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Martin LM, Bukoski AD, Whelchel DD, Evans TJ, Wiedmeyer CE, Black SJ, Johnson PJ. Pharmacokinetics of intravenous lithium chloride and assessment of agreement between two methods of lithium concentration measurement in the horse. Equine Vet J 2017; 50:537-543. [PMID: 29112289 DOI: 10.1111/evj.12778] [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: 02/24/2017] [Accepted: 10/29/2017] [Indexed: 11/28/2022]
Abstract
BACKGROUND Pharmacokinetics of lithium chloride (LiCl) administered as a bolus, once i.v. have not been determined in horses. There is no point-of-care test to measure lithium (Li+ ) concentrations in horses in order to monitor therapeutic levels and avoid toxicity. OBJECTIVES To determine the pharmacokinetics of LiCl in healthy adult horses and to compare agreement between two methods of plasma Li+ concentration measurement: spectrophotometric enzymatic assay (SEA) and inductively coupled plasma mass spectrometry (ICP-MS). STUDY DESIGN Nonrandomised, single exposure with repeated measures over time. METHODS Lithium chloride was administered (0.15 mmol/kg bwt) as an i.v. bolus to eight healthy adult horses. Blood samples were collected pre-administration and at multiple times until 48 h post-administration. Samples were analysed by two methods (SEA and ICP-MS) to determine plasma Li+ concentrations. Pharmacokinetics were determined based on the reference ICP-MS data. RESULTS Adverse side effects were not observed. The SEA showed linearity, R2 = 0.9752; intraday coefficient of variation, 2.5%; and recovery, 96.3%. Both noncompartmental and compartmental analyses (traditional two-stage and nonlinear mixed-effects [NLME] modelling) were performed. Geometric mean values of noncompartmental parameters were plasma Li+ concentration at time zero, 2.19 mmol/L; terminal elimination half-life, 25.68 h; area under the plasma concentration-time curve from time zero to the limit of quantification, 550 mmol/L min; clearance, 0.273 mL/min/kg; mean residence time, 31.22 h; and volume of distribution at steady state, 511 mL/kg. Results of the traditional two-stage analysis showed good agreement with the NLME modelling approach. Bland-Altman analyses demonstrated poor agreement between the SEA and ICP-MS methods (95% limits of agreement = 0.14 ± 0.13 mmol/L). MAIN LIMITATIONS Clinical effects of LiCl have not been investigated. CONCLUSIONS The LiCl i.v. bolus displayed pharmacokinetics similar to those reported in other species. The SEA displayed acceptable precision but did not agree well with the reference method (ICP-MS). The Summary is available in Spanish - see Supporting Information.
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Affiliation(s)
- L M Martin
- Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, USA
| | - A D Bukoski
- Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, USA
| | - D D Whelchel
- Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, USA
| | - T J Evans
- Veterinary Medical Diagnostic Laboratory, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, USA
| | - C E Wiedmeyer
- Veterinary Medical Diagnostic Laboratory, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, USA
| | - S J Black
- Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, Massachusetts, USA
| | - P J Johnson
- Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, USA
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Zizzadoro C, Caruso M, Punzi S, Crescenzo G, Zongoli F, Belloli C. A comparative study between responses of isolated bovine and equine digital arteries to vasoactive mediators. J Vet Pharmacol Ther 2017; 41:51-59. [DOI: 10.1111/jvp.12436] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 06/07/2017] [Indexed: 01/17/2023]
Affiliation(s)
- C. Zizzadoro
- Division of Veterinary Pharmacology and Toxicology; Department of Veterinary Medicine; University of Bari; Valenzano Bari Italy
| | - M. Caruso
- Division of Veterinary Pharmacology and Toxicology; Department of Veterinary Medicine; University of Bari; Valenzano Bari Italy
| | - S. Punzi
- Division of Veterinary Pharmacology and Toxicology; Department of Veterinary Medicine; University of Bari; Valenzano Bari Italy
| | - G. Crescenzo
- Division of Veterinary Pharmacology and Toxicology; Department of Veterinary Medicine; University of Bari; Valenzano Bari Italy
| | | | - C. Belloli
- Division of Veterinary Pharmacology and Toxicology; Department of Veterinary Medicine; University of Bari; Valenzano Bari Italy
