Publications by authors named "Nicola J Menzies-Gow"

16 Publications

  • Page 1 of 1

Pergolide dosing compliance and factors affecting the laboratory control of equine pituitary pars intermedia dysfunction.

Vet Rec 2021 Mar 23:e142. Epub 2021 Mar 23.

Department of Clinical Sciences and Services, Royal Veterinary College, Hawkshead Lane, North Mymms, UK.

Background: Equine pituitary pars intermedia dysfunction (PPID) is treated with daily pergolide therapy. Owner compliance and its effect on PPID control have not been previously investigated.

Methods: Clinical records were searched to identify the sample of animals with PPID treated with pergolide from 2016 to 2019. The signalment was noted and the dose of pergolide received calculated. Animals were classified as compliant (receiving ≥90% of the veterinarian recommended dose of pergolide) or non-compliant, and as controlled (follow-up basal adrenocorticotrophic hormone concentrations within the reference range) or not.

Results: In total, 110 animals were included. The majority (85%) were ≥16 years (mean ± SD 19.8 ± 4.4 years); the most common breeds were Cob (18%), Thoroughbred (16%) and Welsh (15%); 37% were female and 63% male. Overall, 48% were compliant and 52% non-compliant. There was no significant effect of compliance on laboratory control. Of those that were compliant, 74% were controlled, while 67% of non-compliant animals were controlled. Univariable analysis revealed a significant (p < 0.001) effect of age and breed on compliance and control, and of sex on control. On multivariable analysis, only age (compliance) and breed (compliance and control) were retained in the final model.

Conclusion: Only half of animals received the recommended pergolide dose; however, this did not affect laboratory control of PPID.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/vetr.142DOI Listing
March 2021

Comparison of immunofluorescence and chemiluminescence assays for measuring ACTH in equine plasma.

Equine Vet J 2020 Sep 18;52(5):709-714. Epub 2020 Feb 18.

The Royal Veterinary College, North Mymms, Hatfield, Hertfordshire, UK.

Background: The chemiluminescence (CL) and immunofluorescence (IF) assays yield different results for basal adrenocorticotropin hormone concentrations [ACTH] in pony plasma. It is unclear whether this difference also occurs in basal samples from horses or samples from ponies following thyrotropin-releasing hormone (TRH) stimulation.

Objectives: To compare the results of [ACTH] analysis by CL and IF methods in basal samples from horses and pony samples following TRH stimulation.

Study Design: Method comparison.

Methods: Plasma [ACTH] was measured concurrently using CL and IF methods in 12 ponies (basal and post-TRH stimulation) in November and basal samples from horses (n = 45; November and May).

Results: CL and IF methods yielded different results (P < .01). The median difference (CL-IF) (95% CI) for ponies was 5.9 (0.1-7.5) pg/mL at baseline and 227.9 (61-1001) pg/mL post TRH; and horses 1.9 (1.1-5.4) pg/mL in November and 9.4 (8.2-11.5) pg/mL in May, at baseline. Correlation was good in ponies at baseline (R = 0.80, P = .003) but not post-TRH, and good in horses in November and May (R = 0.68 and 0.71, P < .001). Bland-Altman analysis demonstrated moderate bias and wide 95% limits of agreement (95% LOA) in ponies at baseline (bias 5.5 pg/mL; 95% LOA -9.9 to 20.9 pg/mL) and horses in May (bias 10.6 pg/mL; 95% LOA -9 to 30.3 pg/mL) and very large bias and wide 95% LOA in ponies post-TRH (bias 477 pg/mL; 95% LOA -633 to 1587 pg/mL). Using CL cut-offs of >29 and >110 pg/mL, agreement was moderate (ƙ = 0.67) and very good (ƙ = 0.82) for binary classification of PPID in ponies at baseline and post-TRH; and good (ƙ = 0.73) for horses in November, but poor (ƙ = 0.40) in May.

Main Limitations: Limited numbers of horses with [ACTH] above threshold values.

Conclusions: The assays yielded different absolute values, particularly in post-TRH samples from ponies, suggesting TRH stimulates secretion of cross-reacting peptides other than ACTH. Agreement for binary classification for PPID was moderate to good, except in basal samples from horses in May.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/evj.13227DOI Listing
September 2020

Correlation between l-lactate and glucose concentrations and body condition score in healthy horses and ponies.

