bluuebunny/crossref_metadata_2025_split huggingface dataset:
Clenbuterol administration does not attenuate the exercise‐induced pulmonary arterial, capillary or venous hypertension in strenuously exercising Thoroughbred horses
Authors: MANOHAR M. , GOETZ T. E. , ROTHENBAUM P. , HUMPHREY S. 
Published: April 2007

SummaryThe present study was carried out to ascertain whether β2‐adrenergic receptor stimulation with clenbuterol would attenuate the pulmonary arterial, capillary and venous hypertension in horses performing high‐intensity exercise and, in turn, modify the occurrence of exercise‐induced pulmonary haemorrhage (EIPH). Experiments were carried out on 6 healthy, sound, exercise‐trained Thoroughbred horses. All horses were studied in the control (no medications) and the clenbuterol (0.8 μg/kg bwt, i.v.) treatments. The sequence of these treatments was randomised for every horse, and 7 days were allowed between them. Using catheter‐tip‐transducers whosein‐vivosignals were referenced at the point of the left shoulder, right heart/pulmonary vascular pressures were determined at rest, sub‐maximal exercise and during galloping at 14.2 m/s on a 3.5% uphill grade ‐ a workload that elicited maximal heart rate and induced EIPH in all horses. In the control experiments, incremental exercise resulted in progressive significant increments in right atrial as well as pulmonary arterial, capillary and venous (wedge) pressures and all horses experienced EIPH. Clenbuterol administration to standing horses caused tachycardia, but significant changes in mean right atrial or pulmonary vascular pressures were not observed. During exercise performed after clenbuterol administration, heart rate as well as right atrial and pulmonary arterial, capillary and wedge pressures also increased progressively with increasing work intensity. However, these values were not found to be statistically significantly different from corresponding data in the control study and the incidence of EIPH remained unaffected. Since clenbuterol administration also does not affect the transpulmonary pressure during exercise, it is unlikely that the transmural force exerted onto the blood‐gas barrier of exercising horses is altered following i.v. clenbuterol administration at the recommended dosage.
The influence of strenuous exercise on collagen characteristics of articular cartilage in Thoroughbreds age 2 years
Authors: BRAMA P. A. J. , TEKOPPELE J. M. , BANK R. A. , BARNEVELD A. , FIRTH E. C. , WEEREN P. R. van 
Published: April 2007

SummaryIn order to assess the influence of strenuous exercise on collagen characteristics of articularcartilage, the response of the collagen network was studied in seven 2‐year‐old Thoroughbreds subjected to strenuous exercise compared to 7 nontrained individuals. After 13 weeks, the animals were subjected to euthanasia, fetlock joints of the forelimbs were scored macroscopically after Indian Ink staining, and articular cartilage from different locations of the articular surface of the proximal first phalanx was sampled and analysed for water content, collagen content, hydroxylysine content and amount of hydroxylysylpyridinoline (HP) crosslinks. Gross lesions were significantly more severe in the exercised than in the nonexercised group. In the control animals, the characteristic site‐specific differences in collagen parameters were found as described earlier, but in the strenuously exercised animals this physiological biochemical heterogeneity had disappeared. In the exercised animals, an increase in water content and a sharp decrease in HP crosslinking was found that was correlated with the presence of wear lines. It is concluded that the strenuous exercise provoked significant alterations in the characteristics of the collagen network of the articular cartilage of the fetlock joint which were suggestive of microdamage and loosening of the collagen network. The collagen component of cartilage, in contrast to the proteoglycan component, is known to have a very limited capacity for repairand remodelling due to an extremely low turnover rate. Therefore, alterations within the articular collagen network might be expected to play an important role in the pathophysiology of degenerative joint disorders.
Evidence for surfactant contributing to the gastric mucosal barrier of the horse
Authors: ETHELL M. T. , HODGSON D. R. , HILLS B. A. 
Published: April 2007

