21 Artificial Insemination
That depends on what state you live in. The state veterinary medical association or the legislature can provide you with that state’s veterinary practice act. This law outlines what people who are not licensed as veterinarians are prohibited from doing.
TCI stands for transcervical insemination, a technique that allows semen to be introduced directly into the uterus without the bitch having to undergo surgery. This technique is especially useful for chilled or frozen semen.
In general, the more the spermatozoa are manipulated, the worse the conception rate. Natural service is best, with fresh semen a close second, followed by chilled semen, then frozen semen. Conception rate can be improved by good timing of insemination, inseminating more than once whenever possible, and inseminating in the proper location.
Splitting of ejaculates is commonplace in bulls, stallions, and boars but rarely is done with dogs. Dog semen is naturally much more dilute than is large-animal semen, and it is the rare dog that has such a high number of spermatozoa in the ejaculate that he can breed more than one bitch with one ejaculate. Remember, the number we are looking for is 250 million normal spermatozoa at the very least.
Artificial insemination (AI) consists of semen collection from the male and insemination into the bitch. Semen may be used immediately; chilled, shipped, and inseminated within 24 hours of collection; or frozen in liquid nitrogen and stored indefinitely before insemination. AI is used when natural breeding cannot take place because of physical abnormalities of the bitch or stud or a great difference in size of the mating pair, behavioral incompatibilities, or geographic distance separating the mating pair. Popular males that are working dogs that might not be available when necessary for natural service can have semen frozen to permit breeding at all times. Males that have developed a disease condition requiring castration or that have died are still available genetically if they have had semen frozen.
AI with fresh semen may be a method of disease control. Any bacteria present in the reproductive tract of the male or female dog also are present in the vaginal secretions and semen. During natural breeding, many bacteria are exchanged between the dogs. However, it has been demonstrated that the newly introduced bacteria are expelled quickly, and the normal bacterial population is reestablished. Preventing disease transmission by AI will protect bitches only if antibiotic is added to the semen. Stud dogs are protected because they need not come in contact with the bitch. Use of AI to prevent transmission of brucellosis may be effective, but breeders must be aware that brucellosis is more commonly contracted by oral exposure to urine or other body fluids containing Brucella organisms than by breeding.
Breeders should be aware that performing AI on their own and other dogs is illegal for nonveterinarians in some states. For example, in Minnesota owners can perform AI with fresh semen on their own animals but cannot legally perform AI on animals they do not own and cannot use semen that has had anything added to it.
I. TYPES OF INSEMINATION
A. VAGINAL
During natural service, the male dog deposits semen into the bitch’s vagina. The penis cannot reach the cervix because of the fold of tissue hanging from the ceiling of the vagina that decreases size of the vaginal vault. It is thought that this tissue compresses the tip of the penis and promotes ejaculation of semen directly toward the cervix. With vaginal insemination, semen is deposited near the same area of the vagina as in natural service but without the force of ejaculation. Vaginal insemination is noninvasive and can be performed repeatedly during a given estrus.
Semen is placed within the bitch’s vagina using a pipette. I prefer long bovine pipettes to the short canine pipettes that are marketed for AI in dogs (Figure 21-1). A specific insemination pipette for dogs, the Osiris pipette, also is available. This pipette contains a balloon that is inflated to prevent backflow of semen.
The gloved index finger of the nondominant hand is inserted into the vaginal vault; this may not be possible in very small dogs. This finger prevents movement of the insemination pipette into the urinary bladder. The hand is turned so that the palm of the hand is turned up. The semen is drawn into a syringe and connected to the pipette. The pipette is passed over the inserted index finger as far into the vagina as it will pass without causing discomfort to the bitch (Figure 21-2). The pipette is withdrawn slightly to ensure that it is not trapped against the vaginal wall and the semen expressed through the pipette with the syringe. A small amount of air also is introduced to ensure that all the semen has been introduced into the vagina. The pipette is removed, and the gloved finger is used to stroke the ceiling of the vagina. This often stimulates vaginal contraction and may help move spermatozoa forward in the reproductive tract.
During and after insemination, it is important that no pressure be placed upward on the dog’s caudal abdomen. The vagina lies in the horizontal plane in the caudal abdomen and is muscular. Any upward pressure will cause expulsion of the semen introduced. After insemination, the bitch may be “wheelbarrowed” up onto her forelimbs for 5 to 20 minutes to promote semen pooling at the cervix. Holding the bitch up in this fashion is not necessary to achieve good conception rates, however. Similarly, many people recommend that dogs not be allowed to squat to urinate or to jump up into a car or onto furniture for 20 to 30 minutes after insemination; again, this has not been shown to be necessary.
B. INTRAUTERINE
With this technique, as the name implies, semen is deposited directly into the uterus. Conception rate is higher and litter size is larger with intrauterine than with vaginal insemination. Intrauterine insemination is more technically demanding, and some forms are more invasive and dangerous to the bitch.
1. Norwegian Catheter
This is a blind technique. A plastic sheath containing a stainless steel catheter of the appropriate size for that bitch is passed into the vagina as far forward as possible. The veterinarian palpates the dog’s abdomen to find the cervix and immobilizes it. The stainless steel catheter is passed through the cervix, and the semen is expressed through the pipette with a syringe. Because this technique is noninvasive, multiple inseminations can be performed during a given estrus. This technique is technically demanding. There is a possibility of puncture of the cervix or vagina in the hands of an inexperienced veterinarian. This technique is not used routinely in the United States.
2. Endoscopic
This is not a blind technique. The bitch need not be sedated in most cases. The bitch is restrained standing. A long, narrow endoscope is passed the length of the vagina and used to visualize the cervix (Figure 21-3). A urinary catheter is passed through a channel on the endoscope, which is used to guide the catheter through the cervix. Semen is expressed through the catheter with a syringe. Because this technique is noninvasive, multiple inseminations can be performed during a given estrus. This technique requires specialized equipment and is technically demanding. The cervix hangs from the ceiling of the vagina and is muscular. The opening of the cervix lies perpendicular to that of the vagina, requiring deflection of the catheter as it enters the cervix. Often multiple attempts are required before the catheter passes, and in some bitches the catheter cannot be passed using this technique. Endoscopic insemination is available throughout the United States.
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