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Staniar WB, Neuendorf LE, Brooks SA. Preliminary Investigation of the Changes in Fecal Streptococcal Population due to Diet and Time of Day in Horses. J Equine Vet Sci 2016. [DOI: 10.1016/j.jevs.2016.07.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Tadros EM, Frank N. Effects of continuous or intermittent lipopolysaccharide administration for 48 hours on the systemic inflammatory response in horses. Am J Vet Res 2013; 73:1394-402. [PMID: 22924721 DOI: 10.2460/ajvr.73.9.1394] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To determine whether the method of lipopolysaccharide (LPS) administration (intermittent vs continuous) affects the magnitude and duration of the systemic inflammatory response in horses and whether prolonged (48 hours) endotoxemia induces laminitis. ANIMALS 12 healthy adult horses (10 mares and 2 geldings). PROCEDURES Horses were randomly assigned to receive LPS (total dose, 80 μg; n = 4) or saline (0.9% NaCl) solution (80 mL/h; 4) via constant rate infusion or 8 bolus IV injections of LPS (10 μg, q 6 h;4) during a 48-hour period. Physical examinations were performed every 4 hours, inflammatory cytokine gene expression was determined for blood samples obtained every 8 hours, and IV glucose tolerance tests were performed. RESULTS All LPS-treated horses had signs of depression and mild colic; those signs abated as the study progressed. Administration of LPS increased expression of interleukin-1β, interleukin-6, and interleukin-8, but results were not significantly different between LPS treatment groups. Cytokine expression was significantly higher on the first day versus the second day of LPS treatment. Interleukin-1β expression was positively correlated with rectal temperature and expression of other cytokines. Glucose and insulin dynamics for both LPS groups combined did not differ significantly from those of the saline solution group. Signs of laminitis were not detected in any of the horses. CONCLUSIONS AND CLINICAL RELEVANCE Horses developed LPS tolerance within approximately 24 hours after administration was started, and the method of LPS administration did not affect the magnitude or duration of systemic inflammation. Laminitis was not induced in horses.
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Affiliation(s)
- Elizabeth M Tadros
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37996, USA
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Reesink HL, Divers TJ, Bookbinder LC, van Eps AW, Soderholm LV, Mohammed HO, Cheetham J. Measurement of digital laminar and venous temperatures as a means of comparing three methods of topically applied cold treatment for digits of horses. Am J Vet Res 2012; 73:860-6. [PMID: 22620701 DOI: 10.2460/ajvr.73.6.860] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To compare effects of 3 methods of topically applied cold treatment (cryotherapy) on digital laminar and venous temperatures in horses. ANIMALS 9 healthy adult Thoroughbreds. PROCEDURES Thermocouples were placed in palmar digital veins and digital laminae of both forelimbs of horses. Three methods of cryotherapy were applied to the distal aspects of the limbs: wader boot (63-cm-tall vinyl boot filled with ice and water [ice slurry]), ice bag (5-L fluid bag filled with ice slurry), and a gel pack boot (boot containing frozen gel packs). Gel packs and ice slurries were replenished every hour during cryotherapy. The forelimb that received the first treatment was randomly assigned; thereafter, control and treated forelimbs were alternated for each treatment. For each treatment, temperatures were recorded every minute during 15-minute pretreatment, 2-hour treatment, and ≥ 30 minute rewarming periods. Once temperatures had returned to within 3°C below pretreatment values, the experiment was repeated in a similar manner for other cryotherapy methods. RESULTS Digital venous temperatures were similar to laminar temperatures during each treatment. Ice bag and wader boot treatments caused similar cooling of digits. Gel boot treatment did not cause substantial cooling of digits. CONCLUSIONS AND CLINICAL RELEVANCE Ice bag treatment caused laminar and digital venous cooling equivalent to that of wader boot treatment. Cryotherapy by use of 5-L fluid bags with an ice slurry may be a readily available, practical, and efficient method for prevention of laminitis in horses. Digital laminar and venous temperatures were similar in forelimbs of horses before and during cryotherapy.
