Regional lymph node status impacts survival in dogs with malignant mammary tumors. However, few studies have evaluated extracapsular extension and tumor implants in regional lymph node metastases in dogs with mammary carcinoma. Therefore, 84 cases of mammary carcinomas with metastases in inguinal and/or axillary lymph nodes from female dogs of different breeds and a total of 139 metastatic lymph nodes were evaluated by routine histological staining. Clinical and pathological characteristics of primary tumors as well as the presence of extracapsular extension and tumor implants in the lymph nodes were analyzed, in addition to survival. One to 5 lymph nodes were evaluated in each case. Extracapsular extension and tumor implants were present in 17.9% and 39.3% of cases, respectively. The simultaneous presence of extracapsular extension and tumor implants were associated with an increased risk of death (hazard ratio 10.46). In addition, “special type carcinomas”, high histological grade (grade III), and presence of extracapsular extension associated with tumor implants were related to a worse prognosis and shorter survival times (p < 0.05). Based on these results, we highlight the importance of identifying extracapsular extension and tumor implants in dogs with metastatic mammary carcinomas, as they are associated with a higher risk of death and shorter survival.

区域淋巴结状态影响患有恶性乳腺肿瘤的犬的存活率。然而，很少有研究评估乳腺癌犬区域淋巴结转移中的包膜外扩展和肿瘤植入物。因此，通过常规组织学染色评估了84例不同品种雌性犬腹股沟和/或腋窝淋巴结转移的乳腺癌和总共139个转移淋巴结。除了存活率之外，还分析了原发性肿瘤的临床和病理特征以及淋巴结中包膜外扩展和肿瘤植入物的存在。在每个病例中评估了 1 到 5 个淋巴结。囊外扩展和肿瘤植入分别出现在 17.9% 和 39.3% 的病例中。同时存在囊外扩展和肿瘤植入物与死亡风险增加有关（风险比 10.46）。此外，“特殊类型癌”、高组织学分级（III 级）以及与肿瘤植入物相关的包膜外扩展的存在与更差的预后和更短的生存时间有关。p  < 0.05)。基于这些结果，我们强调了在患有转移性乳腺癌的狗中识别包膜外扩展和肿瘤植入物的重要性，因为它们与更高的死亡风险和更短的生存期有关。