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Jayathilake WMNK, de Laat MA, Furr M, Risco C, Lacombe VA. Prolonged hyperinsulinemia increases the production of inflammatory cytokines in equine digital lamellae but not in striated muscle. Vet J 2024; 303:106053. [PMID: 38043699 DOI: 10.1016/j.tvjl.2023.106053] [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: 02/06/2023] [Revised: 11/23/2023] [Accepted: 11/29/2023] [Indexed: 12/05/2023]
Abstract
Hyperinsulinemia is the key feature of equine metabolic syndrome (EMS) which leads to debilitating sequelae. Hyperinsulinemia-associated laminitis (HAL) is one of the major sequelae of EMS, although the pathophysiological mechanisms are not well elucidated. Using an equine model, we hypothesized that expression of inflammatory markers would be increased in digital lamellae and striated muscle following prolonged hyperinsulinemia. Healthy Standardbred horses (5.4 ± 1.9 years) were alternately assigned to a prolonged euglycemic-hyperinsulinemic clamp (pEHC) or control group (n = 4 per group). Following a 48 h pEHC or a 48 h infusion of a balanced electrolyte solution (controls), biopsies were collected from digital lamellar tissue, skeletal muscle and cardiac muscle were obtained. All hyperinsulinemic horses developed laminitis regardless of previous health status at enrollment. Protein expression was quantified via Western blotting. A significant (P < 0.05) upregulation of the protein expression of heat shock protein 90 (HSP90), alpha 2 macroglobulin (A2M) and fibrinogen (α, β isoforms), as well as inflammatory cytokines including interleukin-1β were detected in digital lamellae following prolonged hyperinsulinemia. In contrast, protein expression of cytokines and acute phase proteins in heart and skeletal muscle was unchanged following hyperinsulinemia. Upregulation of inflammatory cytokines and acute phase proteins in digital lamellae during prolonged hyperinsulinemia may reveal potential biomarkers and novel therapeutic targets for equine endocrinopathic laminitis. Further, the lack of increase of inflammatory proteins and acute phase proteins in striated muscle following prolonged hyperinsulinemia may highlight potential anti-inflammatory and cardioprotective mechanisms in these insulin-sensitive tissues.
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Affiliation(s)
- W M N K Jayathilake
- College of Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078, USA
| | - M A de Laat
- School of Biology and Environmental Science, Queensland University of Technology, Queensland, 4001, Australia
| | - M Furr
- College of Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078, USA
| | - C Risco
- College of Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078, USA
| | - V A Lacombe
- College of Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078, USA.
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2
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de Laat MA, Sillence MN. Diagnosis of equine endocrinopathies: The value of measuring blood glucose during an oral glucose test. Vet J 2023; 300-302:106034. [PMID: 37778651 DOI: 10.1016/j.tvjl.2023.106034] [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: 05/03/2023] [Revised: 09/18/2023] [Accepted: 09/27/2023] [Indexed: 10/03/2023]
Abstract
Blood glucose concentration is often measured during an oral glucose test (OGT), but is not thought to aid in diagnosing insulin dysregulation (ID) or pituitary pars intermedia dysfunction (PPID). The aim of this retrospective study was to investigate whether the change in blood glucose concentration during an OGT aligned with indicators of equine metabolic syndrome or PPID, including serum insulin and plasma ACTH concentrations, clinical observations, age, sex, breed type and the test dose. The cohort included 149 horses, miniature horses, and ponies that had undergone an in-feed OGT and clinical examination between 2015 and 2021. The animals were diagnosed as either metabolically healthy, insulin-dysregulated, having PPID or both endocrinopathies. The mean ± standard error increase in blood glucose during the OGT was 3.41 ± 0.21 mM, and this change showed a weak positive correlation with the increase in serum insulin concentration (r = 0.36; P 0.001), body condition score (BCS; r = 0.26; P = 0.002) and cresty neck score (CNS; r = 0.38; P 0.001). The median [interquartile range] increase in blood glucose for miniature horses (5.25 [2.98-6.5] mM), was more than twice that seen in full-sized horses (2.4 [1.33-3.45] mM; P = 0.03). In metabolically healthy animals the increase in blood glucose during an OGT (+2.2 [1-3.5] mM) was smaller (P 0.001) than in animals with ID (+3.8 [2.73-5.33] mM), or both endocrine diseases (+6.1 [3.6-6.85] mM). There was an effect of the dose of dextrose on the blood glucose response, with higher doses yielding larger responses (P 0.001). The variability in these data support that basal and post-prandial blood glucose responses to an OGT are not appropriate as stand-alone diagnostic markers of ID or PPID. However, the association between blood glucose and CNS supports the use of CNS when evaluating animals for ID.
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Affiliation(s)
- M A de Laat
- School of Biology and Environmental Science, Queensland University of Technology, Brisbane, Queensland 4001, Australia.
| | - M N Sillence
- School of Biology and Environmental Science, Queensland University of Technology, Brisbane, Queensland 4001, Australia
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3
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Malacarne BD, Martins RR, Paz CFR, Alves JVA, Dias LA, Cavalcante MA, Santos AM, Silva AGM, Leise BS, Carvalho AM, Faleiros RR. Histological comparison of the lamellar tissue of Iberian origin breed horses created in semi-feral conditions or in an intensive system. PLoS One 2023; 18:e0286536. [PMID: 37262053 DOI: 10.1371/journal.pone.0286536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 05/17/2023] [Indexed: 06/03/2023] Open
Abstract
Although the external conformation of wild horse hooves has been proposed as an ideal model for domesticated modern horses, histological signs of laminitis have been reported among them. With the hypothesis that the lamellar tissue of horses of Iberian origin raised in semi-feral is healthier than those raised in an intensive management system (stall confinement and high-calorie diet intake), the objective was to compare their lamellar tissues. Lamellar tissue samples were taken from the forelimb hoof of eight domesticated Mangalarga Marchador (MM) horses and from six semi-feral Marajoara (MJ) and Puruca (MP) horses. Primary epidermal lamella (PEL) and secondary epidermal lamella (SEL) were measured (length and width) in several regions, and their shapes were morphologically classified into different types. Breed groups were compared using analysis of variance, followed by Tukey or Dunn tests (P<0.05). Early signs of laminitis such as abnormal keratinization of the abaxial primary dermal lamella, tapered tips of the axial PELs, pointed tips of the SEL, nuclei condensation, and abnormal spatial orientation of the secondary epidermal basal cells (SELBC), were seen only in MM horses. MP horses had a greater interface of epidermis/dermis contact than MJ horses and more rounded nuclei in the round SELBC than MM horses. In agreement with the study hypothesis, semi-feral MJ and MP horses' lamellae were classified as healthier than MM horses, which showed early signs of endocrinopathic laminitis.
