Histological evidence of an inflammatory reaction to suture material in the dog vas deferens

Objective. To evaluate changes in histology and semen variables after using an elastomeric-hydrogel matrix plug as a reversible vasectomy device in dogs, and to determine the potential applications for improving fertility after vasectomy reversal. Materials and methods. Semen samples from six adult male dogs were obtained after left vasal ligation, placement of the plug in the right vas deferens, and subsequent removal of the plug. The vasa, epididymides and testes were evaluated histologically in four of the dogs after removal of the implant. Results. No sperm were present in the ejaculate after the plug was removed. Histological sections showed intraluminal spermatids in areas where the plug had been placed. The lumen was occluded, secondary to foreign-body giant-cell reaction, at the vasotomy suture site, but other areas of the vas previously containing the implant remained patent after it was removed. Conclusions. There were no sperm in the ejaculate after the plug was removed because the vasal lumen was occluded as a result of an inflammatory reaction to the suture material. In contrast, areas that had contained the implant but without a vasotomy suture were not inflamed. We suggest that further trials comparing various suture materials are carried out to determine if patency rates can be improved during vasotomy closure or vasovasostomy.