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Dog Suddenly Aggressive Towards Cat? 9 Odd Reasons + 3 Tips

Why Is My Dog Suddenly Aggressive Towards My Cat

Once upon a time, there was a dog and a cat in one household.

They got along well, and there was nothing more you could ever wish for.

But just when you thought that everything looks perfect…

Your pooch attacked your cat out of nowhere.

Oh no! What just happened?

And how can you stop your Fido from doing it?

Keep reading to find out:

  • What makes a dog suddenly hostile to a cat.
  • 5 signs of aggressiveness that you should be aware of.
  • 5 different scenarios of dog aggression towards cats explained.
  • 3 useful tips on how to make them refrain from attacking your cat for good.
  • And a lot more…

Why is my dog suddenly aggressive towards my cat?

Your dog is suddenly aggressive towards your cat because they are in pain, jealous, possessive, stressed due to a change in the environment, anxious, or suffering from dementia. It could also happen because of redirected or leash aggression, a change in hormone levels, or high prey drive.

9 reasons why your dog is suddenly aggressive towards your cat

#1: It’s the hormones

Something might be happening inside your Fido’s body.

So you can’t seem to point out what’s wrong. And why this happens out of the blue.

If so, their hormones could be at play in their aggressiveness.

“Really? But how do they affect them?”

It’s known that testosterone – a male hormone, turns on a specific part of the brain that causes aggression.

While serotonin or ‘happy hormones’ balance their mood.

But guess what, scientists discovered two more.

They found that aggressive hounds have high levels of vasopressin. And those who are calm have a greater amount of oxytocin or ‘love hormones’ instead.

So any changes in these could affect your Fido’s behavior.

Maternal aggression

A dog who has just given birth to pups may also be aggressive all of a sudden.

This is because of their instinct to protect their babies. Which is due to these hormones:

  • Increased prolactin: Being overprotective.
  • Reduced progesterone: Snappy behavior.

You might also like: Why Is My Dog Suddenly Aggressive To Our Other Dog?

#2: Your dog is in pain

Your Dog Is Suddenly Aggressive Towards Your Cat Because It's In Pain

Another reason for a canine to act unusual is when they feel discomfort.

It could be due to an illness, injury, or joint pains.

Your cat might have touched or gone too close to the part that’s hurting. So your Fido’s defense would be growling and snapping at them.

The feline may also want to play. And your pooch could be saying, “I don’t want to!” or  “Go away!”

Usually, dogs will hide their pain. So it’ll come as a surprise when your calm pooch displays sudden aggression.

Aside from changes in their behavior, watch out for these common signs of illness:

  • Lethargy.
  • Lameness.
  • Loss of appetite.

Note: Before treating their aggression as a behavioral problem, have them checked by a vet first. This is to rule out any medical conditions they may have.

#3: Change in the environment

Did anything happen recently?

I ask because a sudden shift in behavior may be due to anxiety.

Like humans, dogs get stressed too. And they can be sensitive to any changes in their surroundings.

Such as moving into a new house, living with an unfamiliar person, or a new animal.

There are new scents and sounds that will be scary for a dog, especially for a nervous one. 

As a result, they’ll become irritable. So if your pooch is indeed stressed out, your cat is no exception to their snapping.

#4: Your dog is possessive

“You want this?

Sorry, but sharing isn’t in my vocabulary.”

Does this usually happen while they’re eating? 

If so, your pooch might dislike sharing their food. Or anything valuable to them such as their bed or toys.

So anyone who goes near those things will have a taste of their aggression instead. And you, your cat, and everyone else is included.

Dogs can also guard their humans as they see their parents as an important source of food and care.

So if you are with your pooch, they might growl and snap at your cat, who’s getting closer.

“What causes them to act like this?”

  • Insecurity.
  • Survival instinct.
  • ‘Competitive’ environment (multiple pets).

Warning: Are there small children in your house? If so, keep your Fido away from them, especially if it’s mealtime. As your dog may lunge at or harm them if they get close. Don’t risk it.

#5: Your dog is jealous

“Wait, do canines really feel jealousy?” you might ask.

Well, research claims they do. And their jealous behavior is similar to a young kid who feels envious when they see their parents with another child.

They’ll snap and have a pushy behavior when their favorite person shows affection to a ‘rival.’ And in your case, that’s you and your cat.

“But why does it only happen now?”

They can become competitive all of a sudden if they don’t feel well. Or your pooch could be feeling insecure nowadays. And they need extra attention from you.

So when they see you having fun with your cat…

Your Fido might snarl or even bite them to make them go away.

Interesting fact: Did you know that dogs can imagine a scenario? A study reveals that they could have a mental picture in their head. So they may feel jealous even if no interaction happens.

