兽研Frontiers in Veterinary Science 01 frontiersin.org 类型：病例报告 发表日期：2026年10月7日 DOI 10.3389/fvets.2026.1969910 开放获取 编辑：Aurelian-Sorin Pasca，雅西生命科学大学（IULS），罗马尼亚 审稿：Radu Andrei Baisan，雅西生命科学大学“Ion Ionescu de la Brad”，罗马尼亚；Raluca Ioana Rizac，农业科学与兽医大学，罗马尼亚 *通讯作者：Hakyoung Yoon hyyoon@jbnu.ac.kr 收稿：2026年8月17日 修回：2026年9月13日 接受：2026年9月21日 发表：2026年10月7日 引用格式：Kim S, Kim M, Han J-I, Lee K and Yoon H (2026) 病例报告：一只韩国貉（Nyctereutes procyonoides koreensis）并发室间隔缺损、肺动脉狭窄及肺内动静脉吻合。Front. Vet. Sci. 13:1969910. doi: 10.3389/fvets.2026.1969910 版权 © 2026 Kim, Kim, Han, Lee and Yoon。本文为开放获取文章，依据知识共享署名许可（CC BY）条款发布。允许在其他论坛使用、分发和复制，前提是注明原作者及版权所有者，并按照公认的学术惯例引用本刊中的原始发表。不符合这些条款的使用、分发或复制均不被允许。病例报告：一只韩国貉（Nyctereutes procyonoides koreensis）并发室间隔缺损、肺动脉狭窄及肺内动静脉吻合 Seoyeon Kim 1，Myeongsu Kim 2,3，Jae-Ik Han 2,3，Kichang Lee 1
及 Hakyoung Yoon 1 * 1 兽医医学影像学，兽医医学院，全北国立大学，益山，韩国；2 珍稀与野生动物医学实验室，兽医医学院，全北国立大学，益山，韩国；3 全北野生动物中心，全北国立大学，益山，韩国 一只3月龄未去势雄性韩国貉（Nyctereutes procyonoides koreensis）被救助并收入全北野生动物救助中心，表现为嗜睡、脱水及符合疥螨（Sarcoptes scabiei）感染特征的皮肤病损。体格检查发现IV/VI级收缩期杂音，胸部X线摄影显示全心增大。经胸超声心动图检查发现膜周部室间隔缺损（VSD），伴左向右分流。尽管未观察到肺动脉瓣明显的结构异常，但肺动脉血流速度增高（3.87 m/s）、轻度肺动脉反流（1.68 m/s）及主肺动脉狭窄后扩张支持肺动脉狭窄（PS）的诊断。振荡生理盐水对比超声心动图显示肺内动静脉吻合（IPAVAs），微泡在第四个心动周期后出现在左心；该分流在吸氧后减少。五周后，胸部X线摄影显示心影缩小，但心脏增大仍持续存在。超声心动图显示VSD进展为双向分流。肺动脉瓣收缩期圆顶状膨隆，伴肺动脉血流速度增高（4.39 m/s）及肺动脉反流速度（2.07 m/s），提示PS加重。重复振荡生理盐水对比超声心动图显示微泡在四个心动周期内出现在左心及腹主动脉，提示存在右向左分流成分，符合双向分流。这些发现在吸氧后减轻。该韩国貉随后在为进一步诊断性影像检查进行麻醉诱导期间死亡。尸检证实为膜周部VSD及A型肺动脉瓣狭窄，以交界融合为特征，并并发右心室肥厚、扩张及室间隔增厚。据我们所知，本病例报告首次描述了韩国貉同时发生VSD、PS及IPAVAs。这提示进行性PS可能促使VSD分流方向逆转。
Kim等 10.3389/fvets.2026.1969910 《兽医科学前沿》02 frontiersin.org 关键词：双向分流、肺内动静脉吻合、貉、肺动脉瓣狭窄、室间隔缺损 1 引言 韩国貉（Nyctereutes procyonoides koreensis）是韩国常见的野生犬科动物，属于犬科（1）。在家犬中，室间隔缺损（VSD）和肺动脉瓣狭窄（PS）是相对常见的先天性心脏缺陷，但两者同时发生较为罕见（2）。据我们所知，心房中隔缺损（ASD）是既往在韩国貉中报道的唯一先天性心脏缺陷，该亚种中尚未有VSD或PS的描述（3）。VSD是胚胎发生过程中室间隔发育异常所致的先天性室间隔缺陷。膜周部VSD是犬中报道的最常见亚型（4, 5）。一般而言，左心室较高的压力产生经缺损的左向右分流（4, 6）。然而，当缺损较大或右心室压力升高时（例如存在PS或肺动脉高压时），可能发生双向分流或逆向（右向左）分流（4, 6–8）。PS是由右心室（RV）与肺动脉之间的半月瓣发育不良所致的先天性心脏缺陷，瓣膜型是犬中最常见的亚型（9–11）。由此产生的右心室流出道梗阻使右心室收缩压升高，并对RV造成压力负荷过重（4）。当PS与VSD共存时，PS引起的右心室压力升高可能逆转室间隔压力阶差（PG），即使没有肺血管疾病也可导致右向左分流（4, 12）。这一机制与艾森门格综合征不同，后者的分流逆转由进行性肺动脉高压所致（4, 8）。肺内动静脉吻合（IPAVAs）是连接肺动脉与肺静脉循环、绕过肺毛细血管网的血管通路。尽管其生理作用尚未完全明了，IPAVAs被认为是缺氧反应性通路，在缺氧条件下被募集，并在补氧后关闭（13, 14）。可使用振荡生理盐水对比超声心动图（气泡试验）检测（13, 14）。在气泡试验中，微气泡在四个心动周期内出现在左心提示心内右向左分流，而在第四个心动周期之后出现则提示心外分流，如IPAVA（13, 15）。既往一项研究报道，健康韩国貉静息状态下IPAVAs的患病率为75%（13）。本病例报告描述了韩国貉中膜周部VSD、瓣膜型PS和IPAVAs并发的情况，通过超声心动图、振荡生理盐水对比超声心动图和死后检查作出诊断。2 病例描述 一只未去势雄性韩国貉（Nyctereutes procyonoides koreensis），估计3月龄，体重1.2 kg，被救助并收入全北野生动物救助中心。就诊时，该动物表现为嗜睡、脱水、全身性脱毛和角化过度，符合严重疥螨（S. scabiei）感染。体格检查发现IV/VI级收缩期杂音，收缩压为120 mmHg。全血细胞计数（CBC）显示贫血（血细胞比容25.3%；参考范围33–47%）和白细胞增多（白细胞计数23.6 × 10^9/L；参考范围6.15–13.65 × 10^9/L），这些发现被认为是继发于并发疥螨感染（16）。胸部X线摄影（HF-525 PLUS，Ecoray，首尔，韩国）显示全心增大，椎体心脏评分（VHS）为12.2，椎体左心房评分（VLAS）为2.8（图1A），心胸比（CTR）为82%（图1B）。所有测量值均超过既往报道的健康韩国貉参考值（VHS，9.12 ± 0.74；VLAS，1.50 ± 0.31；CTR，0.69 ± 0.07）（17）。经胸超声心动图在未镇静或麻醉的情况下使用5 MHz探头（Aplio i800，Canon 图1 初次检查时获得的胸部X线片显示右侧位（A）VHS（12.2）和VLAS（2.8）增高，腹背位（B）CTR（82%）增高。5周随访时，这些指标有所下降；然而，右侧位（C）VHS（9.86）仍处于正常上限，VLAS（2.1）仍增高，腹背位（D）CTR（78%）仍轻度增高。两次检查均可见全心增大。缩写：VSD，室间隔缺损；PS，肺动脉瓣狭窄；IPAVA，肺内动静脉吻合；VHS，椎体心脏评分；VLAS，椎体左心房评分；CTR，心胸比；PG，压力阶差；RV，右心室；LVOT，左心室流出道；LA/Ao比值，左心房与主动脉根部比值；E:E′，E波与舒张早期二尖瓣环组织速度比值；TAPSE，三尖瓣环收缩期位移；RPAD，右肺动脉扩张性。
