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Kruse CJ, Dieu M, Renaud B, François AC, Stern D, Demazy C, Burteau S, Boemer F, Art T, Renard P, Votion DM. New Pathophysiological Insights from Serum Proteome Profiling in Equine Atypical Myopathy. ACS OMEGA 2024; 9:6505-6526. [PMID: 38371826 PMCID: PMC10870397 DOI: 10.1021/acsomega.3c06647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Revised: 12/15/2023] [Accepted: 12/29/2023] [Indexed: 02/20/2024]
Abstract
Equine atypical myopathy (AM) is a severe environmental intoxication linked to the ingestion of protoxins contained in seeds and seedlings of the sycamore maple (Acer pseudoplatanus) in Europe. The toxic metabolites cause a frequently fatal rhabdomyolysis syndrome in grazing horses. Since these toxic metabolites can also be present in cograzing horses, it is still unclear as to why, in a similar environmental context, some horses show signs of AM, whereas others remain clinically healthy. Label-free proteomic analyses on the serum of 26 diseased AM, 23 cograzers, and 11 control horses were performed to provide insights into biological processes and pathways. A total of 43 and 44 differentially abundant proteins between "AM vs cograzing horses" and "AM vs control horses" were found. Disease-linked changes in the proteome of different groups were found to correlate with detected amounts of toxins, and principal component analyses were performed to identify the 29 proteins representing a robust AM signature. Among the pathway-specific changes, the glycolysis/gluconeogenesis pathway, the coagulation/complement cascade, and the biosynthesis of amino acids were affected. Sycamore maple poisoning results in a combination of inflammation, oxidative stress, and impaired lipid metabolism, which is trying to be counteracted by enhanced glycolysis.
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Affiliation(s)
- Caroline-J. Kruse
- Department
of Functional Sciences, Faculty of Veterinary Medicine, Physiology
and Sport Medicine, Fundamental and Applied
Research for Animals & Health (FARAH), University of Liège, Sart Tilman, 4000 Liège 1, Belgium
| | - Marc Dieu
- Namur
Research Institute for Life Sciences (Narilis), University of Namur (UNamur), Namur 5000, Belgium
- MaSUN,
Mass Spectrometry Facility, University of
Namur (UNamur), Namur 5000, Belgium
| | - Benoît Renaud
- Department
of Functional Sciences, Faculty of Veterinary Medicine, Pharmacology
and Toxicology, Fundamental and Applied
Research for Animals & Health (FARAH), University of Liège, Sart Tilman, 4000 Liège 1, Belgium
| | - Anne-Christine François
- Department
of Functional Sciences, Faculty of Veterinary Medicine, Pharmacology
and Toxicology, Fundamental and Applied
Research for Animals & Health (FARAH), University of Liège, Sart Tilman, 4000 Liège 1, Belgium
| | - David Stern
- GIGA
Bioinformatics Platform, GIGA Institute, University of Liège, Sart Tilman, 4000 Liège, Belgium
| | - Catherine Demazy
- Namur
Research Institute for Life Sciences (Narilis), University of Namur (UNamur), Namur 5000, Belgium
- MaSUN,
Mass Spectrometry Facility, University of
Namur (UNamur), Namur 5000, Belgium
| | - Sophie Burteau
- Namur
Research Institute for Life Sciences (Narilis), University of Namur (UNamur), Namur 5000, Belgium
- MaSUN,
Mass Spectrometry Facility, University of
Namur (UNamur), Namur 5000, Belgium
| | - François Boemer
- Biochemical
Genetics Lab, Department of Human Genetics, CHU of Liège, University of Liège, Sart Tilman, 4000 Liège, Belgium
| | - Tatiana Art
- Department
of Functional Sciences, Faculty of Veterinary Medicine, Physiology
and Sport Medicine, Fundamental and Applied
Research for Animals & Health (FARAH), University of Liège, Sart Tilman, 4000 Liège 1, Belgium
| | - Patricia Renard
