Each testicle forms high up near the kidneys in early embryonic life and then descends into the scrotum during late foetal life or early neonatal life (soon after birth). If embryos have a "y" chromosome they do not develop into testis they become ovary's and the pup is female. The testies travel down the inguinal canal passing through a narrow area referred to as the "ring." which is high up in the inguinal canal. Many of the experts state that if a male animal's teste/s have not descended by 2 months of age, then they are very unlikely to do so. Other are a little more generous, allowing the animal up to 16 weeks before deeming the animal's testicles unlikely to descend. Vets suggest that they can take as long as 6 months to fully descend, but with normal puppy growth the ring closes or decrease in size making it impossible for the testicle to pass through, this will then cause the testicle to stay retained. Simply as the animal grows the testicle grows and the ring closes. Another reason for the testicle not to be able to fully descend is if the cord is too short for it to stretch to the scrotal sack.
Late testicular descent certainly can occur though this is extremely rare. I have heard of a case whereby a cryptorchid show dog was given a prosthetic testicle to hide the fact that one of its testicles was not descended, only for the true testicle to descend later on, resulting in the show dog having three testicles for a brief period of time before the prosthesis was removed. A friend with a cryptorchid was also told to consider a trip to Ireland where things could be "sorted" for her, she didn't!
Due to increased heat and blood supply to the retained testicle cryptorchids often have character problems caused by increased testosterone. Some are nervous, some nervous aggressive and some are aggressive. Some hyperactive and difficult to control. Removal of the retained testicle will usually, over a few week alleviate such character problems. But of course the greatest risk is of cancer on the retained testicle spreading within the body in middle age. There is little risk in early life but cryptorchids should have the retained testice/s removed once they are fully grown and the growth plates have closed.
So there you go .. a little copy and paste to help me on the way, but good to know and refer back too in future .....
