Researchers in this study determined that the protein profile of canine seminal plasma is very different from that of stallions or bulls. They also noted that there is significant variability in the seminal plasma of different dogs. This project sought to determine whether a “fertility protein” is present in the seminal plasma of dogs. If such a protein exists, it may act as a genetic marker for fertility, because subfertile dogs may be deficient in the genes responsible for the expression of the protein. Subfertile dogs include those whose semen cannot tolerate being chilled, shipped and frozen. The study sought to explore whether altering the protein used in the extender used for frozen semen might resolve this problem. Unfortunately, the project was terminated due to difficulty in obtaining technical assistance. However, the researchers believe that the preliminary findings of this project warrant further investigation.