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Affiliation(s)
- Bruno Dondoni Malacarne
- Marion DuPont Equine Medical Center, Virginia Tech, Leesburg, Virginia, United States of America
- Equinova Research Group, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Rodrigo Ribeiro Martins
- Equinova Research Group, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
- Centro Universitário de Mineiros-UNIFIMES, Mineiros, Goiás, Brazil
| | - Cahuê Francisco Rosa Paz
- Equinova Research Group, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
- Pontifícia Universidade Católica de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | | | - Lucas Antunes Dias
- Equinova Research Group, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | | | - Alison Miranda Santos
- Instituto de Medicina Veterinária, Universidade Federal do Pará, Castanhal, Pará, Brazil
| | | | - Britta Sigrid Leise
- Veterinary Clinical Sciences, Louisiana State University, Baton Rouge, Louisiana, United States of America
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4
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McGowan CM, Ireland JL. Equine Endocrine Disease: Challenges With Case Definition for Research. J Equine Vet Sci 2023; 124:104491. [PMID: 37236726 DOI: 10.1016/j.jevs.2023.104491] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 04/06/2023] [Accepted: 04/12/2023] [Indexed: 05/28/2023]
Abstract
Equine endocrine disease is an important area for equine research, requiring an appropriate case definition for inclusion and criteria for exclusion from disease. Defining a case for research may be different from criteria for clinical diagnosis. Further, clinical diagnosis recommendations have been changing regularly, making this area challenging for equine scientists. This review discusses the diagnosis of major equine endocrine diseases, pituitary pars intermedia dysfunction, equine metabolic syndrome and insulin dysregulation, focusing on the most appropriate diagnostic methods for research case definitions. Different diagnostic methods, including use of reference intervals and clinical decision limits, will be discussed with their relative merits for use in case definition for research.
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Affiliation(s)
- Catherine M McGowan
- School of Veterinary Science, Institute of Infection, Ecological and Veterinary Sciences, the University of Liverpool, Neston, UK.
| | - Joanne L Ireland
- School of Veterinary Science, Institute of Infection, Ecological and Veterinary Sciences, the University of Liverpool, Neston, UK
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5
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Elliott J, Bailey SR. A review of cellular and molecular mechanisms in endocrinopathic, sepsis-related and supporting limb equine laminitis. Equine Vet J 2023; 55:350-375. [PMID: 36847165 DOI: 10.1111/evj.13933] [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: 05/01/2022] [Accepted: 02/23/2023] [Indexed: 03/01/2023]
Abstract
Equine laminitis has both fascinated and frustrated veterinary researchers and clinicians for many years. The recognition that many ponies suffering from pasture-associated laminitis have an insulin-dysregulated phenotype (endocrinopathic laminitis, EL) and that prolonged insulin and glucose infusions can experimentally induce laminar pathology and functional failure are seminal discoveries in this field. Researchers have studied the molecular basis for disease pathogenesis in models of EL, sepsis-related laminitis and supporting limb laminitis and generated much data over the last 15 years. This review attempts to synthesise those data, drawing comparisons between models and naturally occurring laminitis. A hypothesis is proposed that the basal epithelial cell stress is a central event in each category of laminitis. Furthermore, in naturally occurring pasture-associated laminitis, pathways that predominate in each type of laminitis contribute to laminar lamellar pathology to varying extents. Based on the molecular mechanisms determined in experimental models, interactions between these pathways are identified.
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Affiliation(s)
- Jonathan Elliott
- Department of Comparative Biomedical Sciences, The Royal Veterinary College University of London, London, UK
| | - Simon R Bailey
- Department of Veterinary Biosciences, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Melbourne, Victoria, Australia
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6
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Grenager NS. Endocrinopathic Laminitis. Vet Clin North Am Equine Pract 2021; 37:619-638. [PMID: 34674908 DOI: 10.1016/j.cveq.2021.08.001] [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] [Indexed: 11/19/2022] Open
Abstract
Endocrinopathic laminitis (EL) primarily occurs because of insulin dysregulation (ID) mediated through downstream effects of insulin on IGF-1R in lamellar tissues. There is likely contributing vascular and metabolic dysfunction within the lamellae, but EL is relatively non-inflammatory. EL is associated with lamellar stretching, proliferation, and failure, ultimately causing failure of the suspensory apparatus of the distal phalanx. Proper education regarding mitigating risk factors makes this a largely preventable cause of laminitis. Annual hoof evaluation plus screening geriatric horses for pituitary pars intermedia dysfunction and ID, and younger horses for ID, can significantly decrease the incidence of this devastating condition.
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Affiliation(s)
- Nora S Grenager
- Steinbeck Peninsula Equine Clinics, 100 Ansel Lane, Menlo Park, CA 94028, USA.
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7
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Bäßler SC, Kenéz Á, Scheu T, Koch C, Meyer U, Dänicke S, Huber K. Association between alterations in plasma metabolome profiles and laminitis in intensively finished Holstein bulls in a randomized controlled study. Sci Rep 2021; 11:12735. [PMID: 34140596 PMCID: PMC8211646 DOI: 10.1038/s41598-021-92163-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 06/03/2021] [Indexed: 02/05/2023] Open
Abstract
Metabolic consequences of an energy and protein rich diet can compromise metabolic health of cattle by promoting a pro-inflammatory phenotype. Laminitis is a common clinical sign, but affected metabolic pathways, underlying pathophysiology and causative relationships of a systemic pro-inflammatory phenotype are unclear. Therefore, the aim of this study was to elucidate changes in metabolome profiles of 20 months old Holstein bulls fed a high energy and protein diet and to identify novel metabolites and affected pathways, associated with diet-related laminitis. In a randomized controlled feeding trial using bulls fed a high energy and protein diet (HEP; metabolizable energy [ME] intake 169.0 ± 1.4 MJ/day; crude protein [CP] intake 2.3 ± 0.02 kg/day; calculated means ± SEM; n = 15) versus a low energy and protein diet (LEP; ME intake 92.9 ± 1.3 MJ/day; CP intake 1.0 ± 0.01 kg/day; n = 15), wide ranging effects of HEP diet on metabolism were demonstrated with a targeted metabolomics approach using the AbsoluteIDQ p180 kit (Biocrates Life Sciences). Multivariate statistics revealed that lower concentrations of phosphatidylcholines and sphingomyelins and higher concentrations of lyso-phosphatidylcholines, branched chain amino acids and aromatic amino acids were associated with an inflammatory state of diet-related laminitis in Holstein bulls fed a HEP diet. The latter two metabolites share similarities with changes in metabolism of obese humans, indicating a conserved pathophysiological role. The observed alterations in the metabolome provide further explanation on the underlying metabolic consequences of excessive dietary nutrient intake.
