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Marsella R, White S, Fadok VA, Wilson D, Mueller R, Outerbridge C, Rosenkrantz W. Equine allergic skin diseases: Clinical consensus guidelines of the World Association for Veterinary Dermatology. Vet Dermatol 2023; 34:175-208. [PMID: 37154488 DOI: 10.1111/vde.13168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 02/03/2023] [Accepted: 02/26/2023] [Indexed: 05/10/2023]
Abstract
BACKGROUND Allergic skin diseases are common in horses worldwide. The most common causes are insect bites and environmental allergens. OBJECTIVES To review the current literature and provide consensus on pathogenesis, diagnosis, treatment and prevention. MATERIALS AND METHODS The authors reviewed the literature up to November 2022. Results were presented at North America Veterinary Dermatology Forum (2021) and European Veterinary Dermatology Congress (2021). The report was available to member organisations of the World Association for Veterinary Dermatology for feedback. CONCLUSIONS AND CLINICAL RELEVANCE Insect bite hypersensitivity (IBH) is the best characterised allergic skin disease. An immunoglobulin (Ig)E response against Culicoides salivary antigens is widely documented. Genetics and environmental factors play important roles. Tests with high sensitivity and specificity are lacking, and diagnosis of IBH is based on clinical signs, seasonality and response to insect control. Eosinophils, interleukin (IL)-5 and IL-31 are explored as therapeutic targets. Presently, the most effective treatment is insect avoidance. Existing evidence does not support allergen-specific immunotherapy (ASIT) using commercially available extracts of Culicoides. Hypersensitivity to environmental allergens (atopic dermatitis) is the next most common allergy. A role for IgE is supported by serological investigation, skin test studies and positive response to ASIT. Prospective, controlled, randomised studies are limited, and treatment relies largely on glucocorticoids, antihistamines and ASIT based on retrospective studies. Foods are known triggers for urticaria, yet their role in pruritic dermatitis is unknown. Recurrent urticaria is common in horses, yet our understanding is limited and focussed on IgE and T-helper 2 cell response. Prospective, controlled studies on treatments for urticaria are lacking. Glucocorticoids and antihistamines are primary reported treatments.
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Affiliation(s)
- R Marsella
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida, USA
| | - S White
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, USA
| | - V A Fadok
- Zoetis, US PET CARE, Bellaire, Texas, USA
| | - D Wilson
- School of Clinical Veterinary Sciences, University of Bristol, Bristol, UK
| | - R Mueller
- Medizinische Keleintierklinik, Zentrum für klinische Tiermedizin, LMU, Munich, Germany
| | - C Outerbridge
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, USA
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Mainguy-Seers S, Lavoie JP. Glucocorticoid treatment in horses with asthma: A narrative review. J Vet Intern Med 2021; 35:2045-2057. [PMID: 34085342 PMCID: PMC8295667 DOI: 10.1111/jvim.16189] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Revised: 05/13/2021] [Accepted: 05/18/2021] [Indexed: 12/15/2022] Open
Abstract
Despite substantial research efforts to improve the treatment and outcome of horses with asthma, glucocorticoids (GC) remain the cornerstone of drug treatment of this prevalent disease. The high efficacy of GC to relieve airway obstruction explains their extensive use despite potential deleterious effects. However, much is yet to be uncovered concerning GC use in horses with asthma, including the comparative efficacy of the different drugs, the determination of minimal effective doses and the mechanisms underlying their variable modulation of airway inflammation. The objectives of this structured review were to report and compare the plethora of effects of the various GC used in asthmatic horses with a focus on impact on lung function, airway inflammation, and bronchial remodeling. Adverse effects are also briefly described, with an emphasis on those that have been specifically reported in horses with asthma. Ultimately, we aimed to highlight gaps in the literature and to identify future research areas.