- Namur
Research Institute for Life Sciences (Narilis), University of Namur (UNamur), Namur 5000, Belgium
- MaSUN,
Mass Spectrometry Facility, University of
Namur (UNamur), Namur 5000, Belgium
| | - Dominique-M. Votion
- Department
of Functional Sciences, Faculty of Veterinary Medicine, Pharmacology
and Toxicology, Fundamental and Applied
Research for Animals & Health (FARAH), University of Liège, Sart Tilman, 4000 Liège 1, Belgium
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Acer pseudoplatanus: A Potential Risk of Poisoning for Several Herbivore Species. Toxins (Basel) 2022; 14:toxins14080512. [PMID: 35893754 PMCID: PMC9394473 DOI: 10.3390/toxins14080512] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 07/20/2022] [Accepted: 07/21/2022] [Indexed: 11/17/2022] Open
Abstract
Acer pseudoplatanus is a worldwide-distributed tree which contains toxins, among them hypoglycin A (HGA). This toxin is known to be responsible for poisoning in various species, including humans, equids, Père David's deer and two-humped camels. We hypothesized that any herbivore pasturing with A. pseudoplatanus in their vicinity may be at risk for HGA poisoning. To test this hypothesis, we surveyed the HGA exposure from A. pseudoplatanus in species not yet described as being at risk. Animals in zoological parks were the major focus, as they are at high probability to be exposed to A. pseudoplatanus in enclosures. We also searched for a toxic metabolite of HGA (i.e., methylenecyclopropylacetyl-carnitine; MCPA-carnitine) in blood and an alteration of the acylcarnitines profile in HGA-positive animals to document the potential risk of declaring clinical signs. We describe for the first instance cases of HGA poisoning in Bovidae. Two gnus (Connochaetes taurinus taurinus) exposed to A. pseudoplatanus in their enclosure presented severe clinical signs, serum HGA and MCPA-carnitine and a marked modification of the acylcarnitines profile. In this study, even though all herbivores were exposed to A. pseudoplatanus, proximal fermenters species seemed less susceptible to HGA poisoning. Therefore, a ruminal transformation of HGA is hypothesized. Additionally, we suggest a gradual alteration of the fatty acid metabolism in case of HGA poisoning and thus the existence of subclinical cases.
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In Vitro Assays for the Assessment of Impaired Mitochondrial Bioenergetics in Equine Atypical Myopathy. Life (Basel) 2021; 11:life11070719. [PMID: 34357091 PMCID: PMC8307747 DOI: 10.3390/life11070719] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 07/12/2021] [Accepted: 07/15/2021] [Indexed: 12/30/2022] Open
Abstract
Equine atypical myopathy is a seasonal intoxication of grazing equids. In Europe, this poisoning is associated with the ingestion of toxins contained in the seeds and seedlings of the sycamore maple (Acer pseudoplatanus). The toxins involved in atypical myopathy are known to inhibit ß-oxidation of fatty acids and induce a general decrease in mitochondrial respiration, as determined by high-resolution respirometry applied to muscle samples taken from cases of atypical myopathy. The severe impairment of mitochondrial bioenergetics induced by the toxins may explain the high rate of mortality observed: about 74% of horses with atypical myopathy die, most within the first two days of signs of poisoning. The mechanism of toxicity is not completely elucidated yet. To improve our understanding of the pathological process and to assess therapeutic candidates, we designed in vitro assays using equine skeletal myoblasts cultured from muscle biopsies and subjected to toxins involved in atypical myopathy. We established that equine primary myoblasts do respond to one of the toxins incriminated in the disease.
