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11 x Why Your Younger Dog Suddenly Attacks Your Older Dog

Why Is My Younger Dog Suddenly Attacking My Older Dog

You’re lucky to have two dogs. One is younger than the other. You love them equally.

But all of a sudden, you witness your young dog attacking the older one. 

And you start worrying… Your older dog is more vulnerable. They might not be able to defend themselves on time or at all…

“What gives?! And how do I stop it?” you ask yourself. 

Read on to discover more about dog-to-dog aggression.

This article will reveal:

  • 11 surprising reasons why this happens (don’t underestimate #5)
  • 9 practical tips on how to stop your younger dog from attacking your older one
  • 9 warning signs that will help you recognize dog-to-dog aggression before it escalates into a vicious fight
  • And more…

11 reasons why your younger dog suddenly attacks your older dog

Your younger dog can attack your older dog for a variety of reasons, such as occasional irritation, inability to accept certain boundaries the old dog has recently introduced, the older dog’s misinterpretation of the younger dog’s signals, resource guarding, jealousy, being the same sex, or illness.

Let’s discuss each of these reasons (and more) below:

#1: Occasional snapping at each other 

While this usually is nothing to worry about, you should monitor such situations. It’s understandable if it happens from time to time.

Possible reasons for this could be snappy dogs being tired, enjoying their food, or a treat.

Warning: If you start seeing this situation more often, it means you should take preventive measures. Do it asap as delaying could lead to a fight. 

#2: “Go away” signals

As dogs age, they become slower. Mobility issues and pain cause this.

When your old dog feels this way, they just want to be left in peace. 

To be able to understand them better, Imagine you are an introvert. So you can tolerate being around people but for limited amounts of time.  

Once it gets too much, what would you do? 

Remove yourself from the situation. Go away from the crowds. Leave a gathering. And go home. Where you can rest and recharge for the next day.

Dogs work similarly. Especially young ones.

When they start feeling uneasy or unhappy with something, they will try to move away from it. And since they’re at the peak of their youth, they can easily walk or run away from what’s bothering them.

Old dogs would love to do the same. But sometimes, they won’t be physically able to do so.  

Let’s look at it this way: What happens when a person is forced to undergo a lot of stress? 

At some point, they may snap. It’s unpleasant, could come off as shocking, but it’s nevertheless normal.  

Whenever a dog or a person is exposed to constant stress and their boundaries are pushed, they’re likely to lose it at some point. 

The young dog might have pawed at your older dog until now. Or playfully nipped at them. 

And while this was okay for a certain period of time, it is no longer acceptable. Be it due to arthritic pain or another inconvenience your old dog is experiencing.

If the older dog growls or snarls due to irritation, the young dog might have trouble accepting this reaction. Especially if the two dogs used to get along fine previously. So the young dog could answer with aggression. 

#3: Sensory decline

This one is tough. 

Dogs rely primarily on body language for communication. That’s why eye-sight and hearing are very important to them.

But with age, these start deteriorating. This could lead to cloudy judgment from the old dog’s side. And they might misinterpret the intentions of your young dog. Which could lead to a fight.

#4: Canine Cognitive Dysfunction

Canine Cognitive Dysfunction is similar to what we humans know as Alzheimer’s. 

Dogs who suffer from it experience confusion. They tend to zone out. 

This is why they often fail at reading another dog’s signal properly. Which, on the other hand, prevents them from establishing a solid bond with the younger dog.

#5: Jealousy

Ok, I don’t want to be Captain Obvious but…jealousy is a valid reason for why your younger dog attacks your older one. 

Maybe it’s because you give your older dog special attention. No one can blame you for that – they seem more vulnerable than ever. And you want to make the rest of their life easier.

But your younger dog needs your love and attention as well. And they might perceive the older one as a threat in that sense. 

#6: A “Don’t touch my stuff!” attitude

Younger Dog Attacks Older Dog To Get Toy Meme

This behavior is known as resource guarding or possessive aggression. 

It happens when dogs start to growl, lunge, or bite over food, treats, or toys. What’s more, your younger dog could see you as a resource as well. 

In short – anything your dog perceives to be of high value to them is their resource.

Young dogs who reach social maturity can start guarding their resources.

