Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA.
J Vet Intern Med. 2012 Jul-Aug;26(4):1012-8. doi: 10.1111/j.1939-1676.2012.00957.x. Epub 2012 Jun 18.
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.
To determine if SPM in the United States is caused by MADD.
Six horses diagnosed with SPM based on history, clinical signs, and serum creatine kinase activity, or postmortem findings.
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.
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.
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.
季节性牧场肌病（SPM）是一种在美国放牧马中发生的非运动性横纹肌溶解症的高度致命形式，发生于秋季或春季。在欧洲，一种类似的疾病，非典型肌病（AM），很常见。最近，一种脂质代谢缺陷，多酰基辅酶 A 脱氢酶缺乏症（MADD），已在患有 AM 的马中被发现。
确定美国的 SPM 是否由 MADD 引起。
六匹马根据病史、临床症状和血清肌酸激酶活性或死后发现被诊断为 SPM。
回顾性描述性研究。回顾 2009 年 4 月至 2010 年 1 月期间明尼苏达大学神经肌肉诊断实验室的提交病例，以确定 SPM 病例。纳入标准为放牧、表现为急性非运动性横纹肌溶解症，以及有血清、尿液或肌肉样本可供分析。通过尿液有机酸、血清酰基肉碱、肌肉肉碱或组织病理学评估马是否患有 MADD。
六匹马的临床症状和（4/6 匹马）死后发现与 SPM 一致。受影响的肌肉（4/4）显示出退行性变化，伴有肌纤维内脂质积累、游离肉碱浓度降低和肉碱酯增加。血清酰基肉碱谱（3/3）显示短链和中链酰基肉碱增加，尿液有机酸谱（3/3）显示乙基丙二酸和甲基琥珀酸水平增加，以及甘氨酸结合物增加，与马的 MADD 一致。
与 AM 相似，引起 SPM 的生化缺陷是 MADD，它导致肌肉脂质代谢缺陷和肌纤维内脂质含量过多。通过评估血清酰基肉碱和尿液有机酸谱可以做出诊断。