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Dunkel B, Ryan A, Haggett E, Knowles EJ. Atypical myopathy in the South‐East of England: Clinicopathological data and outcome in hospitalised horses. EQUINE VET EDUC 2018. [DOI: 10.1111/eve.12895] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- B. Dunkel
- Department of Clinical Science and Services The Royal Veterinary College North Mymms Hertfordshire UK
| | - A. Ryan
- Department of Clinical Science and Services The Royal Veterinary College North Mymms Hertfordshire UK
| | - E. Haggett
- Rossdales Equine Hospital and Diagnostic Centre Newmarket Suffolk UK
| | - E. J. Knowles
- Bell Equine Veterinary Clinic Mereworth Maidstone Kent UK
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Fabius LS, Westermann CM. Evidence-based therapy for atypical myopathy in horses. EQUINE VET EDUC 2017. [DOI: 10.1111/eve.12734] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- L. S. Fabius
- Faculty of Veterinary Medicine; Utrecht University; Yalelaan Utrecht The Netherlands
| | - C. M. Westermann
- Faculty of Veterinary Medicine; Utrecht University; Yalelaan Utrecht The Netherlands
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Karlíková R, Široká J, Jahn P, Friedecký D, Gardlo A, Janečková H, Hrdinová F, Drábková Z, Adam T. Equine atypical myopathy: A metabolic study. Vet J 2016; 216:125-32. [PMID: 27687939 DOI: 10.1016/j.tvjl.2016.07.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Revised: 07/25/2016] [Accepted: 07/27/2016] [Indexed: 10/21/2022]
Abstract
Atypical myopathy (AM) is a potentially fatal disease of grazing horses. It is reportedly caused by the ingestion of sycamore seeds containing toxic hypoglycin A. In order to study metabolic changes, serum and urine samples from nine horses with atypical myopathy and 12 control samples from clinically healthy horses were collected and then analysed using a high-performance liquid chromatography coupled with tandem mass spectrometry; serum metabolic profiles as the disease progressed were also studied. Metabolic data were evaluated using unsupervised and supervised multivariate analyses. Significant differences were demonstrated in the concentrations of various glycine conjugates and acylcarnitines (C2-C26). Moreover, the concentrations of purine and pyrimidine metabolites, vitamins and their degradation products (riboflavin, trigonelline, pyridoxate, pantothenate), and selected organic and amino acids (aspartate, leucine, 2-oxoglutarate, etc.) were altered in horses with AM. These results represent a global view of altered metabolism in horses with atypical myopathy.
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Affiliation(s)
- R Karlíková
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacký University, Hněvotínská 5, 779 00 Olomouc, Czech Republic
| | - J Široká
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacký University, Hněvotínská 5, 779 00 Olomouc, Czech Republic.
| | - P Jahn
- Faculty of Veterinary Medicine, University of Veterinary and Pharmaceutical Sciences, Palackého tř. 1/3, 612 42 Brno, Czech Republic
| | - D Friedecký
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacký University, Hněvotínská 5, 779 00 Olomouc, Czech Republic; Laboratory for Inherited Metabolic Disorders, University Hospital and Faculty of Medicine and Dentistry, Palacký University, I.P. Pavlova 6, 775 20 Olomouc, Czech Republic
| | - A Gardlo
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacký University, Hněvotínská 5, 779 00 Olomouc, Czech Republic; Department of Mathematical Analysis and Applications of Mathematics, Palacký University, 17. listopadu 12, 771 46 Olomouc, Czech Republic
| | - H Janečková
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacký University, Hněvotínská 5, 779 00 Olomouc, Czech Republic; Laboratory for Inherited Metabolic Disorders, University Hospital and Faculty of Medicine and Dentistry, Palacký University, I.P. Pavlova 6, 775 20 Olomouc, Czech Republic
| | - F Hrdinová
- Faculty of Veterinary Medicine, University of Veterinary and Pharmaceutical Sciences, Palackého tř. 1/3, 612 42 Brno, Czech Republic
| | - Z Drábková
- Faculty of Veterinary Medicine, University of Veterinary and Pharmaceutical Sciences, Palackého tř. 1/3, 612 42 Brno, Czech Republic
| | - T Adam
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacký University, Hněvotínská 5, 779 00 Olomouc, Czech Republic; Laboratory for Inherited Metabolic Disorders, University Hospital and Faculty of Medicine and Dentistry, Palacký University, I.P. Pavlova 6, 775 20 Olomouc, Czech Republic
