Breitschwerdt E B, Kornegay J N, Wheeler S J, Stevens J B, Baty C J
Department of Companion Animal and Special Species Medicine, College of Veterinary Medicine, North Carolina State University, Raleigh 27606.
J Am Vet Med Assoc. 1992 Sep 1;201(5):731-6.
Two Old English Sheepdog littermates were evaluated for weakness that developed during periods of minimally intense exercise. Lactic acidosis accompanied by increased muscle enzyme activity, an increased lactate/pyruvate ratio, and increased venous PO2 supported the possibility of defective mitochondrial oxygen use. Electromyographic abnormalities included increased insertional activity and complex repetitive discharges. Muscle alterations included scattered myofiber necrosis, abundant endomysial connective tissue, excessive glycogen accumulation, and greater than normal numbers and vacuolation of mitochondria. A distinctive pattern of subsarcolemmal mitochondrial aggregates, referred to as "ragged red fibers" in human mitochondrial myopathies, was observed in muscle biopsy samples from 1 dog. Several features of the disease in these dogs, including onset of weakness during early life, simultaneous disease in littermates, subtle nonprogressive weakness of at least 3 years' duration, and partial reversibility of lactic acidosis following rest were suggestive of an inborn error of metabolism, consistent with mitochondrial myopathy.
对两只英国古代牧羊犬同窝幼犬进行了评估，它们在轻度运动期间出现了虚弱症状。乳酸酸中毒伴有肌肉酶活性增加、乳酸/丙酮酸比值升高和静脉血氧分压升高，支持线粒体氧利用缺陷的可能性。肌电图异常包括插入活动增加和复杂重复放电。肌肉改变包括散在的肌纤维坏死、丰富的肌内膜结缔组织、过多的糖原积累以及线粒体数量多于正常且有空泡化。在1只犬的肌肉活检样本中观察到一种独特的肌膜下线粒体聚集模式，在人类线粒体肌病中被称为“破碎红纤维”。这些犬类疾病的几个特征，包括早年出现虚弱、同窝幼犬同时患病、至少持续3年的轻微非进行性虚弱以及休息后乳酸酸中毒的部分可逆性，提示代谢先天性缺陷，与线粒体肌病一致。
