Indeed. Here's a true story: a 2 year old, sold as a registered gelding and by three had himself an interesting collection of foals scattered about hither and yon until it was realized that he was not really a gelding but a cryptorchid stud. The registry was contacted, his designation changed from gelding to stallion after a running battle between the registry, the owner and the vet. The owner then happy with the value of a surprise stud at gelding price (sold him shortly thereafter). The vet unhappy and insisting that the cryptorchid stud must have surgery or be at risk of imminent death almost daily ( and all the other horror stories about crypts), and the registry insisting that a horse that produces progeny is a horse (stallion, in registry terms). The horse just wanted to have fun.
The horse won the whole pot in the end, became legally a horse again and went on to create many other horses and more than a decade later still lives on. Interestingly enough, few of the many who have visited with this particular horse (who is quite masculine in his appearance and carriage) ever realized he was a crypt. Cowboy