Breeding Options in the Bitch
Rebecca Kestle, DVM
(The following article, reprinted with permission, was taken from the 2008 Canine Breeder’s Symposium, sponsored by the Society for Theriogenology and the American Kennel Club Canine Health Foundation. The Society for Therinogenology will be holding another Breeder Seminar on August 29, 2009 in Albuquerque, New Mexico. It will be a one day seminar and you can find more information and registration requirements posted on their website at http://www.therio.org in the near future.)
The goal of responsible dog breeders is to produce healthy puppies that adhere to specific breed standards and that can fulfill the jobs they are bred to do. With the advances in artificial insemination techniques that have occurred in the last 15 years, breeders have the option of choosing stud dogs from all over the world. That makes choosing the best brood bitch invaluable to a breeder, and knowing the options of breeding the bitch can help one achieve the best outcome.
Fertility in the bitch peaks when she reaches middle age (4 – 5 years) and declines thereafter. This allows breeders enough time to follow the guidelines of their breed clubs for pre-breeding genetic screening before breeding a bitch for the first time. Many breed clubs recommend waiting until bitches are at least two years old of age so that OFA X-rays, eye certifications, and thyroid testing can be done before the bitch is bred. Other breeds have even more stringent testing such as DNA markers for a variety of diseases. It is up to reputable breeders to maintain the quality of their brood bitches. Once the prescribed genetic testing has been performed, breeders must decide which insemination technique will be the best for the bitch depending on the type of semen to be utilized.
The bitch should be examined by a veterinarian who will take a thorough history, check for vaginal strictures, and perform a complete physical exam. A Brucellosis test is recommended since this disease is a contagious, potentially zoonotic (spread to humans), life threatening bacterial disease that can be transmitted via breeding or by coming into contact with infected material such as aborted feti, contaminated uterine secretions, semen or urine.
Guarded, cranial vaginal cultures are recommended on any bitch with a history of fertility problems. The culture is usually obtained on day two to three after bleeding begins and is sent for isolation of aerobic/anaerobic bacteria and Mycoplasma organisms. Many bacterial organisms, and even Mycoplasma, can be normal in the vaginal tract of bitches, but they can also cause infertility if they overgrow the normal bacterial flora of the vagina and are not treated. The veterinarian will start the bitch on the appropriate antibiotic if necessary. For bitches that do not conceive and have grown Mycoplasma on vaginal culture, it is recommended that they undergo treatment with doxycycline for four to eight weeks in between their heat cycles.
Ovulation timing is of the utmost importance, especially if you are using any type of processed semen, such as fresh chilled or frozen. The hormone that induces ovulation in the bitch is luteinizing hormone (LH). Testing for LH can be done using an in-house kit, ICG Status-LH (*1). LH testing must be done daily to catch the LH surge since it may only last 12 – 24 hours. Even with LH testing, it is recommended to confirm ovulation with progesterone assays. Progesterone testing is readily available in most cities in the United States. Different types of progesterone assays are available. In-house kits identify ranges of progesterone, and must be run daily to counter the inaccuracy of the method.
Commercial laboratories either use radio immunoassay (RIA), chemiluminescence (CLI), or enzyme linked fluorescent assays (ELFA). Some practices have in-house numerical progesterone machines (i.e. miniVIDAS or immulite machine) and can run progesterone samples in about an hour. Each veterinarian will have his or her own protocol as to when to breed bitches based on the type of breeding and their experiences.
Progesterone begins its normal rise at the time of the LH surge that stimulates ovulation. Serum progesterone concentrations are about 2 ng/ml on the day of the LH surge, and 4 -10 ng/ml on the day of ovulation. With each different type of assay the actual numerical value may differ, so be careful in memorizing a “magic” number. The eggs of the bitch are not ready to be fertilized at the time of ovulation. They must continue to mature, and it takes about two days before they are ready to be fertilized. The optimal days for breeding will be determined based on the day of ovulation and the type of breeding/insemination chosen.
The vast majority of canine litters are produced by natural matings. Natural breeding is best used for young dogs and bitches that are thought to have good fertility. There is nothing wrong with presenting the bitch to the stud dog at about the time of ovulation and breeding the dogs every other day while she will stand and the stud has interest. It is best to bring the female to the stud dog and have supervised breedings so no fighting or injury occur. In young or inexperienced males, assistance may be required. Semen is not generally evaluated with a natural breeding, so litter size can be used as a potential indicator of semen quality. It must be remembered that small litter size may be due to sub fertility of either the male or female or a combination of both, so small litter size is not a direct indicator of poor semen quality, but rather an indicator that further workup of both male and female are required. With breeds that may require a Caesarian section, it is very important to determine the day of ovulation to help determine the timing of the surgery.