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Affiliation(s)
- Heidi L Reesink
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
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Tadros EM, Frank N, Newkirk KM, Donnell RL, Horohov DW. Effects of a "two-hit" model of organ damage on the systemic inflammatory response and development of laminitis in horses. Vet Immunol Immunopathol 2012; 150:90-100. [PMID: 23026157 DOI: 10.1016/j.vetimm.2012.09.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2012] [Accepted: 09/02/2012] [Indexed: 11/20/2022]
Abstract
The role of endotoxemia in the development of laminitis remains unclear. Although systemic inflammation is a risk factor for laminitis in hospitalized horses, experimental endotoxin administration fails to induce the disease. While not sufficient to cause laminitis by itself, endotoxemia might predispose laminar tissue to damage from other mediators during systemic inflammation. In "two-hit" models of organ damage, sequential exposure to inflammatory stimuli primes the immune system and causes exaggerated inflammatory responses during sepsis. Acute laminitis shares many characteristics with sepsis-associated organ failure, therefore an equine "two-hit" sepsis model was employed to test the hypothesis that laminitis develops with increased frequency and severity when repeated inflammatory events exacerbate systemic inflammation and organ damage. Twenty-four light breed mares (10) and geldings (14) with chronic disease conditions or behavioral abnormalities unrelated to laminitis that warranted euthanasia were obtained for the study. Horses were randomly assigned to receive an 8-h intravenous infusion of either lipopolysaccharide (5 ng/kg/h) or saline beginning at -24h, followed by oligofructose (OF; 5 g/kg) via nasogastric tube at 0 h. Euthanasia and tissue collection occurred at Obel grade 2 laminitis, or at 48 h if laminitis had not developed. Liver biopsies were performed at 24h in laminitis non-responders. Blood cytokine gene expression was measured throughout the study period. Lipopolysaccharide and OF administration independently increased mean rectal temperature (P<0.001), heart rate (P=0.003), respiratory rate (P<0.001), and blood interleukin (IL)-1β gene expression (P<0.0016), but responses to OF were not exaggerated in endotoxin-pretreated horses. The laminitis induction rate did not differ between treatment groups and was 63% overall. When horses were classified as laminitis responders and non-responders, area under the blood IL-1β expression curve (P=0.010) and liver and lung gene expression of IL-1β, IL-6, IL-8, IL-10, and tumor necrosis factor-α (P<0.05) were higher in responders following OF administration. The results indicate that endotoxin pretreatment did not enhance responses to OF. However, systemic inflammation was more pronounced in laminitis responders compared to non-responders, and tissue-generated inflammatory mediators could pose a greater risk than those produced by circulating leukocytes.
