[Kyra]

I couldn't find anything either, but on the subject of why cows rarely get mammary cancer I can think of a few possibilities. To start with, the diet and lifestyle of cows is vastly different to humans, which in itself means their cancer rates can be different. Plus there may be significant genetic factors which protect cows from mammary cancer, their different hormonal conditions may influence cancer development differently or they may have a more robust immune response to potentially cancerous changes in their mammary tissue.