bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of decision criteria for detection of spinal cord compression based on cervical myelography in horses: 38 cases (1981–2001)
Authors: Van Biervliet J. , Scrivani P. V. , Divers T. J. , Erb H. N. , De Lahunta A. , Nixon A.
Published: April 2007

Reasons for performing study: Different criteria have been described based on height reduction of the total myelographic contrast column and components of it as tests for compression of the spinal cord due to cervical stenotic myelopathy (CSM). Fifty percent height reduction of the dorsal myelographic column (DMC), <2 mm empiric height of the DMC and a 40% reduction of the ratio of stenosis calculated based on the height reduction of the entire dural diameter (DD) have been described as decision criteria for considering the test result positive. The reasons for selecting these decision criteria or their accuracies have rarely been reported.

Objectives: To evaluate the accuracy of diagnostic criteria based on reduced height of the total myelographic column and components of it for diagnosing extradural spinal cord compression using different decision criteria, and make recommendations for consistent myelographic interpretation in horses suspected of having CSM.

Methods: Four measurements were obtained by 2 readers in a retrospective sample population of 38 horses in which both cervical myelography and histopathological examination of the cervical spinal cord were performed. The prevalence of CSM in the sample was 50%. At intervertebral sites, the minimum heights of the DD and DMC were measured. At intravertebral sites, the maximum heights of the entire DD and DMC were obtained. Percent height reductions of the DMC and DD were determined as the ratio of minimum intervertebral height to maximum intravertebral height within the next cranial vertebra. Histological examination was used as the gold standard for determining the actual site of spinal cord compression. Sensitivity and specificity for the diagnostic criteria were estimated at each site in neutral and flexed neck positions using several different decision criteria.

Conclusions: At C6‐C7, in neutral or flexed neck position and using 20% reduction of DD, the test was highly sensitive and specific for CSM. At other sites, reduced height of the myelographic column generally was not accurate for diagnosing extradural spinal cord compression. Using 20% reduction of DD in neutral position at the mid‐cervical sites, the test had only low sensitivity and high specificity. Flexion of the neck appeared to increase detection of spinal cord compression in the mid‐cervical region, but also substantially increased the frequency of false‐positive diagnoses.

Potential relevance: By using the reported sensitivity and specificity estimates, readers may decide on a decision criterion for diagnosis of extradural spinal cord compression due to CSM. However, in planning a surgical correction, it is difficult to define a decision criterion that combines acceptable sensitivity and specificity, especially at the mid‐cervical sites.
Efficacy of a live equine herpesvirus‐1 (EHV‐1) strain C147 vaccine in foals with maternally‐derived antibody: protection against EHV‐1 infection
Authors: PATEL J. R. , DIDLICK S. , BATEMAN H.
Published: April 2007

Reasons for performing study: Currently, there is no recommended immunoprophylaxis against febrile respiratory diseases due to equine herpesvirus‐1 (EHV‐1) and ‐4 (EHV‐4) in horses below age 5–6 months. This is because of interference by maternally‐derived antibody (MDA) of vaccines.

Objective: Unweaned equine foals are an important reservoir of EHV‐1 transmission; therefore, we experimentally assessed the efficacy of a live EHV‐1 vaccine in foals age 1.4‐3.5 months with MDA.

Methods: Following vaccination and challenge, parameters assessed were virus shedding in nasal mucus, leucocyte‐associated viraemia, circulating virus neutralising antibody activity and clinical reactions.

Results: Controlled challenge showed that a single intranasal dose of the vaccine afforded partial but significant protection against febrile respiratory disease, virus shedding and viraemia due to EHV‐1 infection, despite virus‐neutralising MDA.

Conclusions and potential relevance: The prospective vaccine would be a significant step forward in reducing the incidence of the disease caused by EHV‐1 infection.
Polymyxin B protects horses against induced endotoxaemiain vivo
Authors: BARTON M. H. , PARVIAINEN A. , NORTON N.
Published: April 2007

Reasons for performing study: A safe, affordable and effective treatment for endotoxaemia in horses is needed in order to reduce the incidence of this potentially fatal condition.