J Vet Intern Med 2019 Sep 7;33(5):2267-2271. Epub 2019 Aug 7.

Department of Clinical Science and Services, The Royal Veterinary College, North Mymms, United Kingdom.

Background: Blood l-lactate and glucose concentrations were higher in ponies with gastrointestinal disease than in horses, possibly because of differences in body condition (BC).

Objectives: To investigate whether l-lactate and glucose concentrations correlate with BC and differ between healthy horses and ponies.

Animals: Systemically healthy client-owned ponies (n = 101) and horses (n = 51).

Methods: Prospective observational study. Breed, weight, height, and subjective and objective measures of BC were recorded and l-lactate and glucose concentrations were measured. Correlations between l-lactate and glucose concentrations and BC were established. The association between l-lactate concentrations, equid type (pony or horse), BC, age, and glucose concentrations was investigated using a multivariable model.

Results: Weak but significant (P = .001) negative correlations were detected between l-lactate concentration and average BC score (r = -0.29), heart girth:height ratio (r = -0.27), and age (r = -0.27). Glucose concentrations were significantly (P < .001) positively correlated with neck length:heart girth ratio (r = 0.37) and heart girth:height ratio (r = 0.31). l-lactate and glucose concentrations were weakly correlated (r = 0.15; P = .04). In the final multivariable model, age (-0.02 ± 0.006; P = .001) and heart girth:height ratio (-1.74 ± 0.53; P = .001) were significantly associated with the natural logarithm of l-lactate concentration (Lnl-Lactate). This represents a 2% decrease in l-lactate concentration per year increase in age and 10% decrease in l-lactate concentration per 0.06 unit increase in heart girth:height ratio.

Conclusions And Clinical Importance: In healthy horses and ponies, age and BC significantly influence l-lactate concentrations.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/jvim.15587DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6766520PMC
September 2019

Response to letter to editor regarding ECEIM consensus statement on equine metabolic syndrome.

J Vet Intern Med 2019 05 16;33(3):1125-1126. Epub 2019 Apr 16.

Equine Clinic, Internal Medicine, Faculty of Veterinary Medicine, Justus-Liebig-University of Giessen, Giessen, Germany.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/jvim.15503DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6524088PMC
May 2019

ECEIM consensus statement on equine metabolic syndrome.

J Vet Intern Med 2019 Mar 6;33(2):335-349. Epub 2019 Feb 6.

Equine Clinic, Internal Medicine, Faculty of Veterinary Medicine, Justus-Liebig-University of Giessen, Giessen, Germany.

Equine metabolic syndrome (EMS) is a widely recognized collection of risk factors for endocrinopathic laminitis. The most important of these risk factors is insulin dysregulation (ID). Clinicians and horse owners must recognize the presence of these risk factors so that they can be targeted and controlled to reduce the risk of laminitis attacks. Diagnosis of EMS is based partly on the horse's history and clinical examination findings, and partly on laboratory testing. Several choices of test exist which examine different facets of ID and other related metabolic disturbances. EMS is controlled mainly by dietary strategies and exercise programs that aim to improve insulin regulation and decrease obesity where present. In some cases, pharmacologic aids might be useful. Management of an EMS case is a long-term strategy requiring diligence and discipline by the horse's carer and support and guidance from their veterinarians.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/jvim.15423DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6430910PMC
March 2019

The effect of tumour necrosis factor-α and insulin on equine digital blood vessel function in vitro.

Inflamm Res 2014 Aug 24;63(8):637-47. Epub 2014 Apr 24.

Royal Veterinary College, London, UK,

Objective And Design: Insulin and inflammatory cytokines may be involved in equine laminitis, which might be associated with digital vascular dysfunction. This study determined the effects of TNF-α and insulin on the endothelial-dependent relaxant responses of equine digital blood vessels and on equine digital vein endothelial cell (EDVEC) cGMP production.

Material: Isolated rings of equine digital arteries (EDAs) and veins (EDVs) were obtained and EDVECs were cultured from horses euthanized at an abattoir.

