bluuebunny/crossref_metadata_2025_split huggingface dataset:
Weight prediction from linear measures of growing Thoroughbreds
Authors: Staniar W. B. , Kronfeld D. S. , Hoffman R. M. , Wilson J. A. , Harris P. A. 
Published: April 2007

Summary Reason for performing study: Monitoring weight of foals is a useful management practice to aid in maximising athletic potential while minimising risks associated with deviations from normal growth. Objective: To develop predictive equations for weight, based on linear measurements of growing Thoroughbreds (TBs). Methods: Morphometric equations predicting weight from measurements of the trunk and legs were developed from data of 153 foals. The accuracy, precision and bias of the best fitting equation were compared to published equations using a naïve data set of 22 foals. Results: Accuracy and precision were maximised with a broken line relating calculated volumes (Vt + l***) to measured weights. Use of the broken line is a 2 step process. Vt + 1 is calculated from linear measures (m) of girth (G), carpus circumference (C), and length of body (B) and left forelimb (F).The broken line was more accurate and precise than 3 published equations predicting the weight of young TBs. Conclusions: Estimation of weight using morphometric equations requires attention to temporal changes in body shape and density; hence, a broken line is needed. Including calculated leg volume in the broken line model is another contributing factor to improvement in predictive capability. Potential relevance: The broken line maximises its value to equine professionals through its accuracy, precision and convenience.;
Equine grass sickness is associated with low antibody levels to Clostridium botulinum: a matched case‐control study
Authors: Mccarthy H. E. , French N. P. , Edwards G. B. , Poxton I. R. , Kelly D. F. , Payne‐Johnson C. E. , Miller K. , Proudman C. J. 
Published: April 2007

Summary Reasons for performing study: Equine grass sickness is a high mortality disease which, despite many years of investigation, is of unknown aetiology. Recent findings indicating that the disease is associated with Clostridium botulinum require support from an epidemiological study that recognises and controls for potential confounders, e.g. age, time of year and premises. Hypothesis: EGS is associated with low antibody levels to C. botulinum antigens. Methods: A matched case‐control study was conducted. Data were collected from 66 histologically confirmed cases of EGS and 132 premises‐matched control horses. The probability of EGS in horses was modelled using conditional logistic regression. Results: EGS was significantly associated (age‐adjusted P<0.005) with low antibody levels to each of 3 clostridial antigens; C. botulinum type C and C. novyi type A surface antigens and a C. botulinum type C toxin complex toxoid. These serological risk factors for EGS remained highly significant when entered into multivariable models. This study also identified new horse‐level risk factors for EGS; feeding hay or haylage was associated with a decreased risk of disease, change of feed type or quantity during the 14 days prior to disease was associated with increased risk, and the use of an ivermectin anthelmintic at both the ultimate and penultimate treatments was also associated with a significantly increased risk of EGS. Conclusions: This study provides strong support for the role of C. botulinum in the aetiology of EGS and identifies managemental risk factors for the disease. Potential relevance: Increasing anticlostridial antibody levels by vaccination and appropriate managemental interventions may decrease the risk of EGS occurring.;
The β‐agonist clenbuterol in mane and tail hair of horses
Authors: Schlupp A. , Anielski P. , Thieme D. , Müller R. K. , Meyer H. , Ellendorff F. 
Published: April 2007

Summary Reasons for performing study: The β2‐agonist clenbuterol is commonly administered for therapeutic purposes in the horse, but its use an an anabolic agent is illegal. Clenbuterol can be detected in blood and urine for a relatively short period after administration and detection in hair could enhance the analytical range and be used to determine the history of clenbuterol application. Hypothesis: That detection in mane or tail hair is possible over an extended period. Methods: Four horses received 0.8 μg elenbuterol hydrochloride/kg bwt b.i.d. for 10 days. Four other horses were used as untreated controls. Blood, urine, mane and tail hair samples were taken on Day 0 (before) and 5, 10, 30, 35, 40, 60, 90, 120, 150 and 360 days after start of treatment. Gas chromotography/high resolution mass spectrometry (GC/HRMS) was developed for clenbuterol analysis: limit of detection was 0.2 pg/mg; intra‐assay repeatability limit r = 0.06 (confidence level 95%); interassay repeatability limit r = 0.03 (confidence level 95%). Prior to treatment, clenbuterol was absent from all samples analysed. Results: Clenbuterol was detectable as early as Day 5 in tail and mane hair of Segment 1 (0–20 mm from the roots) and was maximal on Day 90. However, as time progressed, shift into lower 20 mm segments was observed. On Day 360, the maximum concentration (up to 21 pg/mg) was located in Segment 13, i.e. 26–28 cm from roots of hair. Clenbuterol was not detectable in blood or urine after Day 30. Mane and tail hair results were very similar. Conclusions: The study showed that the β‐agonist clenbuterol can be found in mane and tail hair of horses after extended periods. Potential relevance: It will be possible to detect clenbuterol in breeding and show horses where anabolic drugs have been used illegally to improve conformation. This method may also be helpful to monitor therapeutic clenbuterol treatment.;
Hair analysis as a novel investigative tool for the detection of historical drug use/misuse in the horse: a pilot study
Authors: Dunnett M. , Lees P. 
Published: April 2007