Objective: To evaluate the effect of polymyxin B (PMB) on signs of experimentally‐induced endotoxaemia.

Hypothesis: PMB ameliorates the adverse effects of endotoxaemia without causing nephrotoxicity.

Methods: Four groups of 6 healthy mature horses each received 20 ng endotoxin/kg bwt i.v. over 30 mins. Additionally, each group received one of the following i.v.; 5000 u PMB/kg bwt 30 mins before endotoxin infusion; 5000 u PMB/kg bwt 30 mins after endotoxin infusion; 1000 u PMB/kg bwt 30 mins prior to endotoxin infusion; or saline. Clinical response data and samples were collected to determine neutrophil count, serum tumour necrosis factor (TNF) activity, plasma thromboxane B2concentration and urine gamma glutamyltranspeptidase (GGT) to creatinine ratio.

Results: Treatment with PMB before or after administration of endotoxin significantly reduced fever, tachycardia and serum TNF, compared to horses receiving saline. The differences in response to endotoxin were greatest between horses that received saline vs. those that received 5000 u PMB/kg bwt prior to endotoxin. Urine GGT:creatinine did not change significantly.

Conclusions and potential relevance: This study indicates that PMB may be a safe and effective treatment of endotoxaemia, even when administered after onset. Although nephrotoxicity was not demonstrated with this model, caution should be exercised when using PMB in azotaemic patients.
Medical management of superficial digital flexor tendonitis: a comparative study in 219 horses (1992‐2000)
Authors: DYSON S. J.
Published: April 2007

Reasons for performing study: There is a lack of long‐term follow‐up data for outcome of medical treatment of superficial digital flexor (SDF) tendonitis.

Objectives: To determine whether intralesional injection of hyaluronan, beta aminoproprionitrile fumarate (BAPN) or polysulphated glycosaminoglycans (PSGAG) or systemic administration of PSGAG yielded better results than a controlled exercise programme alone in the management of SDF tendonitis, with a minimum follow‐up period of 2 years after resumption of full work; and to determine whether reinjury rate was related to sports discipline and whether fibre alignment score (FAS) at 4 months could predict outcome.

Methods: In Study 1, 50 horses were managed by controlled exercise alone (Group A), 50 were treated with intralesional injection of hyaluronan (Group B), 20 received intralesional and systemic treatment with PSGAG (Group Ci) and 30 received systemic treatment with PSGAG (Group Cii). Horses inGroups B, CiandCiifollowed the same controlled exercise programme asGroup A.InStudy 2, 69 horses (Group D) were treated by intralesional injection of BAPN and followed a modified controlled exercise programme. Horses were re‐examined clinically and ultrasonographically at intervals. Follow‐up data were obtained for horses 2 years after resuming full work and for up to 6 years.

Results: There was no significant difference in reinjury rate of the treated limb(s) betweenGroups A, B, CiandCii(42.5‐44.4%) (P>0.9). The reinjury rate (16%) in the treated limb(s) inGroup Dwas significantly lower than in the other groups (P<0.001). However, when injury rate of the uninjured limb was considered, the results were similar toStudy 1.InStudy 2, the FAS at 4 months after treatment was a good predictor of outcome (P<0.001). Reinjury rates for different disciplines were similar in the 2 studies, with the risk of reinjury ascending from showjumpers to event horses to National Hunt and flat racehorses.

Conclusions: Treatment with BAPN reduced the risk of reinjury in the treated limb, although the overall rate of subsequent injury was not affected. FAS at 4 months after treatment is a good predictor of outcome in the treated limb(s).

Potential relevance: This study provides long‐term follow‐up data in horses from a variety of sports disciplines that can be used to provide prognostic information.
Ultrasonography of the medial palmar intercarpal ligament in the Thoroughbred: technique and normal appearance
Authors: DRIVER A. J. , BARR F. J. , FULLER C. J. , BARR A. R. S.
Published: April 2007

Reasons for performing study: Tearing of the medial palmar intercarpal ligament (MPICL) has been recognised as a cause of lameness in the Thoroughbred, but diagnosis is difficult due to the nonspecific clinical signs, and can be achieved only by performing arthroscopy on the mid carpal joint (MCJ). It would be beneficial to be able to image the MPICL using ultrasonography to determine whether pathology is present in the ligament in order to aid diagnosis and prognosis.