Methods: The effect of incubation with TNF-α (10 ng/ml) and/or insulin (1,000 μIU/ml) for 1.5 h or overnight under hyperoxic and hypoxic conditions on carbachol (endothelium-dependent) induced relaxation was assessed. The time course and concentration dependency of the effect of TNF-α and the effect of insulin (1,000 μIU/ml) on EDVEC cGMP production was determined.

Results: Incubation of EDAs overnight with TNF-α under hypoxic conditions resulted in endothelial-dependent vascular dysfunction. EDVs produced a more variable response. TNF-α increased EDVEC cGMP formation in a time- and concentration-dependent manner. Insulin had no significant effects.

Conclusions: There is a mismatch between the results obtained from isolated vessel rings and cultured endothelial cells suggesting TNF-α may reduce the biological effect of NO by reducing its bioavailability rather than its formation, leading to endothelial cell dysregulation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00011-014-0736-2DOI Listing
August 2014

Evaluation of a commercially available radioimmunoassay and species-specific ELISAs for measurement of high concentrations of insulin in equine serum.

Am J Vet Res 2012 Oct;73(10):1596-602

Department of Veterinary Clinical Sciences, Royal Veterinary College, North Mymms, Hatfield, Hertfordshire, AL9 7TA, England.

Objective: To evaluate a human radioimmunoassay (RIA) and equine and high-range porcine (hrp) species-specific ELISAs for the measurement of high serum insulin concentrations in ponies.

Samples: Serum samples from 12 healthy nonobese ponies (7 clinically normal and 5 laminitis prone; 13 to 26 years of age; 11 mares and 1 gelding) before and after glucose, insulin, and dexamethasone administration.

Procedures: Intra-and interassay repeatability, freeze-thaw stability, dilutional parallelism, and assay agreement were assessed.

Results: Assay detection limits were as follows: RIA, < 389 μU/mL; equine ELISA, < 175 μU/mL; and hrp ELISA, 293 to 8,775 μU/mL. Mean ± SD intra- and interassay repeatability were respectively as follows: RIA, 6.5 ± 5.1 % and 74 ± 3.4%; equine ELISA, 10.6 ± 11.0% and 9.0 ± 4.6%; and hrp ELISA, 19.9 ± 172% and 173 ± 16.6%. Freezing and thawing affected measured concentrations. Dilutional parallelism in the RIA was only evident when insulin-depleted equine serum was used as a diluent (percentage recovery, 95.7 ± 274%); in the ELISAs, dilutional parallelism was observed when a zero calibrator was used. Agreement between RIA and equine ELISA results was good for samples containing concentrations < 175 μU of insulin/mL (bias, -18.5 ± 25.5 μU/mL; higher in RIA). At higher concentrations, assay agreement was poor between RIA and equine ELISA results (bias, -185.3 ± 98.7 μU/mL) and between RIA and hrp ELISA results (bias, 25.3 ± 183.0 μU/mL).

Conclusions And Clinical Relevance: Agreement among results of the 3 assays was variable, and dilutional parallelism was only evident with the RIA when insulin-depleted equine serum was tested. Caution is recommended when evaluating high insulin concentrations measured with the RIA or ELISAs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2460/ajvr.73.10.1596DOI Listing
October 2012

Evaluation of a technique for measurement of flow-mediated vasodilation in healthy ponies.

Am J Vet Res 2012 Jun;73(6):755-61

Department of Veterinary Clinical Sciences, Royal Veterinary College, University of London, North Mymms, Hatfield, Hertfordshire, AL9 7TA, England.

Objective: To determine between-pony and within-pony variations and interobserver and intraobserver agreements of a technique for measurement of flow-mediated vasodilation (FMD) in healthy ponies.

Animals: 6 healthy pony mares (weight range, 236 to 406 kg; body condition score range, 3/9 to 7/9; age range, 14 to 25 years).

Procedures: In each pony, the left median artery was occluded with a blood pressure cuff (inflated to > 300 mm Hg for 5 minutes). Two-dimensional ultrasonographic images of the artery were recorded for 30 seconds before cuff inflation and for 2 minutes after cuff deflation. Maximum luminal diameters of arteries were compared with their baseline diameters to calculate FMD (relative percentage increase in luminal size). Images were obtained from 6 ponies 1 time and from 1 pony 6 times. Independent analysis of images was performed by 2 investigators, 1 of whom analyzed images on 2 occasions.