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Affiliation(s)
- Sophie Mainguy-Seers
- Faculty of Veterinary Medicine, Department of Clinical Sciences, Université de Montréal, St-Hyacinthe, Quebec, Canada
| | - Jean-Pierre Lavoie
- Faculty of Veterinary Medicine, Department of Clinical Sciences, Université de Montréal, St-Hyacinthe, Quebec, Canada
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Fettelschoss V, Olomski F, Birkmann K, Kündig TM, Bergvall K, Fettelschoss‐Gabriel A. Interleukin 31 and targeted vaccination in a case series of six horses with chronic pruritus. EQUINE VET EDUC 2020. [DOI: 10.1111/eve.13408] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- V. Fettelschoss
- Department of Dermatology University Hospital Zurich SchlierenSwitzerland
- Faculty of Medicine University of Zurich ZurichSwitzerland
- Evax AG MünchwilenSwitzerland
| | - F. Olomski
- Department of Dermatology University Hospital Zurich SchlierenSwitzerland
- Faculty of Medicine University of Zurich ZurichSwitzerland
- Evax AG MünchwilenSwitzerland
| | | | - T. M. Kündig
- Faculty of Medicine University of Zurich ZurichSwitzerland
- Department of Dermatology University Hospital Zurich Zurich Switzerland
| | - K. Bergvall
- Department of Clinical Sciences Swedish University of Agriculture Uppsala Sweden
| | - A. Fettelschoss‐Gabriel
- Department of Dermatology University Hospital Zurich SchlierenSwitzerland
- Faculty of Medicine University of Zurich ZurichSwitzerland
- Evax AG MünchwilenSwitzerland
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Potter K, Stevens K, Menzies-Gow N. Prevalence of and risk factors for acute laminitis in horses treated with corticosteroids. Vet Rec 2019; 185:82. [DOI: 10.1136/vr.105378] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 04/15/2019] [Accepted: 05/15/2019] [Indexed: 12/26/2022]
Affiliation(s)
- Katya Potter
- Department of Clinical Sciences and Services; Royal Veterinary College; North Mymms Hertfordshire UK
| | - Kim Stevens
- Department of Pathobiology and Population Sciences; Royal Veterinary College; North Mymms Hertfordshire UK
| | - Nicola Menzies-Gow
- Department of Clinical Sciences and Services; Royal Veterinary College; North Mymms Hertfordshire UK
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Lavoie JP, Leclere M, Rodrigues N, Lemos KR, Bourzac C, Lefebvre-Lavoie J, Beauchamp G, Albrecht B. Efficacy of inhaled budesonide for the treatment of severe equine asthma. Equine Vet J 2018; 51:401-407. [PMID: 30203854 PMCID: PMC6585971 DOI: 10.1111/evj.13018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 09/06/2018] [Indexed: 01/22/2023]
Abstract
Background Corticosteroids are the most potent drugs for the control of severe equine asthma, but adverse effects limit their chronic systemic administration. Inhaled medications allow for drug delivery directly into the airways, reducing the harmful effects of these drugs. Objectives To evaluate the efficacy of inhaled budesonide specifically formulated for the equine use and administered by a novel inhalation device in horses with severe asthma. Study design Experimental studies in horses with naturally occurring asthma with cross‐over, randomised, blinded experimental designs. Methods In Study 1, budesonide (1800 μg twice daily) administered using a novel Respimat® based inhaler was compared to i.v. dexamethasone (0.04 mg/kg). In Study 2, 3 doses of budesonide (450, 900, and 1800 μg) were compared to oral dexamethasone (0.066 mg/kg). Lung function, bronchoalveolar fluid cytology (Study 1), CBC, serum chemistry, and serum cortisol and adrenocorticotropic hormone (ACTH) values were evaluated. Results In Study 1, there was a marked and significant improvement in the lung function of all horses treated with budesonide and dexamethasone. Neutrophil percentages in bronchoalveolar fluid decreased in all horses treated with dexamethasone and in four of six horses treated with budesonide. Serum cortisol and blood ACTH concentrations decreased with both treatments. In Study 2, there was a significant improvement in the lung function with all dosages of budesonide, and the effects of higher dosages were comparable to those of dexamethasone. Dexamethasone and budesonide at the two higher dosages induced a significant decrease of cortisol concentrations. Main limitations The Respimat® based inhaler is not currently commercially available. Conclusions Administration of budesonide with the Respimat® based inhaler provided dose‐dependent relief of airway obstruction in horses with severe asthma, but also a suppression of serum cortisol.