Summary Reasons for performing study: Analysis of human hair for drug residues is being used increasingly as a diagnostic tool in the investigation of drug use and abuse. Hair analysis is complementary to urine/blood testing in that it can provide an extensive historical record of drug use, is noninvasive, impersonal and can facilitate retesting. However, the technique has not been studied in horses. Hypothesis: That the systemic administration of drugs in horses could be identified by the detection of drug residues in hair. Objective: To evaluate hair analysis as a potential retrospective diagnostic test for drug administration in horses by studying the deposition of systemically administered drugs in tail hair. Methods: Tail hairs (n = 40–50) from 4 horses with known drug histories were washed, chopped into 3–5 mm fragments and extracted overnight, in 0.1 mol/1 hydrochloric acid, prior to solid‐phase extraction and analysis by high‐performance liquid chromatography. Horse 1, a 3‐year‐old Thoroughbred colt (gastric ulcer), was treated for 14 days with omeprazole; Horse 2, a 3‐year‐old Thoroughbred colt (anaerobic infection), was treated for 5 days with metronidazole; Horse 3, an 8‐year‐old Thoroughbred gelding (sinusitis), was treated for 10 days with trimethoprim/sulphadiazine; and Horse 4, a 3‐year‐old Thoroughbred colt (respiratory infection), was treated for 5 days with procaine benzylpenicillin. Results: Omeprazole was not detected in tail hair. Metronidazole was detected in tail hair at a concentration of 0.57 ng/mg, trimethoprim and sulphadiazine at concentrations of 9.14 and 2.26 ng/mg, respectively, and procaine at a concentration of 1.66 ng/mg. Conclusions: The data presented suggest that hair analysis may become a useable technique for the retrospective detection of drug administration in horses. Potential relevance: This technique could ultimately be used as part of a prepurchase veterinary examination to identify misuse of anti‐inflammatory and sedative drugs, in an in‐training testing programme to identify use of anabolic agents, or to provide evidence to support post race blood or urine test results. Clearly, more extensive research will be required to evaluate the effectiveness of the technique over a much broader range of drugs.
Increased expression of MAIL, a cytokine‐associated nuclear protein, in the prodromal stage of black walnut‐induced laminitis
Authors: Waguespack R. W. , Kemppainen R. J. , Cochran A. , Lin H. C. , Belknap J. K. 
Published: April 2007

SummaryReasons for performing study: The mediators and signalling cascades important in the initiation of laminitis remain unclear. We therefore wanted to explore the genes and overall signalling mechanisms that play an important role in the developmental stage of laminitis.Objective: To use a broad genomic screening technique to identify novel genes that are differentially regulated in the equine lamellae during the developmental period of laminitis.Methods: Differential mRNA display (DRD) was performed to discover regulated genes, and real‐time quantitative polymerase chain reaction (RT‐qPCR) was then used to evaluate lamellar mRNA levels of a regulated gene (MAIL) and mediators related to that gene (IL‐1β and IL‐6) in control horses (n = 5) and horses administered black walnut extract (BWE; n = 5).Results: Using DRD, MAIL was identified as a regulated gene. RT‐qPCR indicated a 4‐fold increase in expression of the MAIL mRNA in BWE lamellae compared to controls. A 30‐fold increase in IL‐1β, and a 160‐fold difference in IL‐6 mRNA expression was present in BWE lamellae. Differences in MAIL, IL‐1β and IL‐6 mRNA expression were statistically significant between groups (P<0.05).Conclusions and potential relevance: The data strongly support a role for inflammatory cytokines in the developmental stages of laminitis, possibly inducing the vascular and metabolic alterations reported to occur in the affected digit. These results potentially support the use of anti‐inflammatory drugs in horses at risk of laminitis, and warrant further investigation of the link between systemic disease processes associated with laminitis and the reported digital inflammation.
In vitroandin vivostudies of homocysteine in equine tissues: implications for the pathophysiology of laminitis
Authors: Berhane Y. , Bailey S. R. , Harris P. A. , Griffiths M. J. , Elliott J. 
Published: April 2007