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Affiliation(s)
- Sonja Christiane Bäßler
- grid.9464.f0000 0001 2290 1502Institute of Animal Science, University of Hohenheim, 70599 Stuttgart, Germany
| | - Ákos Kenéz
- grid.35030.350000 0004 1792 6846Department of Infectious Diseases and Public Health, City University of Hong Kong, Hong Kong, SAR China
| | - Theresa Scheu
- Educational and Research Centre for Animal Husbandry, Hofgut Neumuehle, 67728 Muenchweiler a.d. Alsenz, Germany
| | - Christian Koch
- Educational and Research Centre for Animal Husbandry, Hofgut Neumuehle, 67728 Muenchweiler a.d. Alsenz, Germany
| | - Ulrich Meyer
- grid.417834.dInstitute of Animal Nutrition, Friedrich-Loeffler-Institut (FLI), Federal Research Institute for Animal Health, 38116 Brunswick, Germany
| | - Sven Dänicke
- grid.417834.dInstitute of Animal Nutrition, Friedrich-Loeffler-Institut (FLI), Federal Research Institute for Animal Health, 38116 Brunswick, Germany
| | - Korinna Huber
- grid.9464.f0000 0001 2290 1502Institute of Animal Science, University of Hohenheim, 70599 Stuttgart, Germany
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8
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Yang Q, Lopez MJ. The Equine Hoof: Laminitis, Progenitor (Stem) Cells, and Therapy Development. Toxicol Pathol 2019; 49:1294-1307. [PMID: 31741428 DOI: 10.1177/0192623319880469] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The equine hoof capsule, composed of modified epidermis and dermis, is vital for protecting the third phalanx from forces of locomotion. There are descriptions of laminitis, defined as inflammation of sensitive hoof tissues but recognized as pathologic changes with or without inflammatory mediators, in the earliest records of domesticated horses. Laminitis can range from mild to serious, and signs can be acute, chronic, or transition from acute, severe inflammation to permanently abnormal tissue. Damage within the intricate dermal and epidermal connections of the primary and secondary lamellae is often associated with lifelong changes in hoof growth, repair, and conformation. Decades of research contribute to contemporary standards of care that include systemic and local therapies as well as mechanical hoof support. Despite this, consistent mechanisms to restore healthy tissue formation following a laminitic insult are lacking. Endogenous and exogenous progenitor cell contributions to healthy tissue formation is established for most tissues. There is comparably little information about equine hoof progenitor cells. Equine hoof anatomy, laminitis, and progenitor cells are covered in this review. The potential of progenitor cells to advance in vitro equine hoof tissue models and translate to clinical therapies may significantly improve prevention and treatment of a devastating condition that has afflicted equine companions throughout history.
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Affiliation(s)
- Qingqiu Yang
- Department of Veterinary Clinical Sciences, Laboratory for Equine and Comparative Orthopedic Research, Baton Rouge, LA, USA
| | - Mandi J Lopez
- Department of Veterinary Clinical Sciences, Laboratory for Equine and Comparative Orthopedic Research, Baton Rouge, LA, USA
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9
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de Laat MA, Pollitt CC. Ultrastructural examination of basement membrane pathology in horses with insulin-induced laminitis. Domest Anim Endocrinol 2019; 69:30-34. [PMID: 31280023 DOI: 10.1016/j.domaniend.2019.04.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 04/05/2019] [Accepted: 04/18/2019] [Indexed: 01/19/2023]
Abstract
The third phalanx of the equine digit is suspended within the hoof capsule by a specialized interdigitating dermoepidermal layer called the lamellae, which fails during laminitis. Pathology of the basement membrane (BM), which interfaces epidermis and dermis, is evident during acute laminitis. However, BM damage appears to be less prevalent in ponies with the insulin-associated form of laminitis. The aim of the present study was to investigate changes to the ultrastructure and morphometry of the lamellar BM in the acute phase of insulin-induced laminitis in horses. Lamellar tissue from the left forefoot of 3 horses with acute hyperinsulinemic laminitis was examined with transmission electron microscopy and compared with tissue from normal horses. Lamellar BM width and hemidesmosome (HD) density were assessed every 5 μm along ∼200 μm of secondary epidermal lamellar BM. The BM zone of treated horses was extensively disorganized with loss of uniformity of the lamina lucida and lamina densa, fragmentation and disorientation of HDs, and cytoskeletal disengagement of the HDs. The mean (±SD) lamellar BM was twice as wide in treated (0.25 ± 0.05 μm), compared with control (0.14 ± 0.02 μm), horses. The HD density (HDs/μm) was reduced by half in the treatment group (1.88 ± 0.37), compared with controls (3.6 ± 0.13). The reduced number of HDs in horses with laminitis may contribute to the weakening of the dermoepidermal junction and lamellar failure. Disassembly of HDs during excessive cellular proliferation, secondary to hyperinsulinemia, may account for HD loss. Further investigation of the underlying etiopathogenesis of BM dysfunction during hyperinsulinemic laminitis in horses may facilitate an improved understanding of the disease.
