Page 58 - Aussie Magazine - 2024 Issue 3

Breeding

Timing & Monitoring

Timing of insemination is very
important. Monitoring your bitch’s
heat, or estrous cycle, to determine
the optimal time to inseminate
involves carrying out one or a
combination of the following
procedures:
• Blood samples to measure the
hormone progesterone
• Vaginal smears for cytologic
evaluation to help determine
Types when to inseminate and evaluate
for infectious or inflammatory
Many factors contribute to the likelihood of pregnancy processes
when using artificial insemination, including the type • Vaginoscopy to assess the
of semen (fresh or frozen), semen quality and quantity,
age and fertility of both the stud dog and bitch, site of vaginal vault which correlates
semen deposition (intrauterine or vaginal), and time of to the stage of the estrous cycle
insemination. Insemination can be performed using three and is a very helpful tool for
types of canine semen: fresh, fresh-chilled, and frozen. timing. Vaginoscopy can also
Freshly ejaculated canine semen has the longest viability. rule out anatomic abnormalities
Semen from young, fertile stud dogs can survive for up (strictures, septa, persistent
to 5-7 days in the bitch’s reproductive tract. Fresh-chilled hymen) prior to breeding.
semen involves the dilution of ejaculated semen in special
canine extenders which contain egg yolk and buffers The number of samples that need
that protect the sperm during the cooling process. The to be taken to determine when to
extended semen is then slowly cooled to 4˚C and can inseminate varies between bitches.
remain viable at 4˚C for up to 3-4 days. (Semen from Most clinics recommend starting
some stud dogs has been reported to maintain viability testing approximately 5 days after
and fertility after storage at 4˚C for 10 days). Chilling the onset of heat (first observable
semen conserves the sperm’s energy and hence prolongs sign) and then every second or third
its longevity and viability. Preserving semen at fridge day until it´s determine when the
temperatures facilitates the shipment of canine semen bitch has released her ovulatory
either within the United States or internationally to Canada hormone called “luteinizing hormone”
or Mexico. It is a great alternative to shipment of either the or “LH.” The day this occurs is called
stud dog to the bitch or vice versa when each is located the “LH surge” or “LH Day 0” and
at a distance from the other, which can be very costly and coincides with a progesterone level
impractical. Frozen semen is stored in liquid nitrogen at around 2 ng/ml. The day or days
the extreme temperature of -196˚C. Semen is preserved on which are recommend artificial
in a frozen state in either “straws” or “pellets.” The freeze- insemination to be carried out
thawing process causes some degree of sperm damage, depends on the type of semen that is
greatly reducing the lifespan of the sperm to only 12-24 to be used. For example, insemination
hours in the bitch. Therefore, when dealing with frozen with frozen-thawed semen is carried
semen, it is critical to know exactly when ovulation has out on “Day 5” (post LH 0) when only
occurred so that we can make sure the frozen semen is one insemination is to be carried out,
deposited into the uterus when the oocytes or “eggs” are or on Days 4 and 6 or 5 and 6 (post
ready to be fertilized. LH 0) if two inseminations can be
performed.

58 | A Worldwide Magazine for the Aussie • Issue 3/2024