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Affiliation(s)
- J P Lavoie
- Department of Clinical Sciences, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Quebec, Canada
| | - M Leclere
- Department of Clinical Sciences, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Quebec, Canada
| | - N Rodrigues
- Department of Clinical Sciences, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Quebec, Canada
| | - K R Lemos
- Department of Clinical Sciences, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Quebec, Canada
| | - C Bourzac
- Department of Clinical Sciences, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Quebec, Canada
| | - J Lefebvre-Lavoie
- Department of Clinical Sciences, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Quebec, Canada
| | - G Beauchamp
- Department of Veterinary Biomedicine, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Quebec, Canada
| | - B Albrecht
- Boehringer Ingelheim Vetmedica GmbH, Ingelheim am Rhein, Germany
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Hines MT. Clinical Approach to Commonly Encountered Problems. EQUINE INTERNAL MEDICINE 2018. [PMCID: PMC7158300 DOI: 10.1016/b978-0-323-44329-6.00007-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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Borlone C, Morales N, Henriquez C, Folch H, Olave C, Sarmiento J, Uberti B, Moran G. In Vitro effects of tamoxifen on equine neutrophils. Res Vet Sci 2016; 110:60-64. [PMID: 28159238 DOI: 10.1016/j.rvsc.2016.11.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 10/26/2016] [Accepted: 11/03/2016] [Indexed: 10/20/2022]
Abstract
Neutrophils participate in innate immunity as the first line of host defense against microorganisms. However, exacerbated neutrophil activity can be harmful to surrounding tissues; this is important in a range of diseases, including allergic asthma and chronic obstructive pulmonary disease in humans, and equine asthma (also known as recurrent airway obstruction (RAO). Tamoxifen (TX) is a non-steroidal estrogen receptor modulator with effects on cell growth and survival. Previous preliminary studies showed that TX treatment in horses with induced acute pulmonary inflammation promoted early apoptosis of blood and BALF neutrophils, reduction of BALF neutrophils, and improvement in animals' clinical status. The aim of this study was to evaluate the in vitro effect of TX on functional tests in equine peripheral blood neutrophils. Chemotaxis, respiratory burst production and phagocytosis assays were performed on neutrophils isolated from peripheral blood samples from 10 healthy horses. Results showed that IL-8 stimulated cells decrease their chemotactic index when treated with TX (1 and 10μM). Respiratory burst production was also dampened after treatment with TX. In conclusion, these results confirm that tamoxifen has a direct action on equine peripheral blood neutrophils. However, more in vivo and in vitro studies are required to fully understand the mechanisms of action of TX on neutrophils, in order to elucidate if it can be used as treatment in disorders such as allergic asthma in humans and horses.
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Affiliation(s)
- C Borlone
- Department of Pharmacology, Faculty of Veterinary Science, Universidad Austral de Chile, Valdivia, Chile
| | - N Morales
- Department of Pharmacology, Faculty of Veterinary Science, Universidad Austral de Chile, Valdivia, Chile
| | - C Henriquez
- Department of Pharmacology, Faculty of Veterinary Science, Universidad Austral de Chile, Valdivia, Chile
| | - H Folch
- Department of Immunology, Faculty of Medicine, Universidad Austral de Chile, Valdivia, Chile
| | - C Olave
- Department of Pharmacology, Faculty of Veterinary Science, Universidad Austral de Chile, Valdivia, Chile
| | - J Sarmiento
- Department of Physiology, Faculty of Medicine, Universidad Austral de Chile, Valdivia, Chile
| | - B Uberti
- Department of Veterinary Clinical Sciences, Faculty of Veterinary Science, Universidad Austral de Chile, Valdivia, Chile
| | - G Moran
- Department of Pharmacology, Faculty of Veterinary Science, Universidad Austral de Chile, Valdivia, Chile.
