was smaller (P<0.05), due to lower retraction (P<0.001); moreover, maximum retraction appeared earlier (P<0.05). Greater scapular inclination was in evidence (P<0.05) and the shoulder joint extended further (P<0.05). Fore‐ and hind fetlock joints revealed a relatively shorter hyperextension period during the stance phase (P<0.01).

Compared withGroup T, horses fromGroup RThad a longer stance percentage, with belated maximum retraction of the fore‐ and hindlimbs. The range of movement in scapular inclination was greater (P<0.05), due to a smaller minimum angle (P<0.01), and the shoulder joint flexed more (P<0.05). The elbow joint extended more and for longer during the stance phase. Initial extension of the hip joint (P<0.05) and tarsus (P<0.001) lasted longer. The carpal and fore and hind fetlock joints recorded relatively longer hyperextension times, in addition to greater hyperextension during the stance phase.

The results from the present study suggest that rider‐effect must be taken in consideration when well gaited horses are selected for dressage purposes.