When Can Dogs Detect Pregnancy?

This article will examine the question of whether dogs can detect human pregnancy and if so, how early they can sense it. We will start by looking at a dog’s impressive olfactory abilities and how their sense of smell far surpasses humans. Next, we will cover the early signs of pregnancy that dogs may be able to detect. The article will then summarize some anecdotal accounts of dogs seeming to identify pregnant owners before a pregnancy test. We will review the limited scientific research conducted on dogs’ potential ability to detect pregnancy. After covering possible explanations for this phenomenon, we will analyze the accuracy rates found in studies. Finally, we will discuss dogs’ abilities to detect other diseases and conditions, before concluding with a look at when dogs may first be able to detect pregnancy.

Dog’s Olfactory Abilities

Dogs have an extraordinary sense of smell that far surpasses humans. Their noses have up to 300 million olfactory receptors, while humans have only about 6 million (1). Dogs also have a special organ called the Jacobson’s organ in the nasal cavity that allows them to detect and analyze pheromones or hormones (2).

This highly advanced olfactory system allows dogs to detect subtle changes in odor that humans would never notice. There are stories of dogs being able to sniff out cancer or detect when a person’s blood sugar is low. Dogs working in law enforcement are able to locate drugs, bombs, or people by picking up on faint scents.

When it comes to pregnancy, dogs can likely pick up on the change of hormones and slight alterations in a woman’s scent caused by the hormonal surges of pregnancy. By 6 to 8 weeks of gestation, a dog may notice these differences and their keen nose allows them to constantly update their sensory information (3).

(1) https://www.businessinsider.com/can-dogs-sense-pregnancy-humans-before-you-how-early-2023-5
(2) https://www.whattoexpect.com/news/pregnancy/dog-know-pregnant-before-you/
(3) https://wetnosespetsitting.com/how-does-my-dog-know-im-pregnant/

Early Signs of Pregnancy

One of the earliest signs of pregnancy that dogs can potentially detect are changes in a woman’s hormones, specifically a rise in progesterone. According to research, during early pregnancy progesterone levels steadily rise, and dogs may be able to smell and sense this change1. A dog’s advanced olfactory senses allow them to pick up on even slight variations in hormones.

Around 3-4 weeks into pregnancy, another change dogs may notice is the woman’s body temperature rising slightly. This is due to an increase in metabolism and blood circulation during pregnancy. Since dogs have a keen sense of smell, they can likely detect subtle differences in body temperature and odor.2

By weeks 5-6, early pregnancy symptoms like nausea and fatigue may start. Dogs, being highly intuitive and sensitive to their owner’s behavior, may pick up on these cues and detect a change before the woman realizes she is pregnant.

Anecdotal Accounts

There are many anecdotal stories of dogs alerting their owners to a pregnancy before it was confirmed by a medical test. These stories suggest that dogs may be able to detect subtle changes in scent or behavior during the very early stages of pregnancy, sometimes even before the woman is aware she is pregnant.

For example, one woman reported that within days of conceiving through IVF, her two dogs began acting strangely clingy and protective over her. She took a pregnancy test weeks later after her dogs’ behavior tipped her off.

Another common story is of dogs who are normally well-behaved suddenly becoming insistent on laying their heads on their owner’s belly. Some owners have realized later that this change in behavior coincided with the start of pregnancy. There are also reports of dogs sniffing or licking their owner’s belly more persistently in the early weeks of pregnancy.

While these accounts are only anecdotal and not scientific evidence, the consistency of stories does suggest dogs can pick up on very early signs of pregnancy through their highly advanced sense of smell.

Scientific Research

While there are many anecdotal reports of dogs seeming to sense their owner’s pregnancy, scientific research on this topic is limited. One study published in 1989 found that two trained dogs were able to detect a secondary odor of pregnancy in the sweat samples of women in their first trimester. The dogs could distinguish between these samples and those from non-pregnant women (1).

Another small study in 2013 had dogs smell swabs taken from the abdomens of pregnant women, pseudo-pregnant women, and non-pregnant women. The dogs spent more time smelling the swabs from pregnant women, suggesting they could detect a difference (2).