Kim等，10.3389/fvets.2026.1969910，《Frontiers in Veterinary Science》，03frontiersin.org，Medical Systems，东京，日本）。与浣熊的已报道参考范围（94–134次/分）（18）相比，心率轻度升高至161次/分。右侧胸骨旁五腔长轴切面B型超声于主动脉下区域与右心室（RV）之间探及一处3.24 mm的膜周部室间隔缺损（VSD）（图2A）。彩色多普勒与连续波多普勒显像显示收缩早期存在自左心室流出道（LVOT）至RV的左向右分流，峰值流速2.32 m/s（PG：21.5 mmHg）（图2C）。心底水平右侧胸骨旁短轴切面未见明确的狭窄部位，但观察到瓣环远端肺动脉明显扩张，符合狭窄后扩张（图2B）。连续波多普勒显示收缩晚期肺动脉瓣流速增高至3.87 m/s（PG：59.9 mmHg）。另见轻度肺动脉反流，流速1.68 m/s（PG：11.2 mmHg）。综合上述所见，符合PS。主动脉瓣环与肺动脉瓣环比值为1.06（主动脉瓣环：7.0 mm；肺动脉瓣环：6.6 mm），可排除肺动脉瓣环发育不良（>1.2）（10）。左心房与主动脉根部比值（LA/Ao）为1.55，提示相对于已报道的参考值（1.22 ± 0.14）（17）存在轻度左心房增大。组织多普勒显像显示E/E′比值增高至25.72，提示左心室充盈压升高。三尖瓣环收缩期位移（TAPSE）为0.64 cm，提示RV收缩功能减低（17）。超声心动图还显示右心室游离壁肥厚、右心室扩张及室间隔变平。未检出三尖瓣反流。右肺动脉扩张性（RPAD）指数为53%，处于已报道的参考范围内（17）。因合并PS妨碍可靠估算，未计算肺循环与体循环血流量比值（Qp/Qs）（4）。自左侧胸骨旁心尖四腔切面行发泡试验，以评估分流方向并检测IPAVA。经头静脉快速注入振荡生理盐水（2 mL），根据单帧图像中左心室内观察到的微泡最大数量及分布，按既往所述的0–5级评分系统进行微泡评分。评分标准如下：微泡评分0，无微泡；微泡评分1，1–3个微泡；微泡评分2，4–12个微泡；微泡评分3，>12个微泡，呈团注状出现；微泡评分4，>12个微泡，不均匀分布于整个左心室；微泡评分5，>12个微泡，均匀分布于整个左心室（13, 14）。前四个心动周期内左心未检出微泡（微泡评分0，图3A）。第四个心动周期后，左心室内出现大量不均匀分布的微泡（微泡评分4，图3B），符合存在IPAVA。随后经面罩以5 L/min的流量给予100%氧气5 min，之后重复发泡试验（13）。给氧后，第四个心动周期后观察到的微泡数量降至微泡评分2（图3C），提示经IPAVA的分流减少。未见微泡。图2 初次检查（A–C）及5周随访（D–F）时的超声心动图所见。右侧胸骨旁五腔长轴切面于初次检查时探及一处大小为3.24 mm的膜周部室间隔缺损[（A），白色箭头]，5周随访时为4.2 mm[（D），白色箭头]。心底水平右侧胸骨旁短轴切面于初次检查时观察到肺动脉狭窄后扩张[（B），红色箭头]，但肺动脉瓣显示不清。相反，5周随访时于收缩期观察到穹顶状肺动脉瓣[（E），白色箭头]。彩色多普勒与连续波多普勒显像显示初次检查时存在经室间隔缺损的左向右分流（C），而5周随访时观察到双向分流，包括舒张早期右向左分流[（F），红色箭头]。LA，左心房；LV，左心室；Ao，主动脉；RA，右心房；RV，右心室；PA，肺动脉。
Kim等 10.3389/fvets.2026.1969910 Frontiers in Veterinary Science04frontiersin.org 在补充氧气之前或之后于腹主动脉检测到。由于韩国貉的心脏病内科管理标准化指南尚不可用，且该动物未表现出明显的心血管临床症状，因此未启用心血管药物治疗。口服硫酸亚铁用于治疗贫血。伊维菌素、美洛昔康、甲硝唑和多西环素用于治疗疥螨感染和继发性细菌感染，并提供液体疗法以纠正脱水。在5周复诊时，与疥螨感染相关的皮肤病变以及包括嗜睡和脱水在内的全身症状已明显改善。全血细胞计数显示贫血和白细胞增多改善。体格检查时，IV/VI级收缩期杂音持续存在，心率降至140次/分。胸部X线摄影显示VHS为9.86，VLAS为2.1，CTR为78%（图1C,D）。尽管这些指标较初次检查有所下降，但VHS仍处于正常上限，而VLAS和CTR仍轻度升高（17）。经胸超声心动图从右侧胸骨旁五腔长轴切面识别出一处膜周部VSD，尺寸为4.2 mm，较初次测量的3.24 mm有所增大（图2D）。彩色多普勒和连续波多普勒显示收缩期存在左向右分流；然而，在舒张早期观察到另一处从RV到LVOT的右向左分流，形成双向分流模式。收缩期左向右分流的峰值流速为1.81 m/s（PG：13.1 mmHg），而舒张早期右向左分流的峰值流速为0.67 m/s（PG：1.79 mmHg）（图2F）。在心底水平的右侧胸骨旁短轴切面中，新发现肺动脉瓣收缩期圆顶样改变伴轻微瓣叶增厚（图2E）。连续波多普勒显示收缩晚期肺动脉瓣峰值流速增高至4.39 m/s（PG：77.0 mmHg）。与初次检查相比，肺动脉反流峰值流速也增高至2.07 m/s（PG：17.1 mmHg）。主动脉与肺动脉瓣环比值为0.96（主动脉瓣环：8.3 mm；肺动脉瓣环：8.6 mm），与初次测量相似。基于超声心动图发现，PS被认为符合A型瓣膜性PS。LA/Ao比值降至0.94，表明左心房增大已消退。组织多普勒成像显示E/E′比值降低至16.08，提示左心室充盈压下降。TAPSE降至0.48 cm，提示RV收缩功能进一步减低（17）。与既往检查相比，观察到右心室游离壁肥厚、右心室扩张和室间隔变平轻度进展。未检测到三尖瓣反流。RPAD指数为43%，仍处于已报道的参考范围内（17）。总之，这些超声心动图发现支持由VSD和PS组成的复杂先天性心脏异常的诊断。图3 初次检查（A–C）和5周随访（D–F）时进行的振荡生理盐水对比超声心动图（微泡试验）。在补充氧气之前，初次检查时前四个心动周期内左心未检测到微泡（微泡评分0）（A），而在5周随访时前四个心动周期内观察到4–12个微泡（微泡评分2）（D）。该发现提示存在心内右向左分流。在初次诊断时，第四个心动周期之后且补充氧气之前，超过12个微泡不均匀分布于整个左心室（微泡评分4）（B），补充氧气后该数量降至4–12个微泡（微泡评分2）（C）。在5周随访时，补充氧气之前第四个心动周期之后仍可见超过12个不均匀分布的微泡（微泡评分4），但较初次检查时观察到的更少（E）。补充氧气后，数量进一步降至1–3个微泡（微泡评分1）（F）。
Kim等人 10.3389/fvets.2026.1969910 Frontiers in Veterinary Science05frontiersin.org 在补充氧气之前，于最初四个心动周期内在左心室内观察到4–12个微泡（气泡评分2，图3D），提示存在心内右向左分流。在第四个心动周期之后，尽管微泡数量较初次检查略有减少，但仍不均匀地分布于整个左心室（气泡评分4，图3E），与持续性IPAVA一致。随后，采用了与初次检查时相同的补氧方案。补氧后，在最初四个心动周期内未检测到微泡（气泡评分0），第四个心动周期后仅观察到少量气泡（气泡评分1，图3F）。补氧前腹主动脉内存在微泡，但此后消失。计划进行计算机断层扫描（CT）以进一步明确心脏解剖结构，包括VSD和PS。分别给予美托咪定（0.05 mg/kg，IV）和阿法沙酮（2.2 mg/kg，IV）作为前驱麻醉和诱导麻醉剂。然而，在诱导麻醉期间，该韩国貉出现严重心律失常并死亡。尸检证实存在一个4 mm的膜周部VSD，位于LVOT与RV之间（图4A）。还鉴定出A型瓣膜性PS，伴有轻度瓣叶增厚以及中间、右和左瓣尖的连合融合。此外，观察到右心室游离壁肥厚、室间隔肥厚（图4B）和右心室扩张。在组织病理学上，肺动脉瓣的苏木精-伊红（H&E）和Masson三色染色显示瓣叶肥厚、纤维化和变性。3 讨论 VSD的临床意义主要取决于缺损大小和分流流量的大小（19）。小的限制性VSD通常无血流动力学意义，不会引起心脏或肺循环的显著容量超负荷。相反，大的非限制性VSD增加肺血流量，可能导致继发于慢性左向右分流的肺动脉高压（7, 19）。当肺动脉压接近或超过体动脉压时，分流可能变为双向或逆转为右向左，代表进展为艾森门格综合征（4, 7）。在5周随访时，通过VSD出现双向分流，提高了肺动脉高压作为鉴别诊断的可能性（7）。然而，RPAD指数仍在报道的参考范围内。尽管存在与PS相关的肺动脉狭窄后扩张，但未观察到提示肺动脉高压的广泛性肺动脉增粗。肺动脉反流也仍为轻度。这些发现未提供肺动脉高压的充分证据（4, 7, 19, 20）。因此，本病例中的双向分流被认为更可能与继发于肺动脉狭窄的右心室压力增高有关，而非由进行性肺血管疾病引起的艾森门格生理。法洛四联症也被考虑为鉴别诊断，因为VSD、右心室流出道梗阻和右心室肥厚的共存与其特征性表现重叠。然而，在超声心动图或尸检检查中均未发现主动脉骑跨，从而排除了法洛四联症（21, 22）。在5周随访时，新发现肺动脉瓣收缩期圆顶样改变伴轻微瓣叶增厚，同时伴有肺动脉瓣速度和PG升高以及肺动脉反流增加。尽管PS在犬中通常被认为是先天性和固定的瓣膜性狭窄，但已有报道个别轻度PS幼犬在生长过程中出现进展（23）。因此，本病例中观察到的变化可能代表瓣膜性PS的进展，尽管其潜在机制仍不清楚。进行性右心室流出道梗阻可能增加了右心室压力，从而降低了跨VSD的室间PG，并促进了双向分流的形成（24）。由此导致的左向右分流减少 图4 尸检时的大体病理学发现。（A）心脏纵切面显示膜周部室间隔缺损（白色箭头）。（B）心脏横切面显示右心室游离壁肥厚和室间隔肥厚。Ao，主动脉；LV，左心室；RV，右心室；RVW，右心室壁；IVS，室间隔。
