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Ireland JL, Lester A, Banse HE. Factors affecting measurement of basal adrenocorticotropic hormone in adult domestic equids: A scoping review. Vet J 2024; 304:106071. [PMID: 38341024 DOI: 10.1016/j.tvjl.2024.106071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 01/12/2024] [Accepted: 02/01/2024] [Indexed: 02/12/2024]
Abstract
Measurement of basal adrenocorticotropic hormone (ACTH) concentration is the most commonly used diagnostic test for pituitary pars intermedia dysfunction (PPID). Although several pre-analytical and analytical factors have been reported to affect basal ACTH concentrations in equids, the extent to which these have been evaluated in the context of PPID diagnosis is unclear. The objectives of this scoping review were to identify and systematically chart current evidence about pre-analytical and analytical factors affecting basal ACTH concentrations in adult domestic equids. Systematic searches of electronic databases and conference proceedings were undertaken in June 2022, repeated in October 2022 and updated in August 2023. English language publications published prior to these dates were included. Screening and data extraction were undertaken individually by the authors, using predefined criteria and a modified scoping review data extraction template. After removal of duplicates, 903 publications were identified, of which 235 abstracts were screened for eligibility and 134 publications met inclusion criteria. Time of year, exercise, breed/type and transportation were the factors most frequently associated with significant increases in ACTH concentration (n = 26, 16, 13 and 10 publications, respectively). Only 25 publications reported inclusion of PPID cases in the study population, therefore the relationship between many factors affecting basal ACTH concentration and diagnostic accuracy for PPID remains undefined. However, several factors were identified that could impact interpretation of basal ACTH results. Findings also highlight the need for detailed reporting of pre-analytical and analytical conditions in future research to facilitate translation of evidence to practice.
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Affiliation(s)
- J L Ireland
- Department of Equine Clinical Science, Faculty of Health and Life Sciences, The University of Liverpool, Leahurst CH64 7TE, Cheshire, UK.
| | - A Lester
- Department of Equine Clinical Science, Faculty of Health and Life Sciences, The University of Liverpool, Leahurst CH64 7TE, Cheshire, UK
| | - H E Banse
- School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA
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Françoso R, Baccarin RY, de Siqueira RF, Belli CB. Use of FreeStyle Libre for continuous glucose monitoring in adult horses. J Vet Emerg Crit Care (San Antonio) 2024; 34:123-130. [PMID: 38459745 DOI: 10.1111/vec.13367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 11/07/2022] [Accepted: 12/03/2022] [Indexed: 03/10/2024]
Abstract
OBJECTIVES To evaluate the feasibility of using the FreeStyle Libre (a continuous glucose monitoring system [CGMS]) for instantaneous continuous monitoring of interstitial glucose in adult horses and examine the applicability and accuracy of this system in horses submitted to combined glucose-insulin test (CGIT). DESIGN Laboratory measurements and continuous glucose monitoring system (CGMS) readings were analyzed using a 2 × 2 factorial statistical model with repeated measures over time. This analysis assessed the effects of the test (factor 1), group (factor 2), and their interactions (test × group, test × time, and group × time). Pearson's correlation analysis was applied to blood glucose values. Mean comparisons were conducted using the t-test, and agreement between techniques was assessed via the Bland-Altman method, with a 95% confidence interval. SETTING Field study on private horse farms in association with a veterinary school. ANIMALS Ten healthy stallions were assigned to one of two groups based on their body condition scores (BCS). Group 1 (G1, n = 5) consisted of nonobese horses with a BCS of 5 or 6, while Group 2 (G2, n = 5) consisted of obese horses with a BCS of 7 or higher. INTERVENTIONS A CGMS sensor was attached to the dorsolateral aspect of the proximal one third of each horse's neck. Laboratory blood glucose measurements and CGMS interstitial glucose readings were compared at different time points for up to 7 days after sensor fixation. Obese horses were also submitted to CGIT on Day 4. MEASUREMENTS AND MAIN RESULTS A comparative analysis of glucose measurements obtained in G1 and G2 horses using the CGMS and enzymatic methods revealed significant group × time interactions (P < 0.001) and time effects (P < 0.001). No interactions were detected between group (P = 0.45), test (P = 0.62), group and test (P = 0.28), or time and test (P = 0.92). In G1 and G2, tests were significantly correlated (r = 0.84 and P = 0.00) at all time points (T0-T5). Agreement between the glucose values obtained using different methods was excellent despite a small time delay in CGMS detection of rapid changes in blood glucose. CONCLUSIONS It was concluded that the CGMS can be used for indirect assessment of glycemic status (ie, based on interstitial glucose measurements) in nonobese and obese adult horses submitted to CGIT.
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Affiliation(s)
- Rafael Françoso
- Centro de Ciências Agrárias, Universidade Estadual da Região Tocantins do Maranhão, Imperatriz, Brazil
| | - Raquel Y Baccarin
- Departamento de Clínica Médica, Faculdade de Medicina Veterinária e Zootecnia da Universidade de São Paulo, São Paulo, Brazil
| | - Renata F de Siqueira
- Departamento de Clínica de Grandes Animais, Centro de Ciências Rurais da Universidade Federal de Santa Maria, Santa Maria, Brazil
| | - Carla B Belli
- Departamento de Clínica Médica, Faculdade de Medicina Veterinária e Zootecnia da Universidade de São Paulo, São Paulo, Brazil
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Ireland J, McGowan C. Deciphering reference intervals and clinical decision limits in equine endocrine diagnostic testing. Vet J 2023; 300-302:106037. [PMID: 37832629 DOI: 10.1016/j.tvjl.2023.106037] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 10/05/2023] [Accepted: 10/10/2023] [Indexed: 10/15/2023]
Abstract
Reference intervals (RIs) and clinical decision limits (CDLs) are frequently established to facilitate interpretation of values of endocrine biomarkers in the diagnosis of disease. Despite their commonplace use in clinical decision-making, these concepts can be confused. Comparing a test result with a RI provides an estimation as to whether or not the individual is healthy, whereas comparison with a CDL facilitates identification of individuals with a particular disease state or at greater risk of adverse clinical outcomes. In practice, there will also be a range of results for which the discriminative ability of the test is insufficient to inform a specific diagnostic decision. Including a range of uncertain test results, or 'grey zone', between positive and negative avoids the constraint of a binary decision in classifying an individual with a test value above (or below) a single cut-off value as diseased. This review will detail the application of both RIs and CDLs, including defining the range of uncertain test results, in the context of equine endocrinology.
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Affiliation(s)
- Joanne Ireland
- Department of Equine Clinical Science, Faculty of Health and Life Sciences, The University of Liverpool, Leahurst, CH64 7TE Cheshire, UK.
| | - Catherine McGowan
- Department of Equine Clinical Science, Faculty of Health and Life Sciences, The University of Liverpool, Leahurst, CH64 7TE Cheshire, UK
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Bamford NJ, Stewart AJ, El-Hage CM, Bertin FR, Bailey SR. Investigation of breed differences in plasma adrenocorticotropic hormone concentrations among healthy horses and ponies. Vet J 2023; 296-297:105995. [PMID: 37207985 DOI: 10.1016/j.tvjl.2023.105995] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 04/06/2023] [Accepted: 05/16/2023] [Indexed: 05/21/2023]
Abstract
Plasma adrenocorticotropic hormone (ACTH) concentration is commonly measured to diagnose pituitary pars intermedia dysfunction (PPID). Several intrinsic and extrinsic factors affect ACTH concentrations, including breed. The objective of this study was to prospectively compare plasma ACTH concentrations among different breeds of mature horses and ponies. Three breed groups comprised Thoroughbred horses (n = 127), Shetland ponies (n = 131) and ponies of non-Shetland breeds (n = 141). Enrolled animals did not show any signs of illness, lameness or clinical signs consistent with PPID. Blood samples were collected 6 months apart, around the autumn equinox and spring equinox, and plasma concentrations of ACTH were measured by chemiluminescent immunoassay. Pairwise breed comparisons within each season were performed on log transformed data using the Tukey test. Estimated mean differences in ACTH concentrations were expressed as fold difference with 95 % confidence intervals (CI). Reference intervals for each breed group per season were calculated using non-parametric methods. In autumn, higher ACTH concentrations were found among non-Shetland pony breeds compared with Thoroughbreds (1.55 fold higher; 95 % CI, 1.35-1.77; P < 0.001), and in Shetland ponies compared with Thoroughbreds (2.67 fold higher; 95 % CI, 2.33-3.08; P < 0.001) and non-Shetland pony breeds (1.73 fold higher; 95 % CI, 1.51-1.98; P < 0.001). In spring, no differences were identified among breed groups (all P > 0.05). Reference intervals were similar among breed groups in spring, but upper limits for ACTH concentrations were markedly different between Thoroughbred horses and pony breeds in autumn. These findings emphasise that breed should be accounted for when determining and interpreting reference intervals for ACTH concentrations among healthy horses and ponies in autumn.
