Traub-Dargatz J L, Schlipf J W, Granstrom D E, Ingram J T, Shelton G D, Getzy D M, Lappin M R, Baker D C
Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins 80523.
J Am Vet Med Assoc. 1994 Dec 1;205(11):1574-6.
Multifocal myositis was diagnosed in a 7-year-old Quarter Horse gelding on the basis of history and findings on physical examination, serum biochemical analysis, electromyography, and microscopic examination of frozen sections of muscle biopsy specimens. Histologic examination of the muscle specimen revealed multifocal accumulations of histiocytes, lymphocytes, and plasma cells, with attendant myofiber degeneration and necrosis. Parasitic cysts with morphologic characteristics of Sarcocystis sp were found in regions of myocyte degeneration and necrosis, and in regions of normal muscle. Based on a tentative diagnosis of Sarcocystis sp-induced myositis, the horse was treated with trimethoprim/sulfamethoxazole and pyrimethamine for 28 days, phenylbutazone for 5 days, and paddock rest for 30 days. At the end of treatment, the horse had gained 35 kg, its appetite had returned to normal, and muscle mass was returning to normal. Sarcocystis fayeri is the only Sarcocystis sp reported in equine muscle in the United States and is rarely associated with acute myositis or muscle atrophy. The development of clinical signs in this horse could have been the result of an underlying immunosuppression or infection with a particularly pathogenic strain or large infective dose of S fayeri.
根据病史、体格检查结果、血清生化分析、肌电图以及肌肉活检标本冰冻切片的显微镜检查，一匹7岁的夸特马 gelding被诊断为多灶性肌炎。肌肉标本的组织学检查显示，组织细胞、淋巴细胞和浆细胞多灶性聚集，伴有肌纤维变性和坏死。在肌细胞变性和坏死区域以及正常肌肉区域发现了具有肉孢子虫属形态特征的寄生虫囊肿。基于肉孢子虫属引起的肌炎的初步诊断，这匹马接受了甲氧苄啶/磺胺甲恶唑和乙胺嘧啶治疗28天、保泰松治疗5天，并在围场休息30天。治疗结束时，这匹马体重增加了35公斤，食欲恢复正常，肌肉质量也恢复正常。费氏肉孢子虫是美国马肌肉中报道的唯一一种肉孢子虫属，很少与急性肌炎或肌肉萎缩有关。这匹马出现临床症状可能是由于潜在的免疫抑制，或者感染了致病性特别强的菌株或大量感染性剂量的费氏肉孢子虫。
