Today, many dog breeders and veterinarians have found artificial insemination (AI) to be an invaluable tool. It has been seen as a way to increase the quality of a breed by overcoming limitations of both time and space. This breeder is no exception and Dr. Bos had the privilege of performing the procedure on Bailey, a beautiful Boston Terrier.
The actual technique and methods of artificial insemination are relatively easy. Although the field is relatively new in canine medicine due to the relative instability of canine sperm when frozen or chilled, it has been successfully practiced in cattle and other species for many decades.
Collecting semen from a stud dog is very simple. A female in heat is brought together with the male. When he tries to mount her, his penis is redirected into an artificial vagina and stimulated to cause an ejaculation. The presence of the female is useful to excite the male and makes collection easier. (During estrus, organic compounds known as ‘pheromones’ are excreted from the female’s vagina. These airborne chemicals are responsible for attracting males from long distances to the female. They even indicate the stage of her heat.) If such a female is not available when the male is to be sampled a common practice is to save and freeze cotton swabs that have been wiped through the vagina of a female when she was in peak estrus. At the time of semen collection, the swabs can be wiped around the tail area of any dog (even a spayed one). The male will then respond to her just as if she were in heat.
For successful AI, the semen must be collected and handled properly. Semen can be used fresh, it can be chilled and used within 24 hours, or it can be frozen. The more processing that is done to the semen, the less likely it will result in fertilization.
In this case after the collection of the semen, a semen extender was used to protect and nourish the semen. It was then chilled and shipped ‘Next Day Air’ to be used within 24 hours of collection. This procedure has made males available to appropriate females all over the world without either one of them needing to travel.
Once our breeders arrive at the clinic the first step for Dr. Bos is to do a quick evaluation of the semen that has been collected. Dr. Bos looks at the semen through the microscope to ensure that the sperm cells are sufficiently concentrated, adequately motile, and appear anatomically normal.
The microscopic semen evaluation is no guarantee that the sperm present are in fact capable of fertilization however in this case the sperm look well concentrated and motile. Press play to view what Dr. Bos sees through the microscope.
The heat cycle in a bitch
We now move onto the female or bitch. In a canine heat the dog’s vagina swells and she bleeds for 7 to 9 days. This is the preparatory Proestrus stage. Next, the bleeding diminishes and she becomes receptive to the male and allows him to mate. This is Estrus. Only during the 3 to 7 days of Estrus will the bitch be in the proper stage to become pregnant. After 3 to 7 days, she moves into the Diestrous stage, is no longer fertile, and will not accept a male’s advances.
Preparing the Female
Knowing exactly when to inseminate the female can be quite challenging and, if not done properly, fertilization will not occur. In traditional breeding programs, with natural service, the bitch is bred at least three times on the 9th, 11th and 13th day after the vulva begins to swell and blood tinged discharge is seen. On average, bitches tend to ovulate on the 12th day after the onset of vulvar swelling.
Bailey had her progesterone levels taken twice between the 3rd and 7th day of her cycle. For laboratory values, the serum progesterone is typically less than one ng/ml until 2 days before ovulation. At this time, the level of progesterone will rise to 1 to 2 ng/ml. On the following day (one day before ovulation), the progesterone level will be 2 to 4 ng/ml. On the day of ovulation, the progesterone will be 4 to 10 ng/ml. After ovulation, the progesterone levels rapidly rise and can be anywhere between 15 to 90 ng/ml.
The measurement of progesterone levels is an accurate method of determining when a female is ready to be breed but can be time consuming and daily checks throughout the heat cycle is not always practical or affordable. The hormone progesterone can be measured within the blood. The most accurate measurements can effectively predict ovulation.
If the sperm cells seem to be adequate in number and appear normal, they may be immediately infused into a female using a long plastic or glass tube.
Attempts are made to at least reach the level of her cervix, which in large dogs may be several inches inside the animal.
- 1. Dr. Bos lubricates a plastic tube and places inside the vagina
2. By marking the tube Dr. Bos has a good indication of how far into the vaginal cavity he has placed the plastic tube. Once he is sure that he has it in front of the cervix he can now slowly release the sperm.
3. Dr. Bos inflates the tube and massages vaginal area to simulate the “tie”.
4. Bailey is held to allow gravity to help the semen travel down into the uterus and eventually through the fallopian tubes.
Used correctly, artificial insemination is a useful tool in improving the overall quality of all canine breeds, allowing a wider range of potential breeding partners. We were pleased to be a part of Bailey’s breeding and look forward to meeting her pups!