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Affiliation(s)
- N J Bamford
- Melbourne Veterinary School, The Universtiy of Melbourne, Building 400, Parkville, Victoria 3010, Australia.
| | - A J Stewart
- School of Veterinary Science, The University of Queensland, Building 4114, Gatton, Queensland 4343, Australia
| | - C M El-Hage
- Melbourne Veterinary School, The Universtiy of Melbourne, Building 400, Parkville, Victoria 3010, Australia
| | - F R Bertin
- School of Veterinary Science, The University of Queensland, Building 4114, Gatton, Queensland 4343, Australia
| | - S R Bailey
- Melbourne Veterinary School, The Universtiy of Melbourne, Building 400, Parkville, Victoria 3010, Australia
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Kirkwood NC, Hughes KJ, Stewart AJ. Prospective Case Series of Clinical Signs and Adrenocorticotrophin (ACTH) Concentrations in Seven Horses Transitioning to Pituitary Pars Intermedia Dysfunction (PPID). Vet Sci 2022; 9:vetsci9100572. [PMID: 36288186 PMCID: PMC9607114 DOI: 10.3390/vetsci9100572] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 09/29/2022] [Accepted: 10/11/2022] [Indexed: 12/31/2022] Open
Abstract
Simple Summary Pituitary pars intermedia dysfunction (PPID) is a common disease of the geriatric horse population. The most common clinical sign of PPID is hypertrichosis, or a long hair-coat with delayed shedding. Hypertrichosis is the most easily recognized clinical sign of PPID. However, the presence of hypertrichosis is often associated with severe end-stage disease. There is little research investigating sub-clinical or early PPID and the clinical signs associated with these stages of disease. The benefit of being able to recognize early PPID, is that we are able to begin treatment earlier on in disease process, potentially reducing the deleterious consequences of PPID and improving survival. Laboratory tests are available to more accurately diagnose PPID, and these tests include the basal ACTH and TRH-stimulated ACTH tests. Basal ACTH is easy to perform and is recommended in cases where clinical disease is suspected. The TRH-stimulation test improves diagnostic accuracy in early PPID cases. This study documents both test results and clinical signs associated with the transition from subclinical to clinical PPID, so that we are better able to recognize potential early PPID, as well as interpret results in these horses. Abstract Poor recognition of subtle clinical abnormalities and equivocal ACTH concentrations make early diagnosis of PPID difficult. Progressive clinical findings and corresponding ACTH concentrations in horses transitioning to PPID over time have not been documented. Seven horses with ACTH concentrations equivocal for PPID (utilizing locally derived, seasonally adjusted diagnostic-cut off values (DCOV)) and no clinical signs of PPID were selected. Sequential measurement of basal and thyrotropin-releasing hormone (TRH)-stimulated ACTH concentrations and recording of clinical findings occurred from October 2017 to November 2021 in a prospective case series. In two horses, marked hypertrichosis developed. Although 1/11 basal ACTH concentrations were below DCOV in 2018, subsequently all basal ACTH concentrations in these two horses without treatment were greater than DCOV. One horse was treated with pergolide which normalized basal ACTH concentrations. Four horses developed intermittent, mild hypertrichosis, and one horse never developed hypertrichosis. Basal ACTH concentrations in these five horses were greater than DCOV in 63/133 (47.4%) of testing points. TRH-stimulated ACTH concentrations in these five horses were greater than DCOV in 77/133 (57.9%) of testing points, sometimes markedly increased and greater than the assay upper limit of detection (LoD) of 1250pg/mL. TRH-stimulated ACTH concentrations were most frequently positive in late summer and early autumn, with 24/37 (64.9%) of TRH-stimulated ACTH concentrations greater than the DCOV in February and March. Horses transitioning to PPID can have subtle clinical signs and equivocal ACTH concentrations. However, TRH-stimulated ACTH concentrations can be markedly greater than DCOV, especially in late summer and early autumn (February and March) allowing for identification of subclinical and transitional cases.
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Affiliation(s)
- Naomi C. Kirkwood
- School of Agricultural, Environmental and Veterinary Sciences, Charles Sturt University, Wagga Wagga, NSW 2678, Australia
| | - Kristopher J. Hughes
- School of Agricultural, Environmental and Veterinary Sciences, Charles Sturt University, Wagga Wagga, NSW 2678, Australia
| | - Allison J. Stewart
- School of Veterinary Science, Gatton Campus, The University of Queensland, Gatton, QLD 4343, Australia
- Correspondence: ; Tel.: +61-754-601-799
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Pituitary Pars Intermedia Dysfunction (PPID) in Horses. Vet Sci 2022; 9:vetsci9100556. [PMID: 36288169 PMCID: PMC9611634 DOI: 10.3390/vetsci9100556] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 09/25/2022] [Accepted: 10/04/2022] [Indexed: 12/12/2022] Open
Abstract
Substantial morbidity results from pituitary pars intermedia dysfunction (PPID) which is often underestimated by owners and veterinarians. Clinical signs, pathophysiology, diagnostic tests, and treatment protocols of this condition are reviewed. The importance of improved recognition of early clinical signs and diagnosis are highlighted, as initiation of treatment will result in improved quality of life. Future research should be targeted at improving the accuracy of the diagnosis of PPID, as basal adrenocorticotropic hormone (ACTH) concentration can lack sensitivity and thyrotropin releasing hormone (TRH) used to assess ACTH response to TRH stimulation is not commercially available as a sterile registered product in many countries. The relationship between PPID and insulin dysregulation and its association with laminitis, as well as additional management practices and long-term responses to treatment with pergolide also require further investigation.
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Fisher D, Schliewert EC, Hooijberg EH. Temporally specific adrenocorticotropic hormone reference intervals for horses in South Africa. J S Afr Vet Assoc 2022; 93:116-123. [DOI: 10.36303/jsava.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023] Open
Affiliation(s)
- D Fisher
- Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria,
South Africa
| | - E-C Schliewert
- Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria,
South Africa
| | - EH Hooijberg
- Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria,
South Africa
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Thane K, Uricchio C, Frank N. Effect of early or late blood sampling on thyrotropin releasing hormone stimulation test results in horses. J Vet Intern Med 2022; 36:770-777. [PMID: 35049089 PMCID: PMC8965261 DOI: 10.1111/jvim.16362] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 01/05/2022] [Accepted: 01/07/2022] [Indexed: 01/21/2023] Open
Abstract
Background Diagnosis of pituitary pars intermedia dysfunction (PPID) using the thyrotropin‐releasing hormone (TRH) stimulation test requires blood collection 10 minutes after TRH injection; it is unknown if small differences in timing affect test results. Objective To determine whether early or late sampling results in a significant (≥10%) difference in plasma adrenocorticotropic hormone (ACTH) concentration compared to standard 10‐minute sampling. Animals Twenty‐four healthy adult horses with unknown PPID status. Methods In this prospective study, subjects underwent a single TRH stimulation test, with blood collected exactly 9 minutes (early), 10 minutes (standard), and 11 minutes (late) after injection. ACTH was measured by chemiluminescent immunoassay. Two aliquots of the 10‐minute plasma sample were analyzed separately to assess intra‐assay variability. Data were reported descriptively and bias was calculated using Bland‐Altman plots. Significance was set at P = .05. Results Minor variability was observed between the paired 10‐minute sample aliquots (range, 0%‐6%; median 3%). Overall variability of early or late samples compared to the corresponding paired (average) 10‐minute standard concentration ranged from 0% to 92% (median 10%). Seventy‐five percent of horses (18/24) tested had at least 1 early or late reading that differed by ≥10% from its corresponding 10‐minute standard concentration, and 21% of horses (5/24) would have a different interpretation of testing result with either early or late sampling. Incidence of ≥10% variability was independent of PPID status (P = .59). Conclusions and Clinical Importance Precise timing of sample collection is critical to ensure accurate assessment of PPID status given the observation of significant variability associated with minor alterations in timing of sample collection.
