"We know that in a natural mating, or mating with fresh semen ,
the semen can last 7 days or so. Bitches may ovulate over 2 – 3
days. This range of timing means if you don’t hit all the eggs
being released when you mate your bitch, semen is still viable
for several days to “mop up” the later eggs and lead to a
Chilled semen , such as you may send to a bitch owner based in
Europe, will last for approximately 4 days. Again there is some
cross over here for sperm to meet eggs, but success becomes
improved if semen is placed through cervix into uterus.
When frozen semen is used we are dealing with a
much tighter window for success – frozen semen will only last
12 hours when thawed. Timing for AI is therefore critical
and we also need to minimize any barriers to success by placing
the semen into the uterus, most commonly through a TCI technique
. Some operators in recent studies report a greater than 75%
success with frozen semen TCI methods these days."