SummaryThis study was undertaken to determine the hydrophobicity of the luminal surface of the equine stomach and to elucidate the ultrastructure of the lining imparting that property. Gastric and duodenal mucosal samples from 5 horses were collected immediately after euthanasia and subjected to surface contact angle measurement using a goniometer. Gastric mucosal samples from 4 horses and a foal were examined by electron microscopy following a fixation procedure known to preserve phospholipids and oligolamellar structures. Contact angles for the equine gastric glandular mucosal surface (mean ± s.e. 78.0 ± 11.0°) were greater than for the duodenum (33.4 ± 8.7°), (P = 0.003). The contact angles for gastric squamous tissue (50.4 ± 4.5°) tended to be greater than for duodenum (P = 0.15). Electron microscopy revealed the existence of surfactant as abundant osmiophilic phospholipid material within both squamous and glandular gastric mucosae. These results indicate the hydrophobic nature of the equine gastric mucosae. We propose that the water‐repellent nature of the stomach contributes to the ‘gastric mucosal barrier’ and is imparted by surface‐active phospholipid adsorbed to the surface. Phospholipids may also be utilised as a physical barrier to back‐diffusion of acid by lining intracellular canaliculi and oxyntic ducts where other defence mechanisms are absent.
Elimination of guttural pouch infection and inflammation in asymptomatic carriers ofStreptococcus equi
Authors: VERHEYEN K. , NEWTON J. R. , TALBOT N. C. , BRAUWERE M. N. de , CHANTER N. 
Published: April 2007

SummaryThree protracted outbreaks of strangles were investigated using endoscopic examination and a total of 14 asymptomatic carriers ofStreptococcus equiwere identified of which 13 showed evidence of carriage in the guttural pouch. Treatment was initiated to eliminateS. equicolonisation since these animals posed an infectious risk to susceptible horses. Two further horses were referred to us with severe guttural pouch pathology and from whichS. equiwas cultured, and treatment of these cases is also described. Treatment in the first instance was directed towards removal of gross guttural pouch pathology as seen on endoscopic examination. This was done with a combination of irrigation of the pouch with moderate to large amounts of saline, suction of fluid material and endoscopic manipulation of chondroids. Subsequently, antibiotic treatment was used to eliminateS. equiinfection. All animals received systemic antibiotics, in some cases combined with topical antimicrobial treatment. Treatment was generally regarded as successful when the guttural pouches appeared normal andS. equiwas not detected in nasopharangeal swabs and pouch lavages on 3 consecutive occasions. Successful treatment of one carrier required surgical intervention due to occlusion of both guttural pouch pharyngeal openings. Fourteen of 15 carriers were successfully treated by endoscopic removal of inflammatory material and antibiotic treatment, without surgical intervention. Five carriers originally given potentiated sulphonamide (33%) required further therapy with penicillin or ceftiofur, administered both systemically and topically, beforeS. equiinfection and associated inflammation of the guttural pouches were eliminated.
Uroperitoneum in the hospitalised equine neonate: retrospective study of 31 cases, 1988–1997
Authors: KABLACK K. A. , EMBERTSON R. M. , BERNARD W. V. , BRAMLAGE L. R. , HANCE S. , REIMER J. M. , BARTON M. H. 
Published: April 2007

SummaryHistorical, physical and diagnostic data were reviewed retrospectively in 31 equine neonates with uroperitoneum. Genderpredilection was not observed, and classic electrolyte abnormalities were seen in less than 50% of the cases. Aetiologies for uroperitoneum have been well described, but this review found that septicaemia/severe illness played a crucial role in the outcome of uroperitoneum. Approximately half the individuals with uroperitoneum had positive sepsis scores. Foals receiving fluid therapy were more likely to be septic and to have normal electrolyte concentrations. Ultrasonographic findings, serum creatinine and serum:peritoneal creatinine ratios were not affected by previous fluid therapy and were invaluable aids in the diagnosis of uroperitoneum, even with multisystemic disease such as sepsis.
Control of strangles outbreaks by isolation of guttural pouch carriers identified using PCR and culture of Streptococcus equi
Authors: NEWTON J. R. , VERHEYEN K. , TALBOT N. C. , TIMONEY J. F. , WOOD J. L. N. , LAKHANI K. H. , CHANTER N. 
Published: April 2007

