Abstract
Sixty-four metastasized canine malignant mammary tumors were studied. The most important types of canine mammary cancer are discussed. Mammary squamous cell carcinomas of different types are found more frequently in the dog than in man. Mucinous carcinoma, a very rare type in the dog, seems to be more malignant than its counterpart in man. Anaplastic carcinoma in the dog is a very malignant diffusely infiltrating and extensively metastasizing cancer. The malignant mixed tumors, although showing many resemblances to complex carcinomas, are discussed here as a separate group. Both categories of tumors seem to be extremely rare in man. Simple carcinomas are highly infiltrating tumors metastasizing frequently to the regional nodes and lungs; survival time is short. Complex carcinomas are generally less invasive than simple carcinomas, and lymphatic permeation is also less frequent, resulting in a lower percentage of affected nodes; the median survival time is relatively long. The sarcomas, growing mostly in an expansive way, tend to spread mainly to the lungs; survival time is short.