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Affiliation(s)
- M A de Laat
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia.
| | - C C Pollitt
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
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10
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Legere RM, Taylor DR, Davis JL, Bello K, Parker C, Judd RL, Wooldridge AA. Pharmacodynamic Effects of Pioglitazone on High Molecular Weight Adiponectin Concentrations and Insulin Response After Oral Sugar in Equids. J Equine Vet Sci 2019; 82:102797. [PMID: 31732109 DOI: 10.1016/j.jevs.2019.102797] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 07/17/2019] [Accepted: 09/16/2019] [Indexed: 10/26/2022]
Abstract
Chronic insulin dysregulation is challenging to manage with pharmaceuticals in horses. Pioglitazone improves insulin sensitivity in humans, and the pharmacokinetics of pioglitazone have been evaluated in horses. The objectives of this study were to assess the pharmacodynamic effects of oral pioglitazone on morphometric parameters, hepatic enzyme activity and function, adipokines, and enteroinsular response to oral sugar. A prospective pilot study was performed using fifteen adult equids (8 ponies, 7 horses) to evaluate the effects of short-term pioglitazone administration (2 mg/kg PO q 24 hours, 28 days). Oral sugar tests (OST) were performed before and after treatment. Adipokines were measured at day 0, 14, and 28 of administration. Plasma drug concentrations were measured at day 14 and 28 of administration. The subjects were grouped into horses, ponies, and insulin dysregulated (ID) animals. Baseline values for all parameters were compared with values obtained at day 14 and 28 using one-way or two-way analysis of variance. Mild changes were noted in morphometric parameters and hepatic enzymes. No differences were found in leptin concentrations or the blood glucose response to the OST. Significant decreases were found in the insulin response to OST at 90 and 120 minutes time points and the area under the curve after pioglitazone treatment in the pony and ID groups. High-molecular-weight (HMW) adiponectin concentrations were significantly increased in all groups after pioglitazone treatment. Decreased insulin concentrations in response to oral sugar and increased HMW adiponectin concentrations indicate positive effects of pioglitazone for treatment of metabolic derangements in equine metabolic syndrome, which warrant future clinical study.
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Affiliation(s)
- Rebecca M Legere
- Department of Clinical Sciences, College of Veterinary Medicine, Auburn University, Auburn, AL
| | - Debra R Taylor
- Department of Clinical Sciences, College of Veterinary Medicine, Auburn University, Auburn, AL
| | - Jennifer L Davis
- Department of Biomedical Sciences & Pathobiology, VA-MD College of Veterinary Medicine, Blacksburg, VA
| | - Kaitlyn Bello
- Department of Clinical Sciences, College of Veterinary Medicine, Auburn University, Auburn, AL
| | - Caroline Parker
- Department of Clinical Sciences, College of Veterinary Medicine, Auburn University, Auburn, AL
| | - Robert L Judd
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL
| | - Anne A Wooldridge
- Department of Clinical Sciences, College of Veterinary Medicine, Auburn University, Auburn, AL.
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11
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Moeller S, Patan-Zugaj B, Däullary T, Tichy A, Licka TF. The influence of trimming of the hoof wall on the damage of laminar tissue after loading: An in vitro study. Vet J 2019; 250:63-70. [PMID: 31383422 DOI: 10.1016/j.tvjl.2019.07.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 06/30/2019] [Accepted: 07/02/2019] [Indexed: 01/19/2023]
Abstract
Laminitis is associated with failure of the suspensory apparatus of the distal phalanx (SADP) connecting the distal phalanx to the hoof wall. The specific aim of this study was to examine in vitro whether thinning of the hoof wall leading to increased deformability influences the damage of the laminar tissue created by loading of the hoof. Paired cadaver forelimbs from twelve horses were used. For each pair, the hoof wall from one hoof was thinned by 25%; this was ascertained by radiography. The contralateral hooves were used as controls. In a material testing machine, hooves were loaded in a proximodistal direction at 0.5mm/s until a cut-off value of 8kN or 14mm was reached. Afterwards, samples of the SADP were taken for histology. Image-based evaluation of the destruction of the SADP was performed using quantitative histogram analysis. Additionally, three examiners masked to treatment (trimmed/untrimmed) qualitatively evaluated SADP destruction. During hoof loading with forces from 0.5 to 1.8 times the body mass of the donor horses, hooves with thinned hoof wall underwent significantly more deformation (P<0.05). Quantitative histogram analysis detected a shift to higher brightness values and a higher pixel intensity in control hooves, representing disruption in the histologic analysis. Qualitative evaluation of histology sections showed significantly more disruption of the SADP in untrimmed hooves (P=0.03). These results confirm the hypothesis that reduced hoof wall thickness can decrease disruption of laminar tissue in vitro, thus supporting the evaluation of hoof wall reduction as a prophylactic measure in horses at imminent risk of SADP failure.
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Affiliation(s)
- S Moeller
- University Clinic for Horses, Department of Companion Animals and Horses, University of Veterinary Medicine, Veterinärplatz 1, 1210 Vienna, Austria.
| | - B Patan-Zugaj
- Department for Pathobiology, University of Veterinary Medicine, Veterinärplatz 1, 1210 Vienna, Austria
| | - T Däullary
- Institute of Tissue Engineering and Regenerative Medicine, University Clinic Würzburg, Röntgenring 11, 97082 Würzburg, Germany
| | - A Tichy
- Department of Biomedical Sciences, University of Veterinary Medicine, Veterinärplatz 1, 1210 Vienna, Austria
| | - T F Licka
- University Clinic for Horses, Department of Companion Animals and Horses, University of Veterinary Medicine, Veterinärplatz 1, 1210 Vienna, Austria; Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Campus, Midlothian EH25 9RG, Scotland, UK
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12
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Are There Shared Mechanisms in the Pathophysiology of Different Clinical Forms of Laminitis and What Are the Implications for Prevention and Treatment? Vet Clin North Am Equine Pract 2019; 35:379-398. [PMID: 31126692 DOI: 10.1016/j.cveq.2019.04.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Laminitis is a consequence of primary disease processes elsewhere in the body. The key pathophysiologic events are insulin dysregulation in endocrinopathic laminitis, ischemia in supporting limb laminitis, and inflammation in sepsis-related laminitis. These apparently disparate mechanisms converge to cause lamellar attachment failure through epithelial cell adhesion loss and stretch, possibly mediated by common growth factor signaling pathways. Tissue damage through mechanical distraction, inflammation, pain, and a proliferative epithelial healing response are features of acute laminitis regardless of the cause. Preventive and treatment strategies based on knowledge of these unique and common mechanistic events are likely to improve clinical outcomes.