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Lemieux H, Boemer F, van Galen G, Serteyn D, Amory H, Baise E, Cassart D, van Loon G, Marcillaud-Pitel C, Votion DM. Mitochondrial function is altered in horse atypical myopathy. Mitochondrion 2016; 30:35-41. [PMID: 27374763 DOI: 10.1016/j.mito.2016.06.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 05/30/2016] [Accepted: 06/28/2016] [Indexed: 12/31/2022]
Abstract
Equine atypical myopathy in Europe is a fatal rhabdomyolysis syndrome that results from the ingestion of hypoglycin A contained in seeds and seedlings of Acer pseudoplatanus (sycamore maple). Acylcarnitine concentrations in serum and muscle OXPHOS capacity were determined in 15 atypical myopathy cases. All but one acylcarnitine were out of reference range and mitochondrial respiratory capacity was severely decreased up to 49% as compared to 10 healthy controls. The hallmark of atypical myopathy thus consists of a severe alteration in the energy metabolism including a severe impairment in muscle mitochondrial respiration that could contribute to its high death rate.
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Affiliation(s)
- Hélène Lemieux
- Faculty Saint-Jean, University of Alberta, Edmonton, Alberta, Canada
| | - François Boemer
- Biochemical Genetics Laboratory, Human Genetics, CHU Liege, University of Liege, Belgium
| | - Gaby van Galen
- (c)Equine Clinic, Fundamental and Applied Research for Animals & Health (FARAH), Faculty of Veterinary Medicine, University of Liege, Belgium
| | - Didier Serteyn
- (c)Equine Clinic, Fundamental and Applied Research for Animals & Health (FARAH), Faculty of Veterinary Medicine, University of Liege, Belgium; Centre of Oxygen, Research and Development, University of Liege, Liege, Belgium
| | - Hélène Amory
- (c)Equine Clinic, Fundamental and Applied Research for Animals & Health (FARAH), Faculty of Veterinary Medicine, University of Liege, Belgium
| | - Etienne Baise
- (e)Department of Animal Productions: Biostatistics, Economy and Animal Selection, Fundamental and Applied Research for Animals & Health (FARAH), Faculty of Veterinary Medicine, University of Liege, Belgium
| | - Dominique Cassart
- Department of Pathology, Fundamental and Applied Research for Animals & Health (FARAH), Faculty of Veterinary Medicine, University of Liege, Belgium
| | | | | | - Dominique-M Votion
- (i)Equine Pole, Fundamental and Applied Research for Animals and Health (FARAH), Faculty of Veterinary Medicine, University of Liege, Belgium.
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Van Driessche K, Ducatelle R, Chiers K, Van Coster R, van der Kolk JH, van der Kolk H. Ultrastructural mitochondrial alterations in equine myopathies of unknown origin. Vet Q 2014; 35:2-8. [PMID: 25365353 DOI: 10.1080/01652176.2015.983681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
BACKGROUND Very few mitochondrial myopathies have been described in horses. OBJECTIVE To examine the ultrastructure of muscle mitochondria in equine cases of myopathy of unknown origin. MATERIALS & METHODS Biopsies of vastus lateralis of the Musculus quadriceps femoris were taken predominantly immediately post mortem and processed for transmission electron microscopy. As a result, electron micrographs of 90 horses in total were available for analysis comprising 4 control horses, 16 horses suffering from myopathy and 70 otherwise diseased horses. RESULTS Following a thorough clinical and laboratory work-up, four out of five patients that did not fit into the usual algorithm to detect known causes of myopathy showed ultrastructural mitochondrial alterations. Small mitochondria with zones with complete disruption of cristae associated with lactic acidemia were detected in a 17-year-old pony mare, extremely long and slender mitochondria with longitudinal cristae in a 5-year-old Quarter horse stallion, a mixture of irregular extremely large mitochondria (measuring 2500 by 800 nm) next to smaller ones in an 8-year-old Hanoverian mare and round mitochondria with only few cristae in a 11-year-old pony gelding. It remains uncertain whether the subsarcolemmal mitochondrial accumulations observed in the fifth patient have any pathological significance. CONCLUSIONS Ultrastructural alterations in mitochondria were detected in at least four horses. To conclude that these are due to mitochondrial dysfuntions, biochemical tests should be performed. PRACTICAL APPLICATIONS The possibility of a mitochondrial myopathy should be included in the differential diagnosis of muscle weakness.