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Affiliation(s)
- Elizabeth M Tadros
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37996, USA
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Zizzadoro C, Caruso M, Putignano C, Crescenzo G, Ormas P, Belloli C. Effects of endotoxin and influence of cyclooxygenase-2 on β-adrenergic mediated relaxation in isolated equine digital artery. Vet J 2011; 190:e48-e53. [DOI: 10.1016/j.tvjl.2011.03.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Revised: 02/26/2011] [Accepted: 03/08/2011] [Indexed: 10/18/2022]
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Zerpa H, Berhane Y, Elliott J, Bailey SR. The effect of cooling on the contractility of equine digital small lamellar arteries: modulating role of the endothelium. Exp Physiol 2010; 95:1033-42. [PMID: 20660021 DOI: 10.1113/expphysiol.2010.053686] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The equine hoof displays thermoregulatory functions, and the blood vessels lying under the hoof wall are temperature sensitive. The aim of this study was to investigate the effect of cooling on the contractile responses to α-adrenoceptor and 5-HT receptor stimulation in equine small lamellar arteries using wire myography. The role of the endothelium in the response mediated by 5-HT was also evaluated. Moderate cooling caused a reduction of the contraction induced by depolarizing Krebs solution (DKS, containing 118 mm KCl) and the maximal contraction caused by UK-14304 (α(2)-adrenoceptor agonist). The potency of methoxamine (α(1)-adrenoceptor agonist) was reduced by cooling [pD(2) (-log EC(50)) at 22°C, 5.7 (5.5-6.0) versus 30°C, 5.9 (5.7-6.1)]; however, the efficacy was maintained. The contractions evoked by sumatripan and α-methyl 5-HT (5-HT receptor agonists) were not modified by moderate cooling. In contrast, a cooling-enhanced contraction was observed in response to 5-HT [maximum response (E(max)) at 22°C, 213.2 ± 13% DKS versus 30°C, 179.9 ± 11% DKS]. Furthermore, this effect was more evident in endothelium-denuded lamellar arteries (E(max) at 22°C, 270.2 ± 26% DKS versus 30°C, 172.2 ± 20% DKS), suggesting a potential modulating role of the endothelium. The L-NAME/ibuprofen-resistant relaxation in response to carbachol was reduced by cooling in small lamellar arteries precontracted with 5-HT but not phenylephrine. Therefore, a moderate reduction of temperature modulates the reactivity of small lamellar arteries by enhancing the 5-HT-mediated contraction, but inhibits the α-adrenoceptor-mediated response. Furthermore, the endothelium of these blood vessels may play an important role in preventing excessive vasoconstriction in response to 5-HT and maintaining digital blood flow in cool environmental temperatures.
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Affiliation(s)
- Hector Zerpa
- Department of Veterinary Basic Sciences, Royal Veterinary College, University of London, London, UK
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Mallem MY, Thuleau A, Noireaud J, Desfontis JC, Gogny M. Evaluation of the role of superoxide anions in endotoxin-induced impairment of β-adrenoceptor-mediated vasodilation in equine digital veins. Am J Vet Res 2010; 71:773-9. [DOI: 10.2460/ajvr.71.7.773] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Patan B, Budras KD, Licka TF. Effects of long-term extracorporeal blood perfusion of the distal portion of isolated equine forelimbs on metabolic variables and morphology of laminar tissue. Am J Vet Res 2009; 70:669-77. [PMID: 19405908 DOI: 10.2460/ajvr.70.5.669] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To establish an ex vivo model of blood perfusion in the distal portion of isolated equine forelimbs that closely represents the in vivo situation in the laminar tissue of the hoof. SAMPLE POPULATION 18 forelimbs collected from 9 healthy adult horses following slaughter at a licensed abattoir. PROCEDURES The distal portion of isolated equine forelimbs from 9 horses were perfused under physiologic conditions over a period of 6, 8, and 10 hours with autologous blood. To determine cell viability in perfused tissues, indicators for metabolism (lactate generation and glucose and oxygen consumption) as well as indicators for cell damage (potassium concentration and lactate dehydrogenase activity) were examined at 1-hour intervals from samples of the perfusate. Weight gain in the forelimb was used to determine the edema index. After perfusion, light and electron microscopic examinations of laminar tissue specimens were performed. RESULTS During hemoperfusion of the isolated forelimbs, mean +/- SD glucose consumption was 197.4 +/- 65.1 mg/h, lactate generation was 1.84 +/- 0.79 mmol/h, and oxygen consumption was 6.4 x 10(-6) +/- 8.9 x 10(-5) mL.g(-1).min(-1). Neither an efflux of potassium into the perfusate nor a relevant increase of the lactate dehydrogenase activity was detected, indicating low amounts of cellular damage in the perfused tissues. Weight gain of forelimbs was 1.02 +/- 0.95%. Histologic and ultrastructural appearance of the laminar tissue revealed no signs of tissue damage. CONCLUSIONS AND CLINICAL RELEVANCE Isolated equine limbs were perfused under physiologic conditions over a period of < or = 10 hours without structural damage to the laminar tissue.
