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ADVICE FOR RECIPIENTS OF CANINE FROZEN SEMEN 2015
Philip Thomas BVSc PhD FACVSc Dip ACT
INTRODUCTION
Undertaking a canine frozen semen breeding is complex and expensive. This advice is provided to
the owner of the bitch who is to receive the semen. It is intended as a guide and to provide clarity
and transparency about the process of ordering frozen semen.
Dogs make an enormous excess of sperm – most are lost in urination or masturbation. It is
ridiculous that sperm numbers in an insemination dose (or breeding unit) should be restricted and
impact the conception of your bitch.
This note is intended to inform you so that you receive sufficient good quality sperm for your
planned frozen semen breeding.
REAL RESEARCH AND ANECDOTE
Canine semen has been frozen commercially for decades. In spite of this, there are a lot of
anecdotal stories about what works and not much good objective comparative research data. In this
note we will distinguish between good scientific information which is valuable, and opinions which
are of questionable benefit.
SEMEN FREEZING METHODS
There are several methods for freezing canine semen. Most are derivatives of methods developed
for freezing bull sperm in the 1950’s. Some methods have been published and some are proprietary.
There has been no good objective data to suggest that any one method is universally superior to all
others.
Semen freezing involves multiple steps. Incremental benefits in post-thaw motility can be made by
improving each step. The biggest determinant of post-thaw success is the individual dog that
donated the semen, rather than a specific extender, or package, or freeze method.
Beware the claims of proprietary methods. For example, it has been claimed that freezing in pellets
is superior to freezing in straws. There is no objective evidence to support his claim, indeed, of the
many factors that affect post-thaw motility, the freezing package seems to be of little importance.
THAW MEDIUM FOR FROZEN SEMEN
Some semen frozen by “secret” or proprietary methods is intended to be thawed in special thaw
medium. Some thaw medium is simple extender and some is saline and some is more complex.
Please be aware that thaw medium imported from overseas may not be allowed to pass through
Australian Quarantine and Customs.
Thaw medium is mostly not essential for thawing semen, but before ordering semen, you should
contact the providers of the semen and ask if the thaw medium is essential. If it is essential, then do
nor order the semen from overseas unless you are sure that the thaw medium can enter Australia.
BE SKEPITCAL
Be wary of the claims made by the providers of frozen semen. They are often exaggerated. Semen
freezing reports can overstate the quality of the semen.
If it sounds too good to be true then it probably is not true. For example, post-thaw progressive
motility of 80% in unusual in frozen semen.
INSEMINATION DOSE WITH FROZEN-THAWED (FT) SPERM
There is a lot of opinion and almost no good research data about how many frozen-thawed
spermatozoa are necessary for normal fertility. We know the following things:
1. If sperm numbers are not limited, it is possible to achieve acceptable pregnancy rates and
litter size with FT sperm, even if it is deposited in the vagina by traditional artificial
insemination techniques.
2. When an ejaculate is frozen, it is often split into individual breeding units which are fractions
of an ejaculate.
3. As an ejaculate is split into more fractions, sperm numbers in the insemination dose
decrease, and eventually litter size and pregnancy rates are affected
4. There is not yet good information about what is the threshold number of FT sperm for
normal fertility.
5. It is likely that this threshold will be different for vaginal, surgical intra-uterine (SI) and
transcervical insemination (TCI) techniques
6. As more information becomes available, it may be that TCI and SI require the same numbers
of FT sperm.
7. FT sperm are assessed as follows:
a. Total sperm numbers
b. % Pre-freeze normal morphology (sperm cell shapes)
c. % Motile (moving sperm - this may be progressive or total motility)
d. % Live (sperm not damaged by the freeze-thaw process)
8. It is widely believed, with some supporting evidence, that less than 100 million progressively
motile, or 100 million live motile, or 100 million normal motile FT sperm, will adversely
affect conception rates and litter size.
9. Therefore 100 million progressively motile, or 100 million live motile or 100 million normal
motile sperm is the absolute minimum number of FT sperm that you should seek in an
insemination dose.
10. Because of the following factors, we feel that 200 million progressively motile, or live motile
or normal motile sperm is an appropriate number for you to seek when purchasing an
insemination dose
a. Objective data show that the counting methods used to count total sperm numbers
can be up to 20% inaccurate
b. There is an enormous range of skills and knowledge among the centres that freeze
semen – some are well-informed and have excellent technique and others less so.
c. FT semen unpackaged at our centre frequently has poorer characteristics (lower
sperm numbers and worse motility) than what is reported on the semen freezing
report from the freezing centre.
d. The international leader in this field, Dr Catherina Linde Forsberg has the results of
4,000 intra-uterine inseminations submitted to the Swedish Kennel Club. She
recommends for each bitch TWO inseminations of 100-200 million live normal
motile sperm – so a total of 200 to 400 million sperm in total.
11. The more sperm you can inseminate, the better.
INSEMINATION DOSE WITH FROZEN-THAWED (FT) SPERM: SOME NEW INFORMATION
1. In 2011 at QVS we completed a project which examined retrospectively the difference
between insemination doses. This study will be published in the scientific literature in 2012.
2. Our findings can roughly be summarised as follows: for surgical insemination with FT sperm
a.
when 200 million motile sperm post-thaw were inseminated, more than 90% of
bitches conceived
b. when 100 million motile sperm post-thaw were inseminated 70-75% of bitches
conceived and litter sizes were reduced by 1.5 fewer pups per litter when compared
to bitches that received 200 million sperm inseminated
3. These data are not definitive in their own right, but do support our contention that an
insemination dose with more sperm is better, and that 200 million is better than 100 million.
RECOMMENDATIONS AT QUEENSLAND VETERINARY SPECIALISTS
Based on the information we have provided here, we make the following recommendations
1. If you, the bitch owner, pay for the male dogs semen to be frozen and also pay a stud fee
then you should request the WHOLE ejaculate, not just a single breeding unit or a fraction of
the whole ejaculate.
2. If you, the bitch owner, pay a stud fee only, then you should request at least 200 million live
normal or normal motile sperm
3. If the dog owner provides you with less than this threshold, we recommend that you arrange
with the owner of the stud dog EITHER
a. to pay the stud fee only when the bitch is diagnosed pregnant by ultrasound at 28
days, OR
b. to request that if the bitch is not pregnant, then the owner of the stud dog will
provide a second insemination dose at no charge
4. We understand that you may or may not be able to achieve these recommendations, and we
will be happy to help you no matter how few sperm you receive. It is uncommon but
pregnancy has been achieved here at QVS with as little as 20 million normal motile sperm.
WHAT’S IN IT FOR US
There is nothing in it for us. We get paid whether your bitch gets pregnant or not. But we want
what you want – a good healthy litter. We firmly believe that, having invested the time and expense
(and a bitch cycle), you are entitled to receive sufficient good quality sperm to impregnate your
bitch.
WHO IS PHILIP THOMAS?
Philip is a veterinarian, a Diplomate of the American College of Theriogenology, Australian Specialist in
Reproduction, holder of a PhD in Animal Reproduction (Cornell University), a Fellow of the Australian College of
Veterinary Scientists (in Canine Reproduction), and Adjunct Professor (University of Queensland, School of
Veterinary Science). He publishes, teaches and provides continuing education to veterinarians in Animal
Reproduction. He works in general, specialist and academic practice.