Results: Mean ± SD FMD in 6 ponies (1 time) was 12.57 ± 4.28% and in 1 pony (6 times) was 7.30 ± 2.11%. Between-pony and within-pony coefficients of variation were 34.09% and 28.84%, respectively. Interobserver agreement was fair (intraclass correlation coefficient, 0.47); intraobserver agreement was poor (intraclass correlation coefficient, 0.30).

Conclusions And Clinical Relevance: FMD was identified and measured in ponies. Measurement of FMD is used to assess endothelial function in humans and has been investigated in dogs. Measurement of FMD in ponies appeared to be feasible and could be used to assess endothelial function (to determine predisposition for development of laminitis or cardiovascular diseases).
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2460/ajvr.73.6.755DOI Listing
June 2012

Endocrinopathic laminitis: reducing the risk through diet and exercise.

Vet Clin North Am Equine Pract 2010 Aug 9;26(2):371-8. Epub 2010 Jun 9.

Department of Veterinary Clinical Science, Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire, UK.

Certain individual animals appear predisposed to recurrent pasture-associated laminitis, but the exact mechanisms underlying their predisposition remain a fundamental question in laminitis research. The risk of endocrinopathic laminitis can be reduced if steps are taken to improve insulin sensitivity and reduce inflammation using strategies based on exercise and diet. Exercise has been shown to reduce insulin resistance and suppress inflammation, and dietary manipulation can significantly affect insulin sensitivity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.cveq.2010.04.005DOI Listing
August 2010

Endotoxin-induced activation of equine digital vein endothelial cells: role of p38 MAPK.

Vet Immunol Immunopathol 2009 Jun 7;129(3-4):174-80. Epub 2008 Nov 7.

Department of Veterinary Basic Sciences, The Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire AL9 7TA, UK.

The endothelium plays a major role in the pathogenesis of endotoxemia. Binding of endotoxin (lipopolysaccharide; LPS) to endothelium initiates a range of signalling events, including activation of p38 mitogen activated protein kinases (MAPKs) that are involved in the initiation of inflammatory responses. In the present study we have examined whether clinically relevant concentrations of LPS can activate p38 MAPK in equine endothelial cells and have investigated the role of the kinase in neutrophil adhesion and mediator release. Cultured equine digital vein endothelial cells (EDVEC) were exposed to LPS and phosphorylation of p38 MAPK was assessed by Western blotting using phospho-specific antibodies. Neutrophil adhesion was quantified by assaying myeloperoxidase and the release of prostacyclin (PGI(2)) was measured by radioimmunoassay of its stable breakdown product 6-keto-PGF(1alpha). The effects of the p38 MAPK inhibitors, SB203580 and PD169316, on neutrophil adhesion and 6-keto-PGF(1alpha) release were examined, as was the effect of an anti-E-selectin antibody on neutrophil adhesion to LPS-activated EDVEC. LPS treatment significantly increased p38 MAPK phosphorylation, which was maximal after a 1h LPS incubation using a concentration of 10(-5)g/ml (EC(50) = 2 x 10(-7)g/ml). Neutrophil adhesion to LPS-stimulated endothelial cells (maximal at 10(-6)g/ml; EC(50) = 6 x 10(-10)g/ml) was significantly inhibited in the presence of p38 MAPK inhibitors (reduced from a maximum of 33+/-6% to 13+/-4% adhesion at 10(-6)M SB203580 and to 21+/-4% adhesion at 10(-6) M PD169316), or an anti-E-selectin antibody (reduced from 17+/-1% adhesion to 6+/-1% adhesion). 6-keto-PGF(1alpha) release was increased in a concentration-dependent manner following LPS exposure (maximal at 10(-6)g/ml; EC(50) = 1 x 10(-9)g/ml), and was significantly inhibited by p38 MAPK blockade (reduced from 1.6+/-0.3 x 10(-9)g/ml to 4+/-1 x 10(-10)g/ml and 4+/-2 x 10(-10)g/ml with 10(-6) M SB203580 or 10(-6) M PD169316, respectively). This study has demonstrated that clinically relevant concentrations of LPS activate p38 MAPK in equine endothelial cells and that both neutrophil adhesion to LPS-activated EDVEC and PGI(2) release are dependent upon p38 MAPK phosphorylation. These results reveal a key role for p38 MAPK in the response of the endothelium to LPS and suggest that inhibition of this kinase may reduce inflammatory events in the endotoxemic horse.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.vetimm.2008.11.008DOI Listing
June 2009

Evaluation of the induction of vasoactive mediators from equine digital vein endothelial cells by endotoxin.

