Many dog owners wonder if they can use human pregnancy tests to find out if their dog is expecting puppies. This is an understandable question, as home pregnancy tests are relatively inexpensive and easy to find. However, human pregnancy tests are designed to detect a hormone called human chorionic gonadotropin (hCG) that is only present during human pregnancy. Canine pregnancy involves different hormones, so human pregnancy tests will not provide accurate results for dogs.
How Human Pregnancy Tests Work
Human pregnancy tests work by detecting a hormone called human chorionic gonadotropin (hCG). This hormone is produced by the placenta shortly after implantation when a fertilized egg attaches to the uterine lining. HCG levels increase steadily during the early stages of pregnancy. Most home pregnancy tests detect hCG in urine while some detect it in blood.
According to the Cleveland Clinic 1, pregnancy tests contain antibodies that react to the presence of the pregnancy hormone hCG. The antibodies are coated on a test strip or stick. When urine is applied to the test, hCG in the urine binds to antibodies producing a color change on the test. The intensity of the color indicates the level of hCG. Most tests show a positive result when hCG levels reach 25 mIU/mL.
Home pregnancy tests are designed to be qualitative, not quantitative. They confirm either the presence or absence of hCG but do not specify the exact amount. Rather than measuring hCG precisely, most tests use cutoff levels to determine if hCG is detected at high enough levels to indicate pregnancy.
Canine Reproduction
Female dogs carry puppies in litters, going through a gestation period of 57-65 days on average [1][2]. Their reproductive cycle is on a semi-annual schedule, with females being receptive to mating about twice per year. Unlike humans who are pregnant for around 9 months before giving birth to usually just one baby at a time, dogs have evolved to be efficient breeders with larger litters and shorter gestation. The number of puppies in a litter depends on the breed and size of the dog, ranging anywhere from 1 to more than 15 pups. Female dogs go into heat and ovulate before becoming pregnant through mating with a male.
Hormones in Dog Pregnancy
During canine pregnancy, hormonal changes occur to support fetal development. Some key hormones involved include:
Progesterone – Progesterone levels rise after ovulation and peak around day 40-50 of pregnancy. The presence of high progesterone maintains the pregnancy and prevents the uterus from contracting. Progesterone also helps develop the placenta. Near the end of pregnancy, progesterone drops dramatically, resulting in uterine contractions and labor ([1]).
Relaxin – Relaxin is released by the placenta and helps relax pelvic ligaments and soften the birth canal in preparation for delivery. Relaxin levels peak around day 25-35 of pregnancy and drop before parturition ([2]).
Estrogen – Estrogen increases up to 1000-fold during the first half of pregnancy, contributing to mammary development and milk production. Estrogen levels then decline but have a second peak at parturition, stimulating stronger uterine contractions.
Oxytocin – Oxytocin is critical for labor and delivery, stimulating uterine contractions to start labor. As contractions increase, oxytocin further intensifies labor. Oxytocin also promotes milk let-down during nursing.
Prostaglandins – Prostaglandins play an important role in cervical softening before labor and stimulating uterine contractions during labor.
These hormonal changes are critical throughout canine pregnancy and labor. Monitoring hormones can provide insight for veterinarians but is complex due to normal fluctuations throughout gestation.
Do Dogs Produce hCG?
No, dogs do not produce hCG. Human chorionic gonadotropin (hCG) is a hormone produced during pregnancy by the placenta after implantation. It helps maintain progesterone production in early pregnancy. In humans, hCG can be detected in urine and blood tests as early as 8-10 days after conception.
In dogs, the hormone relaxin rises during pregnancy instead of hCG. Relaxin is produced by the developing placenta in dogs, similar to hCG in humans. But relaxin has a different chemical structure than hCG and serves slightly different functions for maintaining pregnancy in dogs.
Since dogs do not produce hCG, they will not have this hormone present in their urine or bloodstream during pregnancy. This is why human pregnancy tests, which detect hCG, do not work for detecting pregnancy in dogs.
Instead, veterinarians can test for the presence of relaxin or progesterone levels to confirm pregnancy in dogs. There are also other physical and behavioral signs that can indicate dog pregnancy. But the lack of hCG production is the main reason why human pregnancy tests are ineffective for dogs.
According to VCA Hospitals, the relaxin blood test is the most accurate way for vets to diagnose pregnancy in dogs, since it detects the hormone actually produced by dog placentas.