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Cuming RS, Groover ES, Wooldridge AA, Caldwell FJ. Review of glucocorticoid therapy in horses. Part 1: Pharmacology. EQUINE VET EDUC 2016. [DOI: 10.1111/eve.12555] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- R. S. Cuming
- J. T. Vaughan Large Animal Teaching Hospital Auburn University Alabama USA
| | - E. S. Groover
- J. T. Vaughan Large Animal Teaching Hospital Auburn University Alabama USA
| | - A. A. Wooldridge
- J. T. Vaughan Large Animal Teaching Hospital Auburn University Alabama USA
| | - F. J. Caldwell
- J. T. Vaughan Large Animal Teaching Hospital Auburn University Alabama USA
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Jordan VJ, Ireland JL, Rendle DI. Does oral prednisolone treatment increase the incidence of acute laminitis? Equine Vet J 2016; 49:19-25. [PMID: 26713748 DOI: 10.1111/evj.12565] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 12/17/2015] [Indexed: 01/11/2023]
Abstract
REASONS FOR PERFORMING STUDY It is accepted among equine practitioners that glucocorticoid treatment is a risk factor for the development of laminitis. However, there is little published evidence of a link between glucocorticoids and laminitis. OBJECTIVES To determine whether horses receiving oral prednisolone are at increased risk of laminitis. STUDY DESIGN Retrospective case-control study. METHODS Clinical records of horses registered with the ambulatory service at Liphook Equine Hospital between January 2001 and November 2014 were reviewed retrospectively to identify horses that had received treatment with oral prednisolone. For each treated horse, 2 time-matched controls that received veterinary attention but were not treated with prednisolone were selected. Incidence of laminitis was compared between the 2 groups and factors associated with laminitis were assessed using Cox regression analysis. RESULTS Of the 416 horses treated with prednisolone, 16 (3.8%) were diagnosed with laminitis subsequent to the initiation of prednisolone treatment with an overall incidence of 2.60 (95% CI 1.49-4.22) cases per 100 horse-years at risk. A total of 7 horses (1.7%) developed laminitis during the course of their treatment and 3 (0.7%) of the horses treated with prednisolone were ultimately subjected to euthanasia as a result of laminitis. A total of 46 (5.7%), of the 814 time-matched control horses were diagnosed with laminitis during the study period with an overall incidence of 3.46 (95% CI 2.54-4.62) cases per 100 horse-years at risk. Of these, 12 (1.5%) were subjected to euthanasia as a result of laminitis. There were no significant differences in the overall laminitis incidence rate (P = 0.8), incidence rate during prednisolone treatment (P = 0.09), or probability of laminitis (P = 0.3) between the 2 groups. Mean survival time was greater in the prednisolone than the control group. Equine metabolic syndrome and increasing age were associated with increased risk of laminitis. CONCLUSIONS Administration of oral prednisolone did not increase the risk of laminitis.
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Affiliation(s)
- V J Jordan
- Liphook Equine Hospital, Liphook, Hampshire, UK
| | - J L Ireland
- The Animal Health Trust, Newmarket, Suffolk, UK
| | - D I Rendle
- Rainbow Equine Hospital, Rainbow Farm, Old Malton, North Yorkshire, UK
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Dauvillier J, Felippe MJB, Lunn DP, Lavoie-Lamoureux A, Leclère M, Beauchamp G, Lavoie JP. Effect of long-term fluticasone treatment on immune function in horses with heaves. J Vet Intern Med 2011; 25:549-57. [PMID: 21488960 DOI: 10.1111/j.1939-1676.2011.0717.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Corticosteroids currently are the most effective pharmacological treatment available to control heaves in horses. Systemically administered corticosteroids have been shown to alter immune response in horses, humans, and other species. Aerosolized administration theoretically minimizes systemic adverse effects, but the effect of inhaled corticosteroids on immune function has not been evaluated in horses. OBJECTIVES To evaluate the effects of prolonged administration of inhaled fluticasone on the immune system of heaves-affected horses. ANIMALS Heaves-affected horses were treated with inhaled fluticasone (n = 5) for 11 months or received environmental modifications only (n = 5). METHODS Prospective analysis. Clinical parameters and CBC, lymphocyte subpopulations and function, and circulating neutrophil gene expression were sequentially measured. Primary and anamnestic immune responses also were evaluated by measuring antigen-specific antibodies in response to vaccination with bovine viral antigen and tetanus toxoid, respectively. RESULTS No clinical adverse effects were observed and no differences in immune function were detected between treated and untreated horses. CONCLUSIONS AND CLINICAL IMPORTANCE The treatment of heaves-affected horses with inhaled fluticasone at therapeutic dosages for 11 months has no significant detectable effect on innate and adaptive (both humoral and cell-mediated) immune parameters studied. These results suggest that prolonged administration of fluticasone would not compromise the systemic immune response to pathogens nor vaccination in adult horses.