Am J Vet Res 2008 Mar;69(3):349-55

Department of Veterinary Clinical Sciences, Royal Veterinary College, North Mymms, Hertfordshire AL9 7TA, England.

Objective: To determine the effect of endotoxin (lipopolysaccharide [LPS]) on vasoactive mediator production by cultured equine digital vein endothelial cells (EDVECs).

Sample Population: EDVECs obtained from forelimb digital veins of 7 healthy adult horses.

Procedures: EDVECs were incubated with or without LPS (1 microg/mL) for 0, 2, 4, 6, 22, and 24 hours. The EDVECs were incubated for 18 hours with LPS (10 pg/mL to 1 microg/mL) with or without ibuprofen, cycloheximide, or L-nitroarginine methyl ester. Medium concentrations of prostacyclin, cyclic guanosine monophosphate, endothelin-1, and thromboxane A(2) were determined. Changes in inducible nitric oxide synthase and cyclooxygenase-2 expression were determined.

Results: LPS stimulated mean 4.2- and 14.1-fold increases in EDVEC prostacyclin and cyclic guanosine monophosphate production, respectively, after 22 hours. These effects were LPS concentration-dependent (LPS concentrations that induced a response halfway between the maximum response and baseline of 1.50 and 1.22 ng/mL, respectively). The LPS-induced cyclic guanosine monophosphate production was significantly inhibited (to basal concentrations) by L-nitroarginine methyl ester, and prostacyclin production was inhibited by cycloheximide and ibuprofen. Production of thromboxane A(2) by EDVECs was not detected. Endothelin-1 accumulated in the medium, but LPS did not enhance its production. Inducible nitric oxide synthase expression in EDVECs was not detected with the available antibodies, whereas LPS stimulated cyclooxygenase-2 expression in a time- and concentration-dependent manner.

Conclusions And Clinical Relevance: LPS stimulated vasoactive mediator production by equine endothelial cells, which may play a role in LPS-induced digital hypoperfusion.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2460/ajvr.69.3.349DOI Listing
March 2008

Roles of thromboxane A2 and 5-hydroxytryptamine in endotoxin-induced digital vasoconstriction in horses.

Am J Vet Res 2008 Feb;69(2):199-207

Department of Veterinary Clinical Sciences, Royal Veterinary College, Hatfield, Hertfordshire AL9 7TA, England.

Objective: To evaluate the roles of 5-hydroxytryptamine (5-HT), thromboxane A2 (TxA2), and platelet-activating factor (PAF) in endotoxin-induced digital hypoperfusion in horses.

Animals: 6 healthy adult Thoroughbreds.

Procedures: Horses were treated with IV administration of saline (0.9% NaCl) solution (control treatment) or the 5-HT 1B/D selective antagonist, GR55562 (0.3 mg/kg), prior to tryptamine infusion (1.6 microg/kg/min for 30 minutes) to establish an effective GR55562 dose. In a crossover study, horses were treated with IV administration of saline solution (control treatment), aspirin (4 mg/kg, 2 hours or 4 days before lipopolysaccharide [LPS] infusion), GR55562 (0.3 mg/kg), the PAF antagonist WEB2086 (3 mg/kg), or aspirin plus GR55562 prior to LPS infusion (30 ng/kg for 30 minutes). Digital blood flow was measured by use of Doppler ultrasonography. Concomitant measurements of hoof wall and coronary band surface temperatures were made. Serial blood samples were collected and plasma 5-HT and TxA2 concentrations determined.