SummaryReasons for performing study: Elevated plasma homocysteine (HCy) concentration is a risk factor for cardiovascular diseases associated with endothelial dysfunction, including the human digital ischaemic disease, Raynaud's phenomenon.Hypothesis: HCy causes dysfunction of equine vascular endothelium and elevated plasma concentrations predispose to laminitis.Objectives: To determine 1) the concentration of HCyin vitro, which inhibits equine vascular endothelial cell function and 2) any association between risk of laminitis and plasma HCy concentration.Methods: Endothelial function was studied by measuring endothelium‐dependent vasodilatory responses of the equine isolated perfused digit and basal nitric oxide (NO) production by cultured equine digital vein endothelial cells (EDVECs). Total plasma HCy (tHCy) concentrations were measured in samples collected in the winter and spring from normal ponies and ponies predisposed to laminitis.Results: HCy (10 and 100 μmol/l) inhibited endothelial function and, at concentrations above 100 μmol/l, inhibited NO production by EDVECs. Plasma tHCy concentration ranged from 1.3 to 14.7 μmol/l. There was no effect of season or disease status on the concentration measured.Conclusions: In vitro, HCy was shown to interfere with endothelial cell function at physiologically relevant concentrations. No evidence was found for an association between risk of laminitis and high plasma concentrations of HCy.Potential relevance: Elevated plasma HCy concentrations could adversely affect endothelial cell function and mangement regimens that lead to increases in plasma HCy concentration should be avoided in ponies predisposed to laminitis.
Equine laminitis: glucose deprivation and MMP activation induce dermo‐epidermal separation in vitro
Authors: French K. R. , Pollitt C. C. 
Published: April 2007

Summary Reasons for performing study: Acute laminitis is characterised by hoof lamellar dermal‐epidermal separation at the basement membrane (BM) zone. Hoof lamellar explants cultured in vitro can also be made to separate at the basement membrane zone and investigating how this occurs may give insight into the poorly understood pathophysiology of laminitis. Objectives: To investigate why glucose deprivation and metalloproteinase (MMP) activation in cultured lamellar explants leads to dermo‐epidermal separation. Methods: Explants, cultured without glucose or with the MMP activator p‐amino‐phenol‐mercuric acetate (APMA), were subjected to tension and processed for transmission electron microscopy (TEM). Results: Without glucose, or with APMA, explants under tension separated at the dermo‐epidermal junction. This in vitro separation occurred via 2 different ultrastructural processes. Lack of glucose reduced hemidesmosomes (HDs) numbers until they disappeared and the basal cell cytoskeleton collapsed. Anchoring filaments (AFs), connecting the basal cell plasmalemma to the BM, were unaffected although they failed under tension. APMA activation of constituent lamellar MMPs did not affect HDs but caused AFs to disappear, also leading to dermo‐epidermal separation under tension. Conclusions: Natural laminitis may occur in situations where glucose uptake by lamellar basal cells is compromised (e.g. equine Cushing's disease, obesity, hyperlipaemia, ischaemia and septicaemia) or when lamellar MMPs are activated (alimentary carbohydrate overload). Potential relevance: Therapies designed to facilitate peripheral glucose uptake and inhibit lamellar MMP activation may prevent or ameliorate laminitis.
Chronic equine laminitis is characterised by loss of GLUT1, GLUT4 and ENaC positive laminar keratinocytes
Authors: Mobasheri A. , Critchlow K. , Clegg P. D. , Carter S. D. , Canessa C. M. 
Published: April 2007

