Fennwick D C, Daniel R C
Department of Physiology and Pharmacology, University of Queensland, St. Lucia, Australia.
Zentralbl Veterinarmed A. 1990 Dec;37(10):721-8. doi: 10.1111/j.1439-0442.1990.tb00965.x.
In one study, 6 cows with high erythrocyte potassium concentrations (HK cows) and 7 with low erythrocyte potassium concentrations (LK cows) were infused with 4.7% Na2EDTA solution intravenously for 4 h. The immediately observable clinical signs and the sequelae over a period of weeks were recorded and compared. There were no differences in the clinical responses of HK or LK cows to the infusion of Na2EDTA. In a second study, these clinical signs plus those produced experimentally by three other research groups were compared with both the clinical signs of milk fever recorded in three text books and those observed by one of the authors over a period of 25 years in dairy cattle practice. All of the clinical signs of milk fever occurred in the experimental model, but there were extra signs (excessive salivation, excessive lip and tongue actions, and tail lifting) which were not present or recorded in naturally occurring cases of hypocalcaemia. Hypocalcaemia induced in cows by the intravenous infusion of 4.7% Na2EDTA solution is a reasonably good model for the reproduction of the clinical signs of milk fever, but because of the extraneous signs, and the unusual nature of the subsequent deaths of 3 of 13 cows infused for 4 h, and the death of 1 of 2 cows infused for 4 h daily for 3 days, the model may not be a valid one for periods longer than 4 h in cows.
在一项研究中，对6头红细胞钾浓度高的奶牛（HK奶牛）和7头红细胞钾浓度低的奶牛（LK奶牛）静脉输注4.7%的乙二胺四乙酸二钠（Na2EDTA）溶液，持续4小时。记录并比较了立即观察到的临床症状以及数周内的后遗症。HK奶牛和LK奶牛对输注Na2EDTA的临床反应没有差异。在第二项研究中，将这些临床症状以及其他三个研究小组通过实验产生的症状，与三本教科书中记录的产乳热临床症状以及一位作者在25年奶牛养殖实践中观察到的症状进行了比较。产乳热的所有临床症状都出现在实验模型中，但也有一些额外的症状（过度流涎、嘴唇和舌头过度活动以及翘尾）在自然发生的低钙血症病例中不存在或未被记录。通过静脉输注4.7%的Na2EDTA溶液诱导奶牛出现低钙血症是模拟产乳热临床症状的一个相当不错的模型，但由于存在额外的症状，以及在输注4小时的13头奶牛中有3头随后死亡、每天输注4小时共3天的2头奶牛中有1头死亡这种不寻常的情况，该模型对于奶牛超过4小时的时间段可能不是一个有效的模型。