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Affiliation(s)
- Kristen Thane
- Tufts Cummings School of Veterinary Medicine, Department of Comparative Pathobiology, North Grafton, Massachusetts, USA
| | - Cassandra Uricchio
- University of Massachusetts, Department of Veterinary and Animal Sciences, Amherst, Massachusetts, USA
| | - Nicholas Frank
- Tufts Cummings School of Veterinary Medicine, Department of Comparative Pathobiology, North Grafton, Massachusetts, USA
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Water- and ethanol-soluble carbohydrates of temperate grass pastures: a review of factors affecting concentration and composition. J Equine Vet Sci 2022; 110:103866. [PMID: 35017041 DOI: 10.1016/j.jevs.2022.103866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 12/29/2021] [Accepted: 01/04/2022] [Indexed: 11/20/2022]
Abstract
Temperate grasses contain both water- and ethanol-soluble carbohydrates. Water-soluble carbohydrates (WSCs) of temperate grasses include glucose, fructose, sucrose, and fructans (fructose polymers) of varying lengths. Ethanol-soluble carbohydrates (ESCs) consist of glucose, fructose, sucrose, and shorter fructans. WSCs and ESCs have been implicated in equine pasture-associated laminitis and other metabolic disorders. In this paper, the peer-reviewed literature of the past decade was summarized for selected factors influencing concentrations and composition of WSCs and ESCs in temperate grasses. WSC concentrations tended to increase under cool temperatures and during cooler seasons. WSC and ESC concentrations generally increased from morning to evening with a range of -20 to 74 g/kg DM for WSCs. Cultivar choice had variable effects on WSC concentrations. Frequent defoliation usually lowered WSC and fructan concentrations. Nitrogen application increased or decreased WSC concentrations, depending on the amount applied and the grass cultivars. Water stress had variable effects on WSC concentration and composition. Multiple factors should be considered before assuming how certain management or environmental conditions will affect WSCs, ESCs, or individual carbohydrates.
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Miller AB, Murphy BA, Adams AA. Impact of blue light therapy on plasma adrenocorticotropic hormone (ACTH) and hypertrichosis in horses with pituitary pars intermedia dysfunction. Domest Anim Endocrinol 2022; 78:106651. [PMID: 34656964 DOI: 10.1016/j.domaniend.2021.106651] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 06/30/2021] [Accepted: 07/21/2021] [Indexed: 11/19/2022]
Abstract
Blue light therapy can be used in horses to alter the natural photoperiod and inhibit winter hair coat growth. Seasonal increases in ACTH occur in the fall season but are exaggerated in horses with pituitary pars intermedia dysfunction (PPID). Additionally, PPID horses frequently present with hypertrichosis. Thus, blue light therapy was proposed as a potential management tool for hypertrichosis and for investigating the impact of photoperiod manipulation on ACTH. Eighteen PPID horses, aged 18 to 31 yr, from a university-owned research herd were selected and assigned to either the control group (n = 10) or the treatment (blue light therapy) group (n = 8) based on age and clinical history, which included the results of multiple endocrine tests. Consistent daylength of approximately 14.5 h was maintained for the treated horses from July 15 through approximately late October via the extension of natural daylength using wearable masks that provided short wavelength blue light (465 nm) to 1 eye. The control group was exposed to only the natural photoperiod during this time. All horses were housed on the same farm and remained on pasture for the duration of the study. On Day 0, thyrotropin-releasing hormone (TRH) stimulation tests were performed to confirm PPID status; there were no differences between the 2 groups in resting plasma ACTH or plasma ACTH at 10 min after TRH administration. To determine an effect of treatment on ACTH, blood was collected via jugular venipuncture for measurement of ACTH at sequential timepoints over a 16-h period in mid-October. Hair weights were also assessed throughout the study. No differences in resting plasma ACTH were observed between the 2 groups across the seasonal analysis (July and October) or during the 16-h testing. The PPID horses receiving blue light therapy had lighter hair weights compared to the PPID control horses. These results suggest that blue light therapy does not alter ACTH concentrations but could potentially be used as an additional management tool for hypertrichosis in PPID horses. Manipulation of the photoperiod using blue light therapy did not affect seasonal changes in ACTH in this study.
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Affiliation(s)
- A B Miller
- M.H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY, USA.
| | - B A Murphy
- School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - A A Adams
- M.H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY, USA
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van Proosdij R, Frietman S. Retrospective Analysis of Cause-of-Death at an Equine Retirement Center in the Netherlands Over an Eight-Year Period. J Equine Vet Sci 2021; 110:103824. [PMID: 34843889 DOI: 10.1016/j.jevs.2021.103824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 10/13/2021] [Accepted: 11/18/2021] [Indexed: 10/19/2022]
Abstract
Geriatric horses (>15 years) represent a substantial proportion of the equine population. The objective of this study was to (1) report on the cause of death in geriatric horses on a single retirement centre, (2) to evaluate the relationship between PPID status, and mortality rate. Data of 194 horses was collected over an eight-year period. This providing data for 80 geriatric cases of mortality. The average age of horses that died was 26.2 years (±4.8 years). The majority (95%) of mortalities were euthanised, most frequently due to colic (20%), old age (19%), and lameness (15%). Overall mortality rate was 16.3 per 100 horse years at risk (95% C.I. 15.2-17.5) for the total geriatric (>15 years) population. PPID had a prevalence of 48.8% (61 out of 125 horses). The results of this study demonstrate increasing mortality rates with increasing age in geriatric horses. The most common reasons for euthanasia were lameness, old age, and colic. The treatment of PPID does not result in an older age of death. The effect of treatment on the welfare status was not studied. Management, of both veterinarians and care taker, has an important role in maintaining health and welfare in geriatric horses. Findings of this study could be relevant to veterinary surgeons and stable managers providing care for geriatric horses.
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Kramer KJ, Kagan IA, Lawrence LM, Smith SR. Ethanol-Soluble Carbohydrates of Cool-Season Grasses: Prediction of Concentration by Near-Infrared Reflectance Spectroscopy (NIRS) and Evaluation of Effects of Cultivar and Management. J Equine Vet Sci 2021; 101:103421. [PMID: 33993929 DOI: 10.1016/j.jevs.2021.103421] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 02/05/2021] [Accepted: 02/08/2021] [Indexed: 11/28/2022]
Abstract
Ethanol-soluble carbohydrates (ESCs) of cool-season grasses include mono- and disaccharides and sometimes short-chain fructans, which may exacerbate the risk of pasture-associated laminitis. A calibration for prediction of ESC concentrations by near-infrared reflectance spectroscopy (NIRS) was developed from 323 samples of four cool-season grass species (orchardgrass, Kentucky bluegrass, tall fescue, and perennial ryegrass) across 10 cultivars collected in central Kentucky in the morning and afternoon over two growing seasons. The calibration, which had accuracy above 95%, was used to predict ESC concentrations of 1,532 samples from the second growing season. ESC concentrations increased in the afternoon compared to the morning across all cultivars. In the majority of samples, ESC concentrations were not affected by nitrogen application to plots. Use of NIRS has the potential to evaluate management and cultivar effects on ESC concentrations in cool-season grass pastures.
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Affiliation(s)
- Kelly J Kramer
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY
| | - Isabelle A Kagan
- US Department of Agriculture, Agricultural Research Service, Forage-Animal Production Research Unit, Lexington, KY.
| | - Laurie M Lawrence
- Department of Animal and Food Sciences, University of Kentucky, Lexington, KY
| | - S Ray Smith
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY
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Miller AB, Loynachan AT, Bush HM, Hart KA, Barker VD, Campana-Emard AG, Grubbs ST, Adams AA. Effects of pituitary pars intermedia dysfunction and Prascend (pergolide tablets) treatment on endocrine and immune function in horses. Domest Anim Endocrinol 2021; 74:106531. [PMID: 32942194 DOI: 10.1016/j.domaniend.2020.106531] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 06/19/2020] [Accepted: 07/24/2020] [Indexed: 11/24/2022]
Abstract
It remains unclear how pituitary pars intermedia dysfunction (PPID) and pergolide treatment (Prascend [pergolide tablets]) affect endocrine and immune function in horses. To evaluate these effects, blood was collected regularly from 28 university-owned horses (10 Non-PPID, 9 PPID control [PC], and 9 PPID treatment [PT]) over approximately 15 mo. Pergolide treatment was initiated after Day 0 collections. Analyses included ACTH, insulin, total cortisol, free cortisol, complete blood counts, plasma myeloperoxidase, and cytokine/receptor gene expression in basal whole blood and in vitro stimulations (PMA/ionomycin, heat-inactivated Rhodococcus equi, and heat-inactivated Escherichia coli) of whole blood and peripheral blood mononuclear cells (PBMCs). The results were analyzed using a linear mixed model (SAS 9.4) with significance set at P < 0.05. Significant group (P = 0.0014) and group-by-time (P = 0.0004) effects were observed in resting ACTH such that PT horses differed from Non-PPID horses only at Day 0. PT horses had significantly lower changes in ACTH responses to thyrotropin-releasing hormone stimulation tests than PC horses at non-fall time points only, mid-late February 2018 (P = 0.016) and early April 2018 (P = 0.0172). When PT and PC horses did not differ, they were combined before comparison to Non-PPID horses. No significant group or group-by-time effects were seen in resting insulin, total cortisol, or free cortisol; however, significant time effects were observed in these measures. PPID horses had lower absolute lymphocyte (P = 0.028) and red blood cell (P = 0.0203) counts than Non-PPID horses. In unstimulated whole blood, PPID horses had increased IL-8 expression compared with Non-PPID horses (P = 0.0102). In addition, PPID horses had decreased interferon γ production from PBMCs after stimulation with R. equi (P = 0.0063) and E. coli (P = 0.0057) and showed increased transforming growth factor β expression after E. coli stimulation (P = 0.0399). The main limitations of this study were a limited sample size and an inability to truly randomize the PPID horses into treatment groups. Resting ACTH is likely the best choice for determining successful responses to pergolide. Neither PPID nor pergolide appears to influence insulin, total cortisol, and free cortisol. As measured, systemic immune function was altered in PPID horses, and it is likely that these horses are indeed at increased risk of opportunistic infection. Despite reducing ACTH, pergolide treatment did not appear to influence immune function.
