A 10-year-old female spayed mixed breed dog that had a transvenous pacemaker implanted four years prior was presented for the evaluation of episodes of transient loss of consciousness without any history of trauma that were unresponsive to anticonvulsant therapies. Intermittent failure to capture coupled with low impedance and high capture threshold were noted upon interrogation of the pacemaker. Radiography and fluoroscopy demonstrated a possible break in the insulation of the lead. After the placement of another transvenous pacemaker, the dog had no additional syncopal episodes, and anticonvulsants were tapered off. The dog developed an implant infection from the newly placed pacemaker, which prompted the removal of the infected pacemaker and the implantation of an epicardial pacemaker. However, the epicardial lead dislodged seven days after placement, and the dog was euthanized. During necropsy, the first transvenous lead was removed, and the insulation break was visually confirmed. Although an insulation break is a rare delayed complication of pacemaker implantation, this report shows how the diagnosis, suspected by typical interrogation findings, can be aided by radiographic and fluoroscopic investigations.

一只 10 岁雌性绝育混种狗，四年前植入了经静脉起搏器，用于评估短暂性意识丧失的发作，没有任何抗惊厥治疗无反应的外伤史。在询问起搏器时注意到间歇性捕获失败以及低阻抗和高捕获阈值。射线照相和透视显示引线的绝缘层可能存在破损。在放置另一个经静脉起搏器后，狗没有再出现晕厥发作，抗惊厥药物也逐渐减少。这只狗因新放置的起搏器而出现植入物感染，这促使移除受感染的起搏器并植入心外膜起搏器。然而，心外膜导线在放置 7 天后脱落，狗被安乐死。在尸检过程中，移除第一根静脉导线，并目视确认绝缘破损。尽管绝缘破损是起搏器植入的一种罕见的迟发性并发症，但本报告显示了如何通过放射线照相和荧光检查检查来辅助通过典型询问结果怀疑的诊断。