The biggest issue for Master was that His slave should only have pleasure when He decided, and even then it should only come from Master's touch. A majority of slave owners would castrate their slaves for this reason. A slave who can orgasm has reason to think of itself. But Master did not want that exactly. He enjoyed having a male slave and especially loved the correction a swift jolt of the testicles always brought around. Being a wise man He also knew that a slave who overcame this natural drive would totally belong to Him.
Being a patient man, Master allowed His slave to learn from experience, and was restraint in His use of severe punishments. He wanted it to always put Him first but to always make a decision to do that. Two years after they signed the contract and the slave had a permanent collar welded on it's neck, Master's patience began to run thin. The slave was doing well in all areas but one - it still would orgasm if given the chance by pleasureing itself even though directed not to. The slave was almost always left in positions that did not allow this but every 3 months or so it would find a way to do it. Master had used extreme physical work to exhaust the slave, a chastity device, punishments, evening piercing the navel and cockhead so the cock was always attached and the slave could only stand straight while in pain. At the end of His patience, Master was about to dispose of the slave and sell it to a man who would cut it, and then resell it as a genderless servant in Saudi Arabia, when He had a better idea. What if He fixed the slave so it still had desires and needs but could not take care of those needs itself?
Master plotted for 6 months on how to make correct modifications. Castration would stop the sex drive but even with hormone injections, Master would lose the music he enjoyed while abusing it's balls. Master also enjoyed teasing the slave to the edge of orgasm and then denying it the chance. Of course with a healthy physical specimen, nature would regurlary discharge the sperm overflow which did not bother Master. That just reinforced that His slave was all male with it's own desires which Master controlled. Removing the penis would leave the sex drive, but Master liked a male slave. He even contemplated having the forearms and hands removed so the slave could not touch itself for pleasure but that was extreme to just the problem the slave was presenting and would limit the ability of the slave to work.
Finally Master came up with a favorable solution. He made a few calls, interviewed some candidiates and then made the final plans. It took another 2 months to arrange but the big day finally arrived. Master wanted the slave to remember so he opted for a live procedure. Everything was ready and the slave was very excited. Master teased it's cock all day, which he usually ignored, but He kept the slave on the verge of orgasm for a couple of hours as a gift.
Now you see the slave was still male, discharged it's sperm through nocturnal erections, still had erections and had abusable testicles. It no longer had the nerve endings that supplied most of the sensation to orgasm. It still had orgasms but needed other stimulation to get to that point. It was the perfect solution and Master was very happy with the outcome and the slave slowly adjusted to life with a headless cock. The slave begged and cried when told of His plan, and the screams during the procedure were so loud the cat hid for a week. After the initial cut the slave was knocked out and when he awoke Master explained how it's life now would work. Care was taken so the urine and sperm would still exit the end of the stump and from now on the slave would remember it's committment to Master always. And the slave was warned that further misdeeds and it would find just a stump under flat pubic skin the next time.