#6: Redirected aggression

In some cases, frustration could be the culprit for this.

Your pooch might be bored all day. Or want to go outside and play, but they can’t. And if this continues for a while, they’ll have a sudden outburst of rage.

So what would they do?

They’ll turn their frustration onto the first thing or person they see. And it just so happened that your cat is passing by. Or they’re resting somewhere at that moment.

#7: Leash aggression

Your Dog Has Leash Aggression

Your Fido is mild-mannered and bonds well with their furry friends. But every time they have their leash on…

They turn into a tiny, fierce beast. Or a huge one, if you have a dog such as a Caucasian Shepherd for example.

What’s the matter?

There’s this thing called ‘leash aggression.’ And it could be due to:

  • Fear.
  • Frustration.
  • Being hypersocial.

Having a leash can make them feel restrained. So they may lash out at anyone who comes close to them.

It’s kind of like the barrier frustration dogs experience (I talk about it in this article). 

#8: Your dog is nervous

When it happens, are there new people at home? Or sudden loud noises?

If so, their aggression may be out of fear.

It could be due to a stranger, random object, high-pitched sounds, or even a storm.

What are the signs?

  • Pacing.
  • Shaking.
  • Licking their lips.
  • ‘Whale eyes’ (exposing the whites in their eyes).

Your dog might be so scared at the moment. So when your cat goes near them, they’re startled. And as a reflex, they may snap or even bite.

You might also like: 5 Reasons Why You Shouldn’t Pet Dogs While They’re Asleep

#9: Canine cognitive disease (CCD)

How old is your pooch?

This is because as dogs age, they may also have dementia. Or the decline of one’s brain functions – remembering and reasoning.

“How common is it?”

One study reports that 60% of senior dogs (above 11 years old) are affected.

And those who have this will become aggressive and anxious due to memory loss.

So this could also be the reason why your Fido confronts your cat. Although they didn’t behave this way before.

They may also show some of these:

  • House-soiling.
  • Disorientation.
  • Irregular sleeping pattern.
  • Other changes in behavior.

#BONUS: Genetics

Lastly, this could be in their blood.

But you might wonder, “If it’s innate, why does it happen only now?”

Well, every dog is different.

For example, some hounds can coexist with cats even if they’re known to have a strong prey drive.

So it might be a particular trigger. Like when they’re having zoomies or being extra noisy.

While other breeds may tend to be more aggressive than others, like Chihuahuas

Warning: Don’t leave your pets unattended. You’ll never know what can happen while you’re away. So separate them while you’re correcting this behavior.

5 signs of dog aggression towards cats

#1: Dog growling while a cat is nearby

How to tell if a dog is aggressive towards cats?

One sign is when they growl. This is only a warning to keep the cat away. 

But if provoked, they may attack. And this could happen when they are:

  • Guarding their human.
  • Threatened and feel insecure.
  • Defending their food or territory.

#2: Dog showing their teeth

Baring their fangs is also a sign that they’re not happy about something.

So if your cat is playing with them and suddenly they do this, they’re telling them to stop. Or if the feline is too close for comfort.

Again, once they’re angered more, it may result in an accident. 

#3: Dog snapping at a cat

Say you’re chilling on the couch with your dog. Then your cat comes near, and your dog snaps and chases them away like crazy…

What happened?

Your pooch could be irritated or anxious. And they don’t want the cat near them. As well as their resources – including you (you might be at the top of the list). 

So they’ll ‘air snap’ as a clear warning sign.

#4: Dog nibbling at your cat

Dog Nibbling At Your Cat

Same with snapping, this could also be their way of telling them to get off.

You might be giving the cat affection. So if your Fido feels insecure, they can become jealous or possessive.

In some cases, they could do this as an instinct. But since they have a bite inhibition, they won’t press it hard if they’re not provoked.

#5: Dog charging at cats

This means that their prey drive is kicking in. And the cats’ swift movements may have triggered it.

5 scenarios of dogs being aggressive towards cats

#1: Dog aggressive to cats

Your Fido’s aggression is consistent. They growl and lunge at any cat they see.

Why is that?

This could be due to:

  • High prey drive.
  • Strong territorial instincts.
  • Lack of socialization at an early age.

So if they’re like this from the start, it might be innate in them. Or because they weren’t raised in a place with cats.

#2: Rescue dog aggressive towards cats

Canines from rescues had a rough start in life. And they’re often fearful.

So their aggression toward cats might be a learned behavior. A defense to make anyone stay away from them.

This could also be due to a bad experience. And they associated the presence of cats with something negative, like being punished.