Objectives: To determine whether the MPICL could be imaged using ultrasound from the dorsal aspect of the MCJ, and to describe the technique and normal ultrasonographic appearance of the ligament.

Methods: A pilot study was performed using 2 cadaver carpi. Each carpus in turn had the MPICL imaged simultaneously using arthroscopy and ultrasound, with a metallic probe positioned on the dorsal aspect of the ligament to highlight the position of the MPICL. Six further pairs of carpi had the MPICL imaged ultrasonographically followed by dissection of the carpus to evaluate the ligament and relate its anatomy to the ultrasound images. Finally, 15 Thoroughbreds with no history of lameness isolated to the carpus had their MPICLs assessed and measured ultrasonographically.

Results: The MPICL could be imaged via the dorsal aspect of the MCJ using standard ultrasound equipment. The body and division into medial and lateral branches could be seen as a distinct, moderately dense granular echogenic structure in the palmar aspect of the joint, with clearly defined margins.

Conclusions: The normal MPICL can be imaged reliably using ultrasound in the Thoroughbred from the dorsal aspect of the MCJ. There is a wide range in the normal width of the lateral aspect of the MPICL, but there is good symmetry between contralateral limbs.

Potential relevance: This report of the normal ultrasonographic appearance of the ligament will be beneficial in acting as a reference for the detection of pathology using ultrasound.
Arthroscopic reattachment of osteochondritis dissecans lesions using resorbable polydioxanone pins
Authors: NIXON A. J. , FORTIER L. A. , GOODRICH L. R. , DUCHARME N. G.
Published: April 2007

Reasons for performing study: Debridement of osteochondritis dissecans (OCD) cartilage lesions results in fibrocartilage and imperfect hyaline repair tissue, and forms a permanent irregularity to the subchondral bone plate.

Objective: To evaluate the clinical, radiographic and outcome effects of OCD cartilage flap reattachment for select lesions as an alternative to OCD debridement.

Hypothesis: Separated cartilage flaps resulting from OCD lesions may be re‐incorporated into the hyaline cartilage surface by reattachment rather than debridement and removal.

Methods: Resorbable polydioxanone pins were used to reattach OCD flap lesions in 16 joints of 12 horses. Criteria for attachment, rather than removal, included an unmineralised cartilage flap on preoperative radiographs and a relatively smooth surface with some residual perimeter attachment at surgery.

Results: There were 12 subjects, 6 males and 6 females, 7 Thoroughbred or Standardbred weanlings, 3 Warmbloods, 1 Arabian and 1 Quarter Horse, mean age at surgery 6.8 months. All horses had effusion of the affected femoropatellar joint (n = 9), tarsocrural joint (n = 1) or fetlock (n = 2). Radiographic lesions varied in length between 1.8–6.3 cm; reattachment was used in 16 of 18 affected joints and the OCD cartilage was not satisfactory for salvage in 2 stifles. Number of pins required was 2–10. One horse was subjected to euthanasia due to a tendon laceration 8 weeks after surgery; of the remaining 11 horses, mean duration of follow‐up was 3.9 years (range 4 months‐8 years). Nine of these were sound and had entered work, while 2 were sound but remained unbroken 4 and 6 months post operatively, respectively. Radiographic resolution of the OCD lesion occurred in 14 of 16 pinned joints in the 9 horses with long‐term follow‐up. The 2 remaining joints had a 3 and a 5 mm mineralised flap in the original defect sites.

Conclusions: This study indicated cartilage flap reattachment was an alternative to removal in selected OCD lesions.