Kim等 10.3389/fvets.2026.1969910 Frontiers in Veterinary Science 06 frontiersin.org 分流可能减少了肺血流，并部分缓解了左侧容量超负荷。这也可能解释随访时观察到的VHS、VLAS和LA/Ao下降（12, 24）。并发PS与VSD之间的血流动力学相互作用可能与肺动脉环缩术所达到的效果相当，后者限制通过VSD的过度左向右分流（12）。通过增加右心室压力，这两种情况均减少左向右分流和肺血流，从而减轻肺循环和左心的容量超负荷。在约5周的随访期间未出现左侧心力衰竭的临床征象，提示维持了相对平衡的血流动力学状态（4, 12, 24）。在初始振荡生理盐水对比研究中，微泡仅在第四个心动周期后出现在左心，与IPAVA的存在一致。补充氧气后，第四个心动周期后出现的微泡数量减少。这一发现与既往研究一致，后者表明IPAVA在缺氧条件下动态开放，并在氧可利用性增加时关闭，导致IPAVA分流减少（13, 14）。在5周随访时，第四个心动周期后观察到的微泡少于初次检查，提示出生后生长过程中IPAVA开放度降低。这一观察与报道人类和羔羊出生后IPAVA退化的研究一致（25, 26）。尽管由于未进行CT血管造影而不能明确排除肺动静脉畸形（PAVM），但微泡通过的氧依赖性减少以及分流明显的出生后退化更符合功能性IPAVA而非固定结构性PAVM（14）。与初次检查不同，随访振荡生理盐水研究显示微泡在最初四个心动周期内出现在左心和腹主动脉。这些发现表明除现有的左向右分流外，还存在通过VSD的右向左分流，与双向分流一致（13）。补充氧气后，最初四个心动周期内不再检测到微泡，腹主动脉中观察到的微泡也消失。这些变化归因于肺血管阻力降低，导致右心室后负荷减少和右向左分流减弱（27, 28）。这些发现提示补充氧气可能减轻IPAVA和通过VSD的右向左分流的血流动力学后果。膜周部VSD直径从初次检查时的3.24 mm增至5周随访时的4.2 mm。描述犬VSD扩大的报道有限。然而在牛中，连续检查已记录到缺损扩大。此类变化被认为与生长相关，尽管其潜在机制仍不清楚。需要进一步研究以阐明这一现象（29）。犬PS的严重程度通常根据RV与肺动脉之间的PG分类：轻度（<50 mmHg）、中度（50–80 mmHg）和重度（>80 mmHg）（10, 24）。然而，多普勒 derived 肺动脉流速和PG取决于跨瓣血流（30, 31）。初次检查时，通过VSD的左向右分流可能增加了肺血流，从而增加肺动脉流速和PG（7）。相反，TAPSE降低提示RV收缩功能受损。然而，TAPSE的解读受到参考值的限制，该参考值建立在体重高于本病例中韩国貉的韩国貉中（17）。如果RV收缩功能确实受损，相关的跨瓣血流减少可能导致多普勒 derived PG的低估（30, 31）。在5周随访时，新出现的右向左分流可能减少了肺血流，这可能导致了多普勒 derived 肺动脉流速和PG的低估。因此，在评估该韩国貉PS严重程度时，应谨慎解读多普勒 derived PG。对于重度PS的犬，通常建议手术或介入治疗，球囊瓣膜成形术被认为是瓣膜性PS的主要治疗方法（10, 32）。介入前应评估冠状动脉解剖，因为冠状动脉异常可能增加球囊瓣膜成形术期间血管破裂或心肌缺血的风险。冠状动脉异常可通过尸检、心血管造影或CT血管造影识别（9, 19）。在5周随访时，峰值肺动脉流速为4.39 m/s，对应PG为77.0 mmHg，符合中度PS。然而，考虑到上述血流动力学因素，PS的实际严重程度可能大于多普勒测量所指示的，介入治疗可能仍有指征。因此，计划进行CT血管造影以评估冠状动脉异常。然而，该韩国貉在麻醉诱导期间死亡。尸检未发现冠状动脉异常。本病例报告存在一些局限性。首先，动物在超声心动图检查期间心率高于报道的参考范围，可能由于兴奋，这可能影响了超声心动图测量（33）。由于镇静剂和麻醉剂对超声心动图参数有潜在影响，故有意避免使用（34）。其次，由于动物死亡，无法进行长期随访。据我们所知，本病例报告是首例记录韩国貉中膜周部VSD、瓣膜性PS和IPAVA共存，并经超声心动图、振荡生理盐水对比超声心动图和尸检确认的病例。这些发现进一步提示PS的进展可能促进VSD双向分流的发展。数据可用性声明 支持本文结论的原始数据将由作者提供，无不当保留。伦理声明 根据当地立法和机构要求，涉及动物的研究无需伦理批准，因为该动物为救助野生动物，所有数据均在常规临床检查和治疗期间获得，未为本研究目的进行额外实验程序。已从相关授权代表处获得发表本病例报告的书面知情同意。作者贡献 SK：概念化、数据管理、调查、验证、写作——原稿、写作——审阅与编辑、方法学、可视化。MK：数据管理、调查、验证、可视化、写作——审阅与编辑、资源。J-IH：资源、验证、写作——审阅与编辑。KL：验证、写作——审阅
Kim等，10.3389/fvets.2026.1969910，《兽医科学前沿》，07，frontiersin.org，及编辑、监督。HY：监督、验证、写作——审阅与编辑、概念化、数据管理、调查、项目管理、资源、写作——初稿。资助 作者声明，本工作及/或其发表获得了财政支持。本主题由国立野生动物疾病控制与预防研究所作为“野生动物疾病专家专门研究生院支持项目”提供支持。利益冲突 作者声明，本工作是在不存在任何可能被解释为潜在利益冲突的商业或财务关系的情况下进行的。生成式人工智能声明 作者声明，本稿件的创作未使用生成式人工智能。本文图表旁提供的任何替代文本（alt文本）均由Frontiers在人工智能支持下生成，并已尽合理努力确保准确性，包括在可能情况下由作者进行审阅。如您发现任何问题，请联系我们。出版者注 本文中表达的所有主张仅代表作者本人，不一定代表其所属组织、出版者、编辑或审稿人的观点。本文中可能评估的任何产品或其制造商可能提出的任何主张，均不受出版者担保或认可。参考文献 1. Park IC, Lee HW, Kim JT. 江原道野生哺乳动物的野生动物困境与救援分析。《韩国兽医服务杂志》。(2012) 35:33–7. doi: 10.7853/kjvs.2012.35.1.033 2. Oliveira P, Domenech O, Silva J, Vannini S, Bussadori R, Bussadori C. 976只犬先天性心脏病的回顾性综述。《兽医内科医学杂志》。(2011) 25:477–83. doi: 10.1111/j.1939-1676.2011.0711.x 3. Yim S, Choi S, Kim J, Chung JY, Park I. 一只韩国野生貉的房间隔缺损。《兽医医学科学杂志》。(2017) 79:1712–5. doi: 10.1292/jvms.17-0217 4. Graczyk S, Grzeczka A, Pasławska U. 犬和猫室间隔缺损的综合综述——从发病机制到长期随访。《动物（巴塞尔）》。(2025) 15:850. doi: 10.3390/ani15060850 5. Bomassi E, Misbach C, Tissier R, Gouni V, Trehiou-Sechi E, Petit AM, 等. 