SummaryPrevious use of repeated nasopharyngeal swabbing and culture of Streptococcus equi showed that healthy carriers developed in more than 50% of ‘strangles’ outbreaks. The guttural pouches were the only detectable site of S. equi colonisation on endoscopic examination of horses during one of these outbreaks and S. equi was sometimes not detected by culture of nasopharyngeal swabs from carriers for up to 2 or 3 months before nasal shedding resumed sporadically. A more sensitive way of detecting S. equi on swabs from established guttural pouch carriers was therefore required. Conveniently selected ‘strangles’ outbreaks were investigated in detail using endoscopy, in order to develop and assess a suitable polymerase chain reaction (PCR) test. We report here 3 protracted ‘strangles’ outbreaks on different kinds of establishments in which between 29 and 52% of sampled horses were infected as detected by culture and/or PCR. Of the infected horses, between 9 and 44% were identified as carrying S. equi after clinical signs had disappeared and the predominant site of carriage was the guttural pouch. Prolonged carriage of S. equi, which lasted up to 8 months, did not cease spontaneously before treatment was initiated to eliminate the infections. The detection and isolation of the carriers, in conjunction with strict hygiene measures, apparently resulted in the control of the outbreaks and allowed the premises to return to normal activity. Comparing PCR and culture, many more swabs were found to be positive using PCR (56 vs. 30% of 61 swabs). Similar results were obtained for guttural pouch samples from 12 established carriers (PCR 76% and culture 59%). These results from repeated samples from relatively few animals need confirming using more long‐term carriers. PCR can also detect dead organisms and is, therefore, liable to yield false positive results. Despite this drawback, it is argued that PCR provides a potentially useful adjunct to culture of nasopharyngeal swabs in the detection of asymptomatic carriers of S. equi following outbreaks of ‘strangles’.
Endotoxin and dietary amines may increase plasma 5‐hydroxytryptamine in the horse
Authors: BAILEY S. R. , CUNNINGHAM F. M. , ELLIOTT J. 
Published: April 2007

SummaryUptake of 5‐hydroxytryptamine (5‐HT) into platelets is an important mechanism by which low plasma concentrations are maintained, and platelet activation may therefore result in significant release of this vasoconstrictor. The present study examined the kinetics of active uptake of radiolabelled [3H]5‐HT by washed equine plateletsin vitro, and investigated the effects on this process of 4 other naturally occurring monoamines which may be released from the caecum in conditions of carbohydrate overload. The release of [3H]5‐HT by platelets was also studied, since platelet accumulation and activation has been associated with acute laminitis. Release of [3H]5‐HT was measured in response to platelet activating factor (PAF), unlabelled 5‐HT and the indirect activation of platelets by endotoxin in the presence of blood leucocytes. Kmvalue for the uptake of 5‐HT by equine platelets was 2.4 ± 0.6 μmol/l and the Vmaxwas 8.3 ± 0.6 pmol [3H]5‐HT/107platelets/min. The rate of uptake of 5 μmol/l [3H]5‐HT was significantly decreased by the uptake inhibitors fluvoxamine and clomipramine. The 4 other monoamines examined all inhibited the uptake of [3H]5‐HT in a noncompetitive manner, decreasing Vmaxby between 17 and 82%. Incubation of platelets with LPS (0.1 mg/ml) in the absence of leucocytes did not result in significant release of [3H]5‐HT; however, in the presence of leucocytes 3.8 ± 1.7 pmol [3H]5‐HT/107platelets (mean ± s.e.) were released. This release was significantly inhibited by parthenolide and WEB2086, but not by aspirin. This suggests that PAF from activated leucocytes was responsible for the 5‐HT release. These data show that 5‐HT uptake by equine platelets is a saturable process operating most efficiently at substrate concentrations in the low micromolar range. The noncompetitive inhibition of 5‐HT uptake by other naturally occurring monoamines may result in increased plasma concentrations of 5‐HT, as would its release by endotoxin. Such a rise in plasma 5‐HT concentrations may contribute to selective vasoconstriction in the equine digital circulation.
Equine proliferative enteropathy: a cause of weight loss, colic, diarrhoea and hypoproteinaemia in foals on three breeding farms in Canada
Authors: Lavoie J. P. , Drolet R. , Parsons D. , Leguillette R. , Sauvageau R. , Shapiro J. , Houle L. , HallÉ G. , Gebhart C. J. 
Published: April 2007

