Dogs have an astounding ability to sense change in the world around them, and that includes when their owner is pregnant. This shouldn’t be surprising. After all, dogs are excellent at reading human body language and behavior, and there is even some evidence that dogs can detect when a person has cancer or is about to have an epileptic fit.

What causes the "pregnancy reaction?"

As you know, the bond between humans and their dogs is astonishingly strong. You’ve probably become accustomed to the all the ways your dog can predict/understand your emotions and desires. So what happens when a dog’s owner becomes pregnant? What is it about her condition that her dog detects?

Here are several factors that may explain how dogs sense when their owner is pregnant.

Change in odor—When a woman becomes pregnant, her body chemistry changes. This, in turn, can cause her distinct odor (an odor her dog knows intimately) to change. Remember, the amazing canine sense of smell can detect even the slightest change in odor. Imagine what a loyal, loving dog must think when the woman of the house suddenly begins to smell different.

Changes in body shape and body language—You don’t have to be as astute an observer as a dog to notice how pregnancy changes the way a woman looks and moves. Dogs can easily notice when his owner has a difficult time standing up, or when she waddles instead of taking big, fast strides. And compared to a human, an acutely observant dog might just notice that his owner is “showing” sooner in her pregnancy.

Changes in mood and behavior—As a dog owner, you've come to realize over the years that your dog can read your moods. He knows when you’re blue (and responds by cheering you up) and he joins in the celebration when you’re bursting with joy. When it comes to moods, you simply cannot fool your dog. So it seems only natural that dogs will sense the mood and behavior changes that the woman of the house undergoes when she is pregnant.

Human change triggers canine change

The changes that occur in a pregnant woman affect everyone in her home. And that includes her steadfast canine companion. Once a sensitive dog realizes that change is happening, he may react with some changes in behavior. Depending on the dog’s personality and the physical and emotional changes of the pregnant woman, the dog may display one or more of these behavioral changes:

Increased affection for—and protection of—the pregnant woman

Agitation, growling, barking, and being uncooperative

Urinating around the house

Chewing new items brought into the house for the baby

Most dogs will eventually become accustomed to the changes in his pregnant owner and return to a more "normal" behavior pattern. However, some dogs have a difficult time adjusting to the changes brought on by pregnancy. Most of the time, paying more attention to the dog goes a long way toward giving him a needed sense of relief and reassurance. In more extreme cases, though, the dog may benefit from attending classes with a professional trainer.

The important thing to remember is that your dog is a sensitive member of your family, and what affects you, your spouse, and your children, also affects him.