SummaryReasons for performing study: Equine laminitis is a multifactorial connective tissue disorder with major implications for the welfare of horses. There are few published studies on phenotypic markers for identification of equine laminar keratinocytes using immunohistochemical techniques.Objectives: To establish whether the epithelial sodium channel (ENaC) and the GLUT1 and GLUT4 facilitative glucose transporters may be used as phenotypic markers for identification of equine laminar keratinocytes using immunohistochemical techniques to monitor changes in the keratinocyte population in laminitis.Methods: Histology and immunohistochemistry using polyclonal antibodies to the α subunit of ENaC (αENaC), GLUT1 and GLUT4 were used to compare the distribution of these proteins in normal and laminitic equine laminae.Results: Immunohistochemistry with antibodies to αENaC, GLUT1 and GLUT4 confirmed the abundant expression of all 3 membrane proteins in healthy laminar keratinocytes. However, in laminitis, the Haematoxylin Van Gieson (HVG) technique revealed disordered laminar arrays and replacement with fibrous scar tissue. Immunostaining of laminitic samples confirmed the loss of αENaC, GLUT1 and GLUT4 positive keratinocytes. Other connective tissue cells did not stain positive for these proteins.Conclusions: This is the first report of αENaC and GLUT1/GLUT4 protein expression in equine laminar keratinocytes, which also confirms that the loss of laminar structure and function in chronic laminitis is accompanied by the loss of laminar keratinocytes.Potential relevance: αENaC, GLUT1 and GLUT4 may be used as phenotypic markers of metabolically active, differentiated equine laminar keratinocytes. Furtherin vitrostudies are necessary to determine the effects of hypoxia, bacterial endotoxins, vasoactive amines, lactic acid and prostaglandins on the expression and activity of these plasma membrane keratinocyte markers.
Equine laminitis: increased transcription of matrix metalloproteinase‐2 (MMP‐2) occurs during the developmental phase
Authors: Kyaw‐Tanner M. , Pollitt C. C. 
Published: April 2007

Summary Reasons for performing study: The dysadhesion and destruction of lamellar basement membrane of laminitis may be due to increased lamellar metalloproteinase activity. Characterising lamellar metalloproteinase‐2 (MMP‐2) and locating it in lamellar tissues may help determine if laminitis pathology is associated with increased MMP‐2 transcription. Objectives: To clone and sequence the cDNA encoding lamellar MMP‐2, develop antibody and in situ hybridisation probes to locate lamellar MMP‐2 and quantitate MMP‐2 transcription in normal and laminitis tissue. Methods: Total RNA was isolated, fragmented by RT‐PCR, cloned into vector and sequenced. Rabbit anti‐equine MMP‐2 and labelled MMP‐2 riboprobe were developed to analyse and quantitate MMP‐2 expression. Results: Western immunoblotting with anti‐MMP‐2 detected 72 kDa MMP‐2 in hoof tissue homogenates and cross‐reacted with human MMP‐2. Immunohistochemistry and in situ hybridisation detected MMP‐2 in the cytoplasm of basal and parabasal cells in close proximity to the lamellar basement membrane. Northern analysis and quantitative real‐time PCR showed MMP‐2 expression significantly (P<0.01) elevated in laminitis affected tissues. Conclusion: The lamellar pathology of laminitis is associated with increased transcription of MMP‐2. Potential relevance: Real‐time PCR analysis of lamellar MMP‐2 accurately monitors laminitis development at the molecular level and can be used diagnostically and for testing preventive strategies. Controlling increased MMP‐2 transcription may ameliorate or prevent laminitis in high risk clinical situations. Our findings represent a warning to clinicians that the basement membrane lesion of laminitis is insidious and well under way before clinical signs are apparent.
Endotoxin‐induced digital vasoconstriction in horses: associated changes in plasma concentrations of vasoconstrictor mediators
Authors: Menzies‐Gow N. J. , Bailey S. R. , Katz L. M. , Marr C. M. , Elliott J. 
Published: April 2007

