Studies on Cryopreservation of Epididymal Sperm in Dogs

Abstract

The current work aimed to investigate effects of methods of collection, type of extenders, type of cryoprotectants, type of egg yolk and the type and concentrations of certain antioxidants on the post-thaw quality of dog epididymal spermatozoa. The study was carried out on a total number of 264 testes of 132 clinically healthy dogs of various breeds (age range 2-5 years, bodyweight 25-45 kg) after a routine castration at the dog shelter of the Egyptian Society of Mercy to Animals (ESMA). Following castration, each dog's testis, epididymis, and surrounding tunics were placed in a thermos flask containing a sterile 0.9 % NaCl and kept at 4oC for 12 hours before being brought to the laboratory. The tunics were removed from each testicle for processing, with special care not to harm the epididymis where it connects to the testis. The cauda epididymis was dissected out of each testis. Five studies were done: Study 1: This study was performed to investigate firstly the effects of method of sperm collection from the dog epididymides (experiment 1), type of the extender (experiment 2) and the type of cryoprotectant (experiment 3) on the post-thaw epididymal sperm quality. Experiment 1: spermatozoa were collected from the left and right cauda epididymides of 21 dogs using mincing or flushing methods. This was established by using one technique on one of both testis and the other technique on the other testis. Samples showing more than 70% motility and 75% live sperm were selected for processing. The collected sperm suspension was diluted with Tris-Citric acid-Fructose (TCF) extender to a final concentration of 300×106 sperm/ml. The diluted samples were gradually cooled to 5oC and held at this temperature for 2 hours to equilibrate, packaged in 0.25 ml straws, and frozen horizontally 5