I came across this huge lump on the left of my boy Thursday morning. This wasn't there the evening before. I rushed him to the vet occasions after I found this. Update: this is triggered by an infection. She has currently on antibiotics and resting to rid of this. The cancer testing came back negative. My personal boy is in pain is a sick puppy dog. Pray or send positive vibes to this special boy. He has recently been my mate for almost eight years now.