The aim of the present study was to retrospectively assess whether spaying at the same time of mastectomy increased disease-free survival (DFS) in bitches with mammary tumours and to investigate the utility of clinical data when designing a surgical plan that includes gonadectomy. Characteristics of 225 bitches carrying 489 tumours were retrieved. Of the116 bitches that underwent surgery, 52 bitches underwent mastectomy and ovariectomy, 46 bitches underwent mastectomy alone, whereas 18 bitches were already spayed. Analysis by Kaplan–Meier and in-between groups comparisons using Student's T, Chi-square, and one-way ANOVA tests were performed. DFS was longer for bitches that underwent ovariectomy and mastectomy compared to those that were left intact (p = .00064) or were already spayed (p = .0098). Spaying status affected tumour size (spayed: 2.75 cm ± 2.72; intact: 1.76 cm ± 2.04; p = .039), but not malignancy (p > .05). Differences in age were detected between animals with benign and malignant tumours (years: 9.1 ± 2.8 and 10 ± 2.3; p = .004), with multiple and single tumours (years: 10.18 ± 2.6 and 9.3 ± 2.8; p = .007), and between purebred and mixed breed bitches (years: 10.46 ±1.78 and 9.27 ±2.68; p = .005). Malignant tumours were larger than benign ones (2.17 cm±2.31 and 1.34 cm ±1.82; p = .005) and size increased according to the degree of malignancy. DFS was shorter for animals presenting tumours >2 cm in size (p < .006) and with tumours in the first pair of thoracic mammary glands (p = .00009). Gonadectomy should be suggested to owners of intact bitches carrying mammary tumours and age, size of the tumour, and location should be carefully considered when performing surgery.

中文翻译：

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母犬乳房切除术同时绝育的回顾性研究及生存分析

本研究的目的是回顾性评估在乳房切除术的同时进行绝育是否会增加患有乳腺肿瘤的母犬的无病生存率（DFS），并在设计包括性腺切除术的手术计划时调查临床数据的效用。检索了携带 489 个肿瘤的 225 只母犬的特征。在接受手术的116只母犬中，52只母犬接受了乳房切除术和卵巢切除术，46只母犬只接受了乳房切除术，而18只母犬已经绝育。进行了 Kaplan-Meier 分析和使用学生 T、卡方检验和单向 ANOVA 检验的组间比较。与保持完整（p  = .00064）或已经绝育（p = .0098)。绝育状态影响肿瘤大小（绝育：2.75 cm ± 2.72；完整：1.76 cm ± 2.04；p  = .039），但不影响恶性肿瘤（p  > .05）。在患有良性和恶性肿瘤的动物（年龄：9.1 ± 2.8 和 10 ± 2.3；p  = .004）、多发和单发肿瘤（年龄：10.18 ± 2.6 和 9.3 ± 2.8；p  = .007）之间检测到年龄差异，以及纯种和混种母犬之间（年数：10.46 ±1.78 和 9.27 ±2.68；p  = .005）。恶性肿瘤比良性肿瘤大（2.17 cm±2.31 和 1.34 cm ±1.82；p  = .005），并且大小根据恶性程度而增加。肿瘤 > 2 cm 的动物的 DFS 较短（p < .006) 和第一对胸乳腺中的肿瘤 ( p  = .00009)。应向携带乳腺肿瘤的完整母犬的主人建议进行性腺切除术，并且在进行手术时应仔细考虑年龄、肿瘤大小和位置。