Hi, My dog Mabel is a rescue dog. Before we got her, they said they were monitoring her mammary glands since when she was spayed they started to swell a bit. After a few weeks, she was all clear and they told us not to worry as it is common for spayed dogs to show lumps and bumps afterwards, but they did disappear completely. 2 days ago I noticed her top right teat had swollen and looked like it was about to burst. It seemed to have happened overnight, as we give her countless belly rubs and have never noticed it before. On closer inspection, it has started to leak pus, like a spot does. We are going to take her to the vets, but since it is Easter we have to wait until they open again. Does anyone have any ideas what this could be before we go to the vets? She is still acting like her normal self, and doesn’t wince or move away when we touch it. Thanks.