患有室间隔缺损的犬和猫的信号特征、临床特征、超声心动图表现及结局：109例（1992–2013）。《美国兽医医学协会杂志》。(2015) 247:166–75. doi: 10.2460/javma.247.2.166 6. Ettinger SJ.《兽医内科学教科书：犬和猫的疾病》，第2卷第8版。密苏里州圣路易斯：Elsevier (2017)。第2181页。 7. Yun S, Kim B, Youn H, Choi M, Yoon J. 一只犬的右向左分流室间隔缺损。《兽医临床杂志》。(2015) 32:343–6. doi: 10.17555/jvc.2015.08.32.4.343 8. de Campos FPFD, Benvenuti LA. 艾森曼格综合征。《尸检病例报告》。(2017) 7:5–7. doi: 10.4322/acr.2017.006 9. Kim J, Kim DH, Jee H, Hwang J, Yoon J. 一只波士顿梗犬的B型瓣膜性和瓣膜上肺动脉狭窄伴异常肺动脉前右冠状动脉，经非心电门控多层计算机断层扫描诊断。《兽医心脏病学杂志》。(2021) 38:12–7. doi: 10.1016/j.jvc.2021.09.003 10. Bussadori C, DeMadron E, Santilli RA, Borgarelli M. 30只肺动脉狭窄犬的球囊瓣膜成形术：瓣膜形态和瓣环大小对初始和1年结局的影响。《兽医内科医学杂志》。(2001) 15:553–8. doi: 10.1111/j.1939-1676.2001.tb01590.x 11. Fingland RB, Bonagura JD, Myer CW. 犬肺动脉狭窄：29例（1975–1984）。《美国兽医医学协会杂志》。(1986) 189:218–26. doi: 10.2460/javma.1986.189.02.218 12. Yamane T, Awazu T, Watanabe N, Ishibashi T, Fujii Y, Watanabe T, 等. 一只犬的室间隔缺损伴肺动脉瓣狭窄。《动物心脏病学进展》。(2001) 34:25–30. doi: 10.11276/jsvc.34.25 13. Lee CE, Kim M, Han JI, Lee K, Yoon H. 使用经胸振荡生理盐水造影超声心动图评估被救助的韩国貉在补氧前后的肺内动静脉吻合。《兽医科学前沿》。(2024) 11:1362363. doi: 10.3389/fvets.2024.1362363 14. Cho K, Kim SS, Lee K, Yoon H. 使用生理盐水造影超声心动图评估健康犬的肺内动静脉吻合及对氧疗的反应。《兽医内科医学杂志》。(2026) 40:aalaf076. doi: 10.1093/jvimsj/aalaf076 15. Bhatia N, Abushora MY, Donneyong MM, Stoddard MF. 确定最佳心动周期数以通过生理盐水造影二维和三维超声心动图区分肺内分流和卵圆孔未闭。《超声心动图》。(2014) 31:293–301. doi: 10.1111/echo.12360 16. Kido N, Kamegaya C, Omiya T, Wada Y, Takahashi M, Yamamoto Y. 感染疥螨病的虚弱自由放养貉（Nyctereutes procyonoides）的血液学和血清生化。《寄生虫学国际》。(2011) 60:425–8. doi: 10.1016/j.parint.2011.06.023 17. Park J, Kim M, Han JI, Lee K, Yoon H. 被救助的韩国貉（Nyctereutes procyonoides koreensis）的放射学和超声心动图评估。《兽医科学前沿》。(2024) 11:1361843. doi: 10.3389/fvets.2024.1361843 18. Heatley JJ. 啮齿动物和小型珍稀哺乳动物的心血管解剖、生理和疾病。《北美兽医临床：珍稀动物实践》。(2009) 12:99–113. doi: 10.1016/j.cvex.2008.08.006 19. Boon JA.《兽医超声心动图》。第2版。纽瓦克：John Wiley & Sons, Inc. (2011)。第640页。 20. Reinero C, Visser LC, Kellihan HB, Masseau I, Rozanski E, Clercx C, 等. ACVIM犬肺动脉高压诊断、分类、治疗和监测共识声明指南。《兽医内科医学杂志》。(2020) 34:549–73. doi: 10.1111/jvim.15725 21. Lombard CW, Ackerman N, Berry CR, King RR, Buergelt CD. 三只犬的肺动脉狭窄和右向左心房分流。《美国兽医医学协会杂志》。(1989) 194:71–5. doi: 10.2460/javma.1989.194.01.71 22. Chetboul V, Pitsch I, Tissier R, Gouni V, Misbach C, Trehiou-Sechi E, 等. 患有法洛四联症的犬和猫的流行病学、临床和超声心动图特征及生存时间：31例（2003–2014）。《美国兽医医学协会杂志》。(2016) 249:909–17. doi: 10.2460/javma.249.8.909 23. Jenni S, Gardelle O, Zini E, Glaus TM. 使用听诊和多普勒超声心动图预测拳师犬幼犬发生主动脉下或肺动脉狭窄。《兽医内科医学杂志》。(2009) 23:81–6. doi: 10.1111/j.1939-1676.2008.0213.x 24. Yilmaz Z, Levent P, Saril A, Uemura A, Kocatürk M, Tanaka R. 一只犬的室间隔缺损和肺动脉狭窄。《卡夫卡斯大学兽医兽医学院杂志》。(2019) 25:729–730. doi: 10.9775/kvfd.2019.22616 25. Lovering AT, Duke JW, Elliott JE. 人类的肺内动静脉吻合——对运动和环境的反应。《生理学杂志》。(2015) 593:507–20. doi: 10.1113/jphysiol.2014.275495 26. McMullan DM, Hanley FL, Cohen GA, Portman MA, Riemer RK. 正常胎儿肺中的肺动脉静脉分流。《美国心脏病学会杂志》。(2004) 44:1497–500. doi: 10.1016/j.jacc.2004.06.064 27. Lyhne MD, Hansen JV, Dragsbæk SJ, Mortensen CS, Nielsen-Kudsk JE, Andersen A. 氧疗降低实验性急性肺栓塞中的右心室后负荷。《重症监护医学》。(2021) 49:e891–901. doi: 10.1097/CCM.0000000000005057 28. Roberts DH, Lepore JJ, Maroo A, Semigran MJ, Ginns LC. 氧疗改善肺动脉高压患者的心指数和肺血管阻力。《胸科》。(2001) 120:1547–55. doi: 10.1378/chest.120.5.1547
