What is a common prognostic factor for canine mammary tumors?

The size of the tumor at the time of diagnosis is a significant prognostic factor for canine mammary tumors. Larger tumors have been associated with a worse prognosis compared to smaller tumors. This is likely due to several reasons, including the potential for a larger tumor to invade surrounding tissues or to metastasize to other regions of the body more readily than smaller tumors. Clinical studies have consistently shown that tumor size correlates with outcomes, making it an essential factor in assessing a dog's prognosis. Smaller tumors often have lower rates of metastatic spread and may respond better to treatment, hence influencing survival rates positively.

While the histological type of tumor, location of the tumor, and age of the dog can also provide useful information regarding prognosis, the size of the tumor remains a prominent and easily measurable characteristic that significantly impacts the overall prognosis in cases of canine mammary tumors.