Histopathologic changes in testes three days after administration of zinc gluconate neutralized with arginine as an intratesticular injection for contraception

Abstract

Five prepuberal mixed breed dogs were treated with zinc gluconate neutralized with arginine as an intratesticular injection, which is approved by the Food and Drug Administration as a non-surgical sterilant for puppies aged 3-10 months with testicular width between 10 and 27 mm. The product was administered following manufacturer’s recommendations. Three days later, all dogs underwent surgical castration and the testes, epididymes, and a portion of the spermatic cord submitted for histopathologic evaluation. Both testes from all five dogs showed variable degrees of liquefactive and coagulative necrosis with focal acute neutrophilic orchitis, hemorrhage, and edema. Percentage of the testis showing degenerative and necrotic changes averaged approximately 45.5% and ranged from 10-90% among the ten testes examined. Unaffected seminiferous tubules were lined by Sertoli cells and spermatogonia with rare elongated spermatids; this was compatible with the prepuberal life stage of the animals. Neutrophilic and lymphohistiocytic epididymitis with edema and vasculitis was present in six of the ten samples. Funiculitis (inflammation of the spermatic cord) was present in nine of the ten samples. This is the first report of testicular and epididymal histologic change within days of administration of the product and the only report documenting changes in the vas deferens at any point after administration of the product.