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Affiliation(s)
- Bianca Patan
- Clinic of Orthopaedics in Large Animals, Department of Horses and Small Animals, Vienna University of Veterinary Medicine, A-1210 Vienna, Austria
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Hackett ES, Hassel DM. Colic: Nonsurgical Complications. Vet Clin North Am Equine Pract 2008; 24:535-55, viii. [DOI: 10.1016/j.cveq.2008.09.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Menzies-Gow NJ, Bailey SR, Berhane Y, Brooks AC, Elliott J. Evaluation of the induction of vasoactive mediators from equine digital vein endothelial cells by endotoxin. Am J Vet Res 2008; 69:349-55. [PMID: 18312133 DOI: 10.2460/ajvr.69.3.349] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To determine the effect of endotoxin (lipopolysaccharide [LPS]) on vasoactive mediator production by cultured equine digital vein endothelial cells (EDVECs). SAMPLE POPULATION EDVECs obtained from forelimb digital veins of 7 healthy adult horses. PROCEDURES EDVECs were incubated with or without LPS (1 microg/mL) for 0, 2, 4, 6, 22, and 24 hours. The EDVECs were incubated for 18 hours with LPS (10 pg/mL to 1 microg/mL) with or without ibuprofen, cycloheximide, or L-nitroarginine methyl ester. Medium concentrations of prostacyclin, cyclic guanosine monophosphate, endothelin-1, and thromboxane A(2) were determined. Changes in inducible nitric oxide synthase and cyclooxygenase-2 expression were determined. RESULTS LPS stimulated mean 4.2- and 14.1-fold increases in EDVEC prostacyclin and cyclic guanosine monophosphate production, respectively, after 22 hours. These effects were LPS concentration-dependent (LPS concentrations that induced a response halfway between the maximum response and baseline of 1.50 and 1.22 ng/mL, respectively). The LPS-induced cyclic guanosine monophosphate production was significantly inhibited (to basal concentrations) by L-nitroarginine methyl ester, and prostacyclin production was inhibited by cycloheximide and ibuprofen. Production of thromboxane A(2) by EDVECs was not detected. Endothelin-1 accumulated in the medium, but LPS did not enhance its production. Inducible nitric oxide synthase expression in EDVECs was not detected with the available antibodies, whereas LPS stimulated cyclooxygenase-2 expression in a time- and concentration-dependent manner. CONCLUSIONS AND CLINICAL RELEVANCE LPS stimulated vasoactive mediator production by equine endothelial cells, which may play a role in LPS-induced digital hypoperfusion.
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Affiliation(s)
- Nicola J Menzies-Gow
- Department of Veterinary Clinical Sciences, Royal Veterinary College, North Mymms, Hertfordshire AL9 7TA, England
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Milinovich GJ, Trott DJ, Burrell PC, Croser EL, Al Jassim RAM, Morton JM, van Eps AW, Pollitt CC. Fluorescence in situ hybridization analysis of hindgut bacteria associated with the development of equine laminitis. Environ Microbiol 2007; 9:2090-100. [PMID: 17635552 DOI: 10.1111/j.1462-2920.2007.01327.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Carbohydrate-induced laminitis in horses is characterized by marked changes in the composition of the hindgut microbiota, from a predominantly Gram-negative population to one dominated by Gram-positive bacteria. The objective of this study was to monitor changes in the relative abundance of selected hindgut bacteria that have previously been implicated in the pathophysiology of equine laminitis using fluorescence in situ hybridization (FISH). Caecal cannulae were surgically implanted in five Standardbred horses and laminitis induced by oral administration of a bolus dose of oligofructose. Caecal fluid and faecal specimens were collected over a 48 h period at 2 to 4 h intervals post-oligofructose administration and subjected to FISH using probes specific for nine bacterial groups to determine changes in their relative abundance compared with total bacteria hybridizing to the generic EUBMIX probe. Additionally, hoof biopsies were taken over the course of the experiment at 6 h intervals and evaluated for histopathological changes consistent with laminitis, allowing changes in hindgut microbiota to be correlated with the onset of lesions in the foot. Of the microorganisms specifically targeted, streptococci of the Streptococcus bovis/equinus complex were the only bacteria that consistently proliferated in both caecal fluid and faeces immediately before the onset of histological signs of laminitis. Furthermore, lactobacilli, Enterobacteriaceae, Allisonella histaminiformans, enterococci, Bacteroides fragilis, Mitsuokella jalaludinii and Clostridium difficile did not establish significant populations in the hindgut before the onset of equine laminitis.