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Frontiers in Veterinary Science01frontiersin.org TYPE Case Report PUBLISHED 07 October 2026 DOI 10.3389/fvets.2026.1969910 OPEN ACCESS EDITED BY Aurelian-Sorin Pasca, Iasi University of Life Sciences (IULS), Romania REVIEWED BY Radu Andrei Baisan, Iasi University of Life Sciences “Ion Ionescu de la Brad”, Romania Raluca Ioana Rizac, University of Agronomic Sciences and Veterinary Medicine, Romania *CORRESPONDENCE Hakyoung Yoon hyyoon@jbnu.ac.kr RECEIVED 17 August 2026 REVISED 13 September 2026 ACCEPTED 21 September 2026 PUBLISHED 07 October 2026 CITATION Kim S, Kim M, Han J-I, Lee K and Yoon H (2026) Case Report: Concurrent ventricular septal defect, pulmonic stenosis, and intrapulmonary arteriovenous anastomoses in a Korean raccoon dog (Nyctereutes procyonoides koreensis). Front. Vet. Sci. 13:1969910. doi: 10.3389/fvets.2026.1969910 COPYRIGHT © 2026 Kim, Kim, Han, Lee and Yoon. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. Case Report: Concurrent ventricular septal defect, pulmonic stenosis, and intrapulmonary arteriovenous anastomoses in a Korean raccoon dog (Nyctereutes procyonoides koreensis) Seoyeon Kim 1 , Myeongsu Kim 2,3 , Jae-Ik Han 2,3 , Kichang Lee 1
and Hakyoung Yoon 1 * 1 Veterinary Medical Imaging, College of Veterinary Medicine, Jeonbuk National University, Iksan, Republic of Korea, 2 Laboratory of Exotic and Wild Animal Medicine, College of Veterinary Medicine, Jeonbuk National University, Iksan, Republic of Korea, 3 Jeonbuk Wildlife Center, Jeonbuk National University, Iksan, Republic of Korea A 3-month-old intact male Korean raccoon dog (Nyctereutes procyonoides koreensis) was rescued and admitted to the Jeonbuk Wildlife Rescue Center with lethargy, dehydration, and dermatologic lesions consistent with Sarcoptes scabiei infestation. Physical examination detected a grade IV/VI systolic murmur, and thoracic radiography revealed generalized cardiomegaly. Transthoracic echocardiography identified a perimembranous ventricular septal defect (VSD) with leftto-right shunting. Although no distinct structural abnormalities of the pulmonic valve were observed, increased pulmonic flow velocity (3.87 m/s), mild pulmonic regurgitation (1.68 m/s), and post-stenotic dilation of the main pulmonary artery supported a diagnosis of pulmonic stenosis (PS). Agitated saline contrast echocardiography demonstrated intrapulmonary arteriovenous anastomoses (IPAVAs), with microbubbles appearing in the left heart after the fourth cardiac cycle; this shunting decreased following oxygen supplementation. Five weeks later, thoracic radiography demonstrated a reduction in cardiac silhouette size, although cardiomegaly persisted. Echocardiography demonstrated progression of the VSD to bidirectional shunting. Systolic doming of the pulmonic valve, together with increased pulmonic flow velocity (4.39 m/s) and pulmonic regurgitation velocity (2.07 m/s), indicated worsening PS. Repeat agitated saline contrast echocardiography revealed microbubbles in the left heart within four cardiac cycles and in the abdominal aorta, indicating a right-to-left shunt component consistent with bidirectional shunting. These findings were attenuated after oxygen supplementation. The Korean raccoon dog subsequently died during anesthetic induction for further diagnostic imaging. Postmortem examination confirmed a perimembranous VSD and type A valvular PS characterized by fused commissures, with concurrent right ventricular hypertrophy, dilation, and interventricular septal thickening. To our knowledge, this case report is the first to describe the concurrence of VSD, PS, and IPAVAs in a Korean raccoon dog. It suggests that progressive PS may contribute to reversal of shunting across a VSD.