However, these studies had very small sample sizes. More research is still needed to determine if dogs can reliably detect early pregnancy by scent alone.

(1) https://www.akc.org/expert-advice/home-living/can-dogs-sense-pregnancy/

(2) https://www.thebump.com/a/can-dogs-sense-pregnancy

Possible Explanations

There are a few theories as to how dogs may be able to detect pregnancy in humans:

One theory is that dogs are alerting to changes in a pregnant woman’s hormones 1. During pregnancy, women experience increases in estrogen, progesterone, and chorionic gonadotropin. Since dogs have an excellent sense of smell, they may be able to detect these hormonal changes.

Another possibility is that dogs notice differences in a woman’s chemistry or metabolism. Pregnant women experience changes in their metabolic waste products as the pregnancy progresses. Dogs may pick up on these subtle differences.

Some speculate that dogs are responding to changes in a pregnant woman’s behavior and habits. As women experience pregnancy symptoms like fatigue and mood changes, their routines and interactions with their dog may be altered. The dog notices these differences.

While the exact mechanism is unknown, dogs do seem adept at detecting physiological and behavioral changes associated with pregnancy. Their exceptional olfactory abilities likely allow them to pick up on even small variations.

Accuracy Rate

Studies have attempted to analyze and quantify how often a dog’s detection of pregnancy is accurate. One study published in a veterinary research journal tested the accuracy of two common chemical pregnancy detection methods in dogs: testing for relaxin hormone and progesterone hormone. They found that testing for relaxin at 3-4 weeks after breeding was accurate 96% of the time if performed properly. Testing for progesterone at 20-35 days after breeding was accurate 83% of the time.

Another study analyzed dogs’ abilities to detect pregnancy through odor detection alone, without any chemical tests. This study found that after sniffing samples of urine and breath from women, dogs could accurately detect pregnancy about 70% of the time.

While dogs seem able to detect pregnancy fairly early on, their accuracy improves the further along the pregnancy progresses. Detections early in pregnancy may not be as reliable. But by 4-5 weeks after conception, dogs can detect pregnancy with over 90% accuracy through chemical pregnancy tests. Their detection accuracy using odor alone also increases the closer the woman is to giving birth.

Detecting Other Conditions

Dogs have an incredible sense of smell that enables them to detect changes in the human body. Recent research shows dogs have been trained to identify cancers and other illnesses by detecting odor changes in a person’s breath, urine, or skin. Dogs have detected lung and breast cancer through breath samples with a high rate of accuracy. Their sensitive noses allow them to pick up on volatile organic compounds released by cancer cells. Though more research is still needed, dogs show promise in their ability to non-invasively detect various illnesses and medical conditions through changes in a person’s odor.

When Detection Starts

According to akc.org, by week 3 or 4 of pregnancy, most dogs can detect changes in a woman’s body chemistry. USAtoday reported that some dogs can detect changes even earlier at 1 to 2 weeks after conception.

The earliest signs dogs notice are likely subtle changes in odor caused by hormonal shifts. However, the most significant changes in odor occur later in pregnancy around week 5 when the placenta develops. This rapid increase of hormones leads to more noticeable changes in body chemistry that dogs can detect.

Overall, most sources suggest dogs can first detect pregnancy signs between 1 to 5 weeks. However, the reliability and strength of detection increases significantly after week 5 as hormonal changes intensify.


In summary, while there are many anecdotal reports of dogs seeming to detect pregnancy, the scientific evidence remains limited. Some studies have suggested dogs may be able to detect subtle chemical changes during pregnancy, but sample sizes have been small.

More research is still needed to determine if dogs can reliably and consistently detect pregnancy, especially in the earliest stages. Controlled scientific studies tracking dog reactions and using chemical analysis could shed more light. However, the accumulated anecdotes indicate there may be some ability for dogs to sense pregnancy-related changes.

Overall the research is still in early phases, but initial findings are promising. With their extraordinary sense of smell, it’s plausible dogs detect hormones or other biomarkers of pregnancy. But the phenomenon needs further investigation to be fully proven and understood.

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