Since that wasn’t previously the case, your old dog might not be willing to surrender. And you have a conflict right there. 

There’s also the possibility that your old dog will back down. If that happens, the fight will be avoided.

#7: Your older dog is in pain 

You might be thinking that a dog attacking the other is all about survival of the fittest. As Charles Darwin would put it. I’ll get to that later.

While it may seem like the most simple or logical explanation, it’s not always the case. 

Dogs who are in pain might whine or yelp often. This could irritate the other dog and even make them anxious. As a result, a healthy dog might respond to these vocalizations by attacking the one in pain.

#8: Epilepsy 

Does your older dog have epilepsy?

If so, and your younger dog witnesses it for the first time, they might become anxious. As a way to deal with the fear they’re experiencing, the young one might attack.

This might seem cruel to you. After all, you know your old dog’s seizures are something out of their control.

But your younger dog doesn’t have that kind of awareness. To them, this is a disturbing situation. And they don’t know how to handle it. 

#9: On sickness and irritation

Some types of sickness can cause a younger dog to become easily irritated and attack your older dog. 

One indication that this is the case is if your younger dog has never done anything of the sort before. 

Examples of such illness include:

  • Rabies.
  • Hormonal imbalances.
  • Genetic and metabolic disorders.

#10: Same-sex issues

If both of your dogs are the same sex, they might fight with each other. This is not a problem when you have an older dog and a puppy.

Older dogs “forgive” a puppy’s mistakes. They will not fight a puppy. But they will correct any unwanted behavior. 

When the puppy grows up, it’s a different story. Both dogs could start perceiving each other as threats. This happens when both of them want to be on top of the hierarchy. 

#11: “Survival of the fittest” in wolf packs

It’s no secret that dogs are descendants of wolves. 

Both are pack animals. And as such, they follow the unwritten rules of the pack. 

When a pack of wolves would travel together, wolves would look out for each other. But what about wolves that were no longer in top shape? Meaning, old and injured?

There’s a belief that old or/and injured pack members were being killed by the pack. The reason is that they could draw unwanted attention. And they couldn’t protect the other members anymore. So they were seen as the weak spot in the group and eliminated.

This, however, is not a law by which wolves or wild dogs function.

While a pack may kill a member, it’s highly unlikely. Wolves perceive the pack members as family. This makes it unnatural to kill one of their own. They aren’t hard-wired to fight each other to death.

9 tips on how to stop your younger dog from attacking your older dog

You can stop your younger dog from attacking your older dog by learning to recognize signs of dog-to-dog aggression, removing both of the dogs from the situation, finding the reason for the behavior, consulting with a vet and a dog trainer or behaviorist, avoiding punishment, and training your dogs.

Now you’ve learned the basics. But would you like to have more in-depth knowledge?

Then dive right in and…

#1: Learn how to recognize arising dog-to-dog aggression

Husky Arousal Aggression Meme

Before you do anything else, it’s vital to learn how to read the signs of aggression. 

The good news is that dogs rarely attack without giving a warning first.

Luckily, you don’t need weeks or even months to be able to tell whether one of your dogs is about to attack the other. 

What you need to remember are the following behaviors:

  • Growling.
  • Snapping.
  • A stiff posture.
  • Raised hackles.
  • Lunging forward.
  • Pinned-back ears.
  • Staring at the other dog.
  • Snarling (growling while showing teeth).
  • Holding their tail high and moving it slowly from side to side.

Note: These signs won’t appear in the same sequence. Dogs often exhibit several of these behaviors at the same time. 

#2: Separate both dogs asap

If you suspect your young dog is showing signs of aggression towards your old dog, better not risk it.

Do not leave them alone, unsupervised. If you do, you risk things to escalate. 

#3: Find the reason for the behavior

As previously mentioned, there could be different types of aggression that cause a dog to attack another one. 

By noticing when this happens, you’ll have higher chances of determining which type you’re dealing with. 

When you know the reason, you’d be able to treat the problem at its core. Otherwise, you’ll just be addressing the symptoms. 

#4: See your vet 

Your young dog may have acted like a sweetheart before. Then, all of a sudden, you see them snapping at your older dog. And no matter how hard you try to figure out the reason, you just can’t.

That’s when you should go to your vet for help. 