SummaryReasons for performing study: Lipopolysaccharide (LPS) infusion reduces digital perfusion, but the mediators responsible remain undetermined.Objectives: To identify vasoconstrictor mediators released following LPS infusion and relate their appearance in plasma to digital blood flow alterations.Methods: Blood flow in the lateral digital vessels of 6 Thoroughbred horses, following a 30 min infusion of LPS (E. coli055:B5; 30 ng/kg), was measured using Doppler ultrasonography. Concomitant measurements of hoof wall and coronary band surface temperatures (HWST and CBST) were made. Serial blood samples were collected and plasma LPS, tumour necrosis factor α (TNFα), 5‐HT, thromboxane B2(TxB2) and endothelin measured.Results: Plasma LPS concentrations reached a maximum of 13.2 pg/ml during the infusion, followed by an increase in plasma TNFα concentration. Digital arterial and venous blood flow decreased by 43 and 63%, respectively; HWST and CBST similarly decreased. Systemic blood pressure remained unaltered. Plasma concentrations of TxB2and 5‐HT increased, coinciding with the onset of digital hypoperfusion. Plasma endothelin concentrations remained unchanged.Conclusions: The temporal relationship between the onset of digital hypoperfusion and increases in plasma 5‐HT and TxB2concentrations is consistent with these platelet‐derived mediators being associated with LPS‐induced laminitis.Potential relevance: These experimental data support the use of anti‐platelet therapy in the prevention of laminitis associated with endotoxaemic conditions.
Serum insulin concentrations in horses with equine Cushing's syndrome: response to a cortisol inhibitor and prognostic value
Authors: Mcgowan C. M. , Frost R. , Pfeiffer D. U. , Neiger R. 
Published: April 2007

Summary Reasons for performing study: Serum insulin concentration and its use as a prognostic indicator in horses with equine Cushing's syndrome (ECS) have been poorly documented. Objectives: To examine daily insulin variations in horses with ECS and the effect of treatment using trilostane, a competitive inhibitor of 3β‐hydroxysteroid dehydrogenase. Further, we aimed to examine the relationship between baseline serum insulin concentration and survival in horses with ECS. Methods: Basal serum insulin concentrations were measured in 20 confirmed ECS cases by taking blood at regular 4 h intervals for 24 h (1200, 1600, 2000, 2400, 0400 and 0800 h) before treatment (Day 0) and 10 days, and 30 days and 1–2 years after the onset of trilostane therapy. The temporal pattern of insulin was analysed using a linear mixed model approach, and the prognostic value of measurements on Day 0 assessed using receiver‐operating characteristic analysis. Results: Horses with ECS showed a diurnal pattern of serum insulin concentration, highest value at 1200 h, and this pattern was not altered by treatment with trilostane. Furthermore, despite a mild increase of serum insulin concentrations after 10 days of trilostane therapy, insulin concentration was unaffected in the long term. Low serum insulin concentrations at the beginning of the trial were significantly associated with improved survival to 1–2 years. The 1200 h sampling before treatment had the highest prognostic value for prediction of survival with a sensitivity and specificity of at least 90% for serum insulin at <62 and >188 μu/ml to predict survival and nonsurvival, respectively. Conclusions and potential relevance: Insulin is a useful prognostic indicator for ECS, but potentially large variations can occur throughout a 24 h period, indicating a single sample may not be representative. Serum insulin concentration did not increase over 1–2 years in horses receiving trilostane therapy.
The effects of vasoactive amines found in the equine hindgut on digital blood flow in the normal horse
Authors: Bailey S. R. , Menzies‐Gow N. J. , Marr C. M. , Elliott J. 
Published: April 2007

SummaryReasons for performing study: Disturbances of digital blood flow are thought to be fundamental to the pathophysiology of acute laminitis. However, factors linking the initiating events in the equine hindgut with these disturbances in the foot remain to be determined.Hypothesis: Amine compounds, formed by bacteria in the equine hindgut, have digital vasoconstrictor effectsin vivo.Methods: Tryptamine (1.6 μg/kg/min) and phenylethylamine (2.13 μg/kg/min) were infused i.v. into standing nonsedated horses. Digital blood flow was measured by Doppler ultrasound and foot surface temperature was monitored. Plasma 5‐hydroxytryptamine (5‐HT) concentrations were measured by HPLC.Results: Tryptamine and phenylethylamine infusions had no effect on systemic arterial blood pressure or heart rate, but caused significant decreases in digital arterial blood flow (mean ± s.e. 29.2 ± 8.5 and 18.4 ± 6.8%, respectively). Both amines also caused decreases in dorsal hoof wall temperature (0.6 ± 0.1 and 0.5 ± 0.1°C for tryptamine and phenylethylamine, respectively) and concomitant increases in plasma 5‐HT concentration.Conclusions: Tryptamine and phenylethylamine caused reduction of digital blood flow, effects which may have been mediated, in part, via displacement of 5‐HT from platelets.Potential relevance: Amine compounds occurring in the equine hindgut, if released into the circulation following carbohydrate overload, could contribute to selective digital vasoconstriction. Further work in ponies and horses, with naturally occurring laminitis, is necessary to determine whether amines represent a therapeutic target in this disease.