Insemination can be performed using three types of canine semen: fresh, fresh-chilled, and frozen.
Fresh
Fresh ejaculated canine semen has the longest viability. Semen from young, fertile stud dogs can survive for up to 5-7 days in the bitch’s reproductive tract.
Fresh-chilled
Fresh-chilled semen involves the dilution of ejaculated semen in special canine extenders which contain egg yolk and buffers that protect the sperm during the cooling process. The extended semen is then slowly cooled to 4˚C and can remain viable at 4˚C for up to 3-4 days. (Semen from some stud dogs has been reported to maintain viability and fertility after storage at 4˚C for 10 days). Chilling semen conserves the sperm’s energy and hence prolongs its longevity and viability.
Preserving semen at fridge temperatures facilitates the shipment of canine semen either within the United States or internationally to Canada or Mexico. It is a great alternative to shipment of either the stud dog to the bitch or vice versa when each are located at a distance from each other, which can be very costly and impractical.
Frozen
Frozen semen is stored in liquid nitrogen at the extreme temperature of -196˚C. Semen is preserved in a frozen state in either “straws” or “pellets.” The freeze-thawing process causes some degree of sperm damage, greatly reducing the lifespan of the sperm to only 12-24 hours in the bitch. Therefore, when dealing with frozen semen, it is critical to know exactly when ovulation has occurred so that we can make sure the frozen semen is deposited into the uterus when the oocytes or “eggs” are ready to be fertilized.
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