this kinda sounds like it is the knot that when dogs mate will cause them to lock. Sometimes when excited it will show up and when relaxed it dosen't. His testicles if he had any would be a the very base of the penis not up where you could easily see them. If any others out there have a better explaination please post. I am not a breeder just an owner with 32yrs of owning these fantastic babies.....good luck, Sharon, PIXI & SPIKE |