We have recently seen several working dogs with very advanced mammary tumours. These present challenges in terms of surgery, recovery and potential for spread of secondary tumours into the dog’s chest. Most mammary lumps in the early stages are cystic or benign. If they are removed when small and the bitch is spayed they usually make a full and uneventful recovery. If surgery is delayed, then it is much more difficult to remove the tumours completely, the surgery is more traumatic and expensive and there is a much greater chance of the tumours becoming malignant and spreading. If you notice any lumps in the mammary region of a bitch, we should attend to it as soon as possible.