Results: GR55562 abolished tryptamine-induced digital hypoperfusion. Neither WEB2086 nor GR55562 affected LPS-induced alterations in digital perfusion or plasma mediator concentrations. Aspirin given 2 hours before LPS administration abolished the increase in plasma TxA2 concentration and significantly attenuated LPS-induced digital hypoperfusion. Aspirin given 4 days before LPS significantly attenuated the increase in plasma TxA2 concentration and digital hypothermia. Aspirin plus GR55562 had a greater effect on LPS-induced digital hypothermia than aspirin alone.

Conclusions And Clinical Relevance: Thromboxane A2 and 5-HT played a role in mediating LPS-induced digital hypoperfusion in horses. Platelet-activating factor appeared unimportant in mediating LPS-induced 5-HT or TxA2 release or digital hypoperfusion.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2460/ajvr.69.2.199DOI Listing
February 2008

Hypertension and insulin resistance in a mixed-breed population of ponies predisposed to laminitis.

Am J Vet Res 2008 Jan;69(1):122-9

Department of Veterinary Basic Sciences, Royal Veterinary College, Royal College Street, London, NW1 0TU, England.

Objective: To determine the metabolic phenotype of a group of laminitis-prone ponies when at pasture in summer, compared with when at pasture in winter.

Animals: 40 ponies of various breeds predisposed to recurrent pasture-associated laminitis and 40 unaffected control ponies.

Procedures: Body condition score and size of the crest of the neck were assessed, blood samples obtained, and blood pressure measured by use of an indirect oscillometric technique, while ponies were kept on winter pasture (last week of November or beginning of December) and again on summer pasture (June). Serum insulin concentration and plasma glucose, triglyceride, uric acid, and ACTH concentrations were measured. Insulin sensitivity was calculated with proxies derived from basal serum insulin and plasma glucose concentrations.

Results: No significant differences were apparent between ponies predisposed to laminitis and control ponies during winter. However, in June, laminitis-prone ponies had increased serum insulin concentration and plasma triglyceride and uric acid concentrations, compared with control ponies. Also, laminitis-prone ponies were relatively insulin resistant, compared with control ponies. Mean blood pressure was significantly higher during summer in laminitis-prone ponies (median [interquartile range], 89.6 mm Hg [78.3 to 96.9 mm Hg]), compared with control ponies (76.8 mm Hg [69.4 to 85.2 mm Hg]).

Conclusions And Clinical Relevance: Summer pastures appear to induce metabolic responses in some ponies, leading to expression of the prelaminitic phenotype, which includes hypertension as well as insulin resistance. Signs of this metabolic syndrome may not be apparent in affected ponies during periods of grazing winter pasture. Understanding this syndrome may enable improved countermeasures to be devised to prevent laminitis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2460/ajvr.69.1.122DOI Listing
January 2008

Effect of dietary fructans and dexamethasone administration on the insulin response of ponies predisposed to laminitis.

J Am Vet Med Assoc 2007 Nov;231(9):1365-73

Department of Veterinary Basic Sciences, Royal Veterinary College, London, NW1 0TU, England.

Objective: To determine whether pasture, and specifically the addition of fructan carbohydrate to the diet, induces exaggerated changes in serum insulin concentration in laminitispredisposed (LP) ponies, compared with ponies with no history of the condition, and also to determine insulin responses to the dexamethasone suppression test.

Design: Prospective study.

Animals: 10 LP and 11 control adult nonobese mixed-breed ponies.

Procedures: Insulin-modified IV glucose tolerance tests were performed (5 ponies/group). In diet studies, ponies were kept on pasture and then changed to a hay diet (10 ponies/group). Second, ponies were maintained on a basal hay diet (4 weeks) before being fed a hay diet supplemented with inulin (3 g/kg/d [1.4 g/lb/d]). Serum insulin and plasma glucose concentrations were analyzed before and after dietary changes. Serum cortisol and insulin concentrations were also measured in a standard dexamethasone suppression test.

Results: The LP ponies were insulin resistant (median insulin sensitivity of 0.27 x 10(4) L min(-1) mU(-1) in LP ponies, compared with 0.64 x 10(4) L min(-1) mU(-1) in control ponies). Median insulin concentration in LP ponies was significantly greater than that in control ponies at pasture, decreased in response to feeding hay, and was markedly increased (5.5-fold) following the feeding of inulin with hay. The LP ponies had a greater increase in serum insulin concentration at 19 hours after dexamethasone administration (median, 222.9 mU/L), compared with control ponies (45.6 mU/L).

