Mulligan R M
Am J Vet Res. 1975 Sep;36(9):1391-6.
Of the 120 cases of mammary cancer occurring in 117 female dogs (15 spayed), 2 male dogs, and 1 dog of undetermined sex, 107 (nearly 90%) were observed in dogs 8 to 15 years old. Mammary tumors occurred in nearly 14% of 875 female dogs with neoplasms. Nearly 60% of 128 neoplasms were located in the 4th and 5th mammary glands. Of the 128 cancers in these 120 dogs, 85 were classified as duct carcinoma, 38 as lobular carcinoma, 3 as malignant mixed tumor, and 2 as duct and lobular carcinomas. Most duct carcinomas originated in the epithelial cells of ducts at all levels, and a few arose in previously benign duct papillomas. The lobular carcinomas arose in alveoli and developed into progressively larger lobules. A negative factor in the development of mammary cancer is ovariectomy before or shortly after the first estrous cycle in the dog and before the age of 40 in women. In both dog and man, aging is a positive factor in the development of mammary cancer. In women, other positive factors are nulliparity and inheritance; e.g., a high rate of breast cancer in close female relatives of Jewish extraction. An epidemiologic study of breast cancer in man and dog in high-risk countries(e.g., United States) and low-risk countries (e.g., Japan) is indicated.
在117只母犬（15只已绝育）、2只公犬和1只性别未明的犬中发生的120例乳腺癌病例中，8至15岁的犬观察到107例（近90%）。乳腺肿瘤发生在875只患有肿瘤的母犬中的近14%。128个肿瘤中近60%位于第4和第5乳腺。在这120只犬的128例癌症中，85例被分类为导管癌，38例为小叶癌，3例为恶性混合瘤，2例为导管和小叶癌。大多数导管癌起源于各级导管的上皮细胞，少数起源于先前的良性导管乳头状瘤。小叶癌起源于腺泡，并发展为逐渐增大的小叶。犬在第一次发情周期之前或之后不久以及女性在40岁之前进行卵巢切除术是乳腺癌发生的一个负面因素。在犬和人类中，衰老都是乳腺癌发生的一个正面因素。在女性中，其他正面因素是未生育和遗传；例如，犹太裔女性近亲中乳腺癌的高发病率。建议对高风险国家（如美国）和低风险国家（如日本）的人类和犬类乳腺癌进行流行病学研究。
