Hello,
I have a 17 months old Dogo who had the same issue, i first discovered the problem when i found drops of blood on the floor.
I will start with the root cause:
The reason for the bleeding was caused by the dog becoming sexually mature and started to mount his brother (15 month old Weimaraner) and the rubbing caused the penis to bleed. After the dogo started licking it making the situation worst, this behavior and bleeding continued from the age of 9 months up until 11 months.
At first I did not know that what I stated above was the root cause, initially I thought it was an infection and later due to feedback from the vet I thought it was due to the penis been large and breaking the skin when the dog had an erection.
I got second opinion and third opinion from a vet that specializes in Dogo Argentino as he is a breeder here in Brazil and he explained that at times this happens with Dogos and gave me tips to overcome this stage.
How I treated it:
The first thing was to buy some sterile water and place it inside the refrigerator. Take the water and place in the freezer 30 minutes before applying it, how you apply it is by getting a syringe and filling it with the really cold sterile water and then squirt the water inside the penis (from the tip of the penis squirt the water inside the skin) and holding the opening so that the sterile water does not spill, hold it for about 1 minute and then proceed to clean it.
This will help clean the penis to prevent infection and also help with healing the area that is bleeding. If you have another dog in the household separate the dogs when not supervised to avoid the dogs from mounting each other. If you don’t have other dogs make sure you observe your dog to see if he is masturbating with an object (like the side of your bead support) and remove that object or the access of the dog to that object. The licking is the hard part to stop so helping the area heal will reduce the urge of the dog to lick himself.
I freaked out at the beginning so I know your concern but it is kind of normal at least from what I have seen (I know all the major breeders here in Brazil) so if you have any questions please let me know.