SummaryProliferative enteropathy (PE) is a transmissible enteric disease caused byLawsonia intracellularis.An outbreak of equine PE was diagnosed in foals from 3 breeding farms. Most foals had been weaned prior to the appearance of clinical signs, which included depression, rapid and marked weight loss, subcutaneous oedema, diarrhoea and colic. Poor body condition with a rough haircoat and a potbellied appearance were common findings in affected foals. Respiratory tract infection, dermatitis and intestinal parasitism were also found in some foals. Haematological and plasma biochemical abnormalities included hypoproteinaemia, transient leucocytosis, anaemia and increased serum creatinine kinase concentration.Postmortemdiagnosis of PE was confirmed on 4 foals based on the presence of characteristic intracellularbacteria within the apical cytoplasm of proliferating crypt epithelial cells of the intestinal mucosa, using silver stains, and by results of PCR analysis and immunohistochemistry.Antemortemdiagnosis of equine PE was based on the clinical signs, hypoproteinaemia and the exclusion of common enteric infections. Faecal PCR analysis was positive for the presence ofL. intracellularisin 6 of 18 foals tested while the serum of all 7 foals with PE serologically evaluated had antibodies againstL. intracellularis.Most foals were treated with erythromycin estolate alone or combined with rifampin for a minimum of 21 days. Additional symptomatic treatments were administered when indicated. All but one foal treated with erythromycin survived the infection. This study indicates that equine PE should be included in the differential diagnosis of outbreaks of rapid weight loss, diarrhoea, colic and hypoproteinaemia in weanling foals.
Evidence supporting an increased presence of reactive oxygen species in the diseased equine joint
Authors: Dimock A. N. , Siciliano P. D. , McIlwraith C. W. 
Published: April 2007

SummaryReactive oxygen species (ROS) are capable of degrading many components of the joint in the presence of insufficient antioxidant defences, and as a result have been implicated in the pathogenesis of joint disease in horses. However, to our knowledge, evidence of ROS occurring in diseased joints of horses has not been reported. The objective of this experiment was to compare differences in synovial fluid protein carbonyl content (as a marker of oxidative modification of synovial fluid proteins by ROS) and the antioxidant status of synovial fluid between clinically normal and diseased equine joints. Synovial fluid was collected from the metacarpophalangeal, metatarsophalangeal, carpal and tarsal joints of 4 horses, age 2–5 years, as controls, and from diseased joints (metacarpophalangeal, metatarsophalangeal, carpal, tarsal and/or femoropatellar) of 61 horses, age 2–5 years.Synovial fluid protein carbonyl content was higher (P<0.01) in diseased joints as compared to controls. Antioxidant status of synovial fluid from diseased joints was higher, but not significantly, than that of controls (P = 0.0595). These findings require further study to determine their contribution to the overall disease process.
Relationship between clinical signs and lung function in horses with recurrent airway obstruction (heaves) during a bronchodilator trial
Authors: Robinson N. E. , Olszewski M. A. , Boehler D. , Berney C. , Hakala J. , Matson C. , Derksen F. J. 
Published: April 2007

SummaryDuring a trial to determine the dose response to the β2‐adrenergic agonist pirbuterol, we judged the severity of airway obstruction by use of a clinical scoring system and compared this to objective data obtained by quantitative measures of lung function. Six horses affected by recurrent airway obstruction were used in this trial. Four hundred and sixty‐eight measurements of lung function and clinical scores were obtained from 13 measurement periods when horses received each of 6 doses of pirbuterol. Scores of 1–4 were assigned to degree of nasal flaring and abdominal effort and summed for a total score. The veterinarian scoring the signs did not know the dose of pirbuterol received by the horse and was unaware of the lung function data. Nasal, abdominal and total scores were significantly related to changes in lung function and changes in breathing pattern. There were significant differences between total scores greater than 5 in indices that reflected changes in breathing strategy (peak inspiratory and expiratory flow), peripheral airway obstruction (dynamic elastance), and effort of breathing (maximal change in pleural pressure). Below a total score of 5, there were fewer significant differences in lung function even though measurements of pulmonary resistance and dynamic elastance indicated considerable airway obstruction. Failure of clinical score to reflect this low‐grade airway obstruction suggests that airway disease is underdiagnosed and its detection would be helped by the availability of a convenient lung function test.
Anaemia, diarrhoea and opportunistic infections in Fell ponies
Authors: Richards A. J. M. , Kelly D. F. , Knottenbelt D. C. , Cheeseman M. T. , Dixon J. B. 
Published: April 2007

