School of Veterinary Science, Massey University, Palmerston North, New Zealand.
Ministry for Primary Industries, Upper Hutt, New Zealand.
N Z Vet J. 2020 Jul;68(4):247-254. doi: 10.1080/00480169.2020.1742815. Epub 2020 Mar 30.
Data were collected from 47 outbreaks of dropped hock syndrome (DHS) that were reported by veterinarians in New Zealand to the Ministry for Primary Industries between October 2012 and August 2017. There were 181 affected dairy cows from 44 farms. Of those with records, all 86 were aged between 2-3 years-old, and 4/94 (4%) were Friesian, 56/94 (60%) were Jersey and 33/94 (35%) were Jersey/Friesian cross. Of the 47 outbreaks, 45 (96%) occurred during winter and 37 (79%) in the South Island. Of 151 cases with records, hindlimb weakness (117 cows), shortened gait (112 cows) and dropped hocks (106 cows) were most commonly reported, with 110 cases being bilaterally affected. The level of diagnostic work-up and the data recorded by veterinarians for each outbreak were highly variable. Creatine kinase and aspartate aminotransferase activities were reported for 22 cases and were within normal ranges for cows with mild disease but increased in cows with severe disease. Concentrations of Cu in serum and liver were below normal for 13/22 and 9/10 cows, respectively, from six outbreaks. Of 41 cows with records for clinical outcomes, 12 had complete resolution, 18 had partial resolution, and 11 had no resolution. Post-mortem data were available from 26 cases. Muscle necrosis and haemorrhage of the origin of the gastrocnemius muscle were the key gross findings. In 14 cows with records for muscle histopathology, myodegeneration and recent haemorrhage were observed, and connective tissue pathology was reported to predate muscular pathology in seven cases. DHS appeared to be a degenerative rather than inflammatory condition primarily affecting the connective tissue of the hind limb, especially at the dense collagen interfaces of the gastrocnemius. Although no evidence of neuropathy was found, this cannot definitively be ruled out as a potential cause. A more standardised and systematic approach to investigating cases and recording case data is required to make robust inferences about the aetiology, risk factors, and treatment interventions for DHS.
数据来源于 2012 年 10 月至 2017 年 8 月期间，新西兰兽医向初级产业部报告的 47 起下降跗关节综合征（DHS）暴发。有 44 个农场的 181 头奶牛受到影响。有记录的奶牛中，所有 86 头奶牛的年龄都在 2-3 岁之间，4/94（4%）是弗里生牛，56/94（60%）是泽西牛，33/94（35%）是泽西/弗里生牛杂交牛。在这 47 起暴发中，45 起（96%）发生在冬季，37 起（79%）发生在南岛。在有记录的 151 例病例中，后腿无力（117 例奶牛）、步态缩短（112 例奶牛）和跗关节下降（106 例奶牛）最为常见，110 例奶牛双侧受影响。兽医对每起暴发进行的诊断工作水平和记录的数据差异很大。有 22 例报告了肌酸激酶和天门冬氨酸氨基转移酶活性，对于轻度疾病的奶牛，这些指标在正常范围内，但对于严重疾病的奶牛，这些指标会升高。来自六个暴发的 13/22 头和 9/10 头奶牛的血清和肝脏中的铜浓度低于正常值。在有临床结果记录的 41 头奶牛中，12 头完全缓解，18 头部分缓解，11 头无缓解。有 26 例病例的尸检数据可用。腓肠肌起点的肌肉坏死和出血是主要的肉眼发现。在有肌肉组织病理学记录的 14 头奶牛中，观察到肌肉变性和近期出血，在 7 例病例中，结缔组织病理学先于肌肉病理学发生。DHS 似乎是一种退行性疾病，而不是炎症性疾病，主要影响后肢的结缔组织，特别是在腓肠肌致密胶原界面。虽然没有发现神经病变的证据，但不能明确排除这是一个潜在的原因。需要更标准化和系统的方法来调查病例并记录病例数据，以便对 DHS 的病因、风险因素和治疗干预措施做出可靠的推断。
