Semen quality during vincristine treatment in dogs with transmissible venereal tumor.

The aim of this study was to evaluate the direct effects of vincristine on semen quality in dogs with transmissible venereal tumor (TVT). We examined the semen of 17 dogs suffering from TVT during vincristine treatment. Each animal received 0.6 mg, i.v. vincristine sulphate per square meter of body surface, per week for 4 wk until complete regression of the tumor. The following semen parameters were evaluated: semen volume (second fraction), sperm concentration, total spermatozoa per ejaculate, percentage of progressively motile spermatozoa, percentage of dead spermatozoa, percentage of swollen spermatozoa (hypo-osmotic swelling test) and percentage of morphologically abnormal spermatozoa (primary and secondary defects). Semen was collected and evaluated prior to the beginning of treatment, 3 d after each vincristine injection and 15 d after the last injection. Semen characteristics transiently deteriorated during treatment, but returned to normal 15 d later. These changes were attributed to a direct effect of vincristine on the extragonadal spermatozoal reserves contained in the epididymis and ductus deferens. A GnRH stimulation test was also performed after each semen collection in order to assess the function of the hypothalamic-pituitary-Leydig cell axis. No effect was noted on the above axis.

Extracellular presence of reactive oxygen species (ROS) in fresh and frozen-thawed canine semen and their effects on some semen parameters.

The objective of this study was to determine the presence of reactive oxygen species (ROS), especially superoxide anion (O2-), in fresh and frozen-thawed canine semen, its effect on other seminal parameters and whether the freezing-thawing process influences the O2- production rate. A total of 56 mature male domestic dogs were used in this study. Their semen was examined before and after freezing-thawing process. Sperm motility, hypo-osmotic swelling, sperm morphology and O2- extracellular production were measured. The dogs were divided in two groups, with the criterion of the absence or presence of O2- in fresh semen (groups A and B, respectively). Values of group A were compared with the respective values of group B. A significant decrease in motility and percentage of swollen spermatozoa and an increase in morphological abnormalities and O2- production in group B were found in comparison with group A after freezing-thawing process (p < 0.05). It seems that the freezing-thawing process leads to an increase of the O2- production. However, it remains to be documented if the increased concentrations of O2- in canine semen are responsible for the alterations in the seminal parameters observed in this study.