Generally a male puppy's testicles drop around 6 or 7 weeks, however it can take up to 3 months or longer in some instances.
When a dog only has one decended, or in fact if neither have dropped he is suffering from what is called Cryptorchidism, or retained testicles which is considered a genetic trait & dogs who have a retained testicle(s) should not be bred from.
Dog in which both testicles fail to descend are sterile. When testicles remain in the abdomen the 4-5 degree higher temperature there prevents the production of sperm. It does not, however, affect the production of testosterone, so these pets exhibit typical male behavior. When one testicle does descend into the scrotum the pet will be fertile. It is a bad idea to breed such dogs because their descendants may show or carry the same defect.
Another point to consider is that a dog with retained testicle(s)
has a higher chance of testicular cancer
& therefore should be neutered.
It would be irresponsible to breed this male his reproducing an inferior gene brings continued defects and heart ache to his offspring.
BE SMART!