Potential relevance: Relatively smooth OCD cartilage flaps may be salvaged by reattachment and can result in normal radiographic subchondral contour and a high likelihood of athletic performance. Further case numbers are required to determine which lesions are too irregular or contain too much mineral for effective incorporation after reattachment.
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

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

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

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

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

Reasons 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

Reasons 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

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

Reasons 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

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

Reasons 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

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

Reasons 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.
Interstitial cells of Cajal (ICC) in equine colic: an immunohistochemical study of horses with obstructive disorders of the small and large intestines
Authors: FINTL C. , HUDSON N. P. H. , MAYHEW I. G. , EDWARDS G. B. , PROUDMAN C. J. , PEARSON G. T.
Published: April 2007

Reasons for performing study: The gastrointestinal pacemaker cells, the interstitial cells of Cajal (ICC), have been implicated in several human gastrointestinal dysmotility syndromes. Recently, the involvement of these cells in equine gastrointestinal diseases has been investigated in cases of equine grass sickness where a significant reduction in ICC density was observed.

Objective: To investigate ICC density in equine obstructive gastrointestinal disorders using immunohistochemical labelling methods.

Methods: Intestinal samples were analysed from 44 horses undergoing exploratory surgery for colic and from 11 control animals subjected to euthanasia for conditions not related to the gastrointestinal tract. Immunohistochemical labelling of ICC was carried out using an anti‐c‐Kit antibody. Two independent observers assessed ICC density using a semiquantitative grading system.

Results: There was a significant reduction in ICC density in horses with large colon disorders compared to the controls (P<0.01). Horses with strangulating lesions of the small intestine showed no difference when compared to the controls.

Conclusions: There was a reduction in ICC density in horses with large intestinal disorders.

Potential relevance: The reduction in ICC density may be associated with the clinical findings as well as recurrent colic episodes observed in a number of these cases. This immunohistochemical study provides a basis for future functional electrophysiological investigations to determine the precise effect of ICC reduction on equine intestinal motility.
The effects of a single acupuncture treatment in horses with severe recurrent airway obstruction
Authors: WILSON D. V. , LANKENAU C. , BERNEY C. E. , PERONI D. L. , MULLINEAUX D. R. , ROBINSON N. E.
Published: April 2007

Reasons for performing study: Acupuncture may be recommended for horses with ‘heaves’ because it is being increasingly applied to treat human asthma. Therefore, its efficacy was investigated in horses with this asthmalike disease.

Objective: To evaluate the efficacy of a single acupuncture treatment for the relief of airway obstruction in heaves‐affected horses.

Methods: The efficacy of a single acupuncture treatment was tested in 10 heaves‐affected horses, and the effect of removal from the dusty stall environment in 5 heaves‐affected horses. Before treatment, horses were stabled to induce airway obstruction and, apart from trips to the laboratory for pulmonary function measurements, they remained stabled for the duration of each treatment. The severity of airway obstruction was quantified by measurement of lung function before treatment (baseline), and at 20, 60, 120 and 240 mins and 24 h after the following treatments administered in random order: halter restraint and patting, a single acupuncture treatment by an experienced acupuncturist, and a single acupuncture treatment using predetermined points (recipe) by a veterinarian with no acupuncture training. In a second study, horses were untreated and remained either in their stall or in a paddock for all measurements of lung function, after baseline readings were made.

Results: In the first study, after all treatments, there was a temporal improvement in maximal change in pleural pressure, pulmonary resistance, dynamic compliance, respiratory rate, and tidal volume that lasted less than 24 h. There was no specific effect of acupuncture treatment. In the second study, removal from the dusty environment did not produce an improvement in lung function in the first 6 h. We conclude that most of the improvements in lung function observed in the study were due to handling.

Conclusions: Assessed objectively, a single acupuncture treatment during an attack of heaves causes no more improvement in lung function than does handling the horse.

Potential relevance: Acupuncture should not replace conventional medical treatments for heaves.
Relationship between scintigraphic and radiographic evaluations of spinous processes in the thoracolumbar spine in riding horses without clinical signs of back problems
Authors: ERICHSEN C. , EKSELL P. , HOLM K. ROETHLISBERGER , LORD P. , JOHNSTON C.
Published: April 2007

Reasons for performing study: Radiography and scintigraphy are used to aid diagnosis of the cause of back pain, but a large variation in appearance and radiopharmaceutical uptake in fully functioning horses make diagnosis difficult.

