Testicular Cancer How Do You Know If Your Dog Has Testicular Cancer?

How do you know if your dog has testicular cancer? - testicular cancer

I have a Maltese, and said that Malta is a high probability of developing testicular cancer if not neutered, we (try to increase). Recently, my brother discovered a lump into it, and it is a kind of the wrong color, black, I'm very concerned and I believe him to the vet, but I wanted to know if someone knows what they are --