Kim et al. 10.3389/fvets.2026.1969910 Frontiers in Veterinary Science02frontiersin.org KEYWORDS bidirectional shunt, intrapulmonary arteriovenous anastomoses, Nyctereutes procyonoides, pulmonic stenosis, ventricular septal defect 1 Introduction The Korean raccoon dog (Nyctereutes procyonoides koreensis) is a wild canid commonly observed in Korea and a member of the family Canidae (1). In domestic dogs, ventricular septal defect (VSD) and pulmonic stenosis (PS) are relatively common congenital heart defects, although their concurrent occurrence is rare (2). To our knowledge, atrial septal defect (ASD) is the only congenital cardiac defect previously reported in Korean raccoon dogs, and neither VSD nor PS has been described in this subspecies (3). VSD is a congenital defect of the interventricular septum resulting from abnormal septal development during embryogenesis. Perimembranous VSD is the most common subtype reported in dogs (4, 5). In general, the higher pressure in the left ventricle produces a left-to-right shunt across the defect (4, 6). However, bidirectional or reversed (right-to-left) shunting may occur when the defect is large or when right ventricular pressure is elevated, such as in the presence of PS or pulmonary hypertension (4, 6–8). PS is a congenital cardiac defect caused by dysplasia of the semilunar valve between the right ventricle (RV) and the pulmonary artery, with valvular form representing the most common subtype in dogs (9–11). The resulting obstruction to right ventricular outflow increases right ventricular systolic pressure and imposes pressure overload on the RV (4). When PS and VSD coexist, the increase in right ventricular pressure caused by PS may reverse the interventricular pressure gradient (PG), resulting in a right-to-left shunt even in the absence of pulmonary vascular disease (4, 12). This mechanism differs from Eisenmenger syndrome, in which shunt reversal results from progressive pulmonary hypertension (4, 8). Intrapulmonary arteriovenous anastomoses (IPAVAs) are vascular pathways that connect the pulmonary arterial and venous circulations, bypassing the pulmonary capillary network. Although their physiological role remains incompletely understood, IPAVAs are considered hypoxia-responsive pathways that recruit under hypoxic conditions and close following oxygen supplementation (13, 14). They can be detected using agitated saline contrast echocardiography (bubble study) (13, 14). During a bubble study, the appearance of microbubbles in the left heart within four cardiac cycles indicates an intracardiac right-to-left shunt, whereas their appearance after the fourth cardiac cycle suggests an extracardiac shunt, such as IPAVA (13, 15). A previous study reported a 75% prevalence of IPAVAs at rest in healthy Korean raccoon dogs (13). This case report describes the concurrent occurrence of perimembranous VSD, valvular PS, and IPAVAs in a Korean raccoon dog, diagnosed using echocardiography, agitated saline contrast echocardiography, and postmortem examination. 2 Case description An intact male Korean raccoon dog (Nyctereutes procyonoides koreensis), estimated to be 3 months old and weighing 1.2 kg, was rescued and admitted to the Jeonbuk Wildlife Rescue Center. On presentation, the animal exhibited lethargy, dehydration, generalized alopecia, and hyperkeratosis consistent with severe S. scabiei infestation. Physical examination revealed a grade IV/VI systolic murmur, and the systolic blood pressure was 120 mmHg. Complete blood count (CBC) demonstrated anemia (hematocrit, 25.3%; reference range, 33–47%) and leukocytosis (white blood cell count, 23.6 × 10 9 /L; reference range, 6.15–13.65 × 10 9 /L), findings considered secondary to the concurrent S. scabiei infestation (16). Thoracic radiography (HF-525 PLUS, Ecoray, Seoul, Korea) revealed generalized cardiomegaly, with a vertebral heart score (VHS) of 12.2, a vertebral left atrial score (VLAS) of 2.8 (Figure 1A), and a cardiothoracic ratio (CTR) of 82% (Figure 1B). All measurements exceeded the previously reported reference values for healthy Korean raccoon dogs (VHS, 9.12 ± 0.74; VLAS, 1.50 ± 0.31; CTR, 0.69 ± 0.07) (17). Transthoracic echocardiography was performed without sedation or anesthesia using a 5-MHz transducer (Aplio i800, Canon FIGURE 1 Thoracic radiographs obtained at the initial examination demonstrated increased VHS (12.2) and VLAS (2.8) on the right lateral view (A), and an increased CTR (82%) on the ventrodorsal view (B). At 5-week follow-up, these indices had decreased; however, the VHS (9.86) remained at the upper limit of normal, the VLAS (2.1) remained increased on the right lateral view (C), and the CTR (78%) remained mildly increased on the ventrodorsal view (D). Generalized cardiomegaly was evident at both examinations. Abbreviations: VSD, ventricular septal defect; PS, pulmonic stenosis; IPAVA, intrapulmonary arteriovenous anastomoses; VHS, vertebral heart score; VLAS, vertebral left atrial score; CTR, cardiothoracic ratio; PG, pressure gradient; RV, right ventricle; LVOT, left ventricular outflow tract; LA/Ao ratio, left atrial to aortic root ratio; E:E′, E wave to early diastolic mitral annular tissue velocity; TAPSE, tricuspid annular plane systolic excursion; RPAD, right pulmonary artery distensibility.
Kim et al. 10.3389/fvets.2026.1969910 Frontiers in Veterinary Science03frontiersin.org Medical Systems, Tokyo, Japan). The heart rate was mildly elevated at 161 beats/min compared with the reported reference range for raccoons (94–134 beats/min) (18). B-mode imaging from the right parasternal five-chamber long-axis view identified a 3.24-mm perimembranous VSD located between the subaortic region and the RV (Figure 2A). Color Doppler and continuous-wave Doppler imaging demonstrated a left-to-right shunt from the left ventricular outflow tract (LVOT) to the RV during early systole, with a peak velocity of 2.32 m/s (PG: 21.5 mmHg) (Figure 2C). In the right parasternal short-axis view at the heart base level, no discrete site of stenosis was identified; however, marked dilation of the pulmonary artery distal to the annulus was observed, consistent with post-stenotic dilation (Figure 2B). Continuous-wave Doppler revealed an increased pulmonic valve velocity of 3.87 m/s (PG: 59.9 mmHg) during late systole. Mild pulmonary regurgitation was also identified at 1.68 m/s (PG: 11.2 mmHg). Collectively, these findings were consistent with PS. The aortic-to-pulmonary annulus ratio was 1.06 (aortic annulus: 7.0 mm; pulmonary annulus: 6.6 mm), excluding pulmonic valve annular hypoplasia (>1.2) (10). The left atrial-to-aortic root ratio (LA/Ao) was 1.55, indicating mild left atrial enlargement relative to the reported reference value (1.22 ± 0.14) (17). Tissue Doppler imaging demonstrated an increased E/E′ ratio of 25.72, suggestive of elevated left ventricular filling pressure. The tricuspid annular plane systolic excursion (TAPSE) was 0.64 cm, indicating reduced RV systolic function (17). Echocardiography also revealed right ventricular free wall hypertrophy, right ventricular dilation, and interventricular septal flattening. Tricuspid regurgitation was not detected. The right pulmonary artery distensibility (RPAD) index was 53%, which was within the reported reference range (17). The pulmonary-to-systemic blood flow ratio (Qp/Qs) was not calculated as concurrent PS precludes reliable estimation (4). A bubble study was performed from the left parasternal apical four-chamber view to evaluate shunt direction and detect IPAVAs. Agitated saline (2 mL) was rapidly injected through the cephalic vein, and bubble scores were assigned according to a previously described 0–5 grading system based on the maximum number and distribution of microbubbles observed in the left ventricle in a single frame. The scoring criteria were as follows: bubble score 0, no microbubbles; bubble score 1, 1–3 microbubbles; bubble score 2, 4–12 microbubbles; bubble score 3, >12 microbubbles appearing as a bolus; bubble score 4, >12 microbubbles heterogeneously distributed throughout the left ventricle; and bubble score 5, >12 microbubbles homogeneously distributed throughout the left ventricle (13, 14). No microbubbles were detected in the left heart during the first four cardiac cycles (bubble score 0, Figure 3A). After the fourth cardiac cycle, numerous heterogeneously distributed microbubbles appeared throughout the left ventricle (bubble score 4, Figure 3B), consistent with the presence of IPAVAs. Subsequently, 100% oxygen was administered via a mask at a flow rate of 5 L/min for 5 min, after which a repeat bubble study was performed (13). Following oxygen supplementation, the number of microbubbles observed after the fourth cardiac cycle decreased to bubble score 2 (Figure 3C), indicating reduced shunt flow through the IPAVAs. No microbubbles were FIGURE 2 Echocardiographic findings at the initial examination (A–C) and the 5-week follow-up (D–F). In the right parasternal five-chamber long-axis view, a perimembranous ventricular septal defect measuring 3.24 mm at the initial examination [(A), white arrow] and 4.2 mm at the 5-week follow-up [(D), white arrow] was identified. In the right parasternal short-axis view at the heart base level, poststenotic dilation of the pulmonary artery was observed at the initial examination [(B), red arrowhead], although the pulmonic valve was not clearly visualized. In contrast, at the 5-week follow-up, a domeshaped pulmonic valve was observed during systole [(E), white arrowhead]. Color Doppler and continuous-wave Doppler imaging demonstrated a left-to-right shunt across the ventricular septal defect at the initial examination (C), whereas bidirectional shunting, including an early-diastolic right-toleft shunt [(F), red arrow], was observed at the 5-week follow-up. LA, left atrium; LV, left ventricle; Ao, aorta; RA, right atrium; RV, right ventricle; PA, pulmonary artery.
