Chemical sterilization with intratesticular administration of zinc gluconate in adult dogs: a preliminary report

BACKGROUND: Chemical sterilization with zinc gluconate is being developed due to its permanent contraceptive effect in prepubertal dogs. In this study, five healthy adult dogs were selected randomly. Semen samples were collected and analyzed before the study to confirm normal testicular function. Under general anesthesia, pH neutralized zinc gluconate was injected directly into their testes. Testes diameter, ultrasonographic appearance, changes in the percentage of white blood cells, and testosterone concentration were monitored twice a week before and 1 month after the injection. At the end of the study, the dogs were castrated and their testes were removed for histopathological evaluation. RESULTS: The general health of all dogs was normal after the injection. The appearance of testicular swelling was limited within 2 days of treatment. The average diameter of left and right testes was 2.48 and 2.03 cm before the injection and reached to diameter 2.12 and 2.15 cm, respectively, at the end of the study. Serum testosterone concentration was 4.2 ng/ml at the start and 4 ng/ml at the end of the study. The percentage of white blood cells at the start and end of the study were within normal ranges reported for dogs. Histopathological analyses indicate a degeneration of germ cells in seminiferous tubules, but Leydig cells retained their structure. CONCLUSIONS: Therefore, It is inferred that the injection of pH neutralized zinc gluconate into the adult dogs’ testes resulted in the loss of sperm-producing tissue without affecting the production of testosterone and the general health of adult dogs.