Spermatogenic Function and Fertility in Unilateral Cryptorchid Dogs after Orchiopexy and Contralateral Castration

Abstract

Orchiopexy and contralateral castration were performed in a total of 5 adult and 2 young unilateral cryptorchid (CR) dogs. In every dog, biopsy was performed on the testes, and peripheral and spermatic venous blood samples were collected at intervals of 2, 4 or 8 weeks after the operation. Biopsy tissue specimens were observed after staining with PAS-hematoxylin. In the young CR dogs semen was collected by digital manipulation every week and the sperm fertility was examined by artificial insemination. Neither spermatid nor spermatozoon was noticed in any CR testis at the time of the operation. Spermatozoa were found in the seminiferous tubules of the young and adult CR dogs for the first time, 8 and 10 weeks after the operation, respectively. Thereafter, the number of sperms and germ cells in the seminiferous tubules increased. In the adult CR dogs plasma testosterone levels increased gradually in both peripheral blood and CR testicular venous blood after orchiopexy. In the young CR dogs spermatozoa first appeared in the ejaculate, 8 weeks after orchiopexy. Then, semen volume and sperm number increased gradually, but a high rate of sperm abnormality continued until 24 weeks after the orchiopexy. Semen quality, however, was relatively excellent when sperm fertility was studied 25 weeks after orchiopexy and later. Eight and three bitches were inseminated artificially with the semen of the 2 young CR dogs, respectively. As a result, two of the former and one of the latter became pregnant and gave birth to 2, 2 and 8 youngs, respectively. In conclusion, in the CR testes of the CR dogs the spermatogenic function was stimulated and spermatozoa with fertilizing capacity were produced by the orchiopexy, and puppies were born by artificial insemination of the spermatozoa. But the fertility of the CR dogs was lower than that of normal dogs.