Pregnancy in Dogs
How can I tell if my dog is pregnant?
This is usually the first question that is asked as soon as the breedings are done. There are several ways to determine if the mating has been successful, but patience may be required. Some people say they know immediately if the breeding “took” because of changes in the bitch’s demeanor, but more definite testing has to wait a couple of weeks.
The gestation period, or length of pregnancy, for dogs ranges between 61 to 65 days. The exact length can vary depending on the breed and the number of puppies. Larger litters tend to be delivered earlier than small litters.
When your bitch is in the first few weeks of her pregnancy, there may be no noticeable changes. However, during this time, she may vomit or have a decreased appetite. Other signs include weight gain and an increase in appetite. Some bitches are more affectionate while others may be more irritable.
When examining pregnant dogs, one of the most reliable indicators is a change in their nipples. If pregnant, the nipples will be enlarged and pinker in color. You may also notice they produce a clear fluid when squeezed. Bitches that have been bred but are not pregnant usually have no change in the size or color of their nipples.
Midway through the pregnancy, as the fetal puppies enlarge, other procedures can be performed to confirm the pregnancy. There is a small window of time at 28 to 30 days of pregnancy when the implanted fetuses are round in shape. Your veterinarian can palpate the bitch’s abdomen in search of these enlargements in the uterus. The puppies feel like slippery golf balls or grapes, depending on the size of the dog. These “balls” are the fluid-filled sacs surrounding the fetuses.
The definition of abdominal palpation is examination by means of the hands to outline organs of the abdomen. The hands are placed on either side of the abdomen and then pressed together while sliding the hands together from the spine to the belly. The enlarged uterus will slip through the fingers and the balls have a distinct feeling.
Abdominal palpation should only be done by a trained veterinarian. Excess pressure may damage the fetuses. As they grow, the fetal sacs elongate and lose their round shape. It is difficult to distinguish them from feces in the colon. The timing of this test is important.
The nice things about palpation, if your veterinarian is skilled at doing it, are that it is quick, does not cause the bitch any discomfort, and doesn’t usually cost more than an examination fee. Your veterinarian may be able to give you a rough idea of the number of puppies, one or more, but this is not a technique that will give you an accurate head count.
Ultrasound uses sound waves that are transmitted through the dog’s body to create an image. It is the same technology used to generate sonograms during human pregnancy. Ultrasound is the best method to evaluate early in pregnancy whether or not there are healthy, growing fetuses in the uterus.
Pregnancy can be confirmed by ultrasound as early as 25 days after breeding. Ultrasound done prior to 21 days can give false negatives. It is the best method of differentiating between pregnancy and an infection of the uterus called pyometra.
At 30 days, the flicker of the fetuses’ heartbeats can be seen. At this stage, the vesicles, which are the capsules containing the fetuses, are small enough to allow easy counting of the fetuses within each uterine horn. Later in the pregnancy the fetuses are so large that the uterine horns overlap, making it hard to count the number of puppies correctly.
Ultrasound is perfectly safe for your pregnant bitch. As with palpation, the success of confirming pregnancy and counting puppies with ultrasound is dependent on the skill of the person performing the procedure.
Your veterinarian can run an in-house test for the hormone relaxin. It is a simple test requiring only two drops of blood. Positive or negative results are apparent within minutes. I have found this to be an extremely reliable test as long as the timing is right. It should be done 35 days after the last breeding. Witness Relaxin, Relaxin Pro and ReproCHEK are the current test kits on the market that measure relaxin in canine blood.
Relaxin is a hormone that is produced by the placenta and found in the bloodstream of the bitch when the fertilized egg implants in the uterine wall at about 21 days post-breeding. This hormone continues to circulate through the blood throughout pregnancy and peaks around day 40 to 50. The level of relaxin remains elevated during pregnancy and declines rapidly at the end of the pregnancy.
This test can determine if the bitch is pregnant or having a false pregnancy. There is no placental development during a false pregnancy, so relaxin is not produced at any time. The relaxin test will always be negative for the falsely pregnant dog.
The relaxin test cannot give you information on the number of puppies present in the bitch. False negative results are possible if the litter size is very small or the test is run too early in gestation. There is also evidence that small and Toy breed bitches may not produce enough relaxin to turn the test positive, especially if they are carrying only one or two puppies.
A positive relaxin test indicates that a dog is pregnant at the time of the test. Conception has occurred, implantation of an embryo has taken place, and a placenta is developing. It does not predict that the pregnancy will end successfully with the delivery of live puppies.
Radiographs, or X-rays, are the most definitive way to determine if your dog is pregnant. However, in order to be accurate, you must wait to take the radiographs until after day 52 post-breeding, when the fetal skeletons are readily visible. It takes about 45 days for the puppies’ bones to begin to mineralize in the uterus, so they would not be visible on a radiograph before this time.
An X-ray at this stage of the pregnancy allows you to get an accurate count of the number of puppies, although it can be tricky to correctly count all the puppies in large litters of 10 or more puppies. This way you will know how many puppies to expect and whether or not your bitch is finished delivering.
Radiographs also allow your veterinarian to compare the fetus size to the size of your dog’s pelvic canal. This can help you recognize potential difficulties in delivering the puppies due to their size.
Most veterinarians agree that the small amount of radiation from X-rays is well outweighed by the benefits of having this diagnostic performed. By the time the puppies can be seen on an X-ray at 52 days of gestation, they have completed much of their critical development. This means the puppies have a low risk of developing complications from radiation.
The health of the puppies cannot be assessed with a radiograph unless obvious lesions such as skeletal collapse or gas within the fetus are seen on the film. Ultrasound is a better way to determine fetal viability.