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13
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Horn R, Bamford NJ, Afonso T, Sutherland M, Buckerfield J, Tan RHH, Secombe CJ, Stewart AJ, Bertin FR. Factors associated with survival, laminitis and insulin dysregulation in horses diagnosed with equine pituitary pars intermedia dysfunction. Equine Vet J 2018; 51:440-445. [DOI: 10.1111/evj.13041] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2018] [Accepted: 11/02/2018] [Indexed: 12/29/2022]
Affiliation(s)
- R. Horn
- School of Veterinary Science The University of Queensland Gatton Queensland Australia
| | - N. J. Bamford
- Faculty of Veterinary and Agricultural Sciences The University of Melbourne Werribee Victoria Australia
| | - T. Afonso
- School of Animal and Veterinary Sciences The University of Adelaide Roseworthy South Australia Australia
| | - M. Sutherland
- Gisborne Veterinary Clinic Gisborne Victoria Australia
| | | | - R. H. H. Tan
- College of Public Health, Medical and Veterinary Sciences James Cook University Townsville Queensland Australia
- Samford Valley Veterinary Hospital Samford Queensland Australia
| | - C. J. Secombe
- School of Veterinary and Life Sciences Murdoch University Perth Western Australia Australia
| | - A. J. Stewart
- School of Veterinary Science The University of Queensland Gatton Queensland Australia
| | - F. R. Bertin
- School of Veterinary Science The University of Queensland Gatton Queensland Australia
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14
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Baskerville CL, Chockalingham S, Harris PA, Bailey SR. The effect of insulin on equine lamellar basal epithelial cells mediated by the insulin-like growth factor-1 receptor. PeerJ 2018; 6:e5945. [PMID: 30519508 PMCID: PMC6275117 DOI: 10.7717/peerj.5945] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Accepted: 10/16/2018] [Indexed: 12/26/2022] Open
Abstract
Background In horses and ponies, insulin dysregulation leading to hyperinsulinemia may be associated with increased risk of laminitis, and prolonged infusion of insulin can induce the condition. It is unclear whether insulin may have a direct or indirect effect on the lamellar tissues. Insulin is structurally related to insulin-like growth factor (IGF-1), and can bind the IGF-1 receptor, albeit at a lower affinity than IGF-1. Methods Immunohistochemistry was performed on formalin-fixed lamellar tissue sections from six normal horses, euthanised for non-research purposes, using an anti-IGF-1 receptor antibody. In further studies, lamellar epithelial cells were obtained by collagenase digestion from the hooves of 18 normal horses, also euthanised for non-research purposes, and incubated for 48 h in the presence of insulin (0–2,000 m IU/ml). The increase in cell numbers was determined using a cell proliferation assay, and compared to the effect of zero insulin using one-way ANOVA. Results Immunohistochemistry demonstrated IGF-1 receptors on lamellar epidermal epithelial cells. With cultured cells, insulin caused a concentration-dependent increase in cell proliferation compared to untreated cells (maximal effect 63.3 ± 12.8% more cells after 48 h with 1,000 m IU/ml insulin; P < 0.01). Co-incubation with a blocking antibody against the IGF-1 receptor significantly inhibited the proliferative effect of insulin (P < 0.01). Discussion These results demonstrate that IGF-1 receptors are present on lamellar epithelial cells. At high physiological concentrations, insulin may activate these cells, by a mechanism involving IGF-1 receptors, resulting in a proliferative effect. This mechanism could help to explain the link between hyperinsulinemia and laminitis.
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Affiliation(s)
- Courtnay L Baskerville
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, VIC, Australia
| | - Subu Chockalingham
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, VIC, Australia
| | - Patricia A Harris
- Equine Studies Group, WALTHAM Centre for Pet Nutrition, Melton Mowbray, Leicestershire, UK
| | - Simon R Bailey
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, VIC, Australia
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Mullard J, Ireland J, Dyson S. Radiographic assessment of the ratio of the hoof wall distal phalanx distance to palmar length of the distal phalanx in 415 front feet of 279 horses. EQUINE VET EDUC 2018. [DOI: 10.1111/eve.13004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- J. Mullard
- Centre for Equine Studies Animal Health Trust Suffolk UK
| | - J. Ireland
- Centre for Preventive Medicine Animal Health Trust Suffolk UK
| | - S. Dyson
- Centre for Equine Studies Animal Health Trust Suffolk UK
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Patterson-Kane JC, Karikoski NP, McGowan CM. Paradigm shifts in understanding equine laminitis. Vet J 2017; 231:33-40. [PMID: 29429485 DOI: 10.1016/j.tvjl.2017.11.011] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 10/08/2017] [Accepted: 11/20/2017] [Indexed: 12/29/2022]
Abstract
Laminitis, one of the most debilitating conditions of all equids, is now known to be the result of several systemic disease entities. This finding, together with other recent developments in the field of laminitis research, have provoked a rethink of our clinical and research strategies for this condition. First, laminitis is now considered to be a clinical syndrome associated with systemic disease (endocrine disease, sepsis or systemic inflammatory response syndrome, SIRS) or altered weight bearing rather than being a discrete disease entity. Next, laminitis associated with endocrine disease (endocrinopathic laminitis) is now believed to be the predominant form in animals presenting (primarily) for lameness. Third, the designation of laminitis as a primary and severe basement membrane pathology now requires revision. Instead, current data now proposes a variable subclinical phase associated with gross changes in the hoof capsule, with stretching and elongation of the lamellar cells an early and key event in the pathophysiology. These findings have fuelled new mechanistic hypotheses and research directions that will be discussed, together with their implications for future clinical management.
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Affiliation(s)
| | - N P Karikoski
- Department of Equine and Small Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, Viikintie49, FIN-00014 Helsinki, Finland
| | - C M McGowan
- Institutes of Veterinary Science and Ageing and Chronic Disease, Faculty of Health and Life Sciences, University of Liverpool, Leahurst CH64 7TE, UK.
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17
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A Novel Equine Hoof Lamellar Tissue Biopsy Technique. J Equine Vet Sci 2017. [DOI: 10.1016/j.jevs.2016.10.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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18
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Dunbar LK, Mielnicki KA, Dembek KA, Toribio RE, Burns TA. Evaluation of Four Diagnostic Tests for Insulin Dysregulation in Adult Light-Breed Horses. J Vet Intern Med 2016; 30:885-91. [PMID: 27013065 PMCID: PMC4913564 DOI: 10.1111/jvim.13934] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 01/26/2016] [Accepted: 02/29/2016] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Several tests have been evaluated in horses for quantifying insulin dysregulation to support a diagnosis of equine metabolic syndrome. Comparing the performance of these tests in the same horses will provide clarification of their accuracy in the diagnosis of equine insulin dysregulation. OBJECTIVES The aim of this study was to evaluate the agreement between basal serum insulin concentrations (BIC), the oral sugar test (OST), the combined glucose-insulin test (CGIT), and the frequently sampled insulin-modified intravenous glucose tolerance test (FSIGTT). ANIMALS Twelve healthy, light-breed horses. METHODS Randomized, prospective study. Each of the above tests was performed on 12 horses. RESULTS Minimal model analysis of the FSIGTT was considered the reference standard and classified 7 horses as insulin resistant (IR) and 5 as insulin sensitive (IS). In contrast, BIC and OST assessment using conventional cut-off values classified all horses as IS. Kappa coefficients, measuring agreement among BIC, OST, CGIT, and FSIGTT were poor to fair. Sensitivity of the CGIT (positive phase duration of the glucose curve >45 minutes) was 85.7% and specificity was 40%, whereas CGIT ([insulin]45 >100 μIU/mL) sensitivity and specificity were 28.5% and 100%, respectively. Area under the glucose curve (AUCg0-120 ) was significantly correlated among the OST, CGIT, and FSIGTT, but Bland-Altman method and Lin's concordance coefficient showed a lack of agreement. CONCLUSIONS Current criteria for diagnosis of insulin resistance using BIC and the OST are highly specific but lack sensitivity. The CGIT displayed better sensitivity and specificity, but modifications may be necessary to improve agreement with minimal model analysis.