Or, they don’t have much experience with felines. As they came from a household without one.

What to do?

Their aggression is mainly due to fear. So, provide a ‘safe place’ for your dog. It’s a spot where they can go whenever they feel anxious.

It could be a separate room or a crate. And they should be trained to go in there at times like this.

Want to know more? Read this article: Why is my dog acting scared?

#3: Dog food aggression towards cats

It’s mealtime.

And while your Fido is eating, they’ll let out a growl whenever a cat goes near them. They even snap too.

Do they dislike sharing food that much?

Well, yup.

Your dog is food aggressive towards your cat due to resource guarding.

They’re protecting an essential item. So they can even bet their life on it. And painful scratches from a cat won’t stop them from doing so.

Things to consider

  1. Make your pets eat separately in different rooms. If possible, watch them until they finish.
  2. Once they’re done eating, pick up their food bowls. This is to prevent your Fido from protecting any leftover.
  3. While your Fido is eating and a cat walks in, show your dog a high-value treat – a yummy snack that they rarely get.
  4. If they looked at it and stopped growling, give them the treat.
  5. Do this every mealtime until they learn that they can get tastier food. But only if they behaved well around your cat.
  6. Teach your pooch commands like “sit,” “lie down,” and “leave it.” This is to distract them from guarding in the first place.

Warning: Only do this if you can still control your dog’s aggression. If not, call a trainer who’s experienced in this matter. It could be dangerous for you and your cat.

#4: New dog aggressive towards cat

Being in an unfamiliar place can stress a dog. So, as a result, they’ll become aggressive. 

And they don’t trust anyone at this point. Not even your cat who only wants to befriend them.

Your new dog may also come from a place without cats. That’s why they’re not used to living with them.

But mainly, this could be due to not having a proper introduction. Because if they had, your furry pets might become ‘besties’ like this:

#5: My dog attacked my cat

If your dog and cat have been coexisting for quite a long time. It could be due to a:

  • Stress.
  • Injury.
  • Anxiety.
  • Prey drive.
  • Dementia.
  • Health issue.
  • Possessiveness.

Dogs can also snap or bite if someone touches or comes close to their body part that’s in pain. Or if they’re possessive, anyone who goes near their:

  • Toys.
  • Food.
  • Human.
  • Territory.

BONUS: Dog attacked cat in my yard

Your pooch is so agitated when seeing cats in your yard.

It might be that your Fido is very territorial. So anyone near or inside their property is considered a threat.

Also, your dog can have a strong prey drive. Which will result in chasing a cat.

If their drive is too strong, they may even capture them. In worse scenarios, some dogs could even kill one.

“How do I stop my dog from attacking my cat?”

I’ll discuss them right after this…

3 tips on how to stop dog aggression towards cats

#1: Be aware of the signs

Usually, canines will not attack right away. 

They’ll give some warnings like a growl. Expose their teeth and stare intensely.

You may also notice some of these:

  • Tense body.
  • Tucked tail.
  • Raised hackles.
  • Ears at the back or upright.

So before anything happens, separate them from each other. And place your dog in their safe spot to settle down.

#2: Manage their place

Dogs can be territorial. So if they see a cat lurking in their place, they’ll defend it and keep the feline away.

And what’s the best way to avoid a fight?

By management. 

So while correcting your dog’s aggression towards cats, ensure they have their own designated areas.

Give your dog a ‘safe place’ with their toys and some treats inside. If they’re fearful, leave an old shirt of yours for a sense of security.

Also, provide high places for your cat. They’ll love it, and these will serve as their ‘safe places’ as well.

#3: Desensitize your dog

One way to stop a dog from being aggressive with cats is by training.


By desensitization. This is making your dog less sensitive or reactive to cats.

Pair this with obedience training, and they may help you curb this behavior.

Try these simple steps:

  1. First, keep your dog in a different room. This is to let them smell and hear each other without seeing face to face.
  2. Feed them separately by a closed door – your dog on one side, your cat on the opposite. This is to make them get used to each other’s presence.
  3. If they seem fine while eating by the door. You may now let them see each other.
  4. Put a leash on your dog. And let your cat move freely.
  5. While they’re in one area, make your Fido do some commands.
  6. Reward your pooch if they obey you. And also give some to your cat.

Keep their interactions short. And ensure that it’s always a positive experience for both of them.

So if your dog becomes aggressive to your cat, redirect their attention. Or firmly say a command. 

Peace won’t happen real fast. So I would say, have faith in your pets and do this consistently.

Warning: If the situation doesn’t improve, consult a dog behaviorist to guide you along the way. This is for everyone’s safety and to ensure you’re doing the right thing.