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Affiliation(s)
- A B Miller
- M.H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY, USA.
| | - A T Loynachan
- Veterinary Diagnostic Laboratory, Department of Veterinary Science, University of Kentucky, Lexington, KY, USA
| | - H M Bush
- Department of Biostatistics, University of Kentucky, Lexington, KY, USA
| | - K A Hart
- Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
| | - V D Barker
- M.H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY, USA
| | - A G Campana-Emard
- M.H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY, USA
| | - S T Grubbs
- Boehringer Ingelheim Animal Health USA, Inc, Duluth, GA, USA
| | - A A Adams
- M.H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY, USA
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14
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Rossi G, Richardson A, Jamaludin H, Secombe C. Preanalytical variables affecting the measurement of serum paraoxonase-1 activity in horses. J Vet Diagn Invest 2021; 33:59-66. [PMID: 33225843 PMCID: PMC7758704 DOI: 10.1177/1040638720974745] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Paraoxonase-1 (PON-1) activity is a new inflammatory and oxidative marker. Technical effects and biological factors could affect the accuracy of PON-1 activity measurement. We investigated the effects of storage at different temperatures, repeated freeze-thaw cycles, interferences from hemolytic, lipemic, and icteric samples, and seasonal effects on PON-1 activity in horses. We evaluated 2 substrates with an automated spectrophotometer. Ten equine serum samples were stored under different conditions. Although storage at room (21°C) or refrigeration (4°C) temperature induced a statistically significant decrease (p < 0.05) in PON-1 activity, this is not diagnostically relevant. PON-1 activity in frozen samples (-20°C) was stable for short-term storage; diagnostically significant (p < 0.01) fluctuations were observed after 1 mo. Four repeated freeze-thaw cycles were assessed, and all cycles affected PON-1 activity (p < 0.01); however, this was diagnostically significant only after the 4th cycle. Hemolysis induced an overestimation of PON-1 activity; lipemia and hyperbilirubinemia did not change PON-1 activity. Thirty-four horses were sampled monthly for 1 y, and PON-1 activity was higher in autumn (p < 0.05) and winter (p < 0.05) than in spring and summer.
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Affiliation(s)
- Gabriele Rossi
- School of Veterinary Medicine, College of Science, Health, Engineering and Education, Murdoch University, Murdoch, Western Australia, Australia
| | - Amy Richardson
- School of Veterinary Medicine, College of Science, Health, Engineering and Education, Murdoch University, Murdoch, Western Australia, Australia
| | - Hali Jamaludin
- School of Veterinary Medicine, College of Science, Health, Engineering and Education, Murdoch University, Murdoch, Western Australia, Australia
| | - Cristy Secombe
- School of Veterinary Medicine, College of Science, Health, Engineering and Education, Murdoch University, Murdoch, Western Australia, Australia
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15
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Bamford NJ, Harris PA, Bailey SR. Circannual variation in plasma adrenocorticotropic hormone concentrations and dexamethasone suppression test results in Standardbred horses, Andalusian horses and mixed-breed ponies. Aust Vet J 2020; 98:616-621. [PMID: 33001453 DOI: 10.1111/avj.13022] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 07/18/2020] [Accepted: 09/04/2020] [Indexed: 01/23/2023]
Abstract
OBJECTIVE To compare circannual plasma concentrations of adrenocorticotropic hormone (ACTH) and seasonal dexamethasone suppression test (DST) results between three different equine breed groups. METHODS Six Standardbred horses, six Andalusian horses and six mixed-breed ponies were followed over a 1-year period, during which time groups were managed identically. Blood samples were collected monthly (around the autumn equinox) or in every second month (other times of the year) for the determination of plasma ACTH concentrations using a chemiluminescent immunoassay. Overnight DSTs were performed quarterly, with suppression of plasma cortisol to below 27 nmol/L at 19 h considered a normal result. RESULTS Seasonal variation in plasma ACTH concentrations was present among all breed groups with, as expected, higher levels detected around the autumn equinox, from February to April (P < 0.001). Plasma ACTH concentrations were different between breed groups in March, with higher levels in Andalusians compared with Standardbreds (P = 0.048) and in ponies compared with Standardbreds (P = 0.010). Suppression of cortisol during the DST was normal for all animals in winter, spring and summer, but five Andalusians and three ponies returned abnormally high results in autumn, compared with zero Standardbreds. CONCLUSION Higher plasma ACTH concentrations and more false-positive DST results were obtained during autumn in ponies and Andalusian horses when compared with Standardbred horses. Potential differences between breeds should be considered when interpreting test results for horses and ponies that are evaluated for pituitary pars intermedia dysfunction. Further work is recommended to establish population-based reference intervals and clinical cut-off values for ACTH in different equine breeds.
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Affiliation(s)
- N J Bamford
- Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria, Australia
| | - P A Harris
- Equine Studies Group, WALTHAM Petcare Science Institute, Melton Mowbray, Leicestershire, UK
| | - S R Bailey
- Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria, Australia
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16
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Hu K, Stewart AJ, Yuen KY, Hinrichsen S, Dryburgh EL, Bertin FR. The effect of freeze-thaw cycles on determination of immunoreactive plasma adrenocorticotrophic hormone concentrations in horses. J Vet Intern Med 2020; 34:1350-1356. [PMID: 32255541 PMCID: PMC7255672 DOI: 10.1111/jvim.15771] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 03/16/2020] [Indexed: 11/28/2022] Open
Abstract
Background Determination of plasma adrenocotrophic hormone (ACTH) concentration (endogenous or thyrotropin‐releasing hormone [TRH] stimulation test) is the most commonly used diagnostic test for pituitary pars intermedia dysfunction (PPID) in horses. Because ACTH is unstable, samples often are frozen to be shipped to laboratories or to allow for batch analysis of research samples. However, the effect of multiple freeze‐thaw cycles on equine ACTH is unknown. Objective To determine the effects of multiple freeze‐thaw cycles on immunoreactive ACTH concentration. Animals Twenty‐eight horses ranging from 10 to 27 years of age were used. Methods Prospective study. Horses were divided into 4 groups: group 1, PPID‐negative, without TRH stimulation; group 2, PPID‐negative, with TRH stimulation; group 3, PPID‐positive, without TRH stimulation; and group 4, PPID‐positive, with TRH stimulation. Whole blood was collected from each horse at baseline or 30 minutes after TRH stimulation. Immunoreactive plasma ACTH concentration was determined using a chemiluminescence assay. Plasma samples then were frozen at −80°C >24 hours, thawed at 4°C and reanalyzed for 5 freeze‐thaw cycles. Changes in plasma ACTH concentration were analyzed using a linear mixed‐effect model. Results Significant effects of freeze‐thaw cycles (P = .001) and PPID status (P = .04) on plasma ACTH concentration were observed, but no significant effect of TRH stimulation was identified. Conclusions and Clinical Importance The plasma ACTH concentration is altered by freeze‐thaw cycles, and the effect is observed sooner in horses with PPID. To diagnose PPID, multiple freeze‐thaw cycles should be avoided when measuring plasma ACTH concentration.
