Permanent contraception of dogs induced with intratesticular injection of a Zinc Gluconate-based solution

Abstract The objective was to evaluate the efficacy of a single intratesticular injection of a Zinc Gluconate-based solution to induce sterility in male dogs. Fifteen pubertal mongrel dogs (8 mo to 4 y old) were assigned to two groups; Control dogs (n = 5) received a single injection of an isotonic saline solution into each testis, whereas Treated dogs (n = 10), were given Testoblock, a proprietary zinc-gluconate (13.1 mg zinc/ml) solution in a physiological vehicle. The volume of saline or Testoblock injected varied from 0.2 to 1.0 ml/testis (based on testis width). Physical examination, testis width, hematology, clinical chemistry (hepatic and renal function), plasma testosterone concentration, semen characteristics, and libido, were assessed until castration (150 d after treatment). In Treated dogs, testis width increased (approximately 20%) relative to that in Control dogs, but subsequently was not significantly different from Controls (group × time interaction, P 6 sperm/ml). We concluded that intratesticular injection of the Zinc Gluconate-based chemical sterilant Testoblock has considerable potential to induce permanent contraception in male dogs.