Why Human Pregnancy Tests Don’t Work on Dogs
Human pregnancy tests work by detecting the presence of human chorionic gonadotropin (hCG), which is a hormone produced by the placenta shortly after implantation. This hormone is not present in normal non-pregnant humans or dogs.
However, while hCG rises steadily during early pregnancy in humans, dogs do not produce hCG at all during pregnancy. Instead, the main hormone indicator of pregnancy in dogs is relaxin. This means human pregnancy tests simply cannot detect pregnancy in dogs, because they are not designed to measure canine relaxin levels.
As explained on PetCareRx, “In order for a human pregnancy test to work for a dog, the dog’s body would have to produce hCG, which it simply does not. The hormones relaxing and estrogen gradually increase over the first month of pregnancy in dogs, but hCG remains totally absent.”
So in summary, human pregnancy tests look for the presence of hCG and dogs do not produce this hormone when pregnant. This makes human pregnancy tests ineffective for detecting pregnancy in canines.
Signs of Pregnancy in Dogs
Some of the earliest signs of pregnancy in dogs include physical changes and nesting behaviors.
As early as week 1, a pregnant dog’s teats or nipples may begin to swell or develop additional pigment. As the pregnancy progresses, the nipples and mammary glands will continue growing. Additionally, around 4-5 weeks into the pregnancy, the dog’s belly will start noticeably growing as the puppies develop.
Many dogs will begin nesting behaviors in preparation for the arrival of a litter. Nesting behaviors can include gathering items like blankets, pillows or toys and arranging them in secluded places she has chosen as a nest. She may also dig and root around as if trying to prep an area. Some dogs may even guard or become protective of the nesting area.
Other behavioral signs of dog pregnancy include lethargy, decreased energy or appetite changes. Pregnant dogs often require more rest. Later in the pregnancy, she may isolate herself or seek more affection from her owner.
When to See the Vet
For confirmation of pregnancy and prenatal care, it’s a good idea to take your dog to the vet 2-3 weeks after mating. The vet can confirm pregnancy through palpation, ultrasound, x-rays, and blood tests. They will also discuss prenatal care and answer any questions you may have.
According to WebMD, the vet will check your dog’s overall health, give nutritional advice, and discuss exercise and medication precautions. They may recommend supplements like folic acid and calcium for your dog. The vet can also estimate delivery dates and litter size from palpation and imaging.
Regular vet checkups can catch potential complications early. These include signs like vaginal discharge, abdominal pain, loss of appetite, vomiting, and fever which may indicate issues like miscarriage or infection. Monitoring your dog’s weight is also important as significant gains or losses can signify problems.
It’s essential to see the vet immediately if your dog is straining or in labor with no puppies being passed. Also seek emergency care if you see expelled fetal membranes without puppies. According to Ethos Veterinary Health, these signs may indicate life-threatening conditions like uterine inertia or vaginal blockage.
Alternative Dog Pregnancy Tests
There are several alternative methods to test for pregnancy in dogs without using human pregnancy tests:
Blood Test
A blood test at the vet can detect the hormone relaxin as early as 22-27 days after breeding (https://vcahospitals.com/know-your-pet/pregnancy-testing-in-the-dog). This hormone is produced by the developing placenta and the presence of relaxin confirms pregnancy.
Ultrasound
An ultrasound allows the vet to visualize the puppies as early as 3-4 weeks after conception. The fetal heartbeat may be detectable as early as 22-25 days after breeding (https://www.carecredit.com/well-u/pet-care/dog-pregnancy-test/).
X-Rays
Abdominal x-rays can confirm pregnancy in dogs after 45 days from the time of breeding. The skeletons of the fetuses will be visible on the radiograph.
The Takeaway
While it may be tempting to use an over-the-counter human pregnancy test on your dog, it’s important to understand that these tests are designed to detect human chorionic gonadotropin (hCG), a hormone only present during human pregnancy. Dogs do not produce hCG, making human pregnancy tests ineffective at detecting pregnancy in canines.
If you suspect your dog may be pregnant, the best option is to schedule an appointment with your veterinarian. They can perform exams and diagnostic tests specifically designed for dogs to accurately determine pregnancy. This is the only reliable way to confirm if your dog is expecting puppies.
Do not rely on human pregnancy tests for your dog. Seek guidance from your veterinarian, as they can ensure the health of your dog and her potential puppies with proper prenatal care if she is indeed pregnant.