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Affiliation(s)
- K Van Driessche
- a Department of Pathology, Bacteriology and Avian Medicine , Faculty of Veterinary Medicine , Ghent University , Merelbeke , Belgium
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Kranenburg L, Westermann C, de Sain-van der Velden M, de Graaf-Roelfsema E, Buyse J, Janssens G, van den Broek J, van der Kolk J. The effect of long-term oral L-carnitine administration on insulin sensitivity, glucose disposal, plasma concentrations of leptin and acylcarnitines, and urinary acylcarnitine excretion in warmblood horses. Vet Q 2014; 34:85-91. [DOI: 10.1080/01652176.2014.919745] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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McKenzie RK, Gibson IR, Ritmeester A. Three cases of a presumptive atypical myopathy in New Zealand horses. N Z Vet J 2013; 61:367-72. [DOI: 10.1080/00480169.2013.796436] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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van Galen G, Cerri S, Porter S, Saegerman C, Lefere L, Roscher K, Marr C, Amory H, Votion DM. Traditional and quantitative assessment of acid-base and shock variables in horses with atypical myopathy. J Vet Intern Med 2012. [PMID: 23193982 DOI: 10.1111/jvim.12003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND Descriptions of acid-base disturbances in atypical myopathy (AM) are limited. OBJECTIVES Describe and compare traditional and quantitative acid-base abnormalities and cardiovascular shock status in horses with AM at admission. ANIMALS 34 horses with AM, 15 healthy controls. METHODS Retrospective case-control study. Records were searched for shock variables (packed cell volume [PCV], blood urea nitrogen [BUN], heart and respiratory rate) and acid-base variables (venous blood gas analysis, electrolytes, total protein, lactate) on admission. Base excess (BE) of free water (BEfw), chloride (BEcl), total protein (BEtp), and unidentified anions (BEua), anion gap (AG), measured strong ion difference (SIDm), and concentration of total nonvolatile weak acids ([Atot]) were calculated. Acid-base classifications, using simplified strong ion model and traditional approach, and shock grades were assigned. A 2-sample Wilcoxon rank-sum test and Bonferroni correction compared variables in AM cases versus control horses. Significance was P < .05/16 for acid-base and P < .05/5 for shock variables. RESULTS Tachycardia, tachypnea, and normal to increased PCV and BUN were common in AM cases. Respiratory, metabolic acid-base alterations, or both were mainly caused by respiratory alkalosis, lactic acidosis, and SIDm alkalosis, alone or in combination. Evaluated variables (except pH, potassium concentration, total protein, and related calculations) were significantly different (P < .001) between AM cases and control horses. The strong ion model provided a more accurate assessment than the traditional approach and identified mixed derangements. CONCLUSIONS AND CLINICAL IMPORTANCE Acid-base derangements should be evaluated in horses with AM and this preferably with the strong ion model.
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Affiliation(s)
- G van Galen
- Department of Epidemiology, Unité de recherche en epidémiologie et analyse de risques appliquées aux sciences vétérinaires, FMV University of Liege, Belgium.