Kim et al. 10.3389/fvets.2026.1969910 Frontiers in Veterinary Science04frontiersin.org detected in the abdominal aorta before or after oxygen supplementation. Because standardized guidelines for the medical management of cardiac disease in Korean raccoon dogs are unavailable and the animal showed no overt cardiovascular clinical signs, cardiac pharmacotherapy was not initiated. Oral ferrous sulfate was administered to treat anemia. Ivermectin, meloxicam, metronidazole, and doxycycline were administered to treat the S. scabiei infestation and secondary bacterial infections, and fluid therapy was provided to correct dehydration. At the 5-week re-examination, dermatologic lesions associated with the S. scabiei infestation, along with systemic signs including lethargy and dehydration, had markedly improved. CBC demonstrated improvement in anemia and leukocytosis. On physical examination, a grade IV/VI systolic murmur persisted, and the heart rate had decreased to 140 beats/min. Thoracic radiography revealed a VHS of 9.86, a VLAS of 2.1, and a CTR of 78% (Figures 1C,D). Although these indices had decreased compared with the initial examination, VHS remained at the upper limits of normal, whereas VLAS and CTR remained mildly increased (17). Transthoracic echocardiography from the right parasternal five-chamber long-axis view identified a perimembranous VSD measuring 4.2 mm, representing an increase from the initial measurement of 3.24 mm (Figure 2D). Color Doppler and continuous-wave Doppler demonstrated a left-to-right shunt during systole; however, an additional right-to-left shunt from the RV to the LVOT was observed during early diastole, resulting in a bidirectional shunt pattern. The peak velocity of the systolic left-toright shunt was 1.81 m/s (PG: 13.1 mmHg), whereas the early-diastolic right-to-left shunt had a peak velocity of 0.67 m/s (PG: 1.79 mmHg) (Figure 2F). In the right parasternal short-axis view at the heart base level, systolic doming of the pulmonic valve with minimal leaflet thickening was newly identified (Figure 2E). Continuous-wave Doppler demonstrated an increased pulmonic valve peak velocity of 4.39 m/s during late systole (PG: 77.0 mmHg). The peak velocity of pulmonic regurgitation also increased to 2.07 m/s (PG: 17.1 mmHg), compared with the initial examination. The aortic-to-pulmonary annulus ratio was 0.96 (aortic annulus: 8.3 mm; pulmonary annulus: 8.6 mm), similar to the initial measurement. Based on the echocardiographic findings, the PS was considered consistent with type A valvular PS. The LA/Ao ratio decreased to 0.94, indicating resolution of left atrial enlargement. Tissue Doppler imaging demonstrated a reduced E/E′ ratio of 16.08, suggesting a decrease in left ventricular filling pressure. The TAPSE decreased to 0.48 cm, suggesting a further reduction in RV systolic function (17). Mild progression of right ventricular free wall hypertrophy, right ventricular dilation, and interventricular septal flattening was observed compared with the previous examination. Tricuspid regurgitation was not detected. The RPAD index was 43%, remaining within the reported reference range (17). Collectively, these echocardiographic findings supported the diagnosis of a complex congenital cardiac anomaly comprising VSD and PS. FIGURE 3 Agitated saline contrast echocardiography (bubble study) performed at the initial examination (A–C) and the 5-week follow-up (D–F). Before oxygen supplementation, no microbubbles were detected in the left heart within the first four cardiac cycles at the initial examination (bubble score 0) (A), whereas 4–12 microbubbles were observed within the first four cardiac cycles at the 5-week follow-up (bubble score 2) (D). This finding suggests the presence of an intracardiac right-to-left shunt. At the initial diagnosis, after the fourth cardiac cycle and pre-oxygen supplementation, more than 12 microbubbles were heterogeneously distributed throughout the left ventricle (bubble score 4) (B), and this number decreased to 4–12 microbubbles (bubble score 2) after oxygen supplementation (C). At the 5-week follow-up, more than 12 heterogeneously distributed microbubbles remained visible after the fourth cardiac cycle before oxygen supplementation (bubble score 4), although fewer were observed than at the initial examination (E). Following oxygen supplementation, the number further decreased to 1–3 microbubbles (bubble score 1) (F).
Kim et al. 10.3389/fvets.2026.1969910 Frontiers in Veterinary Science05frontiersin.org Before oxygen supplementation, 4–12 microbubbles were observed in the left ventricle within the first four cardiac cycles (bubble score 2, Figure 3D), indicating an intracardiac right-to-left shunt. After the fourth cardiac cycle, microbubbles remained heterogeneously distributed throughout the left ventricle despite being slightly reduced in number compared with the initial examination (bubble score 4, Figure 3E), consistent with persistent IPAVAs. Subsequently, the same oxygen supplementation protocol used during the initial examination was applied. Following oxygen supplementation, no microbubbles were detected within the first four cardiac cycles (bubble score 0), and only a few bubbles were observed after the fourth cardiac cycle (bubble score 1, Figure 3F). Microbubbles were present in the abdominal aorta before oxygen supplementation but were absent thereafter. Computed tomography (CT) was planned to further characterize the cardiac anatomy, including the VSD and PS. Medetomidine (0.05 mg/kg, IV) and alfaxalone (2.2 mg/kg, IV) were administered as premedication and induction agents, respectively. During induction, however, the Korean raccoon dog developed severe arrhythmia and died. Postmortem examination confirmed a 4-mm perimembranous VSD located between the LVOT and RV (Figure 4A). Type A valvular PS was also identified, with mild leaflet thickening and commissural fusion of the intermediate, right, and left cusps. In addition, right ventricular free wall hypertrophy, interventricular septal hypertrophy (Figure 4B), and right ventricular dilation were observed. On histopathology, hematoxylin and eosin (H&E) and Masson’s trichrome staining of the pulmonary valve demonstrated leaflet hypertrophy, fibrosis, and degeneration. 3 Discussion The clinical significance of VSD is primarily determined by defect size and the magnitude of shunt flow (19). Small restrictive VSDs are typically hemodynamically insignificant and do not cause substantial volume overload of the heart or pulmonary circulation. By contrast, large nonrestrictive VSDs increase pulmonary blood flow, which may result in pulmonary hypertension secondary to chronic left-to-right shunting (7, 19). As pulmonary arterial pressure approaches or exceeds systemic arterial pressure, the shunt may become bidirectional or reverse to right-to-left, representing progression to Eisenmenger syndrome (4, 7). At the 5-week follow-up, the appearance of bidirectional shunting through the VSD raised the possibility of pulmonary hypertension as a differential diagnosis (7). However, RPAD index remained within the reported reference range. Although post-stenotic dilation of the pulmonary artery associated with PS was present, generalized pulmonary arterial enlargement suggestive of pulmonary hypertension was not observed. Pulmonic regurgitation also remained mild. These findings did not provide sufficient evidence of pulmonary hypertension (4, 7, 19, 20). Therefore, the bidirectional shunt in this case was considered more likely to be associated with increased right ventricular pressure secondary to pulmonic stenosis rather than Eisenmenger physiology caused by progressive pulmonary vascular disease. Tetralogy of Fallot was also considered as a differential diagnosis, as the coexistence of VSD, right ventricular outflow tract obstruction, and right ventricular hypertrophy overlapped with its characteristic features. However, an overriding aorta was not identified on either echocardiographic or postmortem examination, thereby excluding tetralogy of Fallot (21, 22). At the 5-week follow-up, systolic doming of the pulmonic valve with minimal leaflet thickening was newly identified, accompanied by increases in pulmonic valve velocity and PG, as well as an increase in pulmonic regurgitation. Although PS is generally considered a congenital and fixed valvular stenosis in dogs, progression during growth has been reported in individual puppies with mild PS (23). The changes observed in this case may therefore represent progression of valvular PS, although the underlying mechanism remains unclear. Progressive right ventricular outflow tract obstruction may have increased right ventricular pressure, thereby reducing the interventricular PG across the VSD and contributing to the development of bidirectional shunting (24). The resulting reduction in left-to-right FIGURE 4 Gross pathological findings at necropsy. (A) Longitudinal section of the heart demonstrating a perimembranous ventricular septal defect (white arrow). (B) Transverse section of the heart demonstrating right ventricular free wall hypertrophy and interventricular septal hypertrophy. Ao, aorta; LV, left ventricle; RV, right ventricle; RVW, right ventricular wall; IVS, interventricular septum.