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Affiliation(s)
- Ke Hu
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
| | - Allison J Stewart
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
| | - Ka Y Yuen
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
| | - Sophia Hinrichsen
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
| | | | - François-René Bertin
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
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17
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Seasonal and Diurnal Variation in Water-Soluble Carbohydrate Concentrations of Repeatedly Defoliated Red and White Clovers in Central Kentucky. J Equine Vet Sci 2020; 84:102858. [DOI: 10.1016/j.jevs.2019.102858] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 10/07/2019] [Accepted: 11/07/2019] [Indexed: 11/16/2022]
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18
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Elzinga SE, Betancourt A, Stewart JC, Altman MH, Barker VD, Muholland M, Bailey S, Brennan KM, Adams AA. Effects of Docosahexaenoic Acid-Rich Microalgae Supplementation on Metabolic and Inflammatory Parameters in Horses With Equine Metabolic Syndrome. J Equine Vet Sci 2019; 83:102811. [PMID: 31791524 DOI: 10.1016/j.jevs.2019.102811] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 10/14/2019] [Accepted: 10/14/2019] [Indexed: 12/11/2022]
Abstract
Much of the equine population is obese and therefore predisposed to the development of additional health concerns such as equine metabolic syndrome (EMS). However, pharmacologic treatments for EMS are limited. Omega-3 fatty acid supplementation is a therapeutic strategy in humans with metabolic dysfunction that improves insulin sensitivity and reduces inflammation, but the effects of omega-3 fatty acid supplementation in horses with EMS are unclear. Therefore, in this pilot study, 10 mixed-sex and mixed-breed horses with EMS were fed a docosahexaenoic acid (DHA)-rich microalgae containing 16 g DHA/horse/d or served as controls for 46 days. Inflammatory status was measured using serologic enzyme-linked immunosorbent assay and in peripheral blood mononuclear cells (PBMCs) using flow cytometry and reverse transcription polymerase chain reaction. Circulating fatty acids, triglyceride, leptin, and adiponectin concentrations were also determined. Insulin and glucose dynamics were assessed with oral sugar test (OST) and frequently sampled intravenous glucose tolerance testing. Postsupplementation, treated horses had an increase in many circulating fatty acids, including DHA (P < .001). Treated horses also had lower serum triglycerides postsupplementation (P = .02) and a trend (P = .07) for reduced PBMC tumor necrosis factor α. Interestingly, after 46 days, control horses had an increase in insulin responses to the OST (P = .01), whereas treated horses did not (P = .69). These pilot data indicate that DHA-rich microalgae supplementation alters circulating fatty acids, modulates metabolic parameters, and may reduce inflammation in horses with EMS.
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Affiliation(s)
- Sarah E Elzinga
- Department of Veterinary Science, M.H. Gluck Equine Research Center, University of Kentucky, Lexington, KY.
| | - Alejandra Betancourt
- Department of Veterinary Science, M.H. Gluck Equine Research Center, University of Kentucky, Lexington, KY
| | - John C Stewart
- Department of Veterinary Science, M.H. Gluck Equine Research Center, University of Kentucky, Lexington, KY
| | - Melissa H Altman
- Department of Veterinary Science, M.H. Gluck Equine Research Center, University of Kentucky, Lexington, KY
| | - Virginia D Barker
- Department of Veterinary Science, M.H. Gluck Equine Research Center, University of Kentucky, Lexington, KY
| | - Mason Muholland
- Department of Veterinary Science, M.H. Gluck Equine Research Center, University of Kentucky, Lexington, KY
| | - Simon Bailey
- Faculty of Veterinary and Agricultural Sciences, Melbourne Veterinary School, University of Melbourne, Werribee, Victoria, Australia
| | | | - Amanda A Adams
- Department of Veterinary Science, M.H. Gluck Equine Research Center, University of Kentucky, Lexington, KY
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19
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Williams CA, Kenny LB, Burk AO. Effects of grazing system, season, and forage carbohydrates on glucose and insulin dynamics of the grazing horse. J Anim Sci 2019; 97:2541-2554. [PMID: 30911753 PMCID: PMC6541809 DOI: 10.1093/jas/skz103] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 03/22/2019] [Indexed: 11/14/2022] Open
Abstract
Rotational grazing is a recommended practice for grazing livestock, but little is known about its benefits with respect to grazing horses. The objective of this study was to investigate the effects of continuous (CON) and rotational (ROT) grazing on forage nutrient composition and whether those concentrations influenced circulating glucose and insulin concentrations in the grazing horse. Twelve mature Standardbred mares were paired by age and weight and randomly assigned to 1 replicate of either a 1.5 ha cool-season grass CON or ROT system for a total of 3 mares in each system. Mares on CON were allowed to graze the entire system at all times, whereas mares on ROT were given access to a 0.4 ha pasture section and stress lot where they were confined during inclement weather and slow forage growth. Blood and feces from horses and forage from each system were sampled over one 24-h period in June, August, and October. Blood was assessed for plasma glucose (GLU) and serum insulin (INS), feces for pH, and forage for nutritional composition. Data were analyzed by ANOVA with repeated measures with significance set at P < 0.05. There were no treatment differences for water and ethanol soluble carbohydrates (WSC and ESC, respectively), starch, ADF, and NDF, but CP was lower in ROT compared to CON (P = 0.04). With respect to month, WSC were highest in June compared to August and October, whereas ESC were highest in June compared to only August. Starch was lower in October than in June and August. Concentrations of ADF and NDF were lowest in October compared to June and August. Crude protein was higher in October than June and August. Plasma GLU and serum INS were affected by season and time of day but not grazing system. For all horses, GLU was highest in August (105.6 ± 1.3 mg/dL), whereas INS was highest in October (0.21 ± 0.02 μg/L; P < 0.0001). Fecal pH only varied by season and was highest in August (7.06; P < 0.0001). Few consistent correlations between grazing systems were found with the exception of INS with ESC (R = 0.32 to 0.39; P < 0.04) and INS and GLU with ADF and NDF in August and October (R = -0.31 to -0.48; P < 0.04). In conclusion, grazing system did not affect the forage carbohydrate concentrations or GLU or INS in horses; however, season did have an effect on both forage nutrient content and glucose metabolism in horses.
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Affiliation(s)
- Carey A Williams
- Department of Animal Science, Rutgers, The State University of New Jersey, New Brunswick, NJ
| | - Laura B Kenny
- Department of Animal Science, Rutgers, The State University of New Jersey, New Brunswick, NJ
| | - Amy O Burk
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD
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20
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Fitzgerald DM, Walsh DM, Sillence MN, Pollitt CC, de Laat MA. Insulin and incretin responses to grazing in insulin-dysregulated and healthy ponies. J Vet Intern Med 2018; 33:225-232. [PMID: 30506731 PMCID: PMC6335545 DOI: 10.1111/jvim.15363] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 10/19/2018] [Indexed: 12/27/2022] Open
Abstract
Background Supraphysiological insulin and incretin responses to a cereal‐based diet have been described in horses and ponies with insulin dysregulation (ID). However, the hormonal responses to grazing have not yet been described. Objectives To determine if there is a difference in the insulin and incretin responses to grazing pasture between insulin‐dysregulated and healthy ponies. Animals A cohort of 16 ponies comprising 5 with normal insulin regulation (NIR), 6 with moderate ID (MID), and 5 with severe ID (SID). Methods In this case‐control study, an oral glucose test (OGT) was used to determine the insulin responsiveness of each pony to PO carbohydrate before grazing pasture (4 hours) for 3 consecutive days. Serial blood samples collected during grazing were analyzed for glucose, insulin, glucose‐dependent insulinotropic peptide (GIP) and active glucagon‐like peptide‐1 (aGLP‐1), and compared among pony groups and day of pasture access. Results The area under the insulin curve when grazing increased with ID severity (P < .03). The median (range) maximal insulin concentration was greater in the MID (72.5 [129] μIU/mL) and SID (255 [338.5] μIU/mL) groups, compared to the NIR (11.7 [24.9] μIU/mL) group (P < .03) and occurred within 2‐4 hours of grazing. Postprandial OGT insulin concentration was positively correlated with 2 hours post‐grazing insulin across all 3 grazing days (P ≤ .03). The aGLP‐1 and GIP concentrations increased in response to grazing but did not differ among groups. Conclusions and Clinical Importance Grazing pasture provoked an increased insulin and incretin response in insulin‐dysregulated ponies within 4 hours of grazing. The pasture and OGT insulin concentrations were correlated.