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Affiliation(s)
- Gabriel J Milinovich
- Australian Equine Laminitis Research Unit, School of Veterinary Science, The University of Queensland, Brisbane, Qld, Australia.
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Parsons CS, Orsini JA, Krafty R, Capewell L, Boston R. Risk factors for development of acute laminitis in horses during hospitalization: 73 cases (1997–2004). J Am Vet Med Assoc 2007; 230:885-9. [PMID: 17362165 DOI: 10.2460/javma.230.6.885] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To identify risk factors for development of acute laminitis in horses during hospitalization for illness or injury. DESIGN Retrospective case-control study. ANIMALS 73 horses that developed laminitis (case horses) and 146 horses that did not develop laminitis (control horses) during hospitalization. PROCEDURES Case and control horses were matched in a 2:1 ratio by the date on which each horse was evaluated. Potential risk factors investigated included age, breed, and sex; highest and lowest values recorded during hospitalization for fibrinogen concentration, WBC count, PCV, and total solids concentration; and comorbid disease states, including pneumonia, endotoxemia, diarrhea, medically treated colic, surgically treated colic, pituitary adenoma, retained placenta or metritis, forelimb lameness, hind limb lameness, acute renal failure, and vascular abnormalities. A univariate screening of all potential risk factors was performed to determine which variables should be selected for further analysis. All factors found to be associated with development of laminitis were included in a multivariate conditional logistic regression model. RESULTS Development of laminitis was marginally associated with lowest and highest fibrinogen concentrations, highest PCV, and lowest total solids concentration and significantly associated with pneumonia, endotoxemia, diarrhea, abdominal surgery for colic, and vascular abnormalities. In the multivariate analysis, only endotoxemia was significantly associated with laminitis. CONCLUSIONS AND CLINICAL RELEVANCE Endotoxemia is an important risk factor for development of acute laminitis in horses during hospitalization for medical or surgical conditions. Early recognition of endotoxemia, or the potential for it to develop in certain disease states, and initiation of treatment directed at endotoxemia or its consequences may help prevent laminitis in horses during hospitalization.
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Affiliation(s)
- Corrina Snook Parsons
- New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA 19348, USA
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Treiber KH, Kronfeld DS, Geor RJ. Insulin resistance in equids: possible role in laminitis. J Nutr 2006; 136:2094S-2098S. [PMID: 16772509 DOI: 10.1093/jn/136.7.2094s] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Insulin is a major regulatory hormone in glucose and fat metabolism, vascular function, inflammation, tissue remodeling, and the somatotropic axis of growth. Insulin resistance alters insulin signaling by decreasing insulin action in certain resistant pathways while increasing insulin signaling in other unaffected pathways via compensatory hyperinsulinemia. In humans, altered insulin signaling is implicated in reduced glucose availability to insulin-sensitive cells, vasoconstriction and endothelial damage, and inflammatory response. Although no direct evidence exists for insulin's role in these mechanisms in the laminitic horse, changes in the glucose availability, vasculature, and inflammation were all demonstrated in hoof separation. Insulin resistance was first implicated in the pathogenesis of laminitis in the 1980s using tolerance tests. Our present findings provide the first specific evidence of insulin resistance as a major predisposing condition for laminitis. Specific quantitative characterization of insulin resistance is essential toward identifying the following: 1) ponies in need of special management to avoid laminitis, and 2) potential management strategies to avoid laminitis by increasing insulin sensitivity, including reducing obesity, increasing exercise, and moderating dietary carbohydrates, particularly starch.
