Canine Reproduction - Main Techniques of Insemination
These notes form part of the Dogs NSW Member Education Breed Seminars, held on DOGS NSW grounds - Dr. Ciaran Galvin MVB (UCD IRELAND)
What are the main techniques of inseminating dogs other than natural service?
The main techniques of insemination are vaginal, transcervical and surgical:
1. Vaginal Insemination Anatomy The vulvar cleft provides entrance to the ventral clitoral fossa and dorsal vestibule. The vestibule is not horizontal in bitches but instead rises at a 45- degree angle relative to the spine. Anything placed in the canine vagina should be introduced dorsally and aimed toward the spine as it is advanced cranially. The vagina of the bitch is very long and the cranial lumen is compressed to nearly one - third in size by the presence of a tissue fold suspended from the dorsal vaginal surface. The cervix is abdominal and the external cervical os hangs from the dorsal surface of the vagina, with a dead - ended fornix lying cranial to it.
Vaginal insemination is most commonly used for introduction of fresh or fresh chilled semen. This may be necessary if the bitch and stud do not show compatible breeding behaviour, if they are too different in size to permit natural breeding or if the semen is being shipped. All bitches used for breeding should be certiﬁed free of heritable conditions and infectious disease. Progesterone assay and other tests should be used to verify the ovulation date.
Procedure Pass the gloved ﬁnger of the nondominant hand, lubricated with water only, into the vaginal canal. This protects the urethral papilla and prevents accidental introduction of semen into the urinary bladder. Draw semen up into a sterile syringe. Pass a pipette along the gloved index ﬁnger and as far forward into the vagina as possible without causing the bitch discomfort. Pull the pipette back so you know it is not lodged against a fold of vaginal mucosa and introduce the semen . Semen should ﬂow freely through the pipette. Flush the pipette with a small amount of air. Withdraw the pipette, leaving the gloved ﬁnger in place, and use that ﬁnger to tickle the ceiling of the vagina. This may stimulate vaginal contractions as would occur during natural breeding and presumably aids in the forward movement of spermatozoa. Withdraw the gloved ﬁnger, The bitch ’ s hindquarters may be elevated for several minutes. No upward pressure should be placed on the bitch’ s caudal abdomen as she is moved from the examining table or put in the car. She should not be permitted to squat to urinate as she leaves the hospital. All of these instructions may be unnecessary, as it may well be that the spermatozoa that will fertilize the ova are well into the uterus and oviduct within moments of insemination.
2. Transcervical insemination Transcervical insemination most commonly is used for introduction of fresh chilled or frozen semen. The short viability of frozen semen after thawing necessitates it being placed into the uterus and this technique is less invasive than is surgical insemination.
Transcervical insemination may also be desirable if quality of fresh semen is poor. Transcervical insemination can be performed multiple times in one heat cycle and can be performed with vaginal or surgical insemination during a given heat cycle.
A rigid, narrow - diameter endoscope, as is used for cystocopy, is required. Introduce the endoscope dorsally at the vulvar cleft and move it gently forward at a 45- degree angle, then angle it horizontally. Pass a long, sterile, polypropylene urinary catheter through the biopsy channel of the scope, such that its tip comes out at the tip of the endoscope. Rest the tip of the endoscope against the external cervical os and advance the catheter into the cervical lumen. This is most easily achieved by spinning the catheter between the fingers. Several attempts may be necessary. Once the catheter is in place, frozen semen should be thawed. Semen should be drawn into a sterile syringe and introduced through the catheter. The semen should ﬂow easily and be visible ﬂowing through the catheter into the uterus with minimal backﬂow. Withdraw the catheter and the endoscope. If a bitch is jumpy or resists restraint, the long, rigid endoscope should not be passed. There are some bitches whose anatomy is such that passage of the catheter by this route is not possible. In those bitches, vaginal or surgical insemination is recommended.
3. Surgical Insemination The uterus of the bitch has a small body and long, torturous horns. Semen can be deposited anywhere within the lumen of either horn.
Surgical insemination is used to introduce semen directly into the uterus, bypassing the vagina and cervix. It is most commonly used with frozen - thawed semen but it can also be used for breeding bitches with a history of subfertility or when using semen of questionable quality. Although canine oocytes may remain viable for more than 200 hours after ovulation, cervical closure occurs 6 to 8 days after the luteinizing hormone peak, requiring introduction of semen directly into the uterus. All bitches used for breeding should be certiﬁed free of heritable conditions and infectious disease. Frozen semen is usually introduced into the female 3 to 4 days after ovulation. Preparation and diagnostic testing should be completed as for any procedure requiring general anesthesia.
Procedure Place the animal under general anesthesia and shave and prepare the abdomen for sterile surgery. Make a ventral midline incision and exteriorize the uterus. Pass a 22- gauge needle or catheter into the lumen of the uterine body. Semen should be thawed as close to the moment of insemination as possible to minimize the time the thawed semen is held at room temperature. Draw the semen up into a sterile syringe. Introduce the semen through the catheter; it should ﬂow freely into the uterine lumen. Withdraw the needle or catheter and blot the hole with gauze until hemostasis is achieved. Replace the uterus in the abdomen and close in a routine manner.