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Affiliation(s)
- Danielle M Fitzgerald
- Department of Bioscience, Science and Engineering Faculty, Queensland University of Technology, Brisbane, Queensland, Australia
| | | | - Martin N Sillence
- Department of Bioscience, Science and Engineering Faculty, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Christopher C Pollitt
- School of Veterinary Science, University of Queensland, Gatton, Queensland, Australia
| | - Melody A de Laat
- Department of Bioscience, Science and Engineering Faculty, Queensland University of Technology, Brisbane, Queensland, Australia
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21
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Secombe CJ, Bailey SR, de Laat MA, Hughes KJ, Stewart AJ, Sonis JM, Tan RHH. Equine pituitary pars intermedia dysfunction: current understanding and recommendations from the Australian and New Zealand Equine Endocrine Group. Aust Vet J 2018; 96:233-242. [DOI: 10.1111/avj.12716] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 03/29/2018] [Accepted: 05/02/2018] [Indexed: 12/25/2022]
Affiliation(s)
- CJ Secombe
- College of Veterinary Medicine, School of Veterinary and Life Sciences; Murdoch University; Murdoch Western Australia Australia
| | - SR Bailey
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences; The University of Melbourne; Werribee VIC Australia
| | - MA de Laat
- Science and Engineering Faculty; Queensland University of Technology; Brisbane QLD Australia
| | - KJ Hughes
- School of Animal and Veterinary Sciences; Charles Sturt University; Wagga Wagga NSW Australia
| | - AJ Stewart
- Equine Specialist Hospital, School of Veterinary Science; The University of Queensland; Gatton QLD Australia
| | - JM Sonis
- Veterinary Associates Equine and Farm, Karaka; Auckland New Zealand
| | - RHH Tan
- Samford Valley Veterinary Hospital; Samford, QLD Australia
- Discipline of Veterinary Clinical Sciences, College of Public Health, Medical and Veterinary Sciences; James Cook University; Townsville QLD Australia
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22
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Effects of Sampling Time, Cultivar, and Methodology on Water- and Ethanol-Soluble Carbohydrate Profiles of Three Cool-Season Grasses in Central Kentucky. J Equine Vet Sci 2018. [DOI: 10.1016/j.jevs.2017.11.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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23
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Secombe CJ, Tan RHH, Perara DI, Byrne DP, Watts SP, Wearn JG. The Effect of Geographic Location on Circannual Adrenocorticotropic Hormone Plasma Concentrations in Horses in Australia. J Vet Intern Med 2017; 31:1533-1540. [PMID: 28661009 PMCID: PMC5598888 DOI: 10.1111/jvim.14782] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 04/11/2017] [Accepted: 05/17/2017] [Indexed: 01/11/2023] Open
Abstract
Background Longitudinal evaluation of plasma endogenous ACTH concentration in clinically normal horses has not been investigated in the Southern Hemisphere. Objectives To longitudinally determine monthly upper reference limits for plasma ACTH in 2 disparate Australian geographic locations and to examine whether location affected the circannual rhythm of endogenous ACTH in the 2 groups of horses over a 12‐month period. Animals Clinically normal horses <20 years of age from 4 properties (institutional herd and client owned animals) in Perth (n = 40) and Townsville (n = 41) were included in the study. Methods A prospective longitudinal descriptive study to determine the upper reference limit and confidence intervals for plasma ACTH in each geographic location using the ASVCP reference interval (RI) guidelines, for individual months and monthly groupings for 12 consecutive months. Results Plasma endogenous ACTH concentrations demonstrated a circannual rhythm. The increase in endogenous ACTH was not confined to the autumnal months but was associated with changes in photoperiod. During the quiescent period, plasma ACTH concentrations were lower, ≤43 pg/mL (upper limit of the 90% confidence interval (CI)) in horses from Perth and ≤67 pg/mL (upper limit of the 90% CI) in horses from Townsville, than at the acrophase, ≤94 pg/mL (upper limit of the 90% CI) in horses from Perth, ≤101 pg/mL (upper limit of the 90% CI) in horses from Townsville. Conclusions and Clinical Importance Circannual rhythms of endogenous ACTH concentrations vary between geographic locations, this could be due to changes in photoperiod or other unknown factors, and upper reference limits should be determined for specific locations.
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Affiliation(s)
- C J Secombe
- College of Veterinary Medicine, School of Veterinary and Life Sciences, Murdoch University, Murdoch, WA, Australia
| | - R H H Tan
- Discipline of Veterinary Clinical Sciences, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, QLD, Australia
| | - D I Perara
- College of Veterinary Medicine, School of Veterinary and Life Sciences, Murdoch University, Murdoch, WA, Australia
| | - D P Byrne
- College of Veterinary Medicine, School of Veterinary and Life Sciences, Murdoch University, Murdoch, WA, Australia
| | - S P Watts
- Discipline of Veterinary Clinical Sciences, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, QLD, Australia
| | - J G Wearn
- Discipline of Veterinary Clinical Sciences, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, QLD, Australia
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24
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Bertin FR, Laat MA. The diagnosis of equine insulin dysregulation. Equine Vet J 2017; 49:570-576. [DOI: 10.1111/evj.12703] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 05/16/2017] [Indexed: 12/18/2022]
Affiliation(s)
- F. R. Bertin
- School of Veterinary Science The University of Queensland Gatton Queensland Australia
| | - M. A. Laat
- Science and Engineering Faculty Queensland University of Technology Brisbane Queensland Australia
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25
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Frank N, Walsh DM. Repeatability of Oral Sugar Test Results, Glucagon-Like Peptide-1 Measurements, and Serum High-Molecular-Weight Adiponectin Concentrations in Horses. J Vet Intern Med 2017; 31:1178-1187. [PMID: 28543933 PMCID: PMC5508339 DOI: 10.1111/jvim.14725] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 02/01/2017] [Accepted: 04/06/2017] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Repeatability of the oral sugar test (OST) has not been evaluated. OBJECTIVES We hypothesized that OST glucose, insulin, active (aGLP-1) and total (tGLP-1) glucagon-like peptide 1, and high-molecular-weight (HMW) adiponectin results would be repeatable. ANIMALS Fifty-three horses from a Tennessee research facility (n = 23) and private practice in Missouri (n = 30), including animals with medical histories of equine metabolic syndrome. METHODS Two OSTs were performed 7-14 days apart and plasma glucose and insulin concentrations were measured at 0, 60, and 75 minutes; a positive result was defined as detection of an insulin concentration >45 μU/mL at 60 or 75 minutes. Plasma aGLP-1 and serum tGLP-1 concentrations at 75 minutes and serum HMW adiponectin concentrations at 0 minute were measured in the Missouri group. Bland-Altman analyses were performed. RESULTS No adverse events were reported. Bland-Altman analysis indicated mean ± SD bias of 1.5 ± 14.8 μU/mL (95% confidence interval [CI], -27.6 to 30.5 μU/mL) and 1.2 ± 16.1 μU/mL (95% CI, -30.4 to 32.8 μU/mL) for insulin concentrations at 60 and 75 minutes, respectively. There was 91 and 83% agreement in test interpretation between test days for OST insulin results for all horses in the Tennessee and Missouri groups, respectively. CONCLUSIONS AND CLINICAL IMPORTANCE Repeatability of the OST was acceptable when values obtained from Bland-Altman analyses were evaluated, and there was good agreement in binary (negative/positive) test interpretation for insulin concentrations. However, wide 95% CIs were detected for insulin concentrations.
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Affiliation(s)
- N Frank
- Department of Clinical Sciences, Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA
| | - D M Walsh
- Homestead Veterinary Hospital, Pacific, MO
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26
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Martinson KL, Siciliano PD, Sheaffer CC, McIntosh BJ, Swinker AM, Williams CA. A Review of Equine Grazing Research Methodologies. J Equine Vet Sci 2017. [DOI: 10.1016/j.jevs.2017.01.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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27
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Restifo MM, Frank N, Hermida P, Sanchez-Londoño A. Effects of withholding feed on thyrotropin-releasing hormone stimulation test results and effects of combined testing on oral sugar test and thyrotropin-releasing hormone stimulation test results in horses. Am J Vet Res 2016; 77:738-48. [DOI: 10.2460/ajvr.77.7.738] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Spelta CW. Equine pituitary pars intermedia dysfunction: current perspectives on diagnosis and management. VETERINARY MEDICINE-RESEARCH AND REPORTS 2015; 6:293-300. [PMID: 30101114 PMCID: PMC6067528 DOI: 10.2147/vmrr.s74191] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Equine pituitary pars intermedia dysfunction (PPID) is a neurodegenerative disease of the hypothalamus, resulting in the loss of dopaminergic inhibition of pars intermedia. An oxidative stress injury of unknown etiology has been suggested to initiate the neurodegeneration. While hypertrichosis (formerly known as hirsutism) is considered pathognomic for advanced disease, the antemortem diagnosis of subclinical and early disease has continued to prove difficult. Numerous tests have been used with varying sensitivities and specificities. The overnight dexamethasone suppression test, originally documented to have 100% sensitivity and specificity in horses with advanced disease, has proven to be less valuable in identifying early disease. Basal plasma adrenocorticotropin concentrations have improved sensitivity and specificity when sampled during the autumn months, and α-melanocyte-stimulating hormone, while not yet commercially available, shows promise as a sensitive and specific single sample test. Recent advances in our knowledge include the strong association between laminitis and hyperinsulinemia, both common clinical signs associated with PPID. The pathogenesis of hyperinsulinemia, laminitis, and their association with this disease is a focus of current research. The dopamine agonist pergolide mesylate is still the mainstay of medical management, with studies on oral bioavailability, pharmacokinetics, and long-term survival rates now published.
