Sheahan B J, Caffrey J F, Gunn H M, Keating J N
Department of Veterinary Pathology, Faculty of Veterinary Medicine, University College, Ballsbridge, Dublin, Ireland.
Vet Pathol. 1991 Mar;28(2):117-24. doi: 10.1177/030098589102800203.
Degenerative lesions in the spinal cord white matter of 12 English Foxhounds and two Harriers between 3 and 6 years old were associated with a diet composed mainly of ruminant stomachs. Lesions were present throughout the length of the spinal cord and were more severe in ventral and lateral columns than in dorsal columns. Degenerate fibers were accompanied by astrocytic proliferation. Changes suggestive of a primary myelinopathy included vacuolated myelin sheaths around apparently intact axons and thick-thin transitions in myelin sheath thickness. Mixed sensory and motor peripheral nerves and muscle histochemical fiber type profiles appeared normal. Similarities were noted with the changes described in subacute combined degeneration of the spinal cord in human beings, a neuropathy caused by methionine and methylation deficiency in patients with vitamin B12 deficiency. Mean serum methionine levels were significantly lower (P greater than 0.01) and mean liver methionine synthetase levels were significantly greater (P greater than 0.01) in affected dogs restored to a balanced diet than in age-matched controls maintained on the balanced diet. The elevated methionine synthetase levels possibly reflected compensatory reactions to the associated dietary change.
在12只3至6岁的英国猎狐犬和2只哈利犬的脊髓白质中，退行性病变与主要由反刍动物胃组成的饮食有关。病变存在于脊髓全长，腹侧和外侧柱比背侧柱更严重。退化的纤维伴有星形胶质细胞增生。提示原发性髓鞘病的变化包括围绕明显完整轴突的空泡化髓鞘以及髓鞘厚度的厚薄转变。混合感觉和运动外周神经以及肌肉组织化学纤维类型分布看起来正常。注意到与人类脊髓亚急性联合变性中描述的变化有相似之处，后者是一种由维生素B12缺乏患者的蛋氨酸和甲基化缺乏引起的神经病变。与维持均衡饮食的年龄匹配对照组相比，恢复到均衡饮食的患病犬的平均血清蛋氨酸水平显著降低（P大于0.01），平均肝脏蛋氨酸合成酶水平显著升高（P大于0.01）。蛋氨酸合成酶水平升高可能反映了对相关饮食变化的代偿反应。