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Votion DM. The story of equine atypical myopathy: a review from the beginning to a possible end. ISRN VETERINARY SCIENCE 2012; 2012:281018. [PMID: 23762581 PMCID: PMC3671727 DOI: 10.5402/2012/281018] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Accepted: 09/25/2012] [Indexed: 11/23/2022]
Abstract
Atypical myopathy (AM) is a frequently fatal seasonal pasture myopathy that emerges in Europe. Outbreaks are of an acute and unexpected nature and practitioners should be prepared to handle these critically ill patients. This review retraces the history of AM and describes results of epidemiological investigations that were conducted to raise hypotheses concerning the etiology of this devastating disease as well as to be able to suggest potential preventive measures. Also, clinical studies have contributed to a better definition and recognition of the syndrome, whereas elucidation of the pathological process, identified as a multiple acyl-CoA dehydrogenase deficiency (MADD), was a great step forward improving medical management of AM and guiding the search for the etiological agent towards toxins that reproduce the identified defect. Treatment plans can be extrapolated from the described clinical signs and metabolic problems, but they remain limited to supportive care until the causative agent has been identified with certainty. Since treatment is still unsuccessful in the majority of cases, the main emphasis is currently still on prevention. This paper aims at being a practical support for equine clinicians dealing with AM and is based on discussion and comparison of the currently available scientific data.
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Affiliation(s)
- Dominique-Marie Votion
- Equine Clinic, Faculty of Veterinary Medicine, University of Liege, Boulevard de Colonster 20 B41, 4000 Liege, Belgium
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van Galen G, Votion DM. Management of cases suffering from atypical myopathy: Interpretations of descriptive, epidemiological and pathophysiological findings. Part 1: First aid, cardiovascular, nutritional and digestive care. EQUINE VET EDUC 2012. [DOI: 10.1111/j.2042-3292.2012.00439.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Sponseller BT, Valberg SJ, Schultz NE, Bedford H, Wong DM, Kersh K, Shelton GD. Equine multiple acyl-CoA dehydrogenase deficiency (MADD) associated with seasonal pasture myopathy in the midwestern United States. J Vet Intern Med 2012; 26:1012-8. [PMID: 22708588 DOI: 10.1111/j.1939-1676.2012.00957.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Revised: 02/16/2012] [Accepted: 05/09/2012] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Seasonal pasture myopathy (SPM) is a highly fatal form of nonexertional rhabdomyolysis that occurs in pastured horses in the United States during autumn or spring. In Europe, a similar condition, atypical myopathy (AM), is common. Recently, a defect of lipid metabolism, multiple acyl-CoA dehydrogenase deficiency (MADD), has been identified in horses with AM. OBJECTIVE To determine if SPM in the United States is caused by MADD. ANIMALS Six horses diagnosed with SPM based on history, clinical signs, and serum creatine kinase activity, or postmortem findings. METHODS Retrospective descriptive study. Submissions to the Neuromuscular Diagnostic Laboratory at the University of Minnesota were reviewed between April 2009 and January 2010 to identify cases of SPM. Inclusion criteria were pastured, presenting with acute nonexertional rhabdomyolysis, and serum, urine, or muscle samples available for analysis. Horses were evaluated for MADD by urine organic acids, serum acylcarnitines, muscle carnitine, or histopathology. RESULTS Six horses had clinical signs and, where performed (4/6 horses), postmortem findings consistent with SPM. Affected muscle (4/4) showed degeneration with intramyofiber lipid accumulation, decreased free carnitine concentration, and increased carnitine esters. Serum acylcarnitine profiles (3/3) showed increases in short- and medium-chain acylcarnitines and urinary organic acid profiles (3/3) revealed increased ethylmalonic and methylsuccinic acid levels, and glycine conjugates, consistent with equine MADD. CONCLUSIONS AND CLINICAL IMPORTANCE Similar to AM, the biochemical defect causing SPM is MADD, which causes defective muscular lipid metabolism and excessive myofiber lipid content. Diagnosis can be made by assessing serum acylcarnitine and urine organic acid profiles.
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Affiliation(s)
- B T Sponseller
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA.
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