加拿大奶牛肉牛维生素A缺乏症.docx

维生素A缺乏症Vitamin A Deficiency (Hypovitaminosis A)Prepared by: Dr. Terry Hunt病因/发病机理Translated by Dr. Yachun WangCause & Pathogenesis维生素A有维持上皮组织完整性的作用Vitamin A maintains the integrity of epithelial tissue现在，可在日粮中添加Now, supplemented in ration维生素A是脂溶性的，所以长期采食不可消化的油质可导致缺乏症。Vitamin A is fat soluble so deficiencies can occur with long term ingestion of non- digestible oils在所有物种中维生素A都是必须的，在流动放牧的管理系统中也可能发生。Required in all species and may be found with nomadic grazing systems危险因素Risk Factors高精料日粮或粗料质量不好(胡萝卜素含量低)High concentrate diets or poor quality forage (low carotene)经过加工的饲料损失了维生素A临床症状夜盲症角膜有变化被毛粗糙、干燥蹄甲干裂精子数下降流产死胎以及弱犊Losses of levels in processed feedsClinical FindingsNight blindnessCorneal changesRough, dry coatDry scaly hoovesReduced sperm countAbortions, stillbirths and weak calves惊厥，尤其在6-8月龄的肉用犊牛中发生Convulsions especially in beef calves 6-8 months of age 1至2岁的个体出现两侧失明一眼睛肿胀，无反射（恐吓反射和瞳孔对光反射 消失）视神经乳头水肿Bilateral blindness in cattle 1-2 years of age 一 dilated non-responsive eyes (loss of menace reflex & papillary light reflex) and papilledema惊厥、昏迷以致由于大脑水肿致死，尤其发生于6至8月龄犊牛Convulsions, coma and death due to cerebral edema especially in calves 6-8 months of age诊断Diagnosis临床症状以及实验室检测结果Clinical signs and laboratory findings鉴别诊断铅中毒脑灰质软化症狂犬病Differential DiagnosisLead poisoning Polioencephalomalacia Rabies头弛至不U内埋羊修町Laboratory and Pathology血液中胡萝卜素(9 ug/dl)或维生素A (5 ug/dl)含量低Low blood carotene (9 ug/dl) or Vitamin A (5 ug/dl)饲料中维生素A水平低Low Vitamin A levels in feed立即服用维生素A-440 lU/kgImmediate administration of Vitamin A 一 440 lU/kg治疗Treatment预后情况Prognosis及早治疗预后良好，但有可能仍然失明Good if treated early but may remain blind 每 60 天注射 3000 - 6000 lU/kg Inject 3000 - 6000 lU/kg every 60 days后遗症失明预防补充维生素A 60-80 IU/kg/天SequelaeBlindnessPrevention & ControlSupplement with Vitamin A60-80 lU/kg/day