Vaginal Artificial Insemination
The utilization of artificial insemination (AI) has been dramatically increasing over the past few years. Fresh AI offers the advantage of being able to evaluate the semen prior to insemination. The semen is collected with minimal prostatic fluid. An extender can be added if there is any decrease in sperm quality, or an alternative method of insemination may be chosen. An insemination pipette is gently inserted into the vagina with the bitches’ hindquarters being elevated for at least five minutes. There is some evidence that it may not be necessary to elevate the hindquarters after vaginal AI to obtain normal pregnancy rates and litter size. After injection of the semen using a syringe, light feathering of the vagina with a gloved finger is helpful in simulating the action of the copulatory lock. Vaginal AI is usually performed either on days 2 and 4 (or 1 and 3) after ovulation or on day 4 and 6 (or 3 and 5) after the LH surge.
Transcervial Insemination (TCI)
Transcervical inseminations are normally performed with an endoscope to visualize the cervix. An alternative method of TCI uses a blind catheterization technique (Scandinavian catheter) with a rigid vaginal catheter. Either method of TCI requires specialized equipment and training. With endoscopic TCI, a camera on the end of the endoscope allows visualization of the cervix, to allow for passage of a catheter into the uterus, where semen is deposited directly. This increases the number of sperm that enter the uterus as opposed to the loss associated with deposition in the vagina. Use of TCI decreases the number of sperm needed to doses as low as 100 – 200 million normal, motile sperm. The uterus of the bitch can only hold about 2-3 milliliters (ml) of semen depending on the breed (1 – 1.5 ml in toy and small breeds). The semen must either be collected in fractions (pre-sperm, sperm and post-sperm fractions) saving only the sperm-rich fraction for insemination, or the semen must be concentrated by low speed centrifugation and then resuspended with extender.
TCI is normally performed on the unsedated, standing bitch. It is not as easy to perform on maiden bitches, toy breeds and some giant breeds due to either the size of the vaginal canal near the cervix or to the fact that the cervix may not relax adequately prior to whelping to allow passage of the catheter. Lack of visualization of the cervix may occur due to blood and secretions pooling at the front of the vagina. Additionally, the cervix may not be able to be moved to the proper angle to allow passage of the catheter. In rare cases, the vaginal canal of some giant breed bitches may be too long for the scope to reach the cervix.
However, in most cases, in competent hands TCI is a most useful tool. TCI is usually used with fresh or fresh extended semen. The benefits are that a smaller breeding dose is required and conception rates should be higher than with vaginal AI, especially when breeding bitches or dogs with fertility problems. TCI can be used with frozen semen, but surgical insemination is generally still preferred. The disadvantages of TCI include increased cost of the procedure and the need for extensive training and practice for reliable results. TCI is usually performed two times; once on day 2 and 4 (or 3 and 5) post-ovulation, or if performed once, then it is on days 3 or 4 post-ovulation.
Surgicial Insemination (SI)
Surgical inseminations are a routine procedure. During the procedure, the bitch is anesthetized and her abdomen clipped and prepared for surgery. An abdominal incision is made (much like a spay) and the uterus is located. Semen is injected directly into the uterus using a needle or catheter. The entire procedure takes less than 30 minutes. One major advantage of the surgical insemination is that the uterus can be visualized, palpated, and evaluated for pathology. It is not uncommon to find cysts in the uterus that can be gently ruptured prior to insemination to try to improve fertility. Other common pathologic findings include adhesions or thickened uterine walls. With surgical inseminations, the bitch is usually bred one time, 3 – 4 days after ovulation.
Surgical inseminations are useful with any type of semen where semen quality may be compromised, with frozen or fresh chilled breedings, or on females with fertility problems. Similar to transcervical inseminations, the volume inseminated must be small. Frozen semen is packaged such that a breeding dose is in a volume of 1.5 – 2 ml.
The advantages of surgical insemination are the ability to inspect the uterus and ovaries, delivery of the entire breeding dose directly into the uterus, and minimizing contamination during breeding. SI leads to the highest rate of conception in many cases. The disadvantages include cost, risk of anesthesia, risk of abdominal infection (peritonitis), and risk of incisional infection. With a single SI, the cost of the surgery plus semen shipment is often equal to or less than that required for 2 TCI.
Multiple Sire Litters
The AKC allows breeders to use more than one stud dog during a breeding. This is especially useful if one is using semen from a sire that may be of questionable quality. Rather than losing the pregnancy due to failed conception, a second proven sire may be used to back up the sub-fertile sire. Generally speaking, the sub-fertile sire is inseminated first (on day 3 post-ovulation), using SI or TCI, and then the proven sire is inseminated 24 hours later (on day 4 postovulation), using TCI or vaginal AI (or natural breeding if a SI was not performed the day before). The use of 2 fertile sires will generally result in all the puppies being sired by only one of them, even if the semen from both sires is deposited at exactly the same time. DNA testing is required on the dam, both sires and all of the resulting puppies to determine parentage.