Objectives: To describe the range of and compare scintigraphic and radiographic findings in the spinous processes of horses without clinical signs of back problems.

Methods: Thirty‐three apparently normal riding horses underwent scintigraphic and radiographic examinations of the spinous processes in the thoracolumbar spine. Scintigraphic images were evaluated in a continuous blue, green and red colour scale, and the level of radiopharmaceutical uptake in the spinous processes from T10–L2 was graded into none, mild, moderate or severe increased radiopharmaceutical uptake. Structural changes along the borders of the spinous processes and the width of the interspinous spaces from T10–L2 were recorded.

Results: Only 7 horses had no scintigraphic or radiographic findings. Nine horses had no increased radiopharmaceutical uptake, 17 had no sclerosis, 21 had no radiolucencies and 11 had normal spacing of the spinous processes (>4 mm wide). The majority of findings in 26 horses were located from T13–18 and were mild.

Conclusions: The findings of a wide spectrum of scintigraphic and radiographic changes leads to the conclusion that changes within this range found in affected horses cannot be interpreted as clinically significant.

Potential relevance: To determine whether scintigraphy and/or radiography can be used to separate horses with back pain from horses without clinical signs, the results from this study should be compared to the scintigraphic and radiographic findings in horses with clinical signs.
Molecular characterisation of fructose transport in equine small intestine
Authors: MEREDIZ E. FERNANDEZ‐CASTAÑO , DYER J. , SALMON K. S. H. , SHIRAZI‐BEECHEY S. P.
Published: April 2007

Reasons for performing study: Fructose can be a suitable carbohydrate supplement for horses before and/or during endurance exercise. In comparison to glucose, the ingestion of fructose results in a lower insulin peak and less marked fluctuations in blood glucose during exercise, potentially avoiding hypoglycaemia‐induced exhaustion.

Objectives: To assess the capacity of the equine small intestine to absorb fructose and to determine the mechanism, molecular structure and properties of equine intestinal fructose transport.

Methods: Using PCR‐based strategies, RNA isolated from equine small intestine and primers designed to homologous regions of the fructose transporter, GLUT5, cDNA of other species, we cloned and sequenced equine GLUT5 (eGLUT5). Northern and western blot analyses, in conjunction with immunohistochemistry, utilising eGLUT5 cDNA and antibodies, assessed expression of eGLUT5 along the longitudinal and radial axes of the small intestine. Functional properties of fructose transport in intestinal brush‐border membrane vesicles were measured using the rapid‐filtration technique.

Results: eGLUT5 is expressed in the villus enterocytes with highest levels in duodenum>jejunum and lowest in the ileum. Kinetic studies indicate eGLUT5 is a low affinity, high capacity transporter.

Conclusions: Equine small intestine has the capacity to absorb fructose.

Potential relevance: The molecular probes produced in these studies can be used as diagnostic aids to determine equine intestinal monosaccharide malabsorption.
Kinematic evaluation of the back in fully functioning riding horses
Authors: JOHNSTON C. , HOLM K. ROETHLISBERGER , ERICHSEN C. , EKSELL P. , DREVEMO S.
Published: April 2007

Reasons for performing study: Clinical history and examination are important features in diagnosis of equine back dysfunction. However, interpretation is subjective and therefore may vary substantially.

Objectives: To establish a clinical tool to objectively evaluate the function of the equine back, in the form of a database on the kinematics of the back at the walk and trot in fully functioning riding horses.

Methods: Thirty‐three fully functioning riding horses walked and trotted on a treadmill. Morphometrics and kinematics were tested for correlations to age, height, weight and stride length, and differences between gender (geldings and mares) and use (dressage and showjumping).

Results: A database for range of movement and symmetry of movement for extension and flexion, lateral bending, lateral excursion and axial rotation was presented. Symmetry values were very high for all variables. Significant differences were observed in use and gender. Age was negatively correlated to extension and flexion of the thoracolumbar junction.

Conclusions: Interrelationships between use, gender and age to conformation and movement were established.

Potential relevance: The database provides a basis for objective reference for diagnosis, therapy and rehabilitation of clinical cases of back dysfunction.