Conclusions And Clinical Relevance: Nonobese ponies predisposed to develop laminitis had compensated insulin resistance, and this phenotype was revealed by feeding plant fructan carbohydrate or by dexamethasone administration.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2460/javma.231.9.1365DOI Listing
November 2007

Repeatability of Doppler ultrasonographic measurement of equine digital blood flow.

Vet Radiol Ultrasound 2007 May-Jun;48(3):281-5

Department of Veterinary Clinical Sciences, Royal Veterinary College, Hatfield, Hawkshead Lane, North Mymms, Hertfordshire AL9 7TA, UK.

The repeatability and sensitivity of Doppler ultrasonographic measurement of lateral digital arterial and venous blood flow has not been previously determined. Doppler ultrasonography was used to measure blood flow within the forelimb lateral digital vessels in one normal adult Thoroughbred horse on six occasions and in six normal adult Thoroughbred horses on three occasions, each occasion being at least 1 h apart, to determine the within- and between-horse variation. The values obtained from the right and left lateral digital vessels did not differ significantly. The within-horse coefficients of variation (CV) for arterial and venous measurements were all acceptable (< 11%); the between-horse CV were acceptable (< 7%) for all parameters except TaVa (average velocity of first peak of arterial waveform) and TaVb (average velocity of remainder of arterial waveform). The within-horse intraclass correlation coefficients (ICC) demonstrated excellent repeatability (> or = 0.71) for all parameters except venous diameter; the between-horse ICC demonstrated good to excellent repeatability (> or = 0.67) for all parameters except TaVb. Doppler ultrasonography can detect differences of 0.005 and 0.01 ml/ min in digital arterial and venous flow, respectively, using measurements from six horses on three occasions (80% power; P < 0.05). Thus, the technique is sufficiently repeatable and sensitive to be able to detect changes in flow during different physiological or pathological states or following pharmacologic intervention.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/j.1740-8261.2007.00243.xDOI Listing
June 2007

Digital blood flow and plasma endothelin concentration in clinically endotoxemic horses.

Am J Vet Res 2005 Apr;66(4):630-6

Department of Veterinary Clinical Sciences, Royal Veterinary College, Hatfield, Hertfordshire AL9 7TA, United Kingdom.

Objective: To measure plasma endothelin-1 (ET-1) concentrations and digital blood flow in clinically endotoxemic horses.

Animals: 36 adult horses that underwent emergency celiotomy for primary gastrointestinal tract disease.

Procedure: On days 2 and 5 following surgery, Doppler ultrasonographic digital arterial blood flow measurements were obtained. Hematologic and biochemical analyses were performed, and plasma concentrations of ET-1 and endotoxin (lipopolysaccharide) were determined. A scoring system based on 9 clinical variables was used to assign horses to group B (quartile with greatest cumulative score) or group A (remaining 3 quartiles). Follow-up at 2.5 years was obtained by telephone questionnaire.

Results: For all horses on day 2, median (interquartile values) plasma ET-1 concentrations were 1.4 (0.8, 1.7) pg/mL, whereas on day 5, plasma ET-1 concentrations were 1.0 (0.5, 1.6) pg/mL. On day 2, digital blood flow was 0.057 (0.02, 0.07) mL/min in group A horses and 0.035 (0.02, 0.03) mL/min in group B horses. On day 5, plasma ET-1 concentration was significantly (73%) higher in group B horses, compared with group A horses. Thirty of 36 horses were alive at 2.5 years; group A horses were more likely to have survived (odds ratio, 25; 95% confidence interval, 2.4 to 262). Significant associations were found between an increase in digital pulses, hoof wall temperatures, or both and increased digital blood flow (0.14 vs 0.04 mL/min) on day 2 and increased digital arterial diameter (0.32 vs 0.23 cm) on day 5.

Conclusions And Clinical Relevance: Horses with more severe endotoxemia had decreased digital blood flow, increased plasma ET-1 concentrations, and decreased long-term survival.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2460/ajvr.2005.66.630DOI Listing
April 2005