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Affiliation(s)
- L K Dunbar
- Ohio State University College of Veterinary Medicine, Columbus, OH
| | - K A Mielnicki
- Ohio State University College of Veterinary Medicine, Columbus, OH
| | - K A Dembek
- Ohio State University College of Veterinary Medicine, Columbus, OH
| | - R E Toribio
- Ohio State University College of Veterinary Medicine, Columbus, OH
| | - T A Burns
- Ohio State University College of Veterinary Medicine, Columbus, OH
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Karikoski NP, Patterson-Kane JC, Singer ER, McFarlane D, McGowan CM. Lamellar pathology in horses with pituitary pars intermedia dysfunction. Equine Vet J 2015; 48:472-8. [PMID: 25869529 DOI: 10.1111/evj.12450] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 04/07/2015] [Indexed: 01/11/2023]
Abstract
REASONS FOR PERFORMING STUDY Hoof lamellar pathology in horses with pituitary pars intermedia dysfunction (PPID) has not been described previously. OBJECTIVES To describe the histomorphometry and pathological lesions in hoof lamellar tissue of animals that had PPID with or without concurrent laminitis, with reference to age-matched controls. We hypothesised that lamellar lesions consistent with laminitis would be associated with PPID, even in animals without current or historical laminitis. STUDY DESIGN Prospective case-control study. METHODS Mid-dorsal hoof histological sections were obtained post mortem from the forelimbs of 16 PPID-affected animals either with (n = 6) or without laminitis (n = 10) and 10 age- and breed-matched controls. Sections were examined by a blinded veterinary pathologist. The length and width of 10 primary epidermal lamellae were measured using image analysis software. The morphology and pathology of primary and secondary epidermal lamellae were then typed or graded in axial, middle and abaxial regions. Fasting serum insulin, plasma adrenocorticotropin and blood glucose concentration were measured from blood samples taken prior to euthanasia. RESULTS All animals with PPID and laminitis had fasting hyperinsulinaemia (median 74.1 miu/l, interquartile range 49.9-349.5 miu/l) whereas PPID animals without laminitis had serum insulin concentrations below the upper limit of the reference range (<20 miu/l). Lamellar pathology in PPID animals with laminitis was variable in severity and unrelated to the reported duration of laminitis (range 2 months-5 years). Most lesions were located abaxially within the lamellar tissue and included increased length and width of the lamellae, chronic abnormal keratinisation, interlamellar epidermal bridging and cell death with more acute lamellar tearing in some cases. The lamellae of PPID animals without laminitis were normal referent to the relevant control group. CONCLUSIONS Whether PPID and hyperinsulinaemia have a causal inter-relationship or not, it may only be the hyperinsulinaemia that is associated with lamellar morphological alteration and pathology consistent with laminitis.
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Affiliation(s)
- N P Karikoski
- Department of Equine and Small Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - J C Patterson-Kane
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - E R Singer
- Institute of Ageing and Chronic Disease, Faculty of Health and Life Sciences, University of Liverpool, Liverpool, UK
| | - D McFarlane
- Department of Physiological Sciences, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, Oklahoma, USA
| | - C M McGowan
- Institute of Ageing and Chronic Disease, Faculty of Health and Life Sciences, University of Liverpool, Liverpool, UK
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Karikoski NP, McGowan CM, Singer ER, Asplin KE, Tulamo RM, Patterson-Kane JC. Pathology of Natural Cases of Equine Endocrinopathic Laminitis Associated With Hyperinsulinemia. Vet Pathol 2014; 52:945-56. [PMID: 25232034 DOI: 10.1177/0300985814549212] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Laminitis in equids is a clinical syndrome usually associated with systemic disease. Endocrinopathies recently have been recognized as the most common cause of laminitis, with hyperinsulinemia playing a key role. Descriptions of laminitis-associated lesions have been confusing due to the wide range of experimental models used, failure of adequate clinical documentation for naturally occurring cases, lack of separate analysis of inflammatory and endocrinopathic laminitis, and uncertainty regarding normal morphological variation of lamellae. In this study, lamellar morphology and pathology were described in 14 laminitic horses and ponies that had hyperinsulinemia (>20 mIU/l), with reference to 25 age- and breed-matched controls. The type and severity of lesions noted had no correlation with reported clinical duration and in at least some cases must have preceded it. Lesions were largely localized abaxially within the lamellar tissue and included apoptotic cell death, as well as lamellar fusion, hyperplasia, and partial replacement with aberrant keratin containing nucleated debris and proteinaceous lakes. The lesions resulted in irregular margins between the inner horn and the lamellar tissue. Acute separation originated from the abaxial region, with minimal associated inflammation. Axially, epidermal lamellar tapering was the most frequent morphological observation. The lesions in these chronic cases of laminitis were similar to those described in some inflammatory laminitis models and contained features seen in developmental phases of hyperinsulinemic models. These findings support the theory that repeated episodes of subclinical laminitis occur prior to clinical presentation. In addition, the pathology does not include extensive basement membrane failure seen in some inflammatory models.