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Selim S, Elo K, Jaakkola S, Karikoski N, Boston R, Reilas T, Särkijärvi S, Saastamoinen M, Kokkonen T. Relationships among Body Condition, Insulin Resistance and Subcutaneous Adipose Tissue Gene Expression during the Grazing Season in Mares. PLoS One 2015; 10:e0125968. [PMID: 25938677 PMCID: PMC4418745 DOI: 10.1371/journal.pone.0125968] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 03/27/2015] [Indexed: 01/09/2023] Open
Abstract
Obesity and insulin resistance have been shown to be risk factors for laminitis in horses. The objective of the study was to determine the effect of changes in body condition during the grazing season on insulin resistance and the expression of genes associated with obesity and insulin resistance in subcutaneous adipose tissue (SAT). Sixteen Finnhorse mares were grazing either on cultivated high-yielding pasture (CG) or semi-natural grassland (NG) from the end of May to the beginning of September. Body measurements, intravenous glucose tolerance test (IVGTT), and neck and tailhead SAT gene expressions were measured in May and September. At the end of grazing, CG had higher median body condition score (7 vs. 5.4, interquartile range 0.25 vs. 0.43; P=0.05) and body weight (618 kg vs. 572 kg ± 10.21 (mean ± SEM); P=0.02), and larger waist circumference (P=0.03) than NG. Neck fat thickness was not different between treatments. However, tailhead fat thickness was smaller in CG compared to NG in May (P=0.04), but this difference disappeared in September. Greater basal and peak insulin concentrations, and faster glucose clearance rate (P=0.03) during IVGTT were observed in CG compared to NG in September. A greater decrease in plasma non-esterified fatty acids during IVGTT (P<0.05) was noticed in CG compared to NG after grazing. There was down-regulation of insulin receptor, retinol binding protein 4, leptin, and monocyte chemoattractant protein-1, and up-regulation of adiponectin (ADIPOQ), adiponectin receptor 1 and stearoyl-CoA desaturase (SCD) gene expressions in SAT of both groups during the grazing season (P<0.05). Positive correlations were observed between ADIPOQ and its receptors and between SCD and ADIPOQ in SAT (P<0.01). In conclusion, grazing on CG had a moderate effect on responses during IVGTT, but did not trigger insulin resistance. Significant temporal differences in gene expression profiles were observed during the grazing season.
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Affiliation(s)
- Shaimaa Selim
- Department of Agricultural Sciences, P.O. Box 28, FI-00014 University of Helsinki, Helsinki, Finland
| | - Kari Elo
- Department of Agricultural Sciences, P.O. Box 28, FI-00014 University of Helsinki, Helsinki, Finland
- * E-mail:
| | - Seija Jaakkola
- Department of Agricultural Sciences, P.O. Box 28, FI-00014 University of Helsinki, Helsinki, Finland
| | - Ninja Karikoski
- Department of Equine and Small Animal Medicine, P.O. Box 57, FI-00014 University of Helsinki, Helsinki, Finland
| | - Ray Boston
- Department of Clinical Studies, New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States of America
| | - Tiina Reilas
- Department of Green Technology, Natural Resources Institute Finland (Luke), Opistontie 10 A 1, FI-32100 Ypäjä, Finland
| | - Susanna Särkijärvi
- Department of Green Technology, Natural Resources Institute Finland (Luke), Opistontie 10 A 1, FI-32100 Ypäjä, Finland
| | - Markku Saastamoinen
- Department of Green Technology, Natural Resources Institute Finland (Luke), Opistontie 10 A 1, FI-32100 Ypäjä, Finland
| | - Tuomo Kokkonen
- Department of Agricultural Sciences, P.O. Box 28, FI-00014 University of Helsinki, Helsinki, Finland
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Diez de Castro E, Lopez I, Cortes B, Pineda C, Garfia B, Aguilera-Tejero E. Influence of feeding status, time of the day, and season on baseline adrenocorticotropic hormone and the response to thyrotropin releasing hormone-stimulation test in healthy horses. Domest Anim Endocrinol 2014; 48:77-83. [PMID: 24906932 DOI: 10.1016/j.domaniend.2014.02.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 02/21/2014] [Accepted: 02/22/2014] [Indexed: 10/25/2022]
Abstract
Equine pituitary pars intermedia function can be assessed by the measurement of baseline and thyrotropin releasing hormone (TRH)-induced concentrations of adrenocorticotropic hormone (ACTH); however, these measurements may be affected by the environment. Therefore, a prospective observational study evaluated the influence of feeding, time of the day, and season on baseline and TRH-induced concentrations of ACTH in healthy horses. Baseline ACTH was measured in 50 horses before and 2 h after feeding. Six research horses were subjected to a crossover study in which 6 TRH tests were performed in 2 different seasons, March-April (MA) and July-September (JS), at 2 different times of the day, 8 AM and 8 PM, and, under 2 different conditions relative to feeding status, fasted and 2 h after feeding. Differences between fasted and fed horses were found in baseline ACTH, 17.1 ± 1.8 versus 46.1 ± 7.6 pg/mL (P = 0.003) and TRH-stimulated ACTH: 124.1 ± 21.3 versus 192.6 ± 33.1 pg/mL (P = 0.029) at 10 min, and 40.1 ± 4.9 versus 73.2 ± 13.4 pg/mL (P = 0.018) at 30 min post TRH injection. No differences were found between tests performed at different times of the day. Basal ACTH concentrations were greater in JS than in MA, 17.1 ± 1.8 versus 11.9 ± 0.6 pg/mL (P = 0.006). A seasonal influence was also found in stimulated ACTH values, which were much greater in JS 122.7 ± 36.7 versus 31.2 ± 7.4 pg/mL, at 10 min (P = 0.03) and 39.0 ± 7.2 versus 19.8 ± 3.1 pg/mL, at 30 min (P = 0.03). In addition to season, feeding is a potential confounding factor when measuring baseline or stimulated ACTH in horses. In conclusion, feeding status should be standardized for the diagnosis of equine pituitary pars intermedia dysfunction.
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Affiliation(s)
- E Diez de Castro
- Department Medicina y Cirugía Animal, University of Cordoba, Campus Universitario Rabanales, Cordoba, Spain
| | - I Lopez
- Department Medicina y Cirugía Animal, University of Cordoba, Campus Universitario Rabanales, Cordoba, Spain
| | - B Cortes
- Department Medicina y Cirugía Animal, University of Cordoba, Campus Universitario Rabanales, Cordoba, Spain
| | - C Pineda
- Department Medicina y Cirugía Animal, University of Cordoba, Campus Universitario Rabanales, Cordoba, Spain
| | - B Garfia
- Laboratorio Veterinario Garfia S.L, Pol. Ind. Técnocordoba, Cordoba, Spain
| | - E Aguilera-Tejero
- Department Medicina y Cirugía Animal, University of Cordoba, Campus Universitario Rabanales, Cordoba, Spain.
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Banse HE, McFarlane D. Comparison of Three Methods for Evaluation of Equine Insulin Regulation in Horses of Varied Body Condition Score. J Equine Vet Sci 2014. [DOI: 10.1016/j.jevs.2014.01.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Uner AG, Sulu N, Altinsaat C, Ergun A. Blood Levels of Selected Metabolic Factors, Cytokines, and Lymphocyte Subpopulations in Arabian and Thoroughbred Horses During the Longest and Shortest Days of the Year. J Equine Vet Sci 2013. [DOI: 10.1016/j.jevs.2013.03.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Borer-Weir KE, Menzies-Gow NJ, Bailey SR, Harris PA, Elliott J. Seasonal and annual influence on insulin and cortisol results from overnight dexamethasone suppression tests in normal ponies and ponies predisposed to laminitis. Equine Vet J 2013; 45:688-93. [PMID: 23521139 DOI: 10.1111/evj.12053] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Accepted: 01/04/2013] [Indexed: 11/27/2022]
Abstract
REASONS FOR PERFORMING STUDY A simple, accurate test for identifying individual animals at increased risk of laminitis would aid prevention. Laminitis-prone ponies have a greater serum insulin response to dexamethasone administration than normal ponies in the summer, but the response during different seasons is unknown. OBJECTIVE To test the hypothesis that previously laminitic ponies have a greater insulin response to dexamethasone than normal ponies, which is present during all seasons. STUDY DESIGN Prospective longitudinal study. METHODS Overnight dexamethasone suppression tests were performed on 7 normal ponies and 5 previously laminitic ponies in spring 2009 and 2010, summer 2008 and 2010, autumn 2009 and winter 2008, while the ponies were at pasture. In spring 2010, a dexamethasone suppression test was performed after the ponies had been fed only hay for 3 weeks. Serum cortisol and insulin concentrations pre- and post dexamethasone were measured. Linear mixed models were used to analyse the data. RESULTS Insulin concentrations pre- and post dexamethasone were significantly higher in previously laminitic ponies than in normal ponies during spring 2009 and summer 2008, but there was no difference between groups in spring 2010, summer 2010, autumn 2009 or winter 2008. Insulin concentration varied significantly with season. Diet had no apparent effect on insulin concentration pre- or post dexamethasone in spring 2010. Cortisol concentrations post dexamethasone were significantly higher in previously laminitic ponies than in normal ponies in autumn 2009, with concentrations above the reference range (<25 nmol/l) in both groups in summer 2008 and autumn 2009. Individual ponies had insufficient cortisol suppression in all seasons. CONCLUSIONS There were significant differences between groups in insulin and cortisol concentrations post dexamethasone during some seasons, but this was not present in all years. Wide interindividual variation in response limits the usefulness of a dexamethasone suppression test for predicting the susceptibility of an individual animal to laminitis. POTENTIAL RELEVANCE Abnormal insulin and cortisol responses to dexamethasone must be interpreted in the light of the individual animal, seasonal and annual variation reported here.
