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Do pregnant dogs become aggressive?

You’re so excited that your dog is pregnant. You just can’t wait to hold the puppies. Something is different about your dog, though.

Her demeanor has changed. She used to be so warm. Now, she has become aggressive, and you can’t figure out why. Let’s uncover some answers.

Do pregnant dogs become aggressive?

Before we can answer whether dogs become aggressive when they are pregnant, we must know a bit of background. What can we find out?

Do puppies need their mothers?

Unless the dam (mother dog) nurtures her whelps (newborn pups), it is a certainty that they will not live without intervention. Whelps cannot do for themselves; this is true to the point that they cannot even maintain a healthy temperature. They are like babies, who need their human mothers to feed them, bond with them, love them, and teach them by interacting with them.

Are all dams good mothers?

It is a spontaneous, innate instinct that causes most dams to do such a good job caring for her whelps without ever being taught a thing. New dams are obviously not going to be as good at it as those who have had a litter or two, but even most new dams have an instinct for motherhood. 

It makes sense that this is the case, so that the species can continue to procreate. However, every once in a while, you will come across a dam who simply does not possess that motherly instinct. This is one reason why it is very important to keep a close eye on your new family for a bit after birth. It is important to do this anyway to monitor the whelps’ progress.

Are pregnant dogs aggressive?

Dams go through some hormonal changes while they are pregnant. These changes affect the dams physically, but also emotionally. Dogs can sometimes get grumpy due to these hormonal changes, but physical pain and just being uncomfortable can add to this general fussiness. However, this is usually something that doesn’t qualify as aggression, that is unless that dog was at least somewhat aggressive already.

What is maternal aggression?

Dams are protective of their newborn puppies, and this is a sign of their love for them and mindfulness where they are concerned. This is natural, and it’s a beautiful thing — until she starts to become peculiarly aggressive. While a measure of newfound aggression will present most times in all mammals, like wolves, dogs, and horses, maternal aggression refers to an unhealthy, extreme post-partum aggression.

This is a piece of advice that you should heed: Never approach a newborn wolf pup, whelp, or mare incautiously, because the mother may not perceive your intentions, in which case, she may react aggressively, even attack you. This isn’t dominance aggression, but it’s similar. It is aggression caused by hormone changes that cause the dam to protect her litter through aggression.

Maternal aggression in dogs is uncommon, but when it presents, the issue is complex and dangerous. It is an acute behavioral issue of which the causes are known and the signs are detectable. Maternal aggression is a serious problem, and because it can happen, you should be aware of what you need to do to make the first weeks of life as ideal as possible for your whelps and your dam.

Does a dog’s behavior change when pregnant?

The answer is — yes, a dam’s behavior does change when she’s pregnant, but maternal aggression doesn’t really set in until the whelps are born. What are the signs of maternal aggression?

Quick Warnings

The dam will usually, but not always, warn you before she gets too aggressive. She does this with a snarl, a mean bark, growl, or a quick snap. If she feels you did not heed her warning, she may attack you, biting you repeatedly without inhibition.

Body Language

The dam will also show by her body language that she is agitated and upset. She may pace back and forth in front of the litter in an intimidating manner.

Crying Whelps

If you start hearing the whelps cry excessively, there is a problem. When all is normal, the dam keeps her whelps calm and cared for. If they are crying, she may be biting them or trying to smother them.

Killing Whelps (Infanticide)

In some cases, when a pup is stillborn, diseased, or malformed, a dam will smother or even eat it, and in cases where maternal aggression has pushed the dam too far, she may kill the entire litter.

When this is the case, you will see behavior like the following.

Starving Them

The dam may stop feeding them if she gets in a bad frame of mind. If she does this, without intervention, they won’t live long at all.

Smothering Them

If you see the dam sitting or lying on her puppies but hear them crying, she is trying to smother them. They will need to be taken away from her, and you will have to mother them yourself.

Withholding Her Love and Companionship 

If you see her moving away from them and staying away for long periods of time and showing indifference to the whelps’ welfare, she has rejected them, and it is time to intervene.

Moving Them From Their Nesting Place

The dam may start moving them from their nesting place. This is a sure sign that she feels their well-being has been threatened, and her next move probably won’t be a healthy one.

Why is my dog so aggressive lately?

Why is your dog so aggressive lately? It’s all the changes taking place in her body, for one thing. Let’s look at the causes of maternal aggression.

What are the causes of maternal aggression?

There are multiple possible causes of maternal aggression. What are they, and what can I do to help?

Hormonal Changes

Oxytocin is the hormone that ties the bond between dam and whelp. Handling the whelps too much can affect the secretion of this hormone, leading to stress and in some instances, aggression.

Progesterone levels fall as estrogen levels rise. Progesterone has a calming effect, so when its levels go down, its calming effects wear off, as well.

Prolactin is the hormone that has to do with releasing milk for the whelps, and the graphs of prolactin levels parallel those of maternal aggression.

Secondary Causes

While hormonal changes are the catalyst, there are secondary causes that seem to spark the ready-made fire.


You can not touch whelps too much because it can cause the dam to reject them. Even if you think this could never happen with your dog, it can. The instinct to protect her whelps can lead to aggression.


Loud noises near the whelping box can cause the mother to have anxiety and fear, the roots of maternal aggression. Keep her nesting place a quiet and calm area.

Other Animals

A dam may feel threatened by other animals anywhere close to her nesting place. Even if your animals normally get along fine, you will want to separate them and keep other animals away from her and her whelps after birth.

What can I do to help?

You love your dog so much, and you only want to help her. Here are some things you can do.


Handle the whelps at little as possible, and don’t let anyone else handle them.


Make her feel she is safe. Make her warm and cozy, and keep her in food and water.


To reiterate, keep a calm, quiet, serene atmosphere for her and her whelps.


You will want so badly to show off the puppies. Don’t! Let your dam and her whelps have this time to themselves.


To reiterate, also remove other animals, even if they normally get along fine. Right now, she and her whelps need privacy and to feel safe.

As a last resort…

If your dam is still having a problem after the puppies are past whelping stage, you will have to consider more permanent means of handling the situation. You will probably want to have her spayed, or you may even have to part with her. You cannot keep a dangerous dog around your family. Someone in your family could get seriously injured, or someone else could get hurt badly and there could be legal implications.