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Affiliation(s)
- J Dauvillier
- Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, QC, Canada
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ABRAHAM G, ALLERSMEIER M, GOTTSCHALK J, SCHUSSER GF, HOPPEN HO, UNGEMACH FR. Effects of dermal dexamethasone application on ACTH and both basal and ACTH-stimulated cortisol concentration in normal horses. J Vet Pharmacol Ther 2009; 32:379-87. [DOI: 10.1111/j.1365-2885.2008.01054.x] [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]
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Glover CM, Miller LM, Dybdal NO, Lopez A, Duckett WM, McFarlane D. Extrapituitary and Pituitary Pathological Findings in Horses with Pituitary Pars Intermedia Dysfunction: A Retrospective Study. J Equine Vet Sci 2009. [DOI: 10.1016/j.jevs.2009.01.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Abstract
Insulin resistance is thought to be involved in the pathogenesis of many equine conditions such as pars intermedia dysfunction, equine metabolic syndrome, diabetes mellitus, hyperlipaemia, laminitis, endotoxaemia and osteochondrosis dissecans (OCD); whereas polysaccharide storage myopathy in Quarter Horses and equine motor neuron disease (EMD) have been associated with increased insulin sensitivity. However, it is clear that there is not one ideal test, in terms of both practicality and accuracy, for evaluating insulin sensitivity in horses and improved diagnostic techniques are required. This review sets out the background to the subject and identifies current knowledge regarding the measurement of insulin sensitivity by tolerance testing and clamping techniques. Factors affecting insulin sensitivity, such as breed, pregnancy, lactation, obesity and nutritional factors are discussed. In addition, the relationship with training, nutritional supplementation and drug administration are considered.
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Affiliation(s)
- A M Firshman
- Department of Clinical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, Oregon 97331, USA
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Abstract
Polyuria and polydipsia provide a diagnostic challenge for the equine clinician. This article describes the various known causes of polyuria and polydipsia in horses and provides a description of a systematic diagnostic approach for assessing horses with polyuria and polydipsia to delineate the underlying cause. Treatment and management strategies for addressing polyuria and polydipsia in horses are also described.
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Affiliation(s)
- Erica C McKenzie
- Clinical Sciences Department, College of Veterinary Medicine, Oregon State University, 227 Magruder Hall, Corvallis, OR 97331, USA.