SummaryThis report summarises clinical and pathological observations on Fell pony foals with a range of signs that included ill thrift, anaemia, respiratory infection, glossal hyperkeratosis and diarrhoea. Some of the foals had normochromic, normocytic anaemia and some had low levels of plasma proteins, including immunoglobulin G. Antibiotic and supportive treatment was ineffective and all affected foals died or were killed on humane grounds. Postmortem examination of 12 foals and tissues from 2 other foals revealed a range of lesions that included glossal hyperkeratosis, typhlocolitis, intestinal cryptosporidiosis, granulomatous enteritis, proliferative and necrotising bronchiolitis consistent with adenovirus infection; lesions similar to those in the respiratory tract were present in the salivary gland and pancreas of individual foals. Lymphoid tissue was judged to be smaller than expected. These observations suggest the possibility of opportunistic infections secondary to some form of undefined immunocompromised state.
Affinity of isoxsuprine for adrenoreceptors in equine digital artery and implications for vasodilatory action
Authors: Belloli C. , Carcano R. , Arioli F. , Beretta C. 
Published: April 2007

SummaryWe used isolated equine digital arteries to study the vasodilatory mechanism of isoxsuprine, and fowl caecum preparations to investigate the affinity of the drug for β‐adrenoceptors. Isoxsuprine is a potent vasodilator of arterial smooth muscle that has been precontracted by an α‐adrenoceptoragonist such as noradrenaline (log EC50= ‐6.33 [‐5.98; ‐6.68]). The present study indicates that its effect is due to α‐adrenoceptorblockade since: (1) aftera long lasting exposure to cumulative doses of isoxsuprine the vasoconstricting action of noradrenaline cannot be restored; (2) isoxsuprine does not promote relaxation on preparations precontracted by PGF2α; (3) isoxsuprine shifts the dose‐response curve of noradrenaline to the right; and (4) its affinity (pKB= 6.90 [6.60; 7.20]) in this experiment is comparable to that in noradrenaline‐precontracted preparations and is 14 times lower than that of the selective α1‐adrenergic antagonist prazosin [pKB= 8.04 (7.40; 8.68]).The affinity of isoxsuprine for β‐adrenoceptors was 100 times lower than that of isoprenaline when tested on fowl caecum. This preparation has a large β‐adrenoceptor and negligible α‐adrenoceptor population concerned with the control of smooth muscle motility. Our data suggest that the α‐mediated effect of isoxsuprine on horse arterial smooth muscle is due to higher affinity of the drug for α‐ than β‐adrenoceptors ratherthan low concentration orfunctionality of β‐sites at this site. According to these data, pure β2‐agonists seem to be more profitable tools to determine vasodialtion of the arterial bed in horses legs.
Spontaneous production of nitric oxide (NO), prostaglandin (PGE2) and neutral metalloproteinases (NMPs) in media of explant cultures of equine synovial membrane and articular cartilage from normal and osteoarthritic joints
Authors: Von Rechenberg B. , Mcilwraith C. W. , Akens M. K. , Frisbie D. D. , Leutenegger C. , Auer J. A. 
Published: April 2007

SummaryNitric oxide (NO), prostaglandin E2(PGE2), and the activity of neutral metalloproteinases (NMPs) were measured in conditioned media of equine synovial membrane and articular cartilage explant cultures from horses with normal joints (n = 7) and from horses affected with moderate (n = 7) or severe osteoarthritis (n = 14) as judged by macroscopic appearance. Normal articular cartilage appeared glossy and bluish‐white, was of normal thickness and showed no evidence of discolouration, fibrillation or other cartilage discontinuity. Slight discolouration and fibrillation or minor clefts of the cartilage were considered as moderate OA, whereas erosions of articular cartilage down to the subchondral bone were considered as cases of severe OA.Explant cultures of equine synovial membrane and articular cartilage released the local mediators, NO and PGE2, as well as detectable levels of NMP activity into culture media. Concentrations of NO were higherin articular cartilage explants compared to synovial membrane explants, whereas concentrations of PGE2were higher in synovial membrane explants. The NMPs with collagenolytic activities were similar in both explant cultures, whereas gelatinolytic activities were higherin synovial membrane explant cultures and caseinolytic activities were generally higher in articular cartilage explant cultures. Furthermore it was shown that concentrations or enzyme activities increased according to the severity of disease of the joints. Concentrations for NO, collagenolytic and gelatinolytic NMPs were relatively stable, whereas PGE2and caseinolytic NMP concentrations increased over time in culture.