Originally Posted by Sled dog hotel

Cryptorchidism as it is known is im pretty certain congenital and thought to be hereditary, and I pretty certain I read somewhere that in certain breeds including the GSD that it is known to be a problem. Sometimes only one doesnt descend, other times they both dont. Ive also heard that they can be difficult to find too and can sometimes be located in the adominal cavity, Im assuming your vet knows his stuff and would have done a thorough search, it can be quite complex an operation depending where the missing one is, and much more complicated then a normal castration.

The undescended testicle is usually under developed and doesnt work so again I suppose but dont know for sure, that it may be posible where they dont develope at all. There can be alsorts of anomalies like dogs being born with both female and male organs for example and internal organs on the outside, so in theory anything is possible I suppose. Cryprotchidism is the correct name for it, you maybe able to find out more if you use that to search and stick to the more verterinary scientific based sites to find out more information.