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Affiliation(s)
- K E Borer-Weir
- Royal Veterinary College, North Mymms, Hatfield, Hertfordshire, UK
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Schreiber CM, Stewart AJ, Kwessi E, Behrend EN, Wright JC, Kemppainen RJ, Busch KA. Seasonal variation in results of diagnostic tests for pituitary pars intermedia dysfunction in older, clinically normal geldings. J Am Vet Med Assoc 2012; 241:241-8. [PMID: 22765372 DOI: 10.2460/javma.241.2.241] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To determine whether seasonal variations exist in endogenous plasma ACTH, plasma α-melanocyte-stimulating hormone (α-MSH), serum cortisol, and serum insulin concentrations and in the results of a dexamethasone suppression test for older, clinically normal geldings in Alabama. DESIGN Cohort study. ANIMALS 15 healthy mixed-breed geldings (median age, 14 years). PROCEDURES Sample collection was repeated monthly for 12 months. Dexamethasone (0.04 mg/kg [0.02 mg/lb], IM) was administered and cortisol concentrations were determined at 15 and 19 hours. Radioimmunoassays were used to measure ACTH, α-MSH, cortisol, and insulin concentrations at each testing time. Hormone concentrations were compared between months via repeated-measures ANOVA and correlated with age within each month. RESULTS A significant time effect was found between months for α-MSH and insulin concentrations. Endogenous cortisol and ACTH concentrations remained within existing reference ranges. Significant correlations were detected between age and ACTH concentration for several fall and winter months and between age and insulin concentration for September. CONCLUSIONS AND CLINICAL RELEVANCE Older horses have higher ACTH concentrations in several fall and winter months and higher insulin concentrations in September than do younger horses. Seasonally specific reference ranges are required for α-MSH and insulin concentrations, with significantly higher concentrations detected in the fall. Practitioners should be advised to submit samples only to local laboratories that can provide such reference ranges for their local geographic region.
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Affiliation(s)
- Christopher M Schreiber
- Department of Clinical Sciences, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA
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Spelta CW, Axon JE. Case series of equine pituitary pars intermedia dysfunction in a tropical climate. Aust Vet J 2012; 90:451-6. [DOI: 10.1111/j.1751-0813.2012.00997.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/05/2012] [Indexed: 11/30/2022]
Affiliation(s)
- CW Spelta
- Townsville Vet Clinic; 32-34 Anne St; Aitkenvale; Queensland; 4814; Australia
| | - JE Axon
- Scone Equine Hospital; Scone; New South Wales; Australia
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Borer KE, Bailey SR, Menzies-Gow NJ, Harris PA, Elliott J. Effect of feeding glucose, fructose, and inulin on blood glucose and insulin concentrations in normal ponies and those predisposed to laminitis1. J Anim Sci 2012; 90:3003-11. [DOI: 10.2527/jas.2011-4236] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- K. E. Borer
- Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire, AL9 7TA, United Kingdom
| | - S. R. Bailey
- University of Melbourne, Melbourne, Victoria 3031, Australia
| | - N. J. Menzies-Gow
- Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire, AL9 7TA, United Kingdom
| | - P. A. Harris
- Waltham Centre for Pet Nutrition, Freeby Lane, Waltham-on-the-Wolds, Leicestershire, LE14 4RT, United Kingdom
| | - J. Elliott
- Royal Veterinary College, Royal College Street, London, NW1 0TU, United Kingdom
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Funk R, Wooldridge A, Stewart A, Behrend E, Kemppainen R, Zhong Q, Johnson A. Seasonal Changes in the Combined Glucose-Insulin Tolerance Test in Normal Aged Horses. J Vet Intern Med 2012; 26:1035-41. [DOI: 10.1111/j.1939-1676.2012.00939.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Revised: 03/03/2012] [Accepted: 03/27/2012] [Indexed: 11/30/2022] Open
Affiliation(s)
| | | | | | | | - R.J. Kemppainen
- Department of Anatomy; College of Veterinary Medicine; Physiology and Pharmacology; Auburn University; Auburn; AL
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Suagee JK, Corl BA, Swyers KL, Smith TL, Flinn CD, Geor RJ. A 90-day adaptation to a high glycaemic diet alters postprandial lipid metabolism in non-obese horses without affecting peripheral insulin sensitivity. J Anim Physiol Anim Nutr (Berl) 2011; 97:245-54. [PMID: 22129443 DOI: 10.1111/j.1439-0396.2011.01261.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
High glycaemic feeds are associated with the development of insulin resistance in horses. However, studies that evaluated the effect of high glycaemic feeds used horses that either ranged in body condition from lean to obese or were fed to increase body condition over a period of months; thus, the ability of high glycaemic feeds to induce insulin resistance in lean horses has not been determined. This study evaluated the insulin sensitivity of 18 lean horses fed a 10% (LO; n = 6), 20% (MED; n = 6) or 60% (HI; n = 6) non-structural carbohydrate complementary feed for 90 days. Although both the MED and HI diets increased insulinaemic responses to concentrate feeding in relation to the LO diet (p > 0.05), neither induced insulin resistance, as assessed by glucose tolerance test, following the 90-day feeding trial. Interestingly, the post-feeding suppression of plasma non-esterified fatty acids was less pronounced in HI-fed horses (p = 0.054) on days 30 and 90 of the study, potentially indicating that insulin-induced suppression of adipose tissue lipolysis was reduced. As insulin-resistant animals often have elevated plasma lipid concentrations, it is possible that altered lipid metabolism is an early event in the development of insulin resistance. The effects of high glycaemic feeds that are fed for a longer duration of time, on glucose and lipid metabolism, should be investigated further.
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Affiliation(s)
- J K Suagee
- Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, VA 24061, USA
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BORER KE, BAILEY SR, MENZIES-GOW NJ, HARRIS PA, ELLIOTT J. Use of proxy measurements of insulin sensitivity and insulin secretory response to distinguish between normal and previously laminitic ponies. Equine Vet J 2011. [DOI: 10.1111/j.2042-3306.2011.00475.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Copas VEN, Durham AE. Circannual variation in plasma adrenocorticotropic hormone concentrations in the UK in normal horses and ponies, and those with pituitary pars intermedia dysfunction. Equine Vet J 2011; 44:440-3. [PMID: 21848531 DOI: 10.1111/j.2042-3306.2011.00444.x] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
REASONS FOR PERFORMING STUDY Pituitary pars intermedia dysfunction (PPID) is a common endocrinopathy, frequently diagnosed via plasma adrenocorticotropic hormone (ACTH) concentrations. Seasonal variation in plasma ACTH concentrations has been described in normal horses prompting caution in diagnosing PPID at certain times of the year. The aims of this study were to determine appropriate reference intervals for equine plasma ACTH throughout the year; and to examine the circannual variation of plasma ACTH concentrations in PPID cases. HYPOTHESIS Plasma ACTH can be used as a test for PPID throughout the year with the use of appropriate reference intervals. METHODS Data for reference interval calculations were obtained from samples collected from inpatients of Liphook Equine Hospital (non-PPID group, n=156). Data from PPID cases (n=941) were obtained from samples submitted to the Liphook Equine Hospital Laboratory from horses with a clinical suspicion of PPID found to have plasma ACTH concentrations greater than our upper reference interval for that time of year. RESULTS Upper limits for reference interval of plasma ACTH were 29 pg/ml between November and July and 47 pg/ml between August and October. Circannual variation in plasma ACTH occurred in both non-PPID and PPID horses with the highest ACTH concentrations found between August and October in both groups (P<0.0001). The greatest difference between the 2 populations also occurred between August and October. CONCLUSIONS Plasma ACTH can be used for the diagnosis and monitoring of PPID throughout the year with the use of appropriate reference intervals. These findings demonstrate an increase in pituitary gland secretory activity during the late summer and autumn in both normal and PPID cases.
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Abstract
Equine pituitary pars intermedia dysfunction (PPID), also known as equine Cushing's syndrome, is a widely recognized disease of aged horses. Over the past two decades, the aged horse population has expanded significantly and in addition, client awareness of PPID has increased. As a result, there has been an increase in both diagnostic testing and treatment of the disease. This review focuses on the pathophysiology and clinical syndrome, as well as advances in diagnostic testing and treatment of PPID, with an emphasis on those findings that are new since the excellent comprehensive review by Schott in 2002.
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Affiliation(s)
- Dianne McFarlane
- Department of Physiological Sciences, 264 McElroy Hall, Oklahoma State University, Stillwater, OK 74078, USA.
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Klinkhamer K, Menheere PP, van der Kolk JH. Basal glucose metabolism and peripheral insulin sensitivity in equine pituitary pars intermedia dysfunction. Vet Q 2011; 31:19-28. [DOI: 10.1080/01652176.2011.570127] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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