The length of pregnancy (gestation period) varies widely among species. Elephants can remain pregnant for up to 22 months, but how long are dogs pregnant? While your vet will always be the best source of information, there are some things that pet parents should know about pregnancy in dogs.
Whether you have a Chihuahua or a Great Dane, the average canine gestation period is 63 days. This may vary slightly depending on breed and number of puppies. It can also be difficult to predict an exact due date as conception does not always occur on the same day as mating. Therefore, birth can occur 58 to 72 days after mating.
The Canine Reproductive Cycle
You may have seen female dogs wearing diapers and wondered why. That’s because intact (unspayed) female dogs go through a hormonal cycle, which begins when they reach sexual maturity around six months of age. Female dogs come into estrus (the phase during which they can be bred) approximately twice a year or every six to eight months. The other parts of the cycle are as follows:
Proestrus - This is the beginning of the heat cycle and is characterized by firm swelling of the vulva and bloody vaginal discharge, lasting from a couple of days to three weeks (average length of nine days). The female dog will not allow mating at this time.
Estrus - The female dog is receptive to breeding by males during this phase, also known as “heat”, which can last for three to 21 days (average length of nine days). Ovulation occurs during this phase, even if a dog is not bred. The vulva becomes softer and discharge may decrease and become straw-colored. The female may also exhibit behavioral changes to encourage male interest. Vaginal cytology, or examining cells from the vagina, can also help determine if a female is ready to be bred.
Diestrus - Once again the female becomes resistant to breeding, and the vulva begins to decrease in size. If a dog is not pregnant, diestrus usually lasts for about two months.
Anestrus - This is the non-breeding phase of the cycle, and usually lasts four to five months.
Unlike in people, there is no menstruation (the bloody discharge comes directly from the wall of the vagina) or menopause, although cycles may get longer and more irregular as a dog ages. It is important to keep track of your dog’s cycles and relay this information to your vet, as it is a key aspect of their overall health.
Signs of Pregnancy in Dogs
Early signs of dog pregnancy may include vomiting, lethargy, and a change in appetite. As pregnancy progresses, you will notice physical changes including weight gain and mammary development (enlargement and darker pigmentation). Late in pregnancy dogs will display nesting behavior. Prior to the start of labor, their rectal temperature will drop and your dog may become restless and refuse food.
As non-pregnant females can also display some of these same signs, it is best to see your vet if you suspect your dog may be pregnant.
How to Tell if Your Dog is Pregnant
Your vet will be able to diagnose pregnancy in several ways.
Physical exam - As pregnancy progresses your vet will be able to observe physical changes including weight gain and mammary development. After 21 days they may also be able to diagnose pregnancy by feeling fluid-filled sacs in the uterus on abdominal palpation.
Bloodwork - A blood test to measure the hormone relaxin, produced by the placenta, may be used after approximately 30 days.
X-rays - After 45 to 55 days, fetal skeletons will be visible on radiographs. This is also an excellent way to determine the number of puppies expected.
Ultrasound - After 25 to 35 days ultrasound can be used to diagnose pregnancy. It can also be used later in pregnancy to assess fetal health and heart rate.
Health Concerns During and After Pregnancy
Nutrition - Good nutrition is critical during and after pregnancy for both mom and pups. Dogs in late pregnancy and those who are nursing must eat a high-quality diet that is complete and balanced for pregnancy, lactation, or puppies, and should eat small frequent meals to keep up with their increased energy requirements. It is also important to follow your vet's recommendations to keep your dog at a healthy weight during this time, as being either overweight or underweight can increase her risk during pregnancy.
Wellness care - It is important to make sure your dog is up to date on vaccines and parasite prevention prior to becoming pregnant so that she can pass immunity on to her pups. If the pregnancy is accidental be sure to discuss wellness care with your vet, as some products may be contraindicated in pregnant animals.
Dystocia - Abnormal labor encompasses many possible situations and requires immediate evaluation by a veterinarian. This condition can sometimes be managed medically, but often a c-section will be required for the safety of the mom and pups. Make sure you have discussed a birth plan with your vet, know the signs of dystocia to watch for, and have the contact information for a local emergency clinic on hand. It is also important to note that some breeds, especially brachycephalics like bulldogs and Boston terriers, can only give birth via c-section.
Eclampsia - A drop in blood levels of calcium can sometimes occur and should be treated by your veterinarian immediately.
Inflammation or infection - The uterus and mammary glands may become inflamed or infected postpartum. If you are concerned about mastitis or metritis, or if your dog seems otherwise sick or has a fever, please contact your veterinary team.
Spaying Your Dog
Spaying a dog involves surgically removing the uterus and ovaries to prevent possible pregnancy. If you are not planning on breeding your dog then getting her spayed is highly recommended for her health and well-being. Not only do you get to avoid dealing with messy heat cycles and unwanted litters contributing to overpopulation, spaying a female can help her live longer, reduce the risk of diseases such as mammary cancer, pseudopregnancy, and pyometra (infection of the uterus), and improve behavior.
Frequently Asked Questions
Are there pregnancy tests for dogs?
You can’t purchase a home pregnancy test for your dog, but your vet has several ways of determining if she is pregnant. Depending on how early in the pregnancy it is, they may be able to tell if she’s expecting based on a physical exam, blood test, x-rays, or ultrasound.
How often can dogs get pregnant?
Dogs can get pregnant every time they come into estrus, which usually happens twice a year.
How do I prevent unwanted pregnancy?
Spaying your dog is the best way to prevent unwanted pregnancy, and also has benefits for her health and well-being. Keeping intact male and female dogs (even siblings) separate during estrus is also critical. Medications are not commonly used in the United States and have risk of side effects.