Finch S C, Munday J S, Sutherland B L, Vlaming J B, Fletcher L R
a AgResearch Ltd. , Ruakura Research Centre , Private Bag 3123, Hamilton , New Zealand.
b Department of Pathobiology, Institute of Veterinary, Animal and Biomedical Sciences , Massey University , Private Bag 11 222, Palmerston North 4442 , New Zealand.
N Z Vet J. 2017 Nov;65(6):322-326. doi: 10.1080/00480169.2017.1365660. Epub 2017 Aug 23.
AIMS To determine if equine fescue oedema (EFO) induced by grazing Mediterranean-type tall fescue (Lolium arundinaceum) infected with selected endophytes (Epichloë coenophiala) could be prevented by treatment with the corticosteroid, methylprednisolone, and anti-histamine, cetirizine, and to determine concentrations of lolines, specifically N-acetyl norloline (NANL), in grasses grazed by horses that did and did not develop EFO. METHODS Four horses were grazed on AR542-infected Mediterranean tall fescue pasture (from Day 0) for 7 days prior to being subjected to euthanasia. Two of these horses were treated with 250 mg methylprednisolone and 300 mg cetirizine hydrochloride every 12 hours orally from Days 0-7. Two more horses grazed meadow fescue (Festuca pratensis) infected with the naturally-occurring, common endophyte (Epichloë uncinata) for 21 days before euthanasia. All horses were observed closely for signs of EFO, and blood samples were taken daily for measurement of concentrations of total protein (TP) in serum. Following euthanasia post-mortem examinations were conducted on all horses. Pasture samples of meadow fescue and Mediterranean tall fescue from the current study, and endophyte-infected Mediterranean tall fescue from a previous study that were associated with EFO, were analysed for concentrations of lolines using gas chromatography. RESULTS By Day 7, the treated and untreated horses grazing AR542-infected Mediterranean tall fescue all developed signs of EFO, and concentrations of TP in serum of all horses were <45 g/L. No signs of EFO were observed in horses grazing meadow fescue and concentrations of TP remained above 60 g/L. Necropsy showed marked oedema and eosinophilic inflammation in the intestines of all horses grazing Mediterranean tall fescue. In the sample of meadow fescue, concentrations of total lolines and N-acetyl norloline (NANL) were 2,402 and 543 mg/kg, respectively. In the three samples of Mediterranean tall fescue associated with EFO, concentrations of total lolines were 308, 629 and 679 mg/kg, and concentrations of NANL were 308, 614 and 305 mg/kg. CONCLUSIONS AND CLINICAL RELEVANCE In horses grazing Mediterranean tall fescue infected with the AR542 endophyte, treatment with methylprednisolone and cetirizine did not prevent development of EFO. Results of pasture analysis indicated that lolines or NANL are unlikely to be the causative agent of this disease.
目的 确定放牧感染特定内生真菌（Epichloë coenophiala）的地中海型高羊茅（黑麦草）所诱发的马属羊茅水肿（EFO）能否通过使用皮质类固醇甲泼尼龙和抗组胺药西替利嗪进行治疗来预防，并确定出现和未出现EFO的马匹所采食牧草中洛啉类生物碱，特别是N - 乙酰去甲洛啉（NANL）的浓度。方法 四匹马从第0天开始在感染AR542的地中海高羊茅牧场上放牧7天，之后实施安乐死。其中两匹马从第0天至第7天每隔12小时口服250 mg甲泼尼龙和300 mg盐酸西替利嗪。另外两匹马在安乐死之前在感染天然常见内生真菌（Epichloë uncinata）的草地羊茅上放牧21天。密切观察所有马匹是否出现EFO症状，每天采集血样测定血清总蛋白（TP）浓度。安乐死后对所有马匹进行尸检。使用气相色谱法分析本研究中草地羊茅和地中海高羊茅的牧草样本以及先前研究中与EFO相关的感染内生真菌的地中海高羊茅样本中的洛啉类生物碱浓度。结果 到第7天，放牧感染AR542的地中海高羊茅的经治疗和未经治疗的马匹均出现EFO症状，所有马匹血清中的TP浓度均<45 g/L。放牧草地羊茅的马匹未观察到EFO症状，TP浓度保持在60 g/L以上。尸检显示，所有放牧地中海高羊茅的马匹肠道均出现明显水肿和嗜酸性粒细胞炎症。在草地羊茅样本中，总洛啉类生物碱和N - 乙酰去甲洛啉（NANL）的浓度分别为2,402和543 mg/kg。在与EFO相关的三个地中海高羊茅样本中，总洛啉类生物碱浓度分别为308、629和679 mg/kg，NANL浓度分别为308、614和305 mg/kg。结论及临床意义 在放牧感染AR542内生真菌的地中海高羊茅的马匹中，使用甲泼尼龙和西替利嗪治疗不能预防EFO的发生。牧草分析结果表明，洛啉类生物碱或NANL不太可能是该病的致病因子。