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Bailey SR, Elliott J. The corticosteroid laminitis story: 2. Science of if, when and how. Equine Vet J 2007; 39:7-11. [PMID: 17228587 DOI: 10.2746/042516407x166035] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- S R Bailey
- Department of Veterinary Basic Sciences, Royal Veterinary College, London, UK
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Cesarini C, Hamilton E, Picandet V, Lavoie JP. Theophylline does not potentiate the effects of a low dose of dexamethasone in horses with recurrent airway obstruction. Equine Vet J 2006; 38:570-3. [PMID: 17124849 DOI: 10.2746/042516407x153048] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
REASONS FOR PERFORMING STUDY Theophylline has been shown to have corticosteroid-sparing effects for the treatment of human asthma. A similar effect, if present in horses, would allow diminishing the dose of corticosteroids administered to equine patients with inflammatory airway diseases. OBJECTIVES To evaluate whether theophylline potentiates the effects of a low dose of dexamethasone when treating horses with recurrent airway obstruction (RAO). HYPOTHESIS Theophylline has steroid-sparing effects in horses with RAO. METHODS Ten mature mixed breed horses in clinical exacerbation of RAO were studied. Using an incomplete crossover design and 3 experimental periods of 7 days duration, horses were distributed randomly in 5 treatment groups; and administered dexamethasone s.i.d., at either 0.05 mg/kg bwt i.v. or per os, or 0.02 mg/kg bwt alone or combined with theophylline at 5 mg/kg bwt per os b.i.d. A fifth group was treated with theophylline alone at the above dosage. Lung function was evaluated prior to drug administration and then 3 and 7 days later. RESULTS Oral administration of dexamethasone alone or combined with theophylline failed to improve lung function significantly in RAO affected horses. Theophylline alone also failed to improve lung function in all treated horses. Conversely, dexamethasone administration at 0.05 mg/kg bwt i.v. resulted in a significant improvement in lung function starting on Day 3. CONCLUSIONS AND POTENTIAL RELEVANCE Oral theophylline for 7 days did not improve the effects of a low dose of dexamethasone for the treatment of horses with RAO.
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Affiliation(s)
- C Cesarini
- Département des Sciences Cliniques, Faculté de Médecine Vétérinaire, Université de Montréal, CP 5000, Saint-Hyacinthe, Québec J2S7C6, Canada
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Cornelisse CJ, Robinson NE, Berney CA, Eberhart S, Hauptman JE, Derksen FJ. Thermographic study of in vivo modulation of vascular responses to phenylephrine and endothelin-1 by dexamethasone in the horse. Equine Vet J 2006; 38:119-26. [PMID: 16536380 DOI: 10.2746/042516406776563251] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
REASONS FOR PERFORMING STUDY In vitro, glucocorticoids potentiate vasoconstriction of equine digital vessels to catecholamines and this has been implicated as a mechanism of glucocorticoid-induced laminitis. This observation has never been confirmed in vivo. OBJECTIVES To study the effects of glucocorticoid therapy on vasoconstrictor responsiveness in the horse in vivo. METHODS In a blinded, randomised cross-over experiment, 9 horses were treated with either dexamethasone (0.1 mg/kg bwt i.v. q. 24 h) or saline i.v. for 6 days. The changes in local average skin temperature before (baseline) and after intradermal injections of the alpha1-adrenoceptor agonist phenylephrine (PHE; 10(-4), 10(-5), 10(-6), 10(-7) and 10(-8) mol/l), endothelin-1 (ET-1; 10(-5), 10(-6), 10(-7), 10(-8) and 10(-9) mol/l) or ET-1 plus a blocker (BQ-123 10(-6) mol/l; RES-701 10(-6) mol/l; and L-NAME 10(-4) mol/l) were investigated with a thermograph. RESULTS Dexamethasone (DEX) decreased baseline skin temperatures, suggesting reduced blood flow as a consequence of an increase in vasomotor tone. This was accompanied by potentiation of the response to PHE as demonstrated by a left shift in the dose-response curve and a decrease in the EC50. Dexamethasone did not potentiate ET-1, but the interplay with the lower baseline temperature resulted in a significantly lower skin temperature for this vasoconstrictor after DEX. The different ET-1 blockers had no effect on ET-1 modulated skin temperatures. CONCLUSIONS Dexamethasone decreases skin perfusion. This is accompanied by a potentiated alpha1-adrenoceptor agonist response and a greater response to ET-1. POTENTIAL RELEVANCE Glucocorticoid therapy probably decreases perfusion of the equine hoof. During disease states that already are characterised by hypoperfusion and/or increased levels of circulating catecholamines, glucocorticoid therapy could, according to the vascular model of laminitis, tilt the balance in favour of laminitis.
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Affiliation(s)
- C J Cornelisse
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan 48823-1314, USA
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Gastrointestinal Disease. EQUINE NEONATAL MEDICINE 2006. [PMCID: PMC7156017 DOI: 10.1016/b978-1-4160-2353-1.50016-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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