Thing is, dogs are experts at hiding pain. And sometimes, they might even cover it with aggressive behavior. 

So spare your young dog some suffering. And your older dog some stress. 

Before going to the vet, try to do your “homework.” It’s best to prepare some notes in advance. Cover some details if possible. This will give context to the situation you’re explaining and will have to deal with. 

Not only will this be helpful to your vet, but also to a certified dog trainer. In case the reason could not be explained by a medical issue. 

#5: When hiring a trainer is a no-brainer

You’ve been to the vet, and they couldn’t find anything wrong with your dog. Health-related, that is. 

Not to worry! 

A certified dog trainer can help you deal with dog-to-dog aggression.

Warning: Do not disregard this tip and try to fix aggressive behavior on your own. This could result in an injury to you and your other dog. 

Did you know that dog trainers are also called behavioral counselors or pet therapists? 

VCA reports that different dog trainers have different levels of knowledge and expertise. This includes formal and non-formal education, self-teaching, or attending professional classes. 

To make the choice of a dog behaviorist easier, you can turn to your vet. They may be able to refer you to the right kind of trainer for your dog. 

Note: Before choosing a trainer, ask them about their teaching methods. It’s best to attend a group class or an individual session to observe how they carry out a lesson.

#6: Stay calm…and desensitize your dog

Desensitization is an important part of training your younger dog not to attack your older one. 

It means making your younger dog less responsive to stimuli. This can be achieved by gradual and repeated exposure to the stimuli.

When you’re working on desensitization with your trainer, they’ll let you know about the different threshold levels. 

Threshold is the fine line between a relaxed state and one out of control. This is what makes the difference between being able to make your dog calmer around triggers. Or make them even more agitated.

During training, you must stay calm. 


If you start worrying, your younger dog will sense it. And not only that, but they’ll also pick up that energy, and it will affect your training session. 

You can help your dog by being an example for them. Remain calm and focused. 

Note: Remaining calm doesn’t mean being carefree. You should strive to be aware of your environment all the time. That’s how you’ll be able to prevent possible accidents. By being calm, you and your dog could better focus on the tasks at hand. 

#7: Don’t punish your younger dog

You might be wondering why I’m telling you this. Since you could be viewing your younger dog to be at fault here. 

But wait. 

You should know that attempting to punish your younger dog could make their aggression worse. 

Instead, remove the two dogs from the situation.

Note: Don’t raise your tone of voice or scold your younger dog. 

We, humans, operate by the principle of what is good and bad in our social system. 

These two concepts guide our choices. So if we cross certain boundaries, we might feel guilt or appear guilty in the eyes of society.

Dogs don’t function like that. At all.

If your younger dog attacks your older one, they won’t feel guilty. They don’t perceive it as doing something bad. 

Dogs act by following their instincts. 

To people who have scolded their dogs, it looks like the dog feels remorse. But in truth, the dog is actually very scared. And confronted with a situation they don’t understand. 

#8: Do not attempt to make it “fair”

Two Dogs One Toy Meme

You might notice your younger dog is trying to obtain a lot of resources. These could be toys, treats, attention, or a dog’s sleeping spot. 

This might make you feel as if your older dog is being left out. 

Well, if your older dog doesn’t seem to mind, let it be. 

It might seem like the easy way out. But it’s actually much more than that. 

Dr. Debra Horwitz reports that owners who interfere with their dogs instead of letting them sort things out by themselves might be encouraging aggression.

When left alone, two dogs could avoid fighting if one of the dogs is subordinate and backs down.

But if the owner is there, the subordinate dog could act differently than they normally would. And the more the pet parent encourages the subordinate dog, the more confident dog will challenge them.

#9: Use positive reinforcement to train both dogs

Even if both of your dogs manage to resolve confrontations, it’s still a good idea to teach them some safety commands.

These can be verbal commands such as “crate”. 

This command can make your submissive dog retreat to their safe space. Which could save them from unwanted confrontation with the dominant dog.

Whenever your dogs comply with the verbal commands, use rewards.

Don’t just hand the resources to your dogs as if they’re a given. Make them earn it.

Ensure that your dogs are calm and obedient before receiving any reward. 

When both of your dogs learn that you decide when they get rewards, they’ll be less likely to fight so they could get such.