Department of Anatomy and Physiology, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa.
Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa.
Anat Histol Embryol. 2020 Nov;49(6):836-841. doi: 10.1111/ahe.12590. Epub 2020 Jun 30.
Diclofenac has been responsible for the deaths of millions of vultures on the Asian subcontinent. While the pathology of toxicity is well described, the mechanism of toxicity remains elusive. However, it was postulated that toxicity could be related to the unique avian renal vascular structure known as the renal portal valve and that that diclofenac altered valve functionality with subsequent renal ischaemia. While plausible, the valva renalis portalis has only been described in a small number of other bird species such as the chicken (Gallus domesticus), the domestic duck (Anas platyrhynchos domesticus) and ostrich (Struthio camelus) but not a raptor. The aim of this study was to evaluate the renal anatomy and related vasculature of the Cape griffon vulture (Gyps coprotheres) (CGV), a species sensitive to the toxic effects of diclofenac, using gross anatomy, histology and vascular casting. The vasculature of the vulture was found to be almost identical to that of the domestic chicken with the valva renalis portalis present in the v. iliaca externa between the v. renalis renalis cranialis and the v. renalis caudalus. The valve was ring-shaped with finger-like processes and histologically was composed of smooth muscle. The valve was also well vascularized and was associated with a nerve plexus. Based on the findings of this study, the proposed mechanism of toxicity is anatomically possible.
双氯芬酸已导致亚洲次大陆数百万只秃鹫死亡。虽然毒性的病理学已有详细描述，但毒性的机制仍难以捉摸。然而，有人推测毒性可能与称为肾门静脉瓣的独特禽类肾血管结构有关，并且双氯芬酸改变了瓣膜的功能，随后导致肾缺血。虽然这一假说看似合理，但肾门静脉瓣仅在少数其他鸟类物种中有所描述，如鸡（Gallus domesticus）、家鸭（Anas platyrhynchos domesticus）和鸵鸟（Struthio camelus），而猛禽中则没有。本研究的目的是使用大体解剖、组织学和血管铸型来评估对双氯芬酸毒性敏感的海角秃鹫（Gyps coprotheres）（CGV）的肾脏解剖结构和相关血管。发现秃鹫的血管结构几乎与家鸡相同，肾门静脉瓣存在于肾动脉背侧和腹侧之间的髂外动脉中。瓣膜呈环形，有指状突起，组织学上由平滑肌组成。瓣膜也有良好的血管化，并与神经丛有关。基于本研究的发现，毒性的拟议机制在解剖学上是可能的。
