Left atrial tear (LAT) is a life-threatening complication in dogs with myxomatous mitral valve disease (MMVD). The study objective was to describe clinical presentation, echocardiographic findings, treatment strategies, and survival in dogs with LAT compared to a control group of dogs with a similar stage of MMVD but no LAT. Two-center retrospective case–controlled study including 15 dogs with and 15 dogs without LAT was conducted. Clinical and echocardiographic data were reviewed, and survival information were collected. Nine dogs in each group were in stage C of MMVD, while the remaining were in stage B2. No differences between groups were found regarding age, body weight, sex, kidney values, and echocardiography-derived cardiac dimensions. Most reported clinical signs associated with LAT included weakness, respiratory signs, and syncope. Treatment varied and was mainly focused on the management of congestive heart failure. Three dogs with LAT received a pericardiocentesis. All 15 dogs with LAT had died of cardiac causes, five dogs during the first seven days after admission. The median survival time for all 15 dogs with LAT was 52 days compared to 336 days in the control group (P=0.103). When excluding five dogs with LAT that died during the first seven days, the median survival increased to 407 days, not different compared to the control group (P=0.549). Dogs with MMVD and LAT have a high short-term mortality; however, when surviving the acute phase, the long-term prognosis may not differ from dogs with a similarly advanced degree of MMVD but without LAT.

中文翻译：

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因疑似左心房撕裂而出现心包积液的粘液性二尖瓣疾病犬的临床表现、超声心动图检查结果、治疗策略和预后：一项回顾性病例对照研究

左心房撕裂 (LAT) 是患有粘液瘤性二尖瓣疾病 (MMVD) 的犬的一种危及生命的并发症。该研究的目的是描述患有 LAT 的狗的临床表现、超声心动图检查结果、治疗策略和生存情况，并与具有相似 MMVD 阶段但无 LAT 的狗的对照组进行比较。进行了两中心回顾性病例对照研究，包括 15 只患有 LAT 的狗和 15 只未患有 LAT 的狗。回顾了临床和超声心动图数据，并收集了生存信息。每组有9只狗处于MMVD C阶段，其余的则处于B2阶段。各组之间在年龄、体重、性别、肾脏值和超声心动图得出的心脏尺寸方面没有发现差异。大多数报告的与 LAT 相关的临床症状包括虚弱、呼吸系统症状和晕厥。治疗方法多种多样，主要集中在充血性心力衰竭的治疗上。三只患有 LAT 的狗接受了心包穿刺术。所有 15 只患有 LAT 的狗均死于心脏病，其中 5 只狗是在入院后的前 7 天内死亡。所有 15 只患有 LAT 的狗的中位生存时间为 52 天，而对照组为 336 天（P=0.103）。当排除前 7 天内死亡的 5 只患有 LAT 的狗时，中位生存期增加至 407 天，与对照组相比没有差异 (P=0.549)。患有 MMVD 和 LAT 的狗短期死亡率很高；然而，当急性期存活下来时，长期预后可能与具有相似程度的MMVD但没有LAT的狗没有什么不同。