Kim et al. 10.3389/fvets.2026.1969910 Frontiers in Veterinary Science06frontiersin.org shunt flow may have decreased pulmonary blood flow and partially alleviated left-sided volume overload. This may also explain the decreases in VHS, VLAS, and LA/Ao observed at follow-up (12, 24). The hemodynamic interaction between concurrent PS and VSD may be comparable to that achieved by pulmonary artery banding, which limits excessive left-to-right shunting through a VSD (12). By increasing right ventricular pressure, both conditions reduce left-to-right shunt flow and pulmonary blood flow, thereby decreasing volume overload of the pulmonary circulation and left heart. The absence of clinical signs of left-sided heart failure throughout the approximately 5-week follow-up period suggests that a relatively balanced hemodynamic state was maintained (4, 12, 24). During the initial agitated saline contrast study, microbubbles appeared in the left heart only after the fourth cardiac cycle, consistent with the presence of IPAVAs. Following oxygen supplementation, the number of microbubbles appearing after the fourth cardiac cycle decreased. This finding is consistent with previous studies demonstrating that IPAVAs dynamically open under hypoxic conditions and close in response to increased oxygen availability, resulting in reduced IPAVA shunt flow (13, 14). At the 5-week follow-up, fewer microbubbles were observed after the fourth cardiac cycle than at the initial examination, suggesting reduced IPAVA patency during postnatal growth. This observation is consistent with studies reporting postnatal regression of IPAVAs in humans and lambs (25, 26). Although pulmonary arteriovenous malformation (PAVM) could not be definitively excluded as CT angiography was not performed, the oxygen-dependent reduction in microbubble passage and the apparent postnatal regression of shunt flow were more consistent with functional IPAVAs than with a fixed structural PAVM (14). Unlike the initial examination, the follow-up agitated saline study demonstrated microbubbles in the left heart within the first four cardiac cycles and in the abdominal aorta. These findings indicate right-to-left shunting through the VSD in addition to the existing left-to-right shunt, consistent with bidirectional shunting (13). Following oxygen supplementation, microbubbles were no longer detected within the first four cardiac cycles, and those observed in the abdominal aorta also disappeared. These changes were attributed to a reduction in pulmonary vascular resistance, resulting in decreased right ventricular afterload and attenuation of right-to-left shunting (27, 28). These findings suggest that oxygen supplementation may mitigate the hemodynamic consequences of both IPAVAs and right-to-left shunting through the VSD. The diameter of the perimembranous VSD increased from 3.24 mm at the initial examination to 4.2 mm at the 5-week follow-up. Reports describing enlargement of VSDs in dogs are limited. In cattle, however, enlargement of the defect has been documented on serial examinations. Such changes have been proposed to occur in association with growth, although the underlying mechanism remains unclear. Further study is needed to clarify this phenomenon (29). The severity of PS in dogs is commonly classified according to the PG between the RV and the pulmonary artery: mild (<50 mmHg), moderate (50–80 mmHg), and severe (>80 mmHg) (10, 24). However, Doppler-derived pulmonic velocity and PG are dependent on transvalvular flow (30, 31). At the initial examination, the left-to-right shunt through the VSD may have increased pulmonary blood flow, thereby increasing pulmonic velocity and PG (7). In contrast, the reduced TAPSE suggested impaired RV systolic function. However, interpretation of TAPSE was limited by the use of reference values established in Korean raccoon dogs with higher body weights than the Korean raccoon dog in this case (17). If RV systolic function was indeed impaired, the associated reduction in transvalvular flow may have contributed to underestimation of the Doppler-derived PG (30, 31). At the 5-week follow-up, the newly developed right-to-left shunt may have reduced pulmonary blood flow, which may have led to underestimation of the Doppler-derived pulmonic velocity and PG. Therefore, the Doppler-derived PG should be interpreted with caution when assessing the severity of PS in this Korean raccoon dog. For dogs with severe PS, surgical or interventional treatment is generally recommended, and balloon valvuloplasty is considered the primary treatment for valvular PS (10, 32). Before intervention, coronary artery anatomy should be evaluated, as coronary anomalies may increase the risk of vascular rupture or myocardial ischemia during balloon valvuloplasty. Coronary artery anomalies can be identified by necropsy, angiocardiography, or CT angiography (9, 19). At the 5-week follow-up, the peak pulmonic velocity was 4.39 m/s, corresponding to a PG of 77.0 mmHg, consistent with moderate PS. However, considering the hemodynamic factors described above, the actual severity of PS may have been greater than indicated by Doppler measurements, and interventional treatment may still have been indicated. Accordingly, CT angiography was planned to evaluate coronary anomalies. However, the Korean raccoon dog died during anesthetic induction. Postmortem examination revealed no coronary artery abnormalities. This case report has some limitations. First, the animal exhibited a heart rate above the reported reference range during echocardiographic examinations, likely due to excitement, which may have influenced the echocardiographic measurements (33). Sedatives and anesthetics were intentionally avoided owing to their potential effects on echocardiographic parameters (34). Second, long-term follow-up was not possible owing to the animal’s death. To our knowledge, this case report is the first to document the coexistence of perimembranous VSD, valvular PS, and IPAVAs in a Korean raccoon dog, confirmed by echocardiography, agitated saline contrast echocardiography, and postmortem examination. The findings further suggest that progression of PS may contribute to the development of bidirectional shunting across a VSD. Data availability statement The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation. Ethics statement Ethical approval was not required for the study involving animals in accordance with the local legislation and institutional requirements because the animal was a rescued wild animal and all data were obtained during routine clinical examination and treatment, with no additional experimental procedures performed for the purpose of this study. Written informed consent for publication of this case report was obtained from the relevant authorized representative. Author contributions SK: Conceptualization, Data curation, Investigation, Validation, Writing – original draft, Writing – review & editing, Methodology, Visualization. MK: Data curation, Investigation, Validation, Visualization, Writing – review & editing, Resources. J-IH: Resources, Validation, Writing – review & editing. KL: Validation, Writing – review
Kim et al. 10.3389/fvets.2026.1969910 Frontiers in Veterinary Science07frontiersin.org & editing, Supervision. HY: Supervision, Validation, Writing – review & editing, Conceptualization, Data curation, Investigation, Project administration, Resources, Writing – original draft. Funding The author(s) declared that financial support was received for this work and/or its publication. This subject is supported by the National Institute of Wildlife Disease Control and Prevention as “Specialized Graduate School Support Project for Wildlife Disease Specialists.” Conflict of interest The author(s) declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Generative AI statement The author(s) declared that Generative AI was not used in the creation of this manuscript. Any alternative text (alt text) provided alongside figures in this article has been generated by Frontiers with the support of artificial intelligence and reasonable efforts have been made to ensure accuracy, including review by the authors wherever possible. If you identify any issues, please contact us. Publisher’s note All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher. References 1. Park IC, Lee HW, Kim JT. Analysis of the wildlife distress and rescue of wild animal mammals in Gangwon Province. Korean J Vet Serv. (2012) 35:33–7. doi: 10.7853/ kjvs.2012.35.1.033 2. Oliveira P, Domenech O, Silva J, Vannini S, Bussadori R, Bussadori C. 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