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Affiliation(s)
- N P Karikoski
- Department of Equine and Small Animal Medicine, Faculty of Veterinary Medicine, Helsinki, Finland
| | - C M McGowan
- Institute of Ageing and Chronic Disease, Faculty of Health and Life Sciences, University of Liverpool, United Kingdom
| | - E R Singer
- Institute of Ageing and Chronic Disease, Faculty of Health and Life Sciences, University of Liverpool, United Kingdom
| | - K E Asplin
- School of Animal and Veterinary Sciences, Charles Sturt University, Wagga Wagga, Australia
| | - R-M Tulamo
- Department of Equine and Small Animal Medicine, Faculty of Veterinary Medicine, Helsinki, Finland
| | - J C Patterson-Kane
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, United Kingdom
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21
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Karikoski NP, Patterson-Kane JC, Asplin KE, McGowan TW, McNutt M, Singer ER, McGowan CM. Morphological and cellular changes in secondary epidermal laminae of horses with insulin-induced laminitis. Am J Vet Res 2014; 75:161-8. [PMID: 24471752 DOI: 10.2460/ajvr.75.2.161] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To determine cellular changes associated with secondary epidermal laminae (SEL) in forefeet and hind feet of ponies with insulin-induced laminitis. ANIMALS 8 ponies. PROCEDURES Laminitis was induced in 4 ponies by IV administration of insulin and glucose; 4 control ponies received saline (0.9% NaCl) solution IV. Laminar tissue samples obtained from the dorsal aspects of the hooves were histologically evaluated. Primary epidermal lamina (PEL) length and width and SEL length, width, and angle were determined. Numbers of epidermal cell nuclei per micrometer and per total length of SEL and numbers of apoptotic and proliferative cells in axial, middle, and abaxial laminar regions were determined. RESULTS SEL in treatment group ponies were significantly longer, were significantly narrower, and had a smaller angle relative to PEL in all laminar regions versus control ponies. In treatment group ponies, the number of epidermal cell nuclei per SEL was typically higher and the number of cells per micrometer of SEL was lower in laminar regions, apoptotic cell numbers were higher in abaxial and middle regions in forefeet and hind feet, and proliferating cell numbers were higher in axial laminar regions in forefeet and all laminar regions in hind feet, versus control ponies. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated SEL elongation, narrowing, and alteration in orientation developed in all feet of ponies with insulin-induced laminitis. This was primarily attributable to cell stretching that developed at the same time as an accelerated cell death-proliferation cycle; differences in cell cycle responses among laminar regions between forefeet and hind feet may have been attributable to differences in load bearing.
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Affiliation(s)
- Ninja P Karikoski
- Department of Equine and Small Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, 00014 University of Helsinki, Finland
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22
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Patan-Zugaj B, Gauff FC, Plendl J, Licka TF. Effect of endotoxin on leukocyte activation and migration into laminar tissue of isolated perfused equine limbs. Am J Vet Res 2014; 75:842-50. [DOI: 10.2460/ajvr.75.9.842] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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23
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Taylor D, Sperandeo A, Schumacher J, Passler T, Wooldridge A, Bell R, Cooner A, Guidry L, Matz-Creel H, Ramey I, Ramey P. Clinical Outcome of 14 Obese, Laminitic Horses Managed with the Same Rehabilitation Protocol. J Equine Vet Sci 2014. [DOI: 10.1016/j.jevs.2013.10.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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24
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Walsh D, Collins S, Winterford C, Pollitt C. The equine foot lamellar lymphatic system. J Equine Vet Sci 2013. [DOI: 10.1016/j.jevs.2013.08.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Expression of purinergic P2X receptor subtypes 1, 2, 3 and 7 in equine laminitis. Vet J 2013; 198:472-8. [PMID: 24080476 DOI: 10.1016/j.tvjl.2013.08.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2013] [Revised: 08/09/2013] [Accepted: 08/12/2013] [Indexed: 12/13/2022]
Abstract
Tissue sensitisation and chronic pain have been described in chronic-active laminitis in the horse, making treatment of such cases difficult. Purinergic P2X receptors are linked to chronic pain and inflammation. The aim of this study was to examine the expression of purinergic P2X receptor subtypes 1, 2, 3 and 7 in the hoof, palmar digital vessels and nerve, dorsal root ganglia and spinal cord in horses with chronic-active laminitis (n=5) compared to non-laminitic horses (n=5). Immunohistochemical analysis was performed on tissue sections using antibodies against P2X receptor subtypes 1-3 and 7. In horses with laminitis, there was a reduction in the thickness of the tunica media layer of the palmar digital vein as a proportion of the whole vessel diameter (0.48±0.05) compared to the non-laminitic group (0.57±0.04; P=0.02). P2X receptor subtype 3 was expressed in the smooth muscle layer (tunica media) of the palmar digital artery of horses with laminitis, but was absent in horses without laminitis. There was strong expression of P2X receptor subtype 7 in the proliferating, partially keratinised, epidermal cells of the secondary epidermal lamellae in the hooves of horses with laminitis, but no immunopositivity in horses without laminitis.
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27
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Katz LM, Bailey SR. A review of recent advances and current hypotheses on the pathogenesis of acute laminitis. Equine Vet J 2013; 44:752-61. [PMID: 23106629 DOI: 10.1111/j.2042-3306.2012.00664.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
With the increasing number of studies being published on the different experimental models used to induce and study acute laminitis, the pathophysiological events associated with these various models (i.e. starch overload, oligofructose overload, black walnut extract and hyperinsulinaemia) can be compared more realistically. Within this review, the mechanisms for metabolic vs. inflammatory laminitis are discussed, and the question of how pasture laminitis may fit into any of the proposed mechanisms is addressed.
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Affiliation(s)
- L M Katz
- School of Veterinary Medicine, University College Dublin, Dublin, Ireland.
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28
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Bailey SR, Bamford NJ. Metabolic responses of horses and ponies to high and low glycaemic feeds: implications for laminitis. ANIMAL PRODUCTION SCIENCE 2013. [DOI: 10.1071/an13266] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Equine laminitis is the painful condition resulting from disruption of the laminar bonds within the foot. Understanding the dietary triggers may facilitate strategies to prevent laminitis in susceptible animals. The purpose of this review is to examine how dietary factors may lead to insulin resistance and/or excessive insulin production from the pancreas, and why certain breeds or types of horses are more predisposed to this form of laminitis than others. Understanding these relationships will be very important when considering appropriate feeds and the dietary countermeasures necessary for preventing this condition. It is important to note the breed type when considering the likely metabolic effects of dietary carbohydrate, because there are major differences between the Thoroughbred/Standardbred type and some other breeds of horses and ponies. Ponies and certain breeds of horses produce excessive amounts of insulin in response to dietary carbohydrates and this may lead to the development of the three main features of the equine metabolic syndrome, namely obesity, insulin resistance and laminitis. Relative glycaemic index or glycaemic load may be useful in predicting peak plasma insulin (with due consideration for breed type), but carbohydrates such as starch and fructans may have particularly marked effects on insulin sensitivity. Although it is normal for ponies and certain horse breeds to be relatively insulin resistant, it may be possible to reduce the likelihood of exacerbating insulin resistance in obese animals with careful dietary modification. This may help to some extent in reducing hyperinsulinaemia and thereby reducing the risk of laminitis.