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Affiliation(s)
- Kibby H Treiber
- Department Animal and Poultry Science, Virginia Polytechnic and State University, Blacksburg, VA 24061-0303, USA.
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Milinovich GJ, Trott DJ, Burrell PC, van Eps AW, Thoefner MB, Blackall LL, Al Jassim RAM, Morton JM, Pollitt CC. Changes in equine hindgut bacterial populations during oligofructose-induced laminitis. Environ Microbiol 2006; 8:885-98. [PMID: 16623745 DOI: 10.1111/j.1462-2920.2005.00975.x] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the horse, carbohydrate overload is thought to play an integral role in the onset of laminitis by drastically altering the profile of bacterial populations in the hindgut. The objectives of this study were to develop and validate microbial ecology methods to monitor changes in bacterial populations throughout the course of experimentally induced laminitis and to identify the predominant oligofructose-utilizing organisms. Laminitis was induced in five horses by administration of oligofructose. Faecal specimens were collected at 8 h intervals from 72 h before to 72 h after the administration of oligofructose. Hindgut microbiota able to utilize oligofructose were enumerated throughout the course of the experiment using habitat-simulating medium. Isolates were collected and representatives identified by 16S rRNA gene sequencing. The majority of these isolates collected belonged to the genus Streptococcus, 91% of which were identified as being most closely related to Streptococcus infantarius ssp. coli. Furthermore, S. infantarius ssp. coli was the predominant oligofructose-utilizing organism isolated before the onset of lameness. Fluorescence in situ hybridization probes developed to specifically target the isolated Streptococcus spp. demonstrated marked population increases between 8 and 16 h post oligofructose administration. This was followed by a rapid population decline which corresponded with a sharp decline in faecal pH and subsequently lameness at 24-32 h post oligofructose administration. This research suggests that streptococci within the Streptococcus bovis/equinus complex may be involved in the series of events which precede the onset of laminitis in the horse.
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Affiliation(s)
- G J Milinovich
- Australian Equine Laminitis Research Unit, School of Veterinary Science, The University of Queensland, Queensland, Australia.
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Peroni JF, Moore JN, Noschka E, Grafton ME, Aceves-Avila M, Lewis SJ, Robertson TP. Predisposition for venoconstriction in the equine laminar dermis: implications in equine laminitis. J Appl Physiol (1985) 2005; 100:759-63. [PMID: 16269525 DOI: 10.1152/japplphysiol.00794.2005] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Equine laminitis is a crippling condition associated with a variety of systemic diseases. Although it is apparent that the prodromal stages of laminitis involve microvascular dysfunction, little is known regarding the physiology of this vasculature. The aim of the present study was to determine the relative responses of equine laminar arteries and veins to the vasoconstrictor agonists phenylephrine (1 nM-10 microM), 5-HT (1 nM-10 microM), PGF2alpha (1 nM-100 microM), and endothelin-1 (1 pM-1 microM). We have determined that laminar veins were more sensitive, with respect to the concentration of agonist required to initiate a contractile response and to achieve EC(50), for all agonists tested. EC50 values, for veins and arteries, respectively, were 84+/-7 vs. 688+/-42 nM for phenylephrine, 35+/-6 vs. 224+/-13 nM for 5-HT, 496+/-43 nM vs. 3.0+/-0.6 microM for PGF2alpha, and 467+/-38 pM vs. 70.6+/-6.4 nM for endothelin-1. Moreover, when expressed as a percentage of the response to a depolarizing stimulus (80 mM potassium), the maximal contractile response of laminar veins exceeded that for the laminar arteries for each agonist. These results indicate that there may be a predisposition for venoconstriction within the vasculature of the equine digit. While this physiological predisposition for venoconstriction may be important in the regulation of blood flow during exercise, it also may help to explain why laminitis can result from a variety of pathological systemic conditions.
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Affiliation(s)
- John F Peroni
- Dept. of Physiology and Pharmacology, College of Veterinary Medicine, Univ. of Georgia, Athens, Georgia, GA 30602-7389, USA
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