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Affiliation(s)
- N. Menzies-Gow
- Department of Veterinary Clinical Science; Royal Veterinary College; North Mymms; UK
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de Laat MA, Patterson-Kane JC, Pollitt CC, Sillence MN, McGowan CM. Histological and morphometric lesions in the pre-clinical, developmental phase of insulin-induced laminitis in Standardbred horses. Vet J 2012; 195:305-12. [PMID: 22884985 DOI: 10.1016/j.tvjl.2012.07.003] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Revised: 06/07/2012] [Accepted: 07/04/2012] [Indexed: 01/16/2023]
Abstract
Lamellar pathology in experimentally-induced equine laminitis associated with euglycaemic hyperinsulinaemia is substantial by the acute, clinical phase (∼48h post-induction). However, lamellar pathology of the developmental, pre-clinical phase requires evaluation. The aim of this study was to analyse lamellar lesions both qualitatively and quantitatively, 6, 12 and 24h after the commencement of hyperinsulinaemia. Histological and histomorphometrical analyses of lamellar pathology at each time-point included assessment of lamellar length and width, epidermal cell proliferation and death, basement membrane (BM) pathology and leucocyte infiltration. Archived lamellar tissue from control horses and those with acute, insulin-induced laminitis (48h) was also assessed for cellular proliferative activity by counting the number of cells showing positive nuclear immuno labelling for TPX2. Decreased secondary epidermal lamellar (SEL) width and increased histomorphological evidence of SEL epidermal basal (and supra-basal) cell death occurred early in disease progression (6h). Increased cellular proliferation in SELs, infiltration of the dermis with small numbers of leucocytes and BM damage occurred later (24 and 48h). Some lesions, such as narrowing of the SELs, were progressive over this time period (6-48h). Cellular pathology preceded leucocyte infiltration and BM pathology, indicating that the latter changes may be secondary or downstream events in hyperinsulinaemic laminitis.
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Affiliation(s)
- Melody A de Laat
- Australian Equine Laminitis Research Unit, School of Veterinary Science, The University of Queensland, Gatton, Queensland 4343, Australia.
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Hampson BA, de Laat MA, Beausac C, Rovel T, Pollitt CC. Histopathological examination of chronic laminitis in Kaimanawa feral horses of New Zealand. N Z Vet J 2012; 60:285-9. [PMID: 22621688 DOI: 10.1080/00480169.2012.682271] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
AIMS To investigate the prevalence, histopathological and histomorphometric presentation of chronic laminitis in a population of Kaimanawa feral horses. METHODS Following the capture and euthanasia of feral horses from the Kaimanawa Ranges of New Zealand, the left forefoot of 28 stallions and 28 mares aged between 6 and 12 years were removed and processed for histology. Sections of lamellar samples from each horse were examined using light microscopy. The presence of laminitis was assessed and the histopathological lesions were described. Horses were grouped by histological diagnosis into laminitic and non-laminitic groups and histomorphometric analysis was conducted and compared between groups. The parameters examined were total length of primary epidermal lamellae (PEL), keratinised length of PEL, and the length of secondary epidermal lamellae (SEL) at the abaxial end and axial end of each PEL. RESULTS Of the horses examined, 25 (45%) were diagnosed with chronic laminitis. The most prevalent histopathological features were the presence of excessive cap horn, and multi-branched and attenuated SEL. Histomorphometric assessment of the lamellar architecture revealed no difference in morphometric measurements between the normal and laminitic groups for any parameter measured (p>0.05). CONCLUSIONS The current study found a high prevalence of laminitis in feral Kaimanawa horses. The reason for this in the Kaimanawa population is not known. Histomorphometric analysis may not be a good indicator of chronic laminitis in feral horses. CLINICAL RELEVANCE It is an important finding that the feral horse lifestyle in the environment of the Kaimanawa Ranges in New Zealand offers no protection against foot disease. The finding suggests that horses are vulnerable to laminitis whether in domestic care or in a feral habitat.
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Affiliation(s)
- B A Hampson
- School of Veterinary Science, The University of Queensland , Gatton Campus , Australia.
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Holbrook TC, Tipton T, McFarlane D. Neutrophil and cytokine dysregulation in hyperinsulinemic obese horses. Vet Immunol Immunopathol 2011; 145:283-9. [PMID: 22169327 DOI: 10.1016/j.vetimm.2011.11.013] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Revised: 11/07/2011] [Accepted: 11/17/2011] [Indexed: 11/16/2022]
Abstract
Equine metabolic syndrome is characterized by obesity and regional adiposity coupled with evidence of recurrent laminitis. Although inflammation has been well characterized in several experimental models of acute laminitis, the inflammatory events associated with endocrinopathic laminitis are not well documented. The aim of this study was to characterize selected markers of inflammation in horses with clinical evidence of equine metabolic syndrome (EMS). Neutrophil phagocytosis and oxidative burst, as well as endogenous and stimulated cytokine expression were evaluated. A marked increase in neutrophil reactive oxygen species production upon phagocytosis was observed in horses with EMS that was strongly correlated to the blood insulin concentration. Increased oxidative burst activity of neutrophils in hyperinsulinemic horses may predispose horses with metabolic syndrome to laminitis. In contrast, peripheral blood cells of obese hyperinsulinemic horses showed decreased endogenous proinflammatory cytokine gene expression (IL-1 and IL-6) and similar cytokine response following immune stimulation compared to that of control horses. This may suggest that, unlike in people, cytokine-mediated inflammation does not increase in direct response to obesity or insulin resistance in horses. This species-specific disparity may explain the difference in clinical outcomes observed in obese horses compared to obese people.
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Affiliation(s)
- Todd C Holbrook
- Department of Veterinary Clinical Sciences, 002 BVMTH, Oklahoma State University, Stillwater, OK 74078, USA
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de Laat M, van Eps A, McGowan C, Sillence M, Pollitt C. Equine Laminitis: Comparative Histopathology 48 hours after Experimental Induction with Insulin or Alimentary Oligofructose in Standardbred Horses. J Comp Pathol 2011; 145:399-409. [DOI: 10.1016/j.jcpa.2011.02.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Revised: 01/07/2011